Roll Center Calculator for Windows User`s Manual
Contents
1. 18 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Upper Spring Pad Location X is the distance from the car centerline to the center of the upper mounting pad for the spring in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines These inputs are not required for Instant Center calculations Tip If you are more interested in shock travel than spring travel enter the top shock mount location However the Wheel Rate calculated from the Spring Rate you enter in the Other Dimensions amp Specs section will not be exactly correct Lower Spring Pad Location X is the distance from the car centerline to the center of the mounting pad for the spring on lower right arm in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines These inputs are not required for Instant Center calculations Tip If you are more interested in shock travel than spring travel enter the lower shock mount location However the Wheel Rate calculated from the Spring Rate you enter in the Other Dimensions amp Specs section will not be exactly correct Upper Arm Length Figure 2 6 Measuring A Arm Length Top View of A Arm Showing How to Measure Length of A Arm Draw a line to the Correct Incorrect other ball joint lt _____ gt Length of arm is where this line intersects2. Instant Center 2 18 Instant Centers 1 11 14 18 29 King Pin 14 21 22 Layout 5 14 15 18 24 25 29 30 Length 9 17 19 20 28 30 41 Library 12 Lower Arm Length 20 Lower Ball Joint 9 18 Lower Frame Pivot 16 18 Lower Spring Pad 19 20 21 MacPherson 17 28 30 Open 2 5 6 14 27 28 PERFTRNS PTI 2 4 Print 1 2 27 34 Registered Owner 3 4 Roll 1 4 5 1 2 3 4 5 6 10 11 12 13 14 15 18 20 21 22 23 27 28 29 30 32 33 35 36 39 40 Roll Center 1 4 5 1 2 3 4 5 6 11 13 14 18 27 28 29 32 39 40 Safety 4 3 Save 6 28 34 Scrub Radius 21 Setup 4 Shim 27 30 31 Shocks 11 14 19 21 39 Spring 1 6 11 14 19 20 21 Spring Compressn 11 Suspension Library 5 6 Table 5 1 27 32 33 34 35 36 Tech Help first page after cover page 3 4 Upper Arm Angle 20 Upper Arm Length 19 Upper Ball Joint 7 8 9 10 18 Upper Frame Pivot 18 Upper Spring Pad 19 Wheel Rate 19 21 Wheel Rim Offset 22 Wheel Rim Width 22 Windows 1 2 4 5 Worksheet 17 27 X amp Ht Readings 7 9 10 42
3. vertical line See Figure 2 8 This is a calculated spec can not be entered directly 22 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 1 3 Show Dive amp Roll Figure 2 10 Show Dive amp Roll Section of Main Screen Click on Yes to enable these inputs and options Click on up or down buttons to increment Dive or Roll up or down Click on Draw Big button to redraw screen with much larger Layout drawing See Show Dive amp Roll Figure 2 11 You can also just type in most any amount of Dive or Roll in these text entry boxes and press lt enter gt As shown in Figure 2 10 you must first select the Yes option in this section before any of these inputs or command buttons become enabled Dive The amount the car s front end drops compared to its static standing still height To simulate the front end rising enter a negative number Roll The amount the car s front end rolls leans due to cornering forces compared to its static standing still angle A positive angle means the car is leaning to the Right typical of Left turns Use a negative number to lean Left Right turns 23 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Draw Big This command button lets you select a screen mode shown in Figure 2 11 where the Suspension Layout is drawn about twice its normal size In this mode you can see things in more deta
4. Arm Dim 7 m oOM e et ake IGT fore we usually recommend a distance half way between the frame rails or the frame mounts on the lower arms These locations usually will stay in one place Once you ve decided on the method use a tape measure to mark a point on the floor which is halfway between the your references This will now be your car s centerline and is 0 in the X horizontal direction in the Static Layout Dimensions section Once you decide on a centerline for a particular car you must make all measurements from this same centerline 15 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Figure 2 3 Finding Car Centerline and Measuring Front Suspension Points typical X and Height measurement shown for Lower Frame Pivot Car Centerline lt _K gt Height Half the distance between the lower arm mounts Ta can be used as centerline Alt Alternate Car Centerline Half the Track Width the distance between the center of the tire patches can also be CO used as the centerline Track Width In symmetric cars where the left and right side are identical the centerline can also be the center of the engine and can be marked by dropping a plumb bob pointed weight on a string down from the center of the crank pulley Then with the plumb bob place the string on the center of a new suspension point to be measured and drop the bob u
5. Center the more the car rolls in the corners and the farther right the Roll Center the less the right side moves up or down during cornering Camber Gain is the amount of camber change tilt of the tires when viewed from the front you get from a certain amount of body motion typically 1 inch of dive from braking Most race cars want Camber Gain in the range of 1 to 2 degrees for an inch of dive This is expecially true for the outside tire in a turn For circle track cars always turning left the desired camber gain on the left side may be less or even a posifive number depending on track banking and other factors Both of these have a large impact on a car s handling and maximum cornering capability Note from Performance Trends It is difficult to get any agreement from experts on optimum Roll Center location Camber Gain static Camber setting etc This is true for most any suspension setting The reason appears to be that these settings are so combination dependent Traction capability of the track and tires tire construction roughness of track temperatures compliance of the chassis suspension members and bushings shock settings etc However the component with the biggest effect on optimum settings is the driver Driver preference for how a car handles and feels has a huge effect on their confidence aggressiveness on the track and lap times The following statements are ones we have found in various references
6. Graph of Camber Data Selected in ae 2 23 Back Print Options Help Camber deg vs Roll deg Rt dive in 2 00 new Rt dive in 2 00 base Lt dive in 2 00 nev Lt dive in 2 00 base This screen graphs of Camber in degrees on the vertical Y axis versus either Roll or Dive on the horizontal X axis The data graph here is based on what was highlighted in the Camber table when you clicked on the Graph menu item Data is always graphed for the Left side as well as the Right side for whatever conditions you have selected highlighted Read the labels in the legend at the right side of the graph to see which lines are which colors The graph is always autoscaled which means the program picks the scales for drawing it to display all data with good detail Print the graph on your printer using your Windows default printer by clicking on the Print menu command You can change settings labels and Windows printer setup by clicking on the Options menu command See Figure 2 25 You can return to the Camber Table screen by clicking on the Back menu command 36 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Figure 2 25 Graph Options Menu Graph Options for Making Graphs Graph Labels Use Standard Labels Pig Fide O Use Labels Given Here Curent Runs Label Baseline furs Label Back Pr Black amp White Color O Thick Thin Windows Pri
7. Layout Dimensions 2 1 2 Other Dimensions amp Specs 2 1 2 Show Dive amp Roll 2 1 3 Suspension Layout Drawing 2 2 Main Screen Options 2 3 Camber Table amp Graph Appendix 1 Rules of Thumb for Desired Roll Center Camber and Camber Gain Index O Aa O N gt 39 41 C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction Chapter 1 Introduction 1 1 Overview of Features The Roll Center Calculator program by Performance Trends Inc is software to let circle track racers road racers engineers and performance enthusiasts understand tune and even design front suspensions Its many features include Features e Mouse driven user interface compatible with Windows and Window 95 for easy operation and better print capability e Automatically updates the drawing Roll Center Camber and Camber Gain as you change inputs or select various amounts of Dive and Roll You actually watch the car Dive and Roll just like an animation e Displays Spring Compression so you know what the springs are doing during Dive and Roll e For Double A Arm suspensions you can shim the upper arms in or out and watch the effect on Camber e For McPherson Strut suspensions you can move the top of the strut in or out and watch the effect on Camber e Several of example front suspensions preloaded for you to pick from e Different ways for you to enter some measurements either X and Y coordinates or length and angle of
8. based on 1 Dive Camber Gain 1 21 l Help definition Distance from car centegine to center of ball joint on lower arm on right side jh inches The center of the Length Angle Length Angle engine the crankshaft js usually considered the car Upper Arm Dim centerline Lower Arm Dim Changing Specs Enter X amp Ht Readings Frame amp Ball Joints Option First lets try changing a measurement For example lets raise the ball joint on the right upper control arm 1 2 inch This would mean the Right Height measurement for Upper Ball Joint the distance from the ground would increase 5 inches So change 20 to 20 5 When you get ready to press lt enter gt after typing in 20 5 watch the drawing especially the right side suspension at point A and Camber Gain Remember this is a front view so the right side of the car is actually on the left side of the screen Important Always remember you are looking at a Front view of the car This means the Right side of the screen actually shows the Left side of the car and the Left side of the screen shows the Right side of the car C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction Figure 1 4 Main Screen after Raising Right Upper Ball Joint to 20 5 inches Roll Center Performance Trends Inc DBL AARM File Options Suspension Type Shim Table amp Graph Comments Help About This is front view of suspension so left s
9. be better to select the Camber Does Not Change with New Inputs option This prevents Camber from Figure 2 4 Important Options for Entering continually being changed Measurements possibly to very unusual Roll Center Performance Trends values as you enter new euiiem Suspension Type Shim Table amp Gi measurements ony you apa Enter X amp Ht Readings Frame amp Ball Jnts aarti Ca Enter X amp Ht 1 End Arm Len amp Angle Camber Changes with New Draw Extension Lines Inputs option works well to Don t Draw Extension Lines see how suspension adjustments or modifications will change camber v Background Car Layout Color Light Gray Background Car Layout Color Dark Gray v Camber Changes with New Inputs Enter all the X and Height Camber Does Not Change with New Inputs measurements into the screen The screen s drawing and calculated values are updated after each entry This lets you immediately see if a value you entered looks wrong 17 Camber Gain Definition Specs C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions The Roll Center location and Left and Right Instant Centers are also drawn in as large dots Instant Centers are the imaginary points about which each side of the suspension tends to rotate and usually appear on the opposite side of the suspension For example Right side s Instant Center will usually appear on the left side of the Suspension Layout drawing The Roll Cente
10. different suspension layouts A Baseline is some previous condition which was shown in the Table You can select to have the Baseline always be updated to whatever condition was previously in the Table Previous Table is Baseline Data or to save some specific Baseline condition of interest Baseline is Saved Data See Figure 2 21 33 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions To save the current Table as a Baseline click on Figure 2 21 Baseline Commands Baseline then Save This Data as Baseline The program will ask you for a Comment to describe the Baseline condition This Comment will be printed Camber Table Baseline hide saved results Graph with the Table when you print it if you are Showing the F TEEPE Baseline condition This comment can also be edited m Hide Baseline Data by clicking on Baseline and then Baseline Comment J Baseline Comment z Previous Table is Baseline Data After saving a baseline Table you could close the E v Saved Table is Baseline Data Table by clicking on Back in the Menu Bar make a a 3 change in the suspension and create the table again by S Save This Data as Baseline clicking on Table amp Graph You would produce a Camber Table like Figure 2 22 Figure 2 22 Camber Table Showing Baseline Condition Roll Center Performance Trends Inc DBL AARM ria Options Suspension Type Table amp Graph Comments Help About This is fro
11. directory for opening and saving files is RCFILES The program will not allow you to delete files or create different directories However though File Manager Windows 3 1 or Windows Explorer Windows 95 you can do this This will allow you to create a directory folder structure for organizing your files Print prints the Main Screen Print Blank Worksheet prints Figure 2 15 Main Screen Options Menu the main screen with blank boxes for Roll Center Performance Trends all inputs Fi nities Suspension Type Shim Table amp Gi Thi Enter X amp Ht Readings Frame amp Ball Jnts pen Windows Print Setup opens the Enter X amp Ht 1 End Arm Len amp Angle standard Windows menu for selecting Draw Extension Lines the printer page orientation etc Don t Draw Extension Lines lt V Background Car Layout Color Light Gray Background Car Layout Color Dark Gray Opti Camber Changes with New Inputs ptions Camber Does Not Change with New Inputs Click on Options for the list shown in Camber Gain Definition Specs Figure 2 15 Enter X amp Ht Readings Frame amp Ball Jnts Enter X amp Ht at 1 End Arm Len amp Angle If it is easier to measure the lengths or the A Arms and the angle of the A Arms choose the Arm Len amp Angle option You still have to measure the X and Height of one end of the arm but not both For the Upper Arm you will enter the Ball Joint X and Height and the Length and the Angle For the Lo
12. incidental or consequential damages and some states do not allow the exclusion of implied warranties so the above limitations or exclusions may not apply to you No action regardless of form arising out of any claimed breach of this agreement or performance under this agreement may be brought by either party more than one year after the affected party learns of the cause of action Refer to diskette envelope for full license agreement The Roll Center Calculator makes calculations based on equations and data found in various published and heretofore reliable documents The program is designed for use by skilled professionals experienced with vehicles and suspensions The following processes are hazardous particularly if done by an unskilled or inexperienced user Obtaining data to input to the program Interpreting the program s results Before making measurements of or modifications to any suspension engine or driving situation DO NOT FAIL TO Regard the safety consequences Consult with a skilled and cautious professional Read the entire user s manual Obey all federal state amp local laws Respect the rights and safety of others Table of Contents Chapter 1 Introduction 1 1 Overview of Features 1 2 Before You Start 1 3 A Word of Caution 1 4 Getting Started Installation 1 5 Example to Get You Going Chapter 2 Definitions 2 0 Basic Program Operation 2 1 Main Screen Inputs amp Outputs 2 1 1 Static
13. the Ball Joint end will be after the adjustment First select whether you want to Add or Remove shims from the first Combo box Then select whether you want to use standard sixteenth 1 16 and eighth 1 8 inch shims or to enter some other Custom shim adjustment After your selection the lower inputs will become enabled as appropriate Selecting No Shims disables the lower inputs An estimate of the new Camber is given at the top for the shim adjustment currently entered with the Current Camber also given for comparison If you have Not Roll Center Calculator Figure 2 18 Shimming Calc Shim Adjustment Right Side Chapter 2 Definitions Menu for Right Side Shim Thickness Added 1875 Estimated New Camber will be Current Camber is Bo e Shims Added Add Remove 1 16 Shims hooo o Custom Thickness Addad Enz Notes This menu assumes that Adding shims moves the Frame Pivot farther out from the car reducing negative camber increasing positive camber Some chassis ex left side on some Lefthander Chassis work the opposite adding shims moves the pivot inward If your chassis is like this pick Remove Shims when you are actually adding shims and vice versa selected the option at the Main Screen that Camber should be adjusted with changing dimensions you will be asked if you want Camber to be adjusted before it is The entries and suspension layout on the Main Screen are n
14. the axis of the arm Axis of the arm is a line joining front and back mounting points 19 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Length of upper right arm from Pivot Center to Ball Joint center as viewed from the front in inches This can be shorter than actual length measured along the arm if arm is swept forward or back See Figure 2 6 This spec is only enabled if you have chosen the Enter X amp Ht at 1 End Arm Len amp Angle option Upper Arm Angle Angle of the upper left arm as viewed from the front in degrees A positive angle means the arm angles up as the arm goes away from the car centerline which is typical Lower Arm Length Lower Arm Angle See Upper Arm Length and Upper Arm Angle explanations above 2 1 2 Other Dimensions amp Figure 2 7 Other Dimensions amp Specs Section of Specs Main Screen Other Dimensions amp Specs Spring Length eee Spring Length Spring Compressn Spring Angle Spring Rate Installed or Static length of the spring measured along spring centerline before any Dive or Roll You can not enter this value directly This length is calculated from the X and Height for the Upper and Lower Spring Pad Locations This value is useful to check that your X and Wheel Rate Height measurements are entered correctly as it should Scrub Radius closely match your installed spring length Stc Camber deg Dyn Camber deg Hub Dista
15. the Ball Joint Height to 20 5 The choice of which of these options you use Enter X amp Ht Readings Frame amp Ball Joints or Enter X amp Ht at 1 End Arm Len amp Angle can have a significant effect on how your inputs affect other specs Use the one which makes the most sense for the type of modification you are trying to simulate Show Dive amp Roll Now click on the Yes option for Show Dive and Roll You will see the Dive and Roll text and arrow boxes become enabled so you can enter a certain amount of vehicle Dive in inches and Roll in degrees 10 C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction E The arrow boxes let you increment Dive and Roll up and down by clicking on the appropriate arrow You will also see the suspension drawing move just as it would in the real vehicle The suspension in the static position is drawn in light gray for comparison or dark gray if you have chosen that Option The static Instant Centers and Roll Center are also drawn in light gray so you can see how much they have moved due to Dive and Roll To the right of the drawing you will see Spring Compressn and Dyn Camber also change as you go through various amounts of Dive and Roll Both of these numbers are very useful Spring Compressn Positive spring compression means the spring is compressed from its static standing still before any Dive or Roll position or the car is diving Negative spring compression means
16. the spring is elongated or the car is rising By making spring compression match the motion shown by your shock travel indicators you ensure you are moving the suspension through somewhat the same motion which your car sees on the track 11 C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction SSS SS SS SS SSS SS SS eS SS SS SS ee Se Dyn Camber deg Dynamic Camber is the camber the tire will see due to Dive and or Roll Camber has a large impact on the tire patch on the track and therefore tire traction By optimizing camber you can produce higher traction and therefore faster lap times Play around with some of the option buttons or commands in the Menu bar You can t hurt the program Once you feel a little comfortable with the program read the rest of this short manual to learn the definitions of all the specs how to save a set of suspension specifications recall information which has been previously saved or what the various options can do Then you will know all the basic commands to operate the program Figure 1 8 Analyzing the Suspension Motion with Dive and Roll Dynamic suspension is shown in Black Blue and Spring f ar l Compressio Static suspension is shown in gray for comparison n shows how Roll Center Performance Trends Inc DBL AARM spring and File Options Suspension Type Table amp Graph Comments Help About shock is E F ey of suspension so left side of screen is actually righ
17. which appear to be consistent between these references 39 Roll Center Several authorities agree that the static Roll Center before any Dive or Roll should be from 2 5 to 4 5 above the ground For road race cars turning both left and right you want to keep the Roll Center near the car s centerline left or right The farther the Roll Center is to the Left the quicker the car will react more it will Roll when going into a Left turn For this reason many asphalt circle track left turning cars locate the Roll Center to the right of center less Roll and dirt cars locate the Roll Center to the Left of center more Roll and hopefully better bite at the right front However the car is more predictable all around if the Roll Center is kept close to the car s centerline Higher banking 20 degrees or more usually requires a lower Roll Center in the 2 3 inch range The more mass in the front of the car heavier engine or engine more forward the higher the Roll Center should be Some authorities believe a lower Roll Center works better on dirt because the higher body roll produces more side bite from the tires Lower Roll Centers require stiffer springs to control Roll However stiff springs hurt traction on bumpy tracks The less the Roll Center moves during Dive and Roll the more predictable the car s handling Most authorities agree that holding the Roll Center position as constant as practical during Dive and Ro
18. Click on help for information on your options for the Main Screen of this program About Click on About for information on the program Performance Trends and your registered name and code 32 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 3 Camber Table amp Graph If you click on Table amp Graph at the Main Screen you will obtain a screen similar to Figure 2 20 This screen shows you 2 tables of Camber values for a set on Dive and Roll combinations The top table is for the Right side and the bottom is for the Left side igure 2 20 Typical Camber Table hiding the baseline data Roll Center Performance Trends Inc DBL AARM File Options Suspension Type Table 2 Graph Comments Help About This is front view of suspension so left side of screen is actually right side of car Other Dimensions amp Specs TTT Table Back Print Options Baseline hide previous results Graph Help Right side camber table Click and drag the mouse to select highlight rows you want to graph Correspond ing Left rows are also graphed This particular table is not showing a baseline condition for 5 55 5 15 4 77 4 43 comparison 4 20 3 75 3 2 91 1 56 Left side camber 491 1 36 84 table Note you can 9 33 _ 23 not select highlight rows here You can also select to have a Baseline condition displayed in the Table Show Baseline Data This is useful to compare 2
19. E OR PERFORMANCE OF SOFTWARE SHALL BE RELIED UPON BY USER OR BE DEEMED TO BE A WARRANTY OR REPRESENTATION BY PERFORMANCE TRENDS INC FOR ANY PURPOSE OR GIVE RISE TO ANY LIABILITY OF OBLIGATION OF PERFORMANCE TRENDS INC WHATSOEVER USER ACCEPTS ALL RESPONSIBILITY FOR SELECTING THE SOFTWARE TO MEET USER NEEDS OR SPECIFIC PURPOSES PERFORMANCE TRENDS INC IS UNDER NO OBLIGATION TO FURNISH USER UPDATES OR ENHANCEMENTS EVEN IF FURNISHED TO OTHER USERS Continued on next page LIMITATION Of LIABILITY If at the time of delivery to the original User only there are any defects in the media on which the Software is provided User s sole and exclusive remedy shall be the replacement of any media returned to Performance Trends Inc within 90 days of the receipt of the Software by User or at Performance Trends Inc s sole option a refund of the License fees paid to Performance Trends Inc by User IN NO EVENT SHALL PERFORMANCE TRENDS INC OR THIRD PARTIES WHO HAVE RIGHTS IN THE SOFTWARE BE LIABLE TO USER FOR LOSS OF PROFITS INDIRECT SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES EVEN IF PERFORMANCE TRENDS INC IS AWARE OF THE POSSIBILITY OF SUCH DAMAGES IN THE EVENT ANY REMEDY HEREUNDER FAILS OF ITS ESSENTIAL PURPOSE OR IN ANY OTHER EVENT PERFORMANCE TRENDS INC S LIABILITY HEREUNDER SHALL NOT EXCEED ANY AMOUNTS PAID BY USER TO PERFORMANCE TRENDS INC UNDER THIS AGREEMENT Some states do not allow the limitation or exclusion of liability for
20. Gray v Camber Changes with New Inputs Camber Does Not Change with New Inputs Camber Gain Definition Specs C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction You will also notice that the Length and z i Angle of the Upper Arm printed in Figure 1 6 Notice when Changing Options light gray in the lower left corner changed from 11 88 inches to 12 02 and 14 62 degrees to 16 93 You might be From now on the length of the Arms will be held constant as you change X and Height inputs for the thinking that the only way for the length available ends af th A Arms of the arm to change is by installing a different arm which is correct What For the Upper Arm the Frame Pivot is moved based on we simulated was raising the Upper Ball the Ball Joint X amp Height Length and Angle Joint and adjusting the length and angle For the Lower Arm the Ball Joint is moved based on the of the upper arm so the Frame Pivot Frame Pivot X amp Height Length and Angle would stay in the same spot This mode is usually best for watching adjustments you make where the lengths of the arms are NOT changed If you click on Options at the top of the Main Screen you will see that the first option Enter X amp Ht Readings Frame amp Ball Joints is checked This means you enter the X and Height readings of both ends of the arms and the length is calculated from those readings If you select its alternate option Ente
21. Help About This is front view of suspension so left side of screen is actually right side of car Other Dimensions amp Specs i File Click on File to present several standard Windows File options New blanks out all the current spec inputs calculated values New comments and changes the current file name to Untitled Open presents a standard Windows File Open dialog box where you can open a Roll Center file which was previously saved You can select different directories or disk drives for Print files You can choose most any file but if the program senses Print Blank Worksheet the file is not a Roll Center file you will be given notice and Windows Print Setup the file will not be opened Save saves the current specs to the current file name This is a shortcut to update the current file with the current specs and measurements 27 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Save As also presents a standard Windows File Open dialog box where you save a Roll Center file to a name of your choosing Certain names are not acceptable including e Names with more than 3 characters to the right or 8 characters to the left of a period e Names over 11 characters long 12 characters if one is a period e Names which include the characters E lt gt or spaces You can also select different directories or disk drives for saving files Tip to Advance Users The default
22. Roll Center Calculator for Windows User s Manual Performance Trends Inc Performance Trends Inc PO 530164 Livonia MI 48153 Tech Help for Registered Owners 248 473 9230 Fax 248 442 7750 Email feedback performancetrends com Website tips correspond with other users download demos update schedule etc www performancetrends com Copyright Notice Copyright C 1998 Performance Trends Inc All Rights Reserved These software programs and user s manual are reserved by Performance Trends Inc and are intended for the use of the original owner only Copying or duplicating these products except for the personal use of the original owner is a violation of U S Copyright Law and is hereby expressly forbidden Portions Copyright C Microsoft Corp 1993 All Rights Reserved International Business Machines Corp makes no warranties either expressed or implied regarding the enclosed computer package its merchantability or its fitness for any particular purpose IBM PC XT and AT are registered trademarks of International Business Machines Corp DISCLAIMER OF WARRANTIES THE SOFTWARE PROVIDED HEREUNDER IS LICENSED AS IS WITHOUT ANY WARRANTIES EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO ANY WARRANTIES FOR MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE NO ORAL OR WRITTEN STATEMENTS REPRESENTATIONS OR OTHER AFFIRMATION OF FACT INCLUDING BUT NOT LIMITED TO STATEMENTS REGARDING CAPABILITY CAPACITY SUITABILITY FOR US
23. Type Shim Table amp Graph Comments Help File Options This is font view of suspension so left side of screen is actually right side of car Other Dimensio Cambey Gain 1 20 Gain based on 1 Dive Camber Gain 1 21 z Spring Length Spring Compressn Spring Angle Spring Rate Wheel Rate Scrub Radius Stc Camber deg Dyn Camber deg g Hub Distance Click on Yes to enable specs to put suspension through Dive Upper Ball Joint Upper Frame Pivot Lower Ball Joint Lower Frame Pivot Upper Spring Pad Lower Spring Pad Length Angle 114 62 Upper Arm Dim 3 3 Lower Arm Dim m No Help definition Yes inches Roll i Distance from car centerline to center of ball joint on upper arm on right side in inches The center of the engine the crankshaft is usually considered the car centerline Click on most any spec name or input and a brief description of the item is given here Enter dimensions for suspension here Suspension Layout and calculated specs are updated as you enter specs and Roll Click on Draw Big to enlarge suspension drawing C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Le a i n a a a a a U S a a L a a L a a M M The Roll Center Calculator lets you determine a vehicle s front suspension Roll Center and Camber Gain For a quick background Roll Center is an imaginary point about which the chassis tends to roll in
24. aba Windows you can mc phear 1c7 change the rollentr a 5 rcfiles directory folder or disk drive to look for files here Open a File ig mteaa Files are arranged alphabetically Click on a file to Open here then click on the OK button or double click on file name to Open in one operation Click on dbl aarm to Open a set of measurements for a typical double A arm suspension The Suspension Library disappears and the Main Screen returns with measurements loaded for all specs If 6 C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction some measurement is not familiar to you click on its name or the spec and a brief description appears in the Help frame along with a page from this manual for more help Figure 1 3 Specs for the File DBL AARM Roll Center Performance Trends Inc DBL AARM E Options Suspension Type Shim Table amp Graph Comments Help Abort Click on most any Specs fing g Compressn fora Spring Angle g Spring Rate brief Wheel Rate descrip Scrub Radius tion to Stc Camber deg Dyn Camber deg be given Hub Distance in the Whi Rim Width Help Whl Rim Offset box at King Pin Angle g g the L bottom Upper Ball Joint l Show Dive amp Roll of this Upper Frame Pivot OYes Dive inche Roll de Draw Lower Ball Joint No AE screen This is front view of suspension so left side of screen is actually right side of car Camber Gain 1 20 Gain
25. aiting to happen Please read and follow any Safety Notes as highlighted in this manual The software like any computer model can NOT make exact predictions because Much of the input data to the software is estimated Even if the input data were exactly correct the simplifying assumptions within the program will limit the accuracy These assumptions include that there is no flex in the suspension arms or bushings Tire characteristics driver performance track conditions etc are rarely constant and repeatable The software should be used as a guide to Help you understand how a suspension works what parameters are important how parameters interact what are the tradeoffs etc Point you in the correct general direction for making modifications This direction should be verified by other sources like known authorities race results books etc Never trust one single source if it does not make sense to you Make you think not think for you If unexpected results are obtained take a minute to e Double check all your data input e Refer back to this manual e Ask someone else skilled and experienced in the particular area e Give the retailer or Performance Trends Inc s Tech Help Line a call for an explanation Computer programs are written by normal people who can make mistakes It s always possible there may be an error in the calculations Your phone call may help us correct it Please also read the Warranty and War
26. ally RC under PERFTRNS PTI and click on README DOC Notepad will display the contents To read this file in Windows 95 use Windows Explorer to find the Roll Center Calculator directory usually RC under PERFTRNS PTI Then double click on README DOC Wordpad will display the contents Every effort has been made by Performance Trends Inc to provide you with an accurate cost saving high quality tool at a very reasonable price We do not copy protect our software to allow our customers full freedom to make back up copies for their own personal use Please respect the programmer s copyright and do NOT give out copies to your friends C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction 1 3 A Word of Caution The Roll Center Calculator is a comprehensive software package which estimates a suspension s motion based on limited user input These estimates can be used for suspension analysis and tuning However a suspension is a very complex system which makes exact calculations of all details impossible Therefore several simplifying assumptions are made to reduce the calculations to a manageable level The user must recognize The software can not predict the safety of a suspension modification or driving situation Done correctly with the proper quality parts and safety precautions extreme racing conditions can be safe Done by inexperienced racers with standard or low quality parts a race car can be a disaster w
27. ance from where the king pin axis hits the ground and the center of K King Pin Axis the tire patch See Figure 2 8 for King Pin Axis This is a calculated spec can not be entered directly Camber a Scrub Radius The degrees of tilt of the wheel with respect to the ground as viewed from 21 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions the front in degrees Negative camber means the top of the wheel tilts in towards the car which is typical of most race cars This is an input which you enter See Figure 2 8 Dynamic Camber The new Dynamic camber of the wheel caused by Dive and Roll See Camber above Hub Distance The distance from the center of the lower ball joint to the mounting surface of the wheel hub See Figure 2 9 Wheel Rim Width Width of the wheel rim from inside bead to bead in inches This measurement is usually about 1 less than measuring from outside edge to outside edge Figure 2 9 Illustration of Hub Distance Wheel Rim Offset Wheel Mounting Face of Hub The distance from the inside of the wheel rim to the wheel s mounting surface sometimes called backspacing This is usually measured by laying the wheel face up on the floor and measuring from the floor to the mounting surface Center of Ball Joint King Pin Angle King pin axis is the line intersecting the upper and lower ball joints The angle is the angle between this axis and a Hub Distance
28. arms e The Draw Big option to see the suspension components in greater detail e Option to draw in imaginary Extension Lines to show how the Instant Centers and Roll Center are determined e Displays a table of Camber for various increments of Dive and Roll increments which you can change You can also include a Baseline condition suspension setup for comparison e You can graph the Camber Table C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction 1 2 Before You Start What you will need IBM 386 486 or Pentium or 100 compatible 4 Meg of RAM Approximately 5 Megabyte of disk space Windows v3 1 or Windows 95 Windows Compatible Printer optional Many terms used by the Roll Center Calculator and this user s manual are similar to terms used by other publications like Camber Gain Instant Center etc However these terms may have different definitions Therefore read Chapter 2 to see what these terms mean to the Roll Center Calculator Occasionally it will be necessary to identify typos in the manual known bugs and their fixes etc which were not known at the time of publication These will be identified in a file called README DOC in the Roll Center Calculator directory or folder To read this file in Windows 3 1 double click on Notepad in the Accessories program group Then click on File then Open and select All Files for the file type Find the Roll Center Calculator directory usu
29. cornering maneuvers In general the lower the Roll Center the more the car rolls in the corners The farther right the Roll Center the less the right side moves up or down during cornering Camber Gain is the amount of camber change tilt of the tires when viewed from the front you get from a certain amount of body motion typically 1 inch of dive from braking Most race cars want Camber Gain in the range of 1 to 2 degrees for an inch of dive For circle track cars always turning left you may want positive camber gain on the left side Both of these have a large impact on a car s handling and maximum cornering capability See Appendix 1 Basic procedure for using the program 1 You enter measurements from your car or open an example file of measurements provided with the program by clicking on File and then Open 2 The program draws your suspension on the screen including calculated dimensions like King Pin Angle Instant Centers and the Roll Center in the Suspension Layout drawing 3 Once all measurements are entered you can force the suspension into various amounts of Dive and Roll by selecting the Yes option in the Show Dive amp Roll section As the suspension is redrawn with various amounts of Dive and Roll the new Roll Center Camber and Spring Compression are displayed 4 Watching Spring Compression in the Other Dimensions amp Specs section to the right of the layout drawing is useful for matching the actual vehicle mo
30. en Static Layout Dimensions Open to Right Height Left Height f i opena Upper Ball Joint Show Dive amp Roll previous Upper Frame Pivot O Yes Dive inches Roll de Draw y Whi Rim Offset King Pin Angle I 3 Lower Ball Joint No saved set Lower Frame Pivot of Roll Upper Spring Pad M Help definition Center Lower Spring Pad Distance from car centerline to center of ball joint on specs upper arm on right side in inches The center of the Length Angle Length Angle engine the crankshaft is usually considered the car Upper Arm Dim centerline Lower Arm Dim You will notice that a message appears which says you can Open some saved suspension measurements by clicking on File and then Open This opens the Suspension Library which has some example suspensions stored in it right from Performance Trends Click on OK for this message and the other introductory messages you are shown to get to a screen which looks similar to Figure 1 From this main menu you can e Enter or edit any of the measurements and specifications displayed and watch calculated specs and the layout drawing be updated automatically C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction SS SSS ee e Open or Save a file of complete measurements by clicking on the File menu item then either Open Save or Save As e Add edit or review comments to describe the measurements currently displayed in the
31. ide of screen is actually right side of car Other Dimensions amp Spec Camber Gain 1 32 Gain based on 1 Dive Camber Gain 1 21 Ri Spring Length Spring Compressn Spring Angle Spring Rate Wheel Rate Scrub Radius Stc Camber deg Dyn Camber deg Hub Distance Whi Rim Width Whi Rim Offset King Pin Angle Static Layout Dimensions Right x Hei Upper Ball Joint Upper Frame Pivot Lower Ball Joint Lower Frame Pivot Upper Spring Pad Lower Spring Pad Upper Arm Dim Lower Arm Dim Press lt enter gt and notice how Camber gain changed from 1 20 to 1 32 This minor change will produce slightly more negative Camber Gain which means the right tire will see slightly more negative camber for the same amount of Dive in the corner or during braking You will notice that Stc static Camber in the Other Dimensions amp Specs at the right side of the screen changed from 3 to 2 89 degrees Thi Ca Show Dive amp Roll O Yes Dive inches Roll de Draw on e Co l Help definition Distance from ground to center of pivot on the frame mount on upper arm on right side in inches Roll Center Performance Trends item Suspension Type Shim Table amp Gi a v Enter X amp Ht Readings Frame amp Ball Jnts Enter X amp Ht 1 End Arm Len amp Angle Draw Extension Lines Don t Draw Extension Lines Background Car Layout Color Light Gray Background Car Layout Color Dark
32. ifications will change tire Camber Gain Specs camber Camber Gain Specs Type of Cale Use Specs Below l Body Dive inches i Click on this option and you get the Bods Roll decrees menu of Figure 2 16 This menu lets 2 e you change the amount of body movement the program uses to Notes determine Camber Gain Camber Gain is calculated based on how camber changes from static road height to some new combination of dive and roll Standard Conditions are 1 Dive and 0 degrees Roll Camber Gain Definition Specs First you select the Type of Calc which means either to use the program s standard definition of 1 of Dive with No roll or to Use Specs Below in this men OKEn 29 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions SSS ee If you select to Use Specs Below the Body Dive inches and Body Roll degrees specs become enabled so you can enter or change them If you click on the OK Exit button while Use Specs Below is selected the Camber Gain at the Main Screen will now be based on these custom specs This definition is always displayed in the Suspension Layout screen as shown in Figure 2 17 Click on Cancel to close this menu and return to the original specs used for calculating Camber Gain Suspension Type Click on Suspension Type to choose Double A Arm as pictured in Figures 2 1 or 2 11 or MacPherson Strut type shown in Figure 2 17 The Shim option for inputting the Length and A
33. il Figure 2 11 Draw Big Mode Shown with the Draw Extension Lines Option Selected Other Dimensions amp Specs which change with Dive and or Roll or which are a good reference to these specs which change Roll Center Performance Trends Inc DBL AARM File Opfions Suspension Type Table amp Graph Comments Help About This is front view of suspension so left side of screen is actually right side of car Gain based on 1 Dive fe Center height 2 0 Uther Dimensions amp Specs Show Dive amp Roll Dive inches Spring Compression inches Yes Camber degrees New Camber degrees King Pin Angle degrees Click on these arrow buttons to increments Dive or Roll or just type in your desired Dive and Roll in the text box Click here to return to the normal screen with all dimensions displayed 24 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 1 4 Suspension Layout The features of the Suspension Layout drawing are discussed in Figure 2 12 below Figure 2 12 Major Features of the Suspension Layout Screen Camber Gain and the motion on which it is based is given in this line Right Instant Center drawn in blue just like the right side suspension The arrow drawn in this Figure not on the computer screen shows how it has moved from its static location gray dot with blue outline Left Instant Center drawn in red just like the left side suspension The arrow d
34. ll is optimum Camber Camber Gain For Circle Track cars turning left reasonable Static Camber values before any Dive or Roll are Left Side 1 degree Right Side 2 to 3 degrees Wider and or stiffer sidewall tires require less Static Camber Camber Gain should be in the range of 1 75 for a flat track 1 25 for a medium banked track 10 15 degrees and down to 1 for highly banked tracks over 25 degrees on the outside tire right tire in a left turn For circle track cars always turning left the desired camber gain on the left side may be less or even a posifive number depending on track banking and other factors These Camber Gains are based on the program s standard definition as the amount of Camber Change from 1 of Dive 40 Angle 9 10 14 17 20 22 28 30 Arm Len amp Angle 9 10 17 28 Assumptions 3 Baseline 1 33 34 Camber 5 1 2 6 7 8 9 11 12 14 17 21 22 29 30 31 32 33 34 35 36 39 40 Camber Changes with New Inputs 17 29 Camber Gain 5 1 8 9 14 39 40 Centerline 15 16 18 19 20 39 40 Comments 6 Directory 2 4 Dive 5 1 6 8 10 11 12 14 15 20 21 22 23 29 30 32 33 35 36 39 40 Double A Arm 1 17 30 Draw Big 1 Dyn Camber 11 12 Dynamic Camber 12 22 Extension Lines 1 24 29 File 2 4 5 6 7 14 17 27 28 Graph 5 27 32 33 34 35 36 37 Help 3 4 6 7 27 32 Hub Distance 21 22 Install 4 Installation 5 4
35. nce i Whi Rim Width Spring Angle Whl Rim Offset King Pin Angle Installed angle of spring measured between spring centerline and vertical in degrees You can not enter this value directly This angle is calculated from the X and Height for the Upper and Lower Spring Pad 20 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Locations This value is useful to check that your X and Height measurements are entered correctly as it should closely match your installed spring angle Spring Deflection The change in the length of the spring due to Dive or Roll Negative means spring compression from diving positive means elongation from rising Since shocks generally are mounted close to the spring locations shock travel is very similar to Spring Deflection Spring Rate Is the force required to compress the uninstalled spring inch in pounds The spring is assumed to be linear that is if 500 lbs compresses the spring 1 1000 Ibs will compress the spring 2 This is an input which you enter and effects the Wheel Rate described below Wheel Rate Figure 2 8 Illustration of Camber King Pin The force required to move wheel Axis and Scrub Radius center 1 inch up while the chassis does not move in pounds This is a Camber Angle calculated spec can not be entered directly and depends on the Spring Rate and suspension geometry negative angle shown here Scrub Radius The dist
36. ngle of the Strut are not available for this suspension type Also realize that if you switch Suspension Types with a current set of suspension dimensions the drawing will look very unusual Figure 2 17 MacPherson Strut Suspension Type Roll Center Performance Trends Inc rile Options Suspension Type Table 2 Gra Camber Gain Definition is always shown here This is front view of suspension so left side of screen i acfually right side of car y Camber Gain 50 Gain based on 1 D Camber Gain 39 and deg Mol Struts replace the arms drawn for the Double A Arm suspension type Strut dimensions replace Roll Center height 2 6 Roll Center Left 7 the Upper Arm F am aa ae aa dimensions here also Show The Shim option or inputing the Length and L Strut Loc j pation noe pean 2 a Angle of the Strut are not Lower Frame Pivot available for this Upper Spring Pad Help suspension type Lower Spring Pad The dist wheel s by laying Strut Dim measurir Lower Arm Dim C Performance Trends Inc 1998 Shim Click on Shim when this option is enabled and then select from the choices of shimming the left or right arm You are then presented with the menu shown in Figure 2 18 This menu lets you move the Frame Pivot point of the upper A arm in or out as is usually done by adding or removing shims The software keeps the length of the arm constant and calculates where
37. ning at the beginning of this manual and on the diskette envelope Also see Appendix 1 for general tips on optimum suspension settings and how there is little agreement on what is actually optimum C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction 1 4 Getting Started Installation You must install the Roll Center Calculator from the distribution CD to a hard drive before it will run To do this in Windows 95 98 Me NT 2000 e Start your computer e Insert the distribution CD into the CD drive The Installation Wizard should AutoStart where you can select to install the Roll Center Calculator or any other of our programs in demo mode e Ifthe Installation Wizard does not Auto Start then click on Start then Run then Browse e Browse until you find your CD rom drive then the Setup exe file on the CD e Double Click on Setup exe and then click on OK back at the Run screen to run Setup exe Follow the instructions of the SETUP program For most users just click on OK for each question asked to accept the default answers suggested by the Setup program Once you have installed the Roll Center Calculator there should be a Perf Trends icon or program group for you to click on Otherwise use Explorer to find the RC folder under the PERFTRNS PTI folder and click on the RC 32 EXE program Also see section 1 5 next page Entering Registered Owner s Name During your first setup the Roll Center Calc
38. nt view of suspension so left side of screen is actually right side of car Other Dimensions amp Specs Camber Gain ain based on 1 Dive Camber Table Back Print Options Baseline show saved results Graph Help Dive inches 1300 200 7 00 po Prom 3 007 g condition new suspension cam ber baseline camber and the difference in degrees 4 54 4 65 80 4 98 5 20 5 44 1 00 base 72 3 13 3 58 4 B 4 55 5 07 5 61 Roll Cent 76 1 41 1 07 75 13 17 00 fnew 2 48 2 67 2 89 3N4 3 42 3 73 User selected only rows with Dive 2 inches If 7 51 7 3 15 7 17 7 23 you now select 6 90 p 15 4 77 4 43 the Graph ree 00 2 40 2 80 mmand only 2 5 53 3 85 4 77 4 72 command only 1 00 base 5 70 5 18 4 68 4 20 3 75 3 32 2 91 inches of Dive for Difference 17 14 10 1 45 1 81 new amp baseline 3 75 3 l i 81 2 65 252 Left and BD will Click on Print to print the Table 34 C Performance Trends Inc 1998 Click on the Options menu item and select Specs for Table Rows amp Columns to change the Dive and Roll increments and which is used for rows and which is used for columns You will obtain the menu shown in Figure 2 23 As you change the specs in this menu the Preview at the bottom changes to show what the Roll and Dive increments and the general layout of the Camber Table will look like The program allows only up to 10 rows and 11 column
39. nter Setup Windows Printer Setup J co Black White Print Plot Lines The Graph Options screen is divided into 4 sections The first section is called Graph Labels Click on Use Standard Labels for standard labels to be printed on the graph Click on Use Labels Given Here and the program will use the labels which you can enter or change Click on any of the 3 text boxes and type in your chosen titles or labels The second section of the Graph Options is called Print Click on Black and White or Color to tell the program how to print the graph Unless you have a color printer you should choose Black and White The program always graphs in color on the computer screen Click on the Print Now button to print the current plot on the printer the same as selecting the Print menu command Click on the Windows Printer Setup button to see the current printer selection or select a different printer for printing the graph The third section lets you pick the line thickness for the Plot Lines either thick or thin The fourth section lets you pick the color for the Background Color of the graph either black or white Click on OK to return to the Graph Screen with your changes in effect 37 38 Appendix 1 Rules of Thumb for Desired Roll Center Camber and Camber Gain Roll Center is an imaginary point about which the chassis tends to roll in cornering maneuvers In general the lower the Roll
40. ntil it just touches the floor Measure the distance from the car s 16 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions SS centerline to where the plumb bob points on the floor This is the X distance for that particular suspension point You can print a blank worksheet for recording your measurements by clicking on File at the upper left of the Main Screen in the Menu Bar then clicking on Print Blank Worksheet Be sure you have first selected the correct Suspension Type Double A Arm or MacPherson Strut by clicking on Suspension Type in the Menu Bar to obtain the correct worksheet for your car For entering dimensions 2 other options can be important Enter X amp Ht Readings Frame amp Ball Jnts Enter X amp Ht at 1 End Arm Len amp Angle If it is easier to measure the lengths or the A Arms and the angle of the A Arms choose the Arm Len amp Angle option You still have to measure the X and Height of one end of the arm but not both For the Upper Arm you will enter the Ball Joint X and Height and the Length and the Angle For the Lower Arm you will enter the Frame Mount X and Height and the Length and the Angle Changing this option will Enable and Disable the appropriate dimension specs so you know which values to enter This option is not available for MacPherson Strut suspensions Camber Changes with New Inputs Camber Does Not Change with New Inputs For entering a new suspension it may
41. ot updated until you click on Use Calc Value Important This menu assumes that Adding shims moves the Frame Pivot farther out from the car reducing negative camber or increasing positive camber Some chassis for example the left side on some Lefthander Chassis work the opposite adding shims moves the pivot inward If your chassis is like this select Remove Shims if you are actually adding shims or Add Shims if you are actually removing shims 31 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Table amp Graph Click on Table amp Graph for a more detailed analysis of how Camber changes for several combinations of Dive and Roll This option is fairly extensive and is covered in a separate section Section 2 3 on the next page Figure 2 19 Comments Editing Comments This is the suspension setup for Jeff s car when we ran at Click on Richmond last July think we would have run better with less static left camber and more camber gain on the left Comments for the Comment Editing screen shown in Figure 2 19 Comments are printed with your Ea other specs when Tip Enter comments to describe the specs in you request a this file These will be printed with reports and print at least the saved when you save this file first 300 characters or so and are saved with a Roll Center file Comments are a good way to keep track of what each saved Roll Center file is Help
42. ow the Length of the arm stays at 11 88 inches and the Angle stays at 14 62 degrees Frame Pivot X and Height have changed as they would in order to keep the length and angle constant Stc Camber changes just as it did before to 2 89 because the Ball Joint has moved the same as before However the Camber Gain now is C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction Figure 1 7 Changing Upper Ball Joint Height with the Enter X amp Ht at 1 End Arm Len amp Angle Option Selected Roll Center Performance Trends Inc DBL AARM File Options Suspension Type Table amp Graph Comments Help About This is front view of suspension so left side of screen is actually right side of car Other Dimensions amp Specs Camber Gain 1 16 Gain based on 1 Dive Camber Gain 1 20 N Right Left Spring Length Spring Compressn Spring ngle Spring Rate Wheel Rate Scrub Radius Stc Camber deg Dyn Camber deg Hub Distance Whi Rim Width Whl Rim Offset King Pin ngle L 7 Upper Ball Joint l Show Dive amp Roll Upper Frame Pivot O Yes Ss inches Roll de Draw Lower Ball Joint No Co E Lower Frame Pivot ppp pno Help definition Lower Spring Pad Distance from ground to center of ball joint on upper arm on right side in inches F 14 62 Upper Arm Dim 7 53 3 3 Lower Arm Dim 1 16 because the arm angle stayed at 14 62 where the arm angle changed to 16 93 after raising
43. program e Produce various amounts of suspension Dive and Roll and watch Camber Roll Center and Spring Compression change e Change the Options to somewhat customize the program for you e Get Help to explain these options by clicking on Help or pressing lt F1 gt Help definitions are also available anytime you click on an input spec s name or input box or a calculated spec name or value See Figure 1 3 e Quit the program by clicking on File then Exit All these options are explained in detail in Chapter 2 At the top of the main menu the blue title bar shows the current Suspension is untitled which means the current specs displayed have not been saved to the Suspension Library This makes sense since all the measurements are blank So lets do what the introductory message said and open a Suspension file Click on File in the upper left corner then select Open See Figure 1 You will obtain a screen like Figure 2 of the Suspension Library which lists all files of suspension measurements which have been saved These have been saved by Performance Trends for your convenience at getting familiar with the program Figure 1 2 Suspension Library standard Windows File Screen Roll Center Performance Trends Inc UNTITLED For beginner users File Options Suspension Type Table amp Graph Cpffiments Help Ab do NOT click on 7 _ othe Dimensions these boxes However for Fie ame Directories advanced users familiar with dol
44. r X amp Ht at 1 End Arm Len amp Angle then you could change the Height at the Upper Ball Joint and the mount at the frame would change as necessary to hold the length of the arm and its angle constant You could then change the Angle of the arm to produce most any X or Height at the Frame Mount Changing Specs Enter X amp Ht at 1 End Arm Len amp Angle Option Lets try this Click somewhere outside the menu choices of Figure 1 5 to close these choices without changing them Then click on the 20 5 and type in 20 and press lt enter gt to return it to its original value Camber Gain should go back to 1 20 and Stc static Camber should go back to 3 Now click on Options and then on the Enter X amp Ht at 1 End Arm Len amp Angle option You will be given the notice shown in Figure 1 6 and see that the Upper and Lower Arm Dim Dim is an abbreviation for dimensions are now enabled so you can enter them directly The Upper Frame Mount and Lower Ball Joint inputs are disabled printed in light gray meaning these values will be calculated from the other inputs You may notice that the Height of the Upper Frame Mount and Lower Ball Joint change slightly from 17 to 17 01 and 4 to 3 99 which is due to slightly rounding differences in the math This hundredth inch difference will not produce any significant error in the results See Figure 1 7 Now change the Upper Ball Joint Height from 20 to 20 5 and press lt enter gt Notice h
45. r is black on most computers and the Instant Centers match the colors of the Left or Right suspension drawing If these locations are off the screen they are drawn at the correct height with an arrow pointing to their off screen location Upper Ball Joint Location Figure 2 5 Measuring Ball Joint Locations X is the distance from the car centerline to the center of the ball joint on the upper arm on either the right side or left side in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines Upper Frame Pivot Location X is the distance from the car centerline to the center of the pivot on the frame mount on the upper arm on either the right side or left side in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines Lower Ball Joint Location X is the distance from the car centerline to the center of the ball joint on the lower arm on either the right side or left side in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines Lower Frame Pivot Location X is the distance from the car centerline to the center of the pivot on the frame mount on the lower arm on either the right side or left side in inches Height is the distance from the ground to this same location See page 15 16 for a definition of possible centerlines
46. rawn in this Figure not on the computer screen shows how it has moved from its static location gray dot with red outline The red arrow pointing off the screen shows its actual location is off the screen Roll Center drawn in black The arrow drawn in this Figure not on the computer screen shows how it has moved from its static location gray dot with black outline This is front view of suspension so left side of screen is actually right side of c r Gain based on 1 Dive Roll Center height 6 7 Roll Center Left 2 5 Dynamic Roll Center location due to Dive and Roll is shown in black Static Roll Center location is shown in black unless the car is in Dive and or Roll Then it is shown in gray as shown here for comparison to the Dynamic Roll Center Letters A L relate to dimensions listed in Static Layout Dimensions section See page 15 25 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 26 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 2 Main Screen Options In the Menu Bar at the top of the Main Screen there are 8 main menu commands File Options Suspension Type Shim Table amp Graph Comments Help About These are discussed in this section PNOARWN gt Figure 2 13 Menu Bar of Main Screen showing Options Available Roll Center Performance Trends Inc DBL AARM File Options SuspensionType Shim Table amp Graph Comments
47. s Your inputs may be changed if a combination produces more than these limits When you are satisfied with the Preview click on OK Exit Click on Cancel to close this menu and return to the original Table layout Note If you change the Camber Table specs any previously saved baseline conditions will be lost because that baseline has different increments for columns and rows which would not match up to the new increments you have selected Roll Center Calculator Figure 2 23 Menu for Changing Camber Table Specs Camber Table Specs Chapter 2 Definitions Camber Table Settings Data in Rows Dive inches 3 Starting Dive inches 2 Ending Dive inches 2 Dive Step Size i Starting Roll degrees Ending Roll degrees 3 Roll Step Size i l Preview Roll Dive e A s 2 5 rows x 7 columns Maximum of 10 rows by 11 columns Click on the Graph menu item and you can Graph the selected data from the Table To select data you highlight various rows by clicking and dragging the mouse in the top Table for the Right Side These selected highlighted rows AND the corresponding rows in the bottom table for the Left side will be graphed Ifyou have selected more data than the Graph can hold you will be told and the top and bottom rows only of what you ve selected will be graphed 35 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 24
48. t side of car moving with Gain based on 1 Dive 7 Right Dive amp Roll Spring Length Spring Compressn Spring Angle Spring Rate Wheel Rate Dynam ic Scrub Radius 8 Camber Stc Camber deg Dyn Camber deg Hub Distance Whl Rim Width Whi Rim Offset King Pin Angle shows how tire camber changes with Dive amp Click on a ree SO arrow Yes z a Cuno 2 amp 3 00 buttons to increment gt Help definition Dive and Distance from ground to center of pivot on the frame Roll up or mount on lower arm on right side in inches down or just type in your desired Dive and Roll Show Dive amp Roll Car is shown rising negative Dive and rolling to the right positive Roll which is what the car would do accelerating out of a left hand turn C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Chapter 2 Definitions 2 0 Basic Program Operation Figure 2 1 shows the Roll Center Calculator s Main Screen with explanations of your options Figure 2 1 Main Menu Options Menu bar Click here for drop down Suspension Layout diagram to menus of program options show Roll Center location Camber Gain dimensions and Name of current vehicle changes with Roll and Dive i This area holds other specs shows calculated specs and specs that change with Dive and Roll Roll Center Performance Trends Inc DBL AARM Suspension
49. tion you see on the track Adjust Dive amp Roll so the springs go through the range of motion indicated by your shock travel indicators This assumes the shocks and springs have approximately the same motion ratio 14 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions 2 1 Main Screen Inputs amp Outputs The Main Screen has 4 major sections each which will be discussed in this section Show Dive amp Roll Se es Static Layout Dimensions Other Dimensions amp Specs Suspension Layout Drawing 2 1 1 Static Layout Dimensions Before we define the inputs in this section lets take a minute to describe how you will make these measurements Taking Suspension Measurements You enter the measurements from your car s front suspension members into the Layout Screen First park the car on a flat level surface First we must decide on what we will call the car s centerline Many people use a distance half way between the left and right tire patches The disadvantage of this method is if you change rim widths or wheel offsets your centerline can change This means all your measurements are now off also There Figure 2 2 Static Layout Dimensions Section of theMain Screen l Static Layout Dimensions Right Height Left Height A Upper Ball Joint B Upper Frame Pivot Lower Ball Joint Lower Frame Pivot Upper Spring Pad Lower Spring Pad Length Angle Length Angle Upper Arm Dim Lower
50. ulator will ask you to enter your name as the Registered Owner During this first session you can modify it until you are satisfied Once you accept the name the computer will generate a code based on the name To be eligible for Tech Help you will need both your registered name and code and to have sent in your registration card The name you enter should be very similar to the name you enter on the registration card Click on About in the Main Menu to review your name and code C Performance Trends Inc 1998 Roll Center Calculator Chapter 1 Introduction 1 5 Example to Get You Going To start the Roll Center Calculator from Windows 3 1 click on the Roll Center Calculator icon in the Perf Trnds program group From Windows 95 click on Start then Programs then Perf Trends and then Roll Center Calculator Figure 1 1 Blank Main Screen when First Opening Program Roll Center Performance Trends Inc UNTITLED 1 iif Options Suspension Type Table amp Graph Comments Help Untitled is MUU name used for specs until you save specs to a name of your choosing New o left side of screen is actually right side of car 1 Other Dimensions amp Specs Open based on 1 Dive s Save Spring Length m Spring Compressn Spring ngle XQ Print NO Spring Rate Print Blank Worksheet Wheel Rate Windows Print Setup Scrub Radius Stc Camber deg Exit Dyn Camber deg Hub Distance 2 e Save s Click on File th
51. wer Arm you will enter the Frame Mount X and Height and the Length and the Angle Changing this option will Enable and Disable the appropriate dimension specs so you know which values to enter This Len amp Angle option is not available for MacPherson Strut suspensions For more details see the Example in Section 1 5 28 C Performance Trends Inc 1998 Roll Center Calculator Chapter 2 Definitions Draw Extension Lines Don t Draw Extension Lines Lets you choose if imaginary extension lines should be drawn in the Suspension Layout These extension lines help show how the Instant Centers and Roll Center are arrived at Figure 2 11 shows extension lines Figure 2 17 does not Background Car Layout Color Light Gray Background Car Layout Color Light Gray Lets you select the color for the background car and suspension drawing in the Layout screen The Background Car shows the static position of the suspension and car before any Dive and or Roll Camber Changes with New Inputs Camber Does Not Change with New Inputs For entering a new suspension it may be better to select the Camber Does Not Change with New Inputs option This prevents Camber from continually being changed possibly to very unusual values as you enter new measurements Once you have a new suspension entered choosing the Camber Changes with New Inputs option works 5 well to see how suspension adjustments Figure 2 16 Camber Gain Specs Menu or mod
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