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Brake Drums Service Manual

1. CASTLITE SQUEALER 2 FLANGE O POCKETS DJ INSIDE 2 BRAKING SURFACE 106887a Cast Lite Brake Drums FIGURE 2 TruTurn Brake Drums ConMet TruTurn brake drums are precision machined over 95 of their surface area This results in a drum that is inherently balanced eliminating the need for weld on weights or balance cuts Machining the drum inside and out also improves performance due to consistent wall thickness and uniform thermal expansion Figure 3 TRUTURN LETTERING SQUEALER BAND DRUM BARREL PILOT RING S FLANGE STUD HOLE gt Z 106888a f a E STACKING St W2 E L2 BZ TruTurn Brake Drums FIGURE 3 Consolidated Metco Inc 2 IDENTIFICATION WHEEL MOUNTING SYSTEMS Most ConMet brake drums can be used with both hub pilot and ball seat nut configurations Hub Pilot Wheel Mounting The hub pilot wheel mounting system makes use of a single two piece flange nut on each wheel stud for both single and dual wheel applications Figure 4 The hub pilot wheel mounting system is also known as the Uni Mount 10 10 stud WHD 10 10 stud WHD 8 8 stud and ISO system All ConMet brake drums have been designed to be compatible with hub pilot wheel mounting systems There is no need to confirm stud hole size if fitting a ConMet drum to a hub pilot mounting system SINGLE 106821a Hub Pilot Mounting Systems FIGURE 4 Ball Seat Wheel Mounting System
2. CON yon HEAVY DUTY service Manual lt N For All ConMet Brake Drums For Steer Drive and Trailer Brake Drums Standard Cast Brake Drums TruTurn Brake Drums CastLite Brake Drums ABOUT THIS MANUAL e Read this manual carefully providing extra Hazard Alert Messages attention to its explanations and instructions e To ensure safe continuous trouble free operation understand your wheel hub system and keep all A Danger alert indicates a hazardous situation which if not i Sieg i ill result i th or serious injury components in proper operating condition SE e Information relating to brake shoes S cams or other brake system components is not included in A Warning alert indicates a hazardous situation which if not this manual Information regarding brake related avoided could result in death or serious injury components other than the drum should be obtained from the vehicle or component manufacturer s published service information A Caution alert indicates a hazardous situation which if not e Additional information pertaining to servicing avoided could result in minor or moderate injury ConMet wheel hub assemblies can be found in ConMet Service Manual 10041406 Service Manual for Steer Drive amp Trailer Hub Assemblies A note includes additional information that may assist the e Pay particular attention to all NOTES CAUTIONS ee WARNINGS and DANGERS to avoid the risk of personal injury
3. ConMet Identifying Mark The identifying mark CONMET is physically cast into the outside of all drums manufactured by ConMet It appears in large characters and is located on the transition between the mounting flange and the barrel Figure 6 These letters are raised on standard cast and CastLite drums and recessed on TruTurn drums ConMet Part Number The ConMet part number is a 6 or 8 digit number physically cast into the outside of the drum near the identifying mark Figure 6 These numbers are raised on standard cast and CastLite drums and recessed on TruTurn drums 2 IDENTIFICATION CONTINUED IDENTIFYING MARK AND PART NUMBER 106889a ConMet Markings Cast into the Outside of the Drum FIGURE 6 Date Code All ConMet drums have a date code cast into the drum near the same location as the identifying mark and part number Cast dates will have one of two formats YMDD 4F22 June 22 2014 DDMMYY 220614 June 22 2014 The date code provides the date that the drum was manufactured and may be used for warranty purposes These numbers are raised on standard cast and CastLite drums and recessed on TruTurn drums For date codes using a letter to designate the month of manufacture refer to the following table ee ee oe f e May Consolidated Metco Inc 3 BRAKE DRUM REMOVAL HAZARD ALERT MESSAGES Read and observe all Warning and Caution hazard alert Sudden release of compressed air c
4. Do not tighten any nuts at this time Apply sufficient torque about 50 ft lbs to the inner top cap nut to draw the brake drum up on the drum pilot and against the hub and seat the ball seat of the nut into the ball socket of the wheel Figure 35 INNER CAP NUT AT 12 O CLOCK POSITION 106815a Tightening the Inner Cap Nuts FIGURE 35 To properly center the wheel snug the remaining wheel nuts Verify the drum is in place over the drum pilots Starting with the top nut first and using a staggered pattern torque the inner wheel nuts in stages to 450 500 ft lbs Figure 36 The last nut rotation must be with a calibrated torquing device Consolidated Metco Inc 7 BRAKE DRUM AND WHEEL INSTALLATION CONTINUED Use the appropriate nuts with the above technique to install the front and outer dual wheels Follow your shop practice to locate the valve stems 9 Inspect the brake and wheel installation by checking the seating of the wheel s and drum at the pilots and by turning the wheel s and checking for any irregularity Visually inspect the area of contact between the brake shoes and the drum to verify that there is not a significant gap difference from one shoe to the other 105756a 10 Stud Tightening Sequence FIGURE 36 a l Excessive or inadequate wheel nut torque can cause a failure of the wheel mounting system and a wheel separation resulting in 8 Install the outer wheel and nuts and tighten to sever
5. ensures that your brake system s performance service life and safety are maintained In order to determine a proper replacement the following information about the drum that is being replaced will be needed e Manufacturer name e Part number Most manufacturers cast this information into the outside of the brake drum Refer to Section 2 of this manual for specific information on identifying ConMet brake drums If the above information cannot be determined then a truck dealership can be contacted and the Vehicle Identification Number VIN provided The dealership should be able to determine the manufacturer and part number of the drum originally installed on the vehicle If the brake drum being replaced still cannot be identified then measurements of the critical features of the brake drum will be necessary Figure 22 The measurements can be made using a tape measure calipers or other measuring devices DIAMETER AND NUMBER OF BOLT HOLES 106902a Measurements to Determine Brake Drum Size FIGURE 22 Consolidated Metco Inc 6 ADDITIONAL INFORMATION BRAKE DRUM BALANCE All ConMet brake drums are balanced at the factory using either a cut in the squealer band or a Turned to Balance machining process No drums are balanced using weld on weights All steer drums are balanced to 10 inch ounces and all rear drive trailer drums are balanced to 20 inch ounces Balance Cut in Squealer Band ConMet stan
6. knuckle or other flat non rotating surface near the drum For best results ConMet suggests the use of a lever style dial indicator with a magnetic base Figure 20 A standard dial indicator with a magnetic base can also be used Ensure that the base is secure and does not move Lever Style Dial Indicator FIGURE 20 Adjust the dial indicator to contact the braking surface of the drum approximately 0 25 inch from the inboard end of the drum at a location between the brake shoes or between the lining blocks on one shoe If using a lever style dial indicator ensure that the lever clears the wear lip that is often present on the inboard end of a used drum Figure 21 If using a standard dial indicator ensure that the tip clears the wear lip and is perpendicular to the braking surface Measuring Runout with a Lever Style Dial Indicator FIGURE 21 Set the dial indicator to zero rotate the wheel and hub assembly one full revolution while watching the dial indicator and note at what position the dial indicator measures the LOWEST value Rotate the drum to the position of the lowest reading and zero the dial indicator Rotate the drum one full revolution again while watching the dial indicator Record the maximum reading which is the Total Indicator Reading TIR and equals the assembled runout of the drum Consolidated Metco Inc 4 INSPECTION CONTINUED e If TIR is less than 0 020 inch no action is necessary Retu
7. measured from the brake drum to the end of the stud Call ConMet at 1 800 547 9473 for the correct stud part number for your application If you plan to replace the brake drum verify the new drum has the same drum pilot diameter as the one that has been removed 105756a 10 Stud Tightening Sequence FIGURE 28 a Measuring Stud Standout FIGURE 30 2 In environments where a corrosion inhibitor is beneficial ConMet recommends the use of Corrosion Block a product of Lear Chemical Research 905 564 0018 In severely corrosive environments a light coat of Corrosion Block on the drum and wheel pilots has proven beneficial 3 In addition to the above preparation apply two drops of oil to a point between each nut and nut flange washer and two drops to the last two or three 1057574 threads at the end of each stud Also lightly 8 Stud Tightening Sequence lubricate the pilots on the hub to ease wheel FIGURE 29 installation and removal 15 Consolidated Metco Inc 7 BRAKE DRUM AND WHEEL INSTALLATION CONTINUED CAUTION Do not get lubricant on the mounting face of the drum or wheel Failure to clean lubricant from these surfaces may result in decreased clamping load Before installation of brake drums and wheels that utilize the hub piloted system rotate the hub so one of the wheel pilot bosses is at the top 12 o clock position Figure 31 WHEEL PILOT BOSS 105758a Rotating the Hub FIGURE 31 Po
8. the hub s drum pilot Stud hole size has no effect on ease of installation Consolidated Metco Inc 7 BRAKE DRUM AND WHEEL INSTALLATION Clean all mating surfaces on the hub drum and nuts Remove loose paint scale and any material building around the pilots of the drum hub and wheels Be sure paint is fully cured on recently Always snug the top nut first to fully seat the brake drum on the refurbished wheels drum pilot and against the hub face See the adjacent diagram for bolt tightening sequence and tighten in order from 1 through 8 or 10 depending on the bolt pattern Figure 28 and Figure 29 Z CAUTION Hub Pilot Wheel Mounting System 1 Care should be taken to avoid damaging the hub or other CAUTION components The brake drum must be fully seated on the drum pilot and against the hub face during and after installation of the wheel s If you plan to replace the brake drum i e cast in place of Centifuse or wheels i e aluminum in place of steel measure stud standout Figure 30 In hub piloted mounting systems the If your shop practice requires the use of lubricant or anticorrosion studs must be long enough for the threads to be exposed beyond material to the threads and or the drum pilot area avoid getting the installed wheel nut In the ball seat mounting system the stud lubricant on the flat mating surfaces of the hub drum and wheels length beyond the brake drum should be from 1 31 1 44 as
9. Extreme Temperatures on Wheel Torque and Clamp Load Consolidated Metco Inc 18 WHEEL TORQUE SPECIFICATIONS Wheel End Torque Specfications Torque ft lbs Ball Seat 3 4 16 450 500 Always tighten the top nut first or pilot damage may Wheel Nut 1 1 8 16 450 500 result If lubricant is used apply sparingly on threads only Do not lubricate the faces of the hub drum wheel or on the ball seats of the wheel nuts The last nut rotation should be with a calibrated torque device Hub Pilot 22 mm x 1 5 mm 450 500 Always tighten the top nut first or pilot damage may Wheel Nut result Apply two drops of oil between the nut and nut flange and two or three drops to the outermost 2 or 3 threads of the wheel studs Lightly lubricate the wheel pilots on the hub The last nut rotation should be with a calibrated torque device Drive 3 4 16 70 90 Studs 5 8 18 40 90 Installation Torque 9 16 18 40 60 1 2 20 40 60 Hub Cap 5 16 18 12 18 Minimum SAE Grade 5 fasteners flat washers only Oil Fill Plug 20 25 O Ring Style Bolt On ABS Ring 8 32 18 22 in lbs Screw Disc Brake Rotor Nut 5 8 18 190 210 Disc Brake Rotor M16 x 1 5 190 210 Drive Axle Flange Nuts See axle manufacturer s recommendations for inane Kean PreSet 2 Piece Nut 300 Inner 300 minimum Advance to nearest lock Set wrench PreSet 2 Piece Nut 150 Inner 150 minimum Advance to nearest lock Set wrench FC Medium Duty 100 Outer at 100
10. L INSTALLATION 00000 c cc cccceeecceeeeeeeenneeeeeeeeeeeseneseeeeeeeeesesseaaaees 15 Hub Pilot Wheel Mounting System festege Eege ENEE AEN Eege 15 Ball Seat Wheel Mounting System sxsexscccosccesaxcecarecedeanetasecaduet cecnsavoesbecnsverikenasdediaceQeracedandentecedarans 16 WHEEL TORQUE SPECIFICATIONS 0 ceeececeseeeeseee cence seeeeeeaeeeeeneeessaeeseaneeseneeeseeereeaeeessaeereaes 19 1 INTRODUCTION Consolidated Metco ConMet brake drums are designed for superior performance and long life and are available for most commercial vehicle applications ConMet currently offers three types of brake drums e Standard cast brake drums e CastLite brake drums e TruTurn brake drums Standard Cast Brake Drums ConMet standard cast brake drums are available for a wide range of heavy and severe duty vehicle applications Critical areas are precision machined and all are balanced using a cut in the squealer band Figure 1 BALANCE CUT STACKING SQUEALER BAND DRUM Se PILOT STUD pert 2 Zeen SURFACE On ii FLANGE 106886a Standard Cast Drums FIGURE 1 CastLite Brake Drums ConMet CastLite brake drums are designed with a computer optimized shape that results in up to a 15 weight savings over standard drums Critical areas are precision machined and all CastLite drums are balanced using a cut in the squealer band Figure 2 WEBBING REAR DRUMS ONLY BALANCE CUT
11. Mounting EEN 2 Ball Seat Wheel Mounting System eedegEueee gece ENEE GEES ege 2 IDENTIFYING CONMET HUB ASSEMBLIES EE 2 Vehicle Identification Number VIN sssssssssssssssssrrrrrrrrerrrenrsrrsrssnrrnsrrenstttttttttnttnnttttttttttnttEEtEEEnEEE nannt 2 ConMet Identifying Mark EE 2 ConMet Part ten e 2 Ree EE 3 3 BRAKE DRUM REMOVAL cicscistestccccsicscsssstssecsectcnwsnsdtsasesreseadabscansnddeettestesetosseccasacanendecaesdedisonsaeceasaie 4 HAZARD ALERT MESSAGES ger ehtesee geed Eege 4 4 INSPECTION cco sconce cece E A A epee Se awa th eect ieee ee eee 5 BRAKE DRUM INSPECTION EE 5 Heat e EE 5 Cracked Drum E EE E 5 Cracked Drum Mounting Flange eegen ees entgeet 6 Bloe DUM r a DEE DEE EE ees 6 Polished Drum sarr aon e tee EE 7 Martensite Spotted DrTUM EE 7 Gre s Oil Stained Drun WEE 7 Scored Grooved DR kse serann ia de E e E E e a E 8 Oversize Worm IR ee ebe 8 Outo I I Laera 8 CITT Resu urtacihg EE 10 5 BRAKE DAUM REPLACEMENT icscicssscsccecsicccdlessties secstatiareescieisteassseansbls deet dE A E a ENl aistideades 11 SELECTION OF NEW BRAKE DRUMS EE 11 6 ADDITIONAL INFORMATION gege ess Se ete a ed he ele 12 BRAKE DRUM BALANC EE 12 Balance Cut in Squealer Band ege ere EEN 12 T rned to Balance EE 12 BRAKE DRUM STORAGE AND HANDLING EE 12 ue Eege EE 13 Gast Stud e 13 Large Diameter Stud Holes in Front Drums geesde eege geb eege 13 Stud Hole MiIScCOncCeptOnS isrener E a ae aiaiai apea aN Aa at eai 14 7 BRAKE DRUM AND WHEE
12. ONTINUED Polished Drum A polished drum will have a mirror like finish on the braking surface Figure 15 This condition may be caused by an improper lining friction rating or the drum having been resurfaced with too fine of a micro finish Lightly dragging brakes can also cause polished drums so the return springs camshaft bushings air system and brake adjustment should be inspected It is not necessary to replace the drum but the braking surface should be sanded with 80 grit emery cloth to correct the polished condition Polished Drum FIGURE 15 Martensite Spotted Drum Drums exposed to extremely high heat followed by rapid cooling can exhibit a martensite spotted condition which is a structural change to the drum material that makes the drum more susceptible to cracking This condition appears as black spots on the braking surface that are slightly raised and are hard and brittle Figure 16 Typically the high heat needed to generate martensite spots in drums is caused by brake drag or improper brake balance Drums with this condition should be replaced Martensite Spotted Drum FIGURE 16 Grease Oil Stained Drum A brake drum that has discolorations due to grease or oil on the braking surface should be removed from the vehicle and cleaned Figure 17 The brake linings should be replaced and any other brake system components that have oil or grease spattered on them should be removed from the vehicle and cleane
13. The ball seat wheel mounting system makes use of the spherical contact area between the nut and wheel to both locate the wheel and hold the wheel tight against the brake drum Figure 5 The ball seat wheel mounting system is also known as stud piloted ball seat cap nut BCN and double cap nut DCN system All ConMet brake drums are compatible with ball seat systems in dual wheel applications Brake drum stud hole size must be confirmed for single wheel applications however In this case drum stud hole diameters must be greater than 1 1 4 inch to be compatible Consolidated Metco Inc SINGLE wy 106822a Ball Seat Mounting Systems FIGURE 5 IDENTIFYING CONMET BRAKE DRUMS Identifying your brake drum is important for many reasons It will enable you to purchase the appropriate replacement if needed In addition if a warranty issue arises you will then be able to provide details on all aspects of the ConMet drum This section is devoted to finding and understanding the different identification numbers associated with ConMet drums Vehicle Identification Number VIN One method of identifying your drums is to note the vehicle identification number VIN and call a truck dealership The dealership can then tell you what drums were installed on your vehicle If this is not possible there is a ConMet identifying mark and part number cast into the drum that will identify it
14. a drum is dropped at any time it should be discarded Dropping 3 Place safety stands under the trailer frame or under a drum can cause cracks to develop that may not be detectable each axle spring seat Figure 7 visually and could result in a failure of the drum when put into i f service If the drum is difficult to remove apply a corrosion penetrant between the hub and drum mating surfaces Allow enough time for the penetrant to release the frozen joint Do NOT use a hammer to release the drum from the hub Prior to reinstallation of the drum all hub and drum mating surfaces must be cleaned to remove any residual penetrant 1003159a FIGURE 7 4 Remove the tire and wheel assembly using procedures specified by the wheel manufacturer 5 Ifthe axle is equipped with spring brake chambers carefully compress and lock the springs so that they cannot actuate Figure 8 Consolidated Metco Inc 4 4 INSPECTION BRAKE DRUM INSPECTION A drum brake component inspection should be part of any regularly scheduled preventive maintenance program Vehicles on jacks can fall causing serious personal injury or property damage Never work under a vehicle supported by a jack without supporting the vehicle with stands and blocking the wheels Wear safe eye protection Follow all shop safety procedures before beginning vehicle inspection Heat Checks Heat checks are caused by the repeated heating and cooling of the brak
15. an cause serious personal messages in this publication They provide information injury and damage to components that can help prevent serious personal injury damage to Before you service a spring chamber carefully follow the components or both manufacturer s instructions to compress and lock the spring to completely release the brake Verify that no air pressure remains in the service chamber before you proceed To prevent serious eye injury always wear safe eye protection when you perform vehicle maintenance or service Do not work under a vehicle supported only by jacks Jacks can slip and fall over Serious personal injury and damage to components can result Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving Support the vehicle with safety stands Some brake linings contain asbestos fibers a cancer and lung disease hazard Some brake linings contain non asbestos fibers 103161a whose long term effects to health are unknown When working FIGURE 8 with asbestos and non asbestos materials follow proper safety precautions and procedures as specified by the Occupational 6 Remove the brake drum Support the drum during Safety amp Health Administration www osha gov the removal process to prevent damage to the axle spindle threads 1 Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving 2 Raise the axle until the tires are off the floor If
16. d Typically this condition is caused by improper lubrication of the brake components or a leaking oil grease seal in the hub Oil Stained Drum FIGURE 17 Consolidated Metco Inc 4 INSPECTION CONTINUED Scored Grooved Drum A scored drum will show defined grooving on the braking surface Figure 18 Replace the brake drum if any of the following occurs in addition to the scoring grooving e The drum braking surface diameter exceeds the maximum specified by the lettering cast into the drum e Grooved linings are replaced due to an out of service condition defined in TMC RP 627 or per the lining manufacturer s requirements Typically grooving alone is not an out of service condition for linings Scoring is typically caused by e Foreign debris becoming trapped between the lining and drum This is usually indicated by uniform grooving across the entire braking surface or bands of grooving on the inboard and or outboard edges of the braking surface Adding dust shields may correct this condition If the vehicle is already equipped with dust shields removing them may correct this condition e Loose rivets or bolts or foreign debris buildup in the rivet holes of the linings This is usually indicated by bands of grooving on the drum corresponding to the location of the rivet holes Repairing the linings or installing rivet plugs may correct this condition e Poor quality brake linings If this is suspected consult t
17. d Cast and CastLite Drums et the wheel studs pass through the drum and FIGURE 25 clearance hole size does not affect the stopping ability of the brake drum This section explains the types of stud holes used by ConMet drums and also addresses the common misconceptions about stud holes 106905a Cast Stud Holes Most ConMet drums utilize cast stud holes These holes are generated during the sand casting process rather than with a drill Cast holes intentionally have a 0 10 inch larger diameter than comparable drilled holes This size difference does not affect the drum s ability to stop CORRECT STACKING OF the vehicle Both cast and machined holes meet the alae DRUMS Society of Automotive Engineers SAE J1671 specification which governs brake drum hole size Figure 27 106906a Storing TruTurn Drums FIGURE 26 106907a Brake drums manufactured by companies other than ConMet may z not be designed to be stored by nesting Consult the drum Drilled Hole Left vs Cast Hole Right manufacturer to determine the proper way to store the drums FIGURE 27 Brake drums should never be stored on their side as this may cause an out of round condition to occur 13 Consolidated Metco Inc 6 ADDITIONAL INFORMATION CONTINUED Large Diameter Stud Holes in Steer Drums Many ConMet steer drums are designed to work with both hub piloted and stud piloted wheel mounting systems Hub piloted s
18. dard cast and CastLite brake drums are 100 balanced at the factory by machining a balance cut in the squealer band Figure 23 Each drum is first checked for imbalance cut to correct any imbalance found and then rechecked to ensure it meets specifications The balance cut can easily be found by inspecting the squealer band BALANCE 106903a Balance Cut in Squealer Band FIGURE 23 THERE CAN BE DEVIATIONS IN WALL THICKNESS THAT WOULD CAUSE A DRUMTO BE UNBLALNCED TO MAKE A DRUM TRUE IT MUST BE MACHINED ON BOTH INTERIOR AND EXTERIOR WALLS Consolidated Metco Inc Turned to Balance ConMet TruTurn brake drums are 100 balanced at the factory using a Turned to Balance machining process These drums are machined over 95 of their surface area in a single machining operation resulting in drums that are inherently balanced and eliminating the need for balance cuts Figure 24 There are no physical indicators on the drums to indicate they are balanced but ConMet s manufacturing process ensures that the drums do meet the balance specifications BRAKE DRUM STORAGE AND HANDLING All ConMet brake drums are designed to be stored by nesting up to 4 drums 3 for 16 5x8 625 drums in a vertical stack with the open ends of the drums down All standard cast and CastLite brake drums have 3 to 6 stacking tabs on the outside that are designed to support and center the drum being stacked on it Figure 25 All Tr
19. e drum during normal vehicle operation They appear as short fine axial hairline cracks in the braking surface Heat checking can range from light Figure 9 to heavy Figure 10 Heat checking is a normal condition and will not affect braking performance However the brake drum should be replaced if heavy heat checking is encountered and any of the following conditions occur e One or more heat check cracks extend continuously over 75 of the braking surface in the axial direction e One or more heat check cracks are over 0 060 inch wide and or over 0 060 inch deep If heavy heat checking is localized on only one side of the drum then the drum should be replaced Heavy heat checking on one side of the drum is typically caused by improper drum mounting or a drum that is out of round Light Heat Checks FIGURE 9 Heavy Heat Checks FIGURE 10 Cracked Drum Barrel If a crack is discovered that extends through the entire brake wall of the drum barrel then the drum must be replaced immediately Figure 11 Cracked drum barrels are typically caused by mishandling if the drum is new or excessive heating and cooling if the drum is used The most common form of mishandling that causes cracks is dropping the drum Possible causes of excessive heating and cooling include improper brake balance the use of drums and linings that are not adequate for the application or driver abuse Applying the parking brake while the drum is e
20. e personal injury or death and property damage Always use 450 500 ft lbs Figure 37 The last nut rotation a device that measures the torque being applied After the first must be with a calibrated torque device 50 100 miles retorque all the nuts to 450 500 ft lbs Loosen the outer nuts to retorque the inner nuts 106824b Torquing the Outer Wheel Nuts FIGURE 37 When torquing wheel nuts the temperature of all the wheel end components should be as close as possible to the midpoint of the expected operating range For example if the hub will operate between 0 F and 150 F 75 F is a good temperature to torque at Room temperature is often a close approximation of the midpoint temperature This recommendation is due to the differences in the coefficient of thermal expansion for the various materials in the wheel end including the hub studs wheel and brake drum If the wheel nuts are torqued at temperatures well below the midpoint when the system warms up the studs may become overstressed This could cause the studs to be permanently stretched leading to nut loosening or damage to the wheel or hub If the torque is applied at elevated temperatures the system may become loose and lose clamp at lower temperatures resulting in wheel damage and broken wheel studs If the nuts must be torqued at extreme temperatures the nut torque should be readjusted when the temperature is in the desired range See also TMC RP250 Effects of
21. for outer nut NO BACK OFF Disc Brake Rotor M8 x 1 25 Screw 1 2 20 9 16 12 5 8 11 5 8 18 ES Pet Steer Hub PreSet 1 Piece Nut 300 300 minimum Advance to nearest lock FF FL R TN TP L NO BACK OFF PreSet 1 Piece Nut 150 minimum Advance to nearest lock FC Medium Duty NO BACK OFF Steer Hub PreSet Plus Drive and 500 Set wrench at 500 NO BACK OFF Trailer Nut PreSet Plus Steer Nut 300 Set wrench at 300 NO BACK OFF 19 Consolidated Metco Inc Consolidated Metco Inc 20 CON yp T Part No 10081803 Consolidated Metco Inc 7 2015 Printed in the USA 5701 SE Columbia Way Vancouver WA 98661 800 547 9473 www conmet com Se ee Amsted
22. he lining or vehicle manufacturer Grooves on Drum Braking Surface FIGURE 18 Consolidated Metco Inc Oversize Worn Drum A worn brake drum will typically have a defined lip on the open end of the drum that can be observed during inspection and or felt when running a finger across it If excessive wear is suspected the diameter of the drum should be measured Using a drum gage or 2 point bore gage measure the drum braking surface diameter at the locations of maximum wear If wear is uniform measure the diameter approximately 1 inch from the outer edge of the braking surface on the open end of the drum All ConMet brake drums have the maximum diameter cast on the outside of the drum near other identifying lettering If this lettering cannot be located use the following table Nominal Brake Maximum Drum Diameter inch Diameter inch 16 620 If the diameter measurement exceeds the maximum replace the brake drum Drum wear is a normal condition However if the drum is wearing excessively fast or unevenly refer to the causes listed in the Scored Drum section above Out of Round Drum A drum is considered out of round when it shows variations in diameter around the circumference of the braking surface This condition is typically caused by e Distortion or warping due to excessive heat generation during braking e The drum was improperly installed on the vehicle e The drum was dropped or sto
23. hen the maximum rebore diameter allowed is 16 50 0 080 16 580 inches In addition the braking surface finish must not exceed 200 microfinish and the TIR must not exceed 0 020 inch when the drum is assembled on the vehicle Consolidated Metco Inc 5 BRAKE DRUM REPLACEMENT Brake drums should be replaced if any of the following conditions are found e Heavy heat checking in addition to the criteria described in Section 4 e Cracked drum barrel e Cracked mounting flange e Martensite spotting on the braking surface e Grooving in addition to the criteria described in Section 4 e The drum is worn beyond the maximum diameter limit e The drum is out of round e The drum has been dropped e The drum is known to have been severely overheated or abused Drums should always be replaced in pairs on the same axle to ensure the same braking power and load is achieved Uneven braking load on the axle can reduce the brake performance service life and or safety of the vehicle Linings should also always be replaced in pairs though it is not always necessary to replace linings when replacing drums and vice versa See Section 4 of this manual for more details BRAKING SURFACE DIAMETER WIDTH OF BRAKING SURFACE OVERALL DEPTH FLANGE THICKNESS PILOT DIAMETER BOLT CIRCLE DIAMETER SELECTION OF NEW BRAKE DRUMS Selecting the correct replacement brake drum for your application is very important as it
24. nd the brake drum standout should be from 1 31 1 44 as measured from the brake drum to the end of the stud Figure 33 When mounting dual aluminum wheels use ALCOA inner cap nuts 5978R and 5978L or equivalent These nuts can also be used with longer studs up to 1 88 standout For special single aluminum wheel applications on drive and trailer hubs use ALCOA single cap nuts 5995R and 5995L or 5554R and 5554 L or the equivalent depending on the stud thread length Table A For single steel wheel applications use BATCO 13 3013R and 13 3013L or the equivalent Table B 106812a Stud Standout FIGURE 33 Table A Single Aluminum Wheel Applications Aluminum Wheels ALCOA Cap Nut Number 3 4 16 Threaded 5995R and 5995L or 5554R and 5554L depending on stud length Table B Single Steel Wheel Applications Steel Wheels BATCO Cap Nut Number 3 4 16 Threaded 13 3013R and 13 3013L Studs 2 When installing the inner wheel and tire assembly verify the inner nuts being used are suitable for the application aluminum wheels steel wheels brake drum thickness etc 3 Rotate the hub to bring a drum pilot to the top 12 o clock position Figure 34 Position the inner wheel and tire assembly over the studs against the drum Rotating the Wheel Pilot to 12 O Clock FIGURE 34 Beginning in the 12 o clock position install the inner cap nuts by hand to ensure they are not cross threaded
25. or property damage and realize How to Obtain Additional Maintenance and these statements are not exhaustive ConMet Service Information cannot possibly know or evaluate all conceivable methods in which service may be performed or the On the Web possibly hazardous consequences of each method Accordingly those who use a procedure Visit www conmet com to access ConMet s product not recommended by ConMet must first satisfy sales service and maintenance literature themselves that neither their safety nor the safety of the product will be jeopardized by the service method selected ConMet Customer Service Call ConMet s Customer Service at 1 800 547 9473 Before You Begin 1 Read and understand all instructions and procedures before you begin to service drums 2 Read and observe all Warning and Caution hazard alert messages in this publication They provide information that can help prevent serious personal injury damage to components or both 3 Follow your company s maintenance and service installation and diagnostics guidelines 4 Use special tools when required to help avoid serious personal injury and damage to components TABLE OF CONTENTS 1 INTRODUCTION ME 1 Standard Cast Brake DrumS stscaccaniutcccodsancgacnnesisa des gecetadiweisangadengsesiaineacengacg ma eaadseascsuddetiaaensceces 1 E E Brake DrUMS EE 1 Tr Turmn Brake DrUMS E 1 2 IDENTIFICATION EE 2 WHEEL MOUNTING ET ac eege ees 2 Hub Pilot Wheel
26. red on its side prior to installation e The parking brake was applied while the drum was extremely hot If an out of round condition is suspected the runout of the brake drum should be checked Perform the following procedure on the drum when it is still assembled on the vehicle 4 INSPECTION CONTINUED To prevent serious eye injury always wear safe eye protection when you perform vehicle maintenance or service Do not work under a vehicle supported only by jacks Jacks can slip and fall over Serious personal injury and damage to components can result Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving Support the vehicle with safety stands Measuring the runout of a drum that is still assembled on the vehicle is the best way to determine if the drum is out of round Always perform the runout measurement before loosening the wheel nuts and disassembling the wheel and drum This will give the most accurate runout reading Do not attempt to determine if a drum is out of round by measuring the drum when it is not assembled on a vehicle Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving Raise the axle until the tires are off the floor Place safety stands under the trailer frame or under each axle spring seat Figure 19 1003159a FIGURE 19 If equipped remove the dust shields Attach the base of a dial indicator to the axle steering
27. rn the drum to service e If TIR exceeds 0 020 inch mark the drum and hub so that the original position of the drum relative to the hub is known Perform the following actions a Remove the drum and inspect the hub drum mating surfaces for damage Pay special attention to the pilots on the hub If damage is found replace the damaged components b If no damage is found reinstall the brake drum 180 degrees from its original position relative to the hub Make sure to rotate the hub so that one wheel pilot boss is at the 12 o clock position prior to reinstalling the drum Remeasure the runout If the TIR is less than 0 020 inch keep the drum in the new position and reassemble the wheel again making sure that the hub is rotated so that one wheel pilot boss is at the 12 o clock position Return the drum to service If the TIR exceeds 0 020 inch replace the brake drum For detailed drum and wheel installation procedures refer to Section 7 Some vehicle manufacturers specify a lower hub drum assembled runout limit on steer axles than 0 020 inch In those cases the vehicle manufacturer s limits must be met Check with the vehicle manufacturer to confirm runout limits Drum Resurfacing ConMet does not recommend resurfacing brake drums However if drum resurfacing is necessary ensure that the finished diameter does not exceed 0 080 inch over the original diameter For example if the original drum diameter was 16 50 inches t
28. se clamp at lower temperatures resulting in wheel damage and broken wheel studs If the nuts must be torqued at extreme temperatures the nut torque should be readjusted when the temperature is in the desired range See also TMC RP250 Effects of Extreme Temperatures on Wheel Torque and Clamp Load Use the appropriate nuts with the above technique to install the front and outer dual wheels Follow your shop practice to locate the valve stems Inspect the brake and wheel installation by checking the seating of the wheel s and drum at the pilots and by turning the wheel s and checking for any irregularity Visually inspect the area of contact between the brake shoes and the drum to verify that there is not a significant gap difference from one shoe to the other Excessive or inadequate wheel nut torque can cause a failure of the wheel mounting system and a wheel separation resulting in severe personal injury or death and property damage Always use a device that measures the torque being applied After the first 50 100 miles retorque all the nuts to 450 500 ft lbs Ball Seat Wheel Mounting System Clean all mating surfaces on the hub drum wheels and nuts Remove loose paint scale and any material building around the pilots of the drum hub and wheels Be sure paint is fully cured on recently refurbished wheels 16 7 BRAKE DRUM AND WHEEL INSTALLATION CONTINUED When dual wheels are mounted the stud length beyo
29. sition the brake drum over the hub so it seats on the drum pilot and against the hub face Place the wheel s into position One or more nuts can be started in order to hold wheel s and drum into position Snug the top nut first Apply 50 ft lbs torque to draw the brake drum up fully against the hub Figure 32 106824b Reinstalling the Drum and Wheel FIGURE 32 Install the remaining wheel nuts and using the sequence as shown torque all the nuts to 50 ft lbs then retorque to 450 500 ft lbs Figures 29 and 30 The last nut rotation must be with a calibrated torque device Consolidated Metco Inc When torquing wheel nuts the temperature of all the wheel end components should be as close as possible to the midpoint of the expected operating range For example if the hub will operate between 0 F and 150 F 75 F is a good temperature to torque at Room temperature is often a close approximation of the midpoint temperature This recommendation is due to the differences in the coefficient of thermal expansion for the various materials in the wheel end including the hub studs wheel and brake drum If the wheel nuts are torqued at temperatures well below the midpoint when the system warms up the studs may become overstressed This could cause the studs to be permanently stretched leading to nut loosening or damage to the wheel or hub If the torque is applied at elevated temperatures the system may become loose and lo
30. uTurn brake drums have a stacking ring on the outside that serves the same purpose Figure 26 When stacking brake drums ensure that each drum is fully centered and resting on the stacking tab or ring of the drum below it Never stack brake drums of different sizes types or more than 4 high 3 for 16 5x8 625 drums Never stack drums on top of a drum with a damaged stacking tab s Failure to stack the drums correctly can result in the stack becoming unstable and collapsing resulting in serious personal injury THE FINAL RESULT IS AN INHERENTLY BALANCED DRUM THAT IS READY TO INSTALL FROM THE FACTORY 106904a MACHINING REMOVES THE DEVIATIONS WITHOUT AFFECTING THE DRUMS STRENGTH Turn to Balance Process FIGURE 24 6 ADDITIONAL INFORMATION CONTINUED Brake drums are very heavy and manually handling them should be avoided Specialty drum handling devices are available to aid in brake drum transport installation and removal These devices are recommended to prevent personal injuries and component damage If a drum is dropped at any time it should be discarded Dropping a drum can cause cracks to develop that may not be detectable visually and could result in a failure of the drum when put into service CORRECT STACKING OF STANDARD CAST AND CastLite DRUMS WHEEL STUD HOLES The stud holes in all of ConMet s drum flanges are clearance holes They serve no purpose other than to Storing Standar
31. xtremely hot can also result in a cracked barrel Consolidated Metco Inc 4 INSPECTION CONTINUED Cracked Drum Barrel FIGURE 11 Cracked Drum Mounting Flange If a crack is discovered through one or more bolt holes in the mounting flange then the drum must be replaced immediately Figure 12 Cracked mounting flanges are typically caused by mishandling or improper installation The compatibility of the hub and drum should be verified and the hub pilots inspected for damage Figure 13 In addition pilot surfaces on both the hub and drum must be cleaned of rust and debris before installation of the drum Cracked Mounting Flange FIGURE 12 Consolidated Metco Inc Damaged Pilot on Hub due to Drum Mismount FIGURE 13 Blue Drum Drums that show bluing on the braking surface have been exposed to excessive heat and extremely high temperatures Figure 14 This condition may be caused by repeated hard stops improper brake balance or dragging brakes due to improperly functioning return springs or swollen linings Brake actuation should also be checked to ensure there is no binding The cause of overheating should be determined and corrected to prevent the drum from cracking in the future but it is not necessary to replace the drum as long as no other replacement conditions are present and if it meets the proper dimensional specifications for runout and diameter Blue Marks FIGURE 14 4 INSPECTION C
32. ystems utilize M22 wheel studs while stud piloted systems utilize 1 1 8 inch wheel studs ConMet steer drums will often have stud hole diameters designed to clear the 1 1 8 inch wheel studs in stud piloted systems These holes may look overly large when used with M22 studs in hub piloted systems This is normal and does not affect the performance of the drum See Section 2 of this manual for more information on hub and stud piloted systems Stud Hole Misconceptions Several misconceptions exist about the function of the stud holes in brake drums e Misconception 1 The stud holes and studs prevent the drum from rotating with respect to the hub during braking Properly torqued fasteners provide twice the necessary clamp load to prevent the wheel drum and hub flanges from rotating with respect to one another Clamp load generates friction between the flanges that prevents the drum from rotating relative to the hub and wheel not shear loading of the wheel studs against the holes e Misconception 2 Drums pilot off of the stud hole and studs All drums have a precision machined pilot hole in the flange and all hubs have precision drum pilots These pilots are what center the drum on the hub not the studs and stud holes This is true for both hub piloted and stud piloted systems e Misconception 3 Drum installation difficulty depends on stud hole size Brake drums are located on a truck axle with the help of the brake shoes and

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