Technical Bulletin
Contents
1. surfaces They are the result of disc brake operation They are caused by the heating and cooling that occurs as the brakes are applied time after time Heat checks will frequently wear away and reform or they may become braking surface cracks depending on such factors as the lining and rotor wear rate brake balance and how hard the brakes are used There are two kinds of heat checking light and heavy Light Heat Checking Cracks on the surface of the rotor that result from light heat checking are small and fine and do not require rotor replacement Heavy Heat Checking Heavy heat checking is surface cracks that have width and depth Figure 10 If you find heavy heat checking replace the rotor 4001600a Figure 10 Deep Grooves or Scores Inspect both sides of the rotor If you find deep grooves or scores replace the rotor Figure 11 If the grooves or scores are not too deep you may continue to use the rotor TP 02173 Revised 11 04 4001601a Figure 11 Blue Marks or Bands Blue marks or bands indicate that the rotor was very hot Refer to the diagnostics table in this bulletin to determine the cause and correct the condition Figure 12 4001602a Measure the Rotor Thickness Use a micrometer to measure the rotor thickness The rotor must be at least 1 626 inches 41 3 mm Figure 13 e lf the rotor thickness is less than the specification Replace the rotor 16579 24240 Page 4 Copyright ArvinM2. 2 MERITOR Technical Bulletin Air Disc Brake Inspection Intervals and Procedures A ASBESTOS AND NON ASBESTOS FIBERS WARNING some brake linings contain asbestos fibers a cancer and lung disease hazard Some brake linings contain non asbestos fibers whose long term effects to health are unknown You must use caution when you handle both asbestos and non asbestos materials 4 amp WARNING To prevent serious eye injury always wear safe eye protection when you perform vehicle maintenance or service Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving Support the vehicle with safety stands 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 Intervals Periodically inspect the brakes Check the stroke length and inspect the brake components for signs of wear and damage Use the schedule below that gives the most frequent inspections e Fleet chassis lubrication schedule e Chassis manufacturer lubrication schedule e Atleast four times during lining life e Attire replacement Check the Push Rod Travel or Adjusted Chamber Stroke Length Use the following procedure to check the in service push rod travel or adjusted chamber stroke 1 Wear safe eye protection Park the vehicle on a level surface Block the wheels to prevent the vehicle from moving 2 The engine must be OFF Check the gauges
3. 4240 Page 6 Copyright ArvinMeritor Inc 2004 Printed in the USA Air Disc Brake Troubleshooting Diagnostics DX195 and DX225 Air Disc Brakes Conditions Possible Causes Air chamber Incorrect Initial adjustment exceeds 2 51 mm or inoperative automatic at 90 100 psi adjuster 620 689 kPa in cab Brake drag Incorrect initial adjustment Incorrect pad to rotor clearance spring or service brake not releasing Vehicle air system malfunction Brake not releasing Air line too short Short brake pad lining life Slide pins Damaged rotor surface Vehicle overload Companion brakes do not work correctly Smoking brakes Contamination on the linings or rotor 16579 24240 Printed in the USA Refer to Brake drag Caliper seized or sticking on High brake temperature Check For Recheck chamber stroke after 20 brake applications Correct pad to rotor clearance Correct operation of air system or air chamber Damaged slide pin boots caliper should move back and forth by hand with linings removed Corroded pin in chamber clevis and lever Incorrect position of load plate between Saddle abutments Water entry or seized operation shaft internal Correct air line length Refer to Brake drag Damaged slide pin boots caliper should move back and forth by hand with linings removed Cracks or heavy heat checking Refer to the weight limitations on the vehicle identification pla
4. e bent cracked or broken springs Figure 6 ANTI RATTLE SPRING FRICTION MATERIAL LINING lt LINING THICKNESS BRAKE PAD ASSEMBLY 4004415a Figure 6 7 Measure the friction material lining thickness Replace the brake pad assembly before the lining thickness reaches Q 200 inch 5 1 mm Figure 6 8 Remove dirt or dust from the brake pad contact surfaces of the saddle abutments 9 Verify that the caliper slides freely on the slide pins Figure 7 OUTBOARD DIRECTION 4004416a Figure 7 10 Inspect the caliper boots If the boots are damaged replace the caliper Figure 8 e If you are replacing the calipers Refer to the caliper assembly removal and installation procedures in this bulletin 16579 24240 Printed in the USA PISTON BOOT 2X SADDLE ABUTMENT SLIDE PIN BOOTS 2X HIDDEN 400441 7a Figure 8 Disc or Rotor Inspection With the pads removed rotate the wheel and inspect the rotor Inspect both sides of the rotor for cracks and heat checks Replace the rotor if necessary Cracks 4 amp WARNING Always replace a cracked rotor to avoid serious personal injury and damage to components When the crack extends through a section of the rotor replace the rotor Figure 9 4001599a TP 02173 Revised 11 04 Copyright ArvinMeritor Inc 2004 Page 3 Heat Checking Heat checks are short thin sometimes numerous radial interruptions of the rotor braking
5. eritor Inc 2004 Printed in the USA 2 Install the adjuster plug and washer Tighten to 8 12 lb ft THICKNESS MEASUREMENT 11 17 Nem Figure 2 Leje 1 626 41 3 MM 3 Have another person make 10 or more brake applications to MINIMUM THICKNESS set the brake pad to rotor running clearance Verify that all air chambers and calipers correctly apply and release during the brake applications Applies to solid Remove the Caliper Assembly or vented rotor CAUTION Do not use the stabilizer bar to lift the caliper onto or off of the Fo 4 MICROMETER axle Damage to the stabilizer bar can result 4004422a 1 Remove the clevis pin from the lever Figure 13 2 Remove the air chamber 3 Remove the four saddle bolts Figure 14 Install the Brake Pads AIR 4 CAUTION CHAMBER NUT Replace the pads on both brakes of a single axle or on all four COTTER PIN WASHER brakes of a tandem axle at the same time If you do not replace IR CHAMBER CLEVIS AIR CHAMBER NUT all the pads at the same time poor brake performance can occur 1 Slide the caliper OUTWARD Install the OUTBOARD pad and spring assembly into the OUTBOARD side of the caliper Confirm that the load plate is correctly located between the saddle abutments Figure 8 2 Slide the caliper INWARD Install the INBOARD pad and spring assembly into the INBOARD side of the caliper 3 Close the stabilizer bar Install the stabilizer bar pin and cotter pin or tighten the hex
6. head bolt to 23 29 Ib ft 30 40 Nem 4 4 WASHER CALIPER AND j SADDLE BOLT Initial Brake Adjustment SADDLE J ASSEMBLY Dei e 4 amp CAUTION CRER 4004423a You must adjust the initial brake pad to rotor clearance or an IDENTIFICATION NUMBER inefficient dragging brake can occur Damage to components can result Figure 14 4 Lift the caliper and saddle assembly away from the rotor 1 Use the following procedure to adjust the initial brake p L aay pad to rotor clearance The air chamber must be installed and Replace the Rotor attached to the lever with the clevis pin before you proceed p with the initial brake adjustment procedure 1 Remove the caliper assembly Refer to the procedure in this A Use a 6 mm Allen wrench to adjust the caliper by reducing bulletin the brake pad to rotor clearance to ZERO Figure 3 2 Remove the hub and rotor assembly Refer to the axle B Verify that the load plate is in full contact with the brake manufacturer s service manual pad backing plate Figure 6 and Figure 8 C Increase the brake pad to rotor clearance 10 clicks or 3 4 turn de adjust to set the initial clearance Figure 3 TP 02173 16579 24240 Revised 11 04 Printed in the USA Copyright ArvinMeritor Inc 2004 Page 5 AQ WARNING 4 Attach a new rotor to the hub Use a brass or synthetic mallet for assembly and disassembly e For stud mounted rotors Press or pull the wheel studs procedures Do not hit steel parts with a steel ham
7. in the cab to verify that the air pressure in the tanks is 90 100 psi 620 689 kPa TP 02173 Revised 11 04 DiscPlus DX195 and DX225 Air Disc Brakes Inspection Installation and Diagnostics Release the parking brake Measure the distance from the bottom of the air chamber to the center of the clevis pin while the brakes are released This distance should be approximately 1 46 inches 37 mm Figure 1 e If the distance is greater than 1 62 inches 41 mm Refer to the diagnostics table in this bulletin to determine the cause and correct the condition MEASURE ADJUSTED CHAMBER STROKE Measure this distance 4004410a Figure 1 Have another person apply and hold the brakes one full application Measure the distance from the bottom of the air chamber to the center of the clevis pin while the brakes are applied subtract the measurement you obtained in Step 4 from the measurement you obtained in Step 5 The difference is the push rod travel or adjusted chamber stroke e f push rod travel or adjusted chamber stroke is greater than two inches 51 mm Refer to the diagnostics table in this bulletin e f push rod travel or adjusted chamber stroke is less than 0 88 inches 22 mm Readjust the brake Refer to the initial brake adjustment procedure in this bulletin Caliper Assembly Inspection 1 Remove the adjuster plug and washer Figure 2 ADJUSTER PLUG WASHER 4004411a Figure 2 4 amp CAUTION Alwa
8. lace the pads Readjust to set the correct pad to rotor clearance Observe the vehicle manufacturer s load recommendations Adjust or repair as required Replace the pads Correct the pad installation Replace the pads and rotor if necessary Clean or replace the pads if necessary Clean the pad abutments on the carrier Replace the pads if necessary Tighten the connections and fasteners to the specified torque Replace the rotor Install the pad springs Replace the pads Replace or tighten the pad retainer DRIVETRAIN PLUS Q THE COMPLETE SYSTEM ArvinMeritor Information contained in this publication was in effect at the time the publication was approved for printing and is subject to change without notice or liability Meritor Heavy Vehicle Systems LLC reserves the right to revise the information presented or discontinue the production of parts described at any time Copyright 2004 ArvinMeritor Inc All Rights Reserved Printed in the USA TP 02173 Revised 11 04 16579 24240
9. mer Pieces through the rotor into the hub Figure 15 of a part can break off Serious personal injury and damage to e For bolt mounted rotors Tighten the hub to rotor bolts to components can result 175 195 lb ft 238 265 Nem Figure 16 gt 3 Detach the rotor from the hub Use one of the following 5 Install the hub and rotor assembly Refer to the axle procedures manufacturer s service manual e For stud mounted rotors Use a brass or synthetic mallet 6 Install the caliper assembly Refer to the procedure in this to remove the hub to rotor studs Figure 15 Be careful not bulletin to damage the studs during this process Install the Caliper Assembl e For bolt mounted rotors Unscrew the hub to rotor bolts p y Figure 16 1 Place the caliper assembly over the rotor 2 Align the caliper saddle bolt holes and assemble to the torque plate using saddle bolts and washers 3 Tighten the saddle bolts to 400 500 Ib ft 544 680 Nem 4 STUD MOUNTED 4 Mount the air chamber to the caliper assembly Tighten the air chamber nuts and washers to 133 155 Ib ft 180 210 Nem T 5 Apply a coating of anti seize compound to the clevis pin Install the clevis pin and cotter pin 6 Install the brake pads Refer to the procedure in this bulletin Wheel studs go through rotor and hub 4004424a Figure 15 Ni BOLT MOUNTED Wheel studs go through hub only 4004425a Figure 16 TP 02173 Revised 11 04 16579 2
10. te Inspect the companion vehicle brakes and air system Refer to Brake drag and Short brake pad lining life Grease oil undercoating paint etc on the linings or rotor Copyright ArvinMeritor Inc 2004 Corrections lf the air chamber still overstrokes then replace the caliper and saddle assembly Readjust to set the correct rotor to pad clearance Refer to the vehicle manufacturer s instructions Repair or replace parts as required Replace the caliper assembly Clean or replace the clevis pin apply anti seize compound before reassembly Remove the brake pads and reinstall Refer to the procedure in this bulletin Replace the caliper assembly and air chamber Replace the air line Refer to the vehicle manufacturer s instructions Refer to Brake drag Replace the caliper assembly Replace the rotor Observe the vehicle manufacturer s load recommendations Adjust or repair as required Refer to Brake drag and Short brake pad lining life Can be a temporary situation with new or low mileage pads e Inspect the hub seal Replace as required e Clean the rotor and caliper assembly e Replace the pads TP 02173 Revised 11 04 Page 7 Conditions Poor stopping power e Long stopping distances e Poor driver feel e High brake pressures e Vehicle pulls to one side Brake noise Possible Causes Vehicle air system malfunction Contamina
11. tion on the linings or rotor Brakes out of adjustment Vehicle overload Companion brakes not working correctly Incorrect pads installed Incorrect pad installation Brake pads not free to move in the caliper Worn brake pads Brake component attachments are not installed to specification Rotor cracks or excessive runout Pad spring damaged or not installed Incorrect pads installed Bent or loose pad retainer ArvinMeritor Meritor Heavy Vehicle Systems LLC 2135 West Maple Road Troy MI 48084 USA 800 535 5560 arvinmeritor com Check For Correct air pressure at the chamber inlet Grease oil undercoating paint etc on the linings or rotor Excessive pad to rotor clearance Refer to the weight limitations on the vehicle identification plate Inspect the companion vehicle brakes and air system Refer to the vehicle manufacturer for the correct pads Friction material facing the rotor surface Corrosion or debris on the pads or carrier abutments Lining thickness Check for loose connections and fasteners Excessive cracking heat checking or runout Correct pad spring installation Refer to the vehicle manufacturer for the correct pads Bent pad retainer or loose pad retainer bolt Corrections Have the air system evaluated by a qualified brake system specialist e Inspect the hub seal Replace as required e Clean the rotor and caliper assembly e Rep
12. ys use a 6 mm Allen wrench to manually adjust and de adjust the brake Do not use air or power tools Damage to components can result 2 Usea6mm Allen wrench to de adjust the brake Stop turning the Allen wrench when you feel resistance When you feel resistance adjust the brake 1 4 turn to ensure that automatic adjustment will occur Figure 3 Note the location of the air chamber with respect to the adjustment direction ALLEN WRENCH DECREASE CLEARANCE ADJUST INCREASE CLEARANCE DE ADJUST DECREASE INCREASE CLEARANCE CLEARANCE ADJUST DE ADJUST 400441 2a Figure 3 TP 02173 Revised 11 04 Page 2 Copyright ArvinMeritor Inc 2004 3 Remove the stabilizer bar retainer and cotter pin Open the bar so that it is out of the way Figure 4 STABILIZER BAR OPEN POSITION DX225 uses bolt and washer to fasten the stabilizer bar STABILIZER BAR PIN COTTER PIN 400441 3a Figure 4 4 Lift the INBOARD brake pad out of the caliper assembly Mark the brake pad INBOARD Figure 5 INBOARD BRAKE PAD OUTBOARD BRAKE PAD 400441 4a 5 slide the caliper OUTWARD and remove the OUTBOARD brake pad Mark the brake pad OUTBOARD Figure 5 16579 24240 Printed in the USA 6 Inspect the brake pads for cracked friction material lining Check if the friction material is loose or detached from the backing plate Inspect the anti rattle springs attached to the brake pad Replac
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