9.23
BRAKES
9
REAR BRAKE DISC
Disc Inspection
1. Visually inspect disc for scoring, scratches, or gouges.
Replace the disc if any deep scratches are evident.
2. Use a 0-1"micrometer and measure disc thickness at 8
different points around perimeter of disc. Replace disc if
worn beyond service limit.
3. Mount dial indicator and measure disc runout. Replace the
disc if runout exceeds specifications.
4. Install brake line and tighten with a flare nut wrench.
5. Follow bleeding procedure outlined earlier in this chapter.
6. Field test unit for proper braking action before putting into
service. Inspect for fluid leaks and firm brakes. Make sure
the brake is not dragging when pedal is released. If the brake
drags, re-check assembly and installation.
TROUBLESHOOTING
Brakes Squeal / Poor Brake Performance
• Air in system
•Water in system (brake fluid contaminated)
•Caliper/disc misaligned
•Caliper dirty or damaged
•Brake line damaged or lining ruptured
•Worn disc and/or friction pads
•Incorrectly adjusted stationary pad
• Worn or damaged master cylinder or components
•Damaged break pad noise insulator
Pedal Vibration
•Disc damaged
•Disc worn (runout or thickness variance exceeds
service limit)
Caliper Overheats (Brakes Drag)
•Compensating port plugged
•Pad clearance set incorrectly
•Parking brake lever incorrectly adjusted
• Brake pedal binding or unable to return fully
•Parking brake left on
• Residue build up under caliper seals
• Operator riding brakes
Brakes Lock
•Alignment of caliper to disc
•Caliper pistons sticking
•Improper assembly of brake system components
Brake Disc Thickness
New .150-.165” (3.81-4.19 mm)
Service Limit .140” (3.56 mm)
Brake Disc Thickness Variance
Service Limit .002” (.051 mm)
difference between measurements
Brake Disc Runout
Service Limit .010” (.254 mm)
Rear Brake Disc
Rear Brake
Measure
Thickness
Disc
Front View of Brake Disc
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