Brake system troubleshooting guide
PROBLEM |
POSSIBLE CAUSE |
SOLUTION |
| SOFT PEDAL FEEL | AIR IN SYSTEM | BLEED BRAKE SYSTEM OPENING BOTH FRONT AND REAR BLEEDERS AT SAME TIME (3-PERSON JOB) |
| LEAK IN HYDRAULIC LINES, CALIPER OR MASTER CYLINDER |
VISUALLY INSPECT SYSTEM FOR LEAKS AND PRESSURE CHECK SYSTEM |
|
| CALIPERS FLEXING EXCESSIVELY | CHECK MOUNTING BOLTS AND AMOUNT OF SPACERS BEHIND MOUNTING EARS (AN EXCESSIVE NUMBER OF SPACERS WILL LET THE CALIPER FLEX TOO MUCH RESULTING IN SPONGY PEDAL) |
|
| FAULTY MASTER CYLINDER | SWITCH OR REPLACE MASTER CYLINDER | |
| PEDAL GOES TO FLOOR ABRUPTLY | PEDAL ASSEMBLY LINKAGE FAILURE | CHECK ALL PUSH RODS AND JAM NUTS ALONG WITH PEDAL MOUNT TO ENSURE THAT ALL IS TIGHT AND WITHOUT SLOP, INCLUDING BALANCE BAR (REFER TO BIAS BAR NOTES) |
| PADS FEEL LIKE THEY DRAG ON DISCS |
RESIDUAL PRESSURE VALVE LEFT IN MASTER CYLINDER |
TAKE PISTON OUT OF MASTER CYLINDER AND REMOVE RESIDUAL VALVE FROM FRONT END OF MASTER CYLINDER AND REPLACE PISTON ASSEMBLY |
| BAD MASTER CYLINDER | SWITCH OR REPLACE MASTER CYLINDER | |
| EXCESSIVE DISC RUN-OUT (WARPING OF DISC) |
CHECK RUN-OUT OF DISCS AND REPLACE IF NECESSARY. RUN-OUT SHOULD BE BETWEEN .000 – .015 (RESURFACING OF DISC IS NOT RECOMMENDED) |
|
| CALIPERS OUT OF SQUARE WITH DISC FACE |
RE-CENTER AND SQUARE CALIPERS TO FACE OF DISC WITH SHIMS IF NECESSARY YOU SHOULD BE WITH IN .005 TOP TO BOTTOM (SQUARE) AND .020 SIDE TO SIDE (CENTERED) |
|
| BRAKE PADS TAPERED END-TO-END (MORE THAN .060) |
REPLACE PADS WITH NEW AND CHECK CALIPER FOR CENTER AND SQUARE |
|
| PISTON HANGING IN CALIPER | REBUILD CALIPER, INSPECT PISTONS AT SEAL SURFACE, LOOK FOR SCARRING AND CHECK PISTON AND CALIPER FOR OUT OF ROUND |
|
| CAR DOES NOT STOP WELL | WORN OUT PADS | REPLACE PADS |
| PEDAL RATIO INCORRECT | REFER TO BRAKING FORCE CALCULATION FORMULAS CHART TO FIND CORRECT PEDAL RATIO |
|
| INCORRECT MASTER CYLINDERS | REFER TO BRAKING FORCE CALCULATION FORMULAS CHART TO CHOOSE CORRECT MASTER CYLINDER |
|
| INCORRECT PAD SELECTION | REFER TO COMPOUND DESCRIPTIONS | |
| PISTONS HANGING IN CALIPERS | REBUILD CALIPER, INSPECT PISTONS AT SEAL SURFACE, LOOK FOR SCARRING AND CHECK PISTON AND CALIPER FOR OUT OF ROUND |
|
| LEAKING CALIPERS | SEALS DRIED AND OR CRACKED | REBUILD CALIPERS AND INSTALL NEW SEALS |
| CUT OR ABRASION IN SEAL | REBUILD CALIPER, INSPECT PISTONS AT SEAL SURFACE, LOOK FOR SCARRING AND INSTALL NEW SEALS |
|
| FEEDBACK IN PEDAL | EXCESSIVE RUN-OUT OF DISCS | REPLACE DISCS |
| CRACKED DISCS | REPLACE DISCS | |
| LOOSE MOUNTING BOLTS IN CALIPER | CHECK ALL MOUNTING BOLTS ON CALIPERS | |
| EXCESSIVE BEARING CLEARANCE (LOOSE HUBS) |
INSPECT HUB MOUNTING NUTS AND BEARING RUN-OUT. LOOK FOR BAD BEARING |