Brake Pad/Disc Help
- Thread starter kieranjs
- Start date
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- Location
- the post-brexit wasteland
replacing the discs is one of those jobs that's easy with the right tool but impossible without. needs a torx head driver to undo the bolts.
my cable disc braked boardman went through pad/discs at a rate of 3-1, commuting 60km a day in all weathers.
my cable disc braked boardman went through pad/discs at a rate of 3-1, commuting 60km a day in all weathers.
the snail
Guru
- Location
- Chippenham
Could be that the pads were contaminated or glazed, so you coud clean the rotors, or rub them on wet and dry paper to get a clean surface, then bed the new pads in. While you're at it make sure the cables are lubed/moving freely, as well as the levers and calipers.
Those pads look very glazed you could try some sanding with heavy duty sandpaper but the bad news is mechanical disc brakes like you have are crap, in my experience worse than rim brakes. I hadn't some TRP spyres supposed to be just about the best mechanical brakes you can get but they were awful so much do I got rid of the bike. No amount of adjusting would get them to perform well.
I now have hydraulic brakes on all my bikes.
So try sanding, if that doesn't work try some new pads. Also clean the rotor with brake disc cleaner or isopropyl alcohol just in case they have been contaminated, be aware that they may never perform the way you expect. Good luck
I now have hydraulic brakes on all my bikes.
So try sanding, if that doesn't work try some new pads. Also clean the rotor with brake disc cleaner or isopropyl alcohol just in case they have been contaminated, be aware that they may never perform the way you expect. Good luck
Correct function of mechanical disc brakes is very reliant on excellent alignment. If the pads don't engage with the discs perfectly, they don't work.
The procedure for setting caliper position on hydraulic brakes doesn't apply to mechanical systems. Give me a day or two to write up a set of instructions for you.
The procedure for setting caliper position on hydraulic brakes doesn't apply to mechanical systems. Give me a day or two to write up a set of instructions for you.
Important info:
**The following relates to Single Arm mechanical disc brakes only. There is a slightly different methodology for Avid BB7s. I have no experience of Double Arm types.**
*Ensure the caliper mount adapters are compatible with the rotor size used*
A. Start with new pads. Trying to do this with even slightly worn pads is an exercise in futility.
B. Start with very clean calipers. Pad adjusters and lever arm must move freely. Ensure pad adjusters are fully retracted.
(Most easily seen without pads installed) *DO NOT unscrew too far*
C. Use good quality compressionless cable housings.
D. Ensure all cable housings ends are properly prepped and fitted with METAL caps.
E. Rotors must be true to within 0.3mm and fitted to hubs. Tighten all bolts.
F. If brake levers allow for fine tuning of modulation, start with modulation knobs turned fully in.
G. Ensure all wheel nuts, QRs, etc. are tight and wheel is correctly set in dropouts.
H. Use Loctite Blue 242 on all bolts.
J. 'Loose fit' means half turn back from finger tight on bolts.
K. 'Tighten' means torque to manufacturer's specifications.
L. Counterclockwise means as viewed from non-drive side.
. . . . . . . . . . . . . . . . . . . . .
Procedure:
1. Loose fit adapter to frame. Push adapter firmly in direction of rotor (counterclockwise) whilst tightening bolts.
2. Loose fit caliper (with pre-installed pads) to adapter.
3. Turn pad adjuster in fully (*Record number of rotations for reference*)
4. Double check brake lever barrel adjuster is turned in fully and cable housing is sitting correctly in lever.
5. Feed cable into caliper lever arm pinch bolt ensuring there is no slack in cable. Tighten cable pinch bolt. Ensure caliper lever arm remains in neutral/home/relaxed position.
6. Pull and hold brake lever. Rotor should not move in caliper but caliper may move on its mount. Rotate wheel in counterclockwise direction whilst tightening caliper bolts.
7. Activate lever four times to seat everything. DO NOT over tension/force levers.
8. If inner pad rubs against rotor, turn pad adjuster ⅛ turn out. Pull and release brake lever. Keep adjusting ⅛ turn at a time (activate brake lever each time) until no rubbing is heard.
9. Visually establish that the full face of the brake pad sweeps the braking area on the rotor disc. Any mismatch here means braking power will be diminished.
. . . . . . . . . . . . . . . . . . . .
Refinements:
9. If lever throw is not to your liking, caliper must be moved laterally on its mount. This normally requires repeating steps 3 - 8 with a spacer inserted between either outer or inner pads and rotor face immediately prior to step 6. Start with thin business card thickness and adjust thickness of spacer accirdingly.
10. Turn modulation knob on REAR brake lever out to compensate for housing compression.
. . . . . . . . . . . . . . . . . . . .
And finally:
Mechanical disc brakes are very sensitive to alignment. For trouble free stopping power it is imperative to get the whole of both pad faces exactly parallel to the rotor AT THE MOMENT OF CONTACT.
Regular inspection of brake pads for wear patterns will allow for realignment if so required. Once the pad shows uneven wear it will be almost impossible to achieve optimum stopping power.
**The following relates to Single Arm mechanical disc brakes only. There is a slightly different methodology for Avid BB7s. I have no experience of Double Arm types.**
*Ensure the caliper mount adapters are compatible with the rotor size used*
A. Start with new pads. Trying to do this with even slightly worn pads is an exercise in futility.
B. Start with very clean calipers. Pad adjusters and lever arm must move freely. Ensure pad adjusters are fully retracted.
(Most easily seen without pads installed) *DO NOT unscrew too far*
C. Use good quality compressionless cable housings.
D. Ensure all cable housings ends are properly prepped and fitted with METAL caps.
E. Rotors must be true to within 0.3mm and fitted to hubs. Tighten all bolts.
F. If brake levers allow for fine tuning of modulation, start with modulation knobs turned fully in.
G. Ensure all wheel nuts, QRs, etc. are tight and wheel is correctly set in dropouts.
H. Use Loctite Blue 242 on all bolts.
J. 'Loose fit' means half turn back from finger tight on bolts.
K. 'Tighten' means torque to manufacturer's specifications.
L. Counterclockwise means as viewed from non-drive side.
. . . . . . . . . . . . . . . . . . . . .
Procedure:
1. Loose fit adapter to frame. Push adapter firmly in direction of rotor (counterclockwise) whilst tightening bolts.
2. Loose fit caliper (with pre-installed pads) to adapter.
3. Turn pad adjuster in fully (*Record number of rotations for reference*)
4. Double check brake lever barrel adjuster is turned in fully and cable housing is sitting correctly in lever.
5. Feed cable into caliper lever arm pinch bolt ensuring there is no slack in cable. Tighten cable pinch bolt. Ensure caliper lever arm remains in neutral/home/relaxed position.
6. Pull and hold brake lever. Rotor should not move in caliper but caliper may move on its mount. Rotate wheel in counterclockwise direction whilst tightening caliper bolts.
7. Activate lever four times to seat everything. DO NOT over tension/force levers.
8. If inner pad rubs against rotor, turn pad adjuster ⅛ turn out. Pull and release brake lever. Keep adjusting ⅛ turn at a time (activate brake lever each time) until no rubbing is heard.
9. Visually establish that the full face of the brake pad sweeps the braking area on the rotor disc. Any mismatch here means braking power will be diminished.
. . . . . . . . . . . . . . . . . . . .
Refinements:
9. If lever throw is not to your liking, caliper must be moved laterally on its mount. This normally requires repeating steps 3 - 8 with a spacer inserted between either outer or inner pads and rotor face immediately prior to step 6. Start with thin business card thickness and adjust thickness of spacer accirdingly.
10. Turn modulation knob on REAR brake lever out to compensate for housing compression.
. . . . . . . . . . . . . . . . . . . .
And finally:
Mechanical disc brakes are very sensitive to alignment. For trouble free stopping power it is imperative to get the whole of both pad faces exactly parallel to the rotor AT THE MOMENT OF CONTACT.
Regular inspection of brake pads for wear patterns will allow for realignment if so required. Once the pad shows uneven wear it will be almost impossible to achieve optimum stopping power.
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