Disc brakes, not working

[Philip Benstead]

I can't get mechainical disc brake to work.

I done the following.

Remove rotor and pads

Degrease pads
Rud with emery paper 320 grade
Degrease rotor and dryed
Rub with emery paper 320 grade

On rhe second attemp
I even lite the degreaser to burn the containmination of
Still does not work.

I have ordered some pads
I will buy some emery paper 120 grade

Comments welcomed.

[cyclop]

Changing pads is the obvious first port of call.You,ve already degreased disc.Are your brake levers of the adjustable type i.e. can you alter the mechanical advantage and if so, has the fulcrum somehow changed inadvertantly? Unlikely.Once pads are contaminated,always ditch as I believe they are somewhat porous so you,ll never get rid of contamination,even if you burn them,put them in the dishwasher,whatever as oil/grease/contaminents can penetrate deep into a pad.

[gregoryoftours]

You can lose a lot of power through cable corrosion/outer lining wear too.

[RickH]

Are the brakes & levers compatible? Road pull levers & mountainbike pull callipers will never work satisfactorily (at least not with out a cable pull widget in the system).

Is there enough pad material left? Pads usually start with about 2mm thickness of the friction material & should be replaced when there is about 1mm left.

Are the pads adjusted right. Many cable discs need clearance adjusting using the pad adjusters & only use any cable adjustment just to take up slack when the calliper arm is resting against its stop.

In the absence of specific instructions, I would make sure the calliper's slot is centrally over the rotor (maybe a little offset to give more space on the side with the fixed pad). Adjust the pads so that they are against the rotor without bending it as you adjust them in, then back of both pads just enough for them not to catch the rotor. Finally, slacken the bolts fixing the calliper on so that they can move sideways, hold the brake hard on & retighten the bolts to make sure the calliper is aligned with the rotor.

[jb]

Sounds like the pads are at fault if they worked okay in the past. Is the non-moving pad properly adjusted up to the rotor?

[gom]

I have mechanical disks on my Genesis touring bike - single sided. On a recent two-week trip as the pads wore I was adjusting the cable pull, but found the performance had become much worse than expected. Turning the adjuster for the fixed pad restored the performance.
This is not something I was expecting, but I now know needs to be look out for.

[sizbut]

Perhaps help others help you by saying what you mean by "I can't get mechainical (sic) disc brake to work".

The actions you say you've taken imply you think its a lack of pad grip on the rotor, but already that's us guessing. If we have to guess the actual problem, then we're double guessing possible solutions.

- Do the brake levers move? Freely or do they seem stiff?

- Do the pads move when the brake levers are operated? Both side?

- When the levers are moved all the way, do the pads appear to be in contact with the rotors> Again, both sides? (yes, that can all require contortions to see)

- What make and model of disk brake?

[Milfred Cubicle]

Well, you've made a decent start, but I'd say you would be better off starting with a fresh set of pads. Once they have got grease embedded, cleaning used pads doesn't really get rid if it..
I know some people will cry 'NO', but I've found some of the cheaper organic pads from Amazon to be great...they have stood up to loads of mountain bike abuse. I used to use sintered...but on some my bikes the organics work so much better...they wear faster, but are cheaper anyway so it offsets the wear rate.
Maybe try the cleaning/roughening process again, a good quality cable inner replacement then new pads.
I don't want to insult your intelligence,but are you bedding them in/glazing them? Half a dozen high speed stops on each brake usually does it...obviously a safe environment!