Brake Fluctuating Prob - 16V

[moggs]

My Valver has yet again gone and failed the MOT. The main problem was the brakes. apparently the brake readings they took were "fluctuating too excess" He said it Could be the discs are warped but these were replaced a couple of months ago along with the pads, but the back discs are shot and need replacing but these passed fine,

could this be the problem as the backs dont really do much under braking. I also think the pedal is traveling to far before any braking happens.

Any help much appreciated

Cheers Ian

 

[Ben j]

is ya brake bias valve set properly? and wat discs and pads did u put on?

 

[BenR]

SO its your front brakes?

The compensator will have no effect, the fronts sould always work.

By fluctuating does he mean that DURING the braking procedure the brake effort goes up and down, or during every application (press off the pedal) the braking effor is different.

 

[moggs]

Put Standard disks and kevlar pads. Havent done anything with the bias valve so would think its ok.

 

[BenR]

still need the details mate.

 

[moggs]

Yes during the braking procedure the reading was going up and down. If the brakes were warped wouldnt i be able to feel it through the pedal if it was as bad as they say??

 

[BenR]

well, typically, actually, i have never seen a warped disc. Warped means that one side is curved and the other side of the disc follows that curve. This is VERY hard to acheive on vented discs as they just dont get hot enough.

What does happen alot is pad deposits are left on teh disc, leaving an imprint that isnt visible to the eye (sometimes is a tiny about). The deposit of pad material creasats a high point, aswell as a higher mu so it feels like the pedal is juddering.

This is because people sit on the brakes when they are hot, or come to a complete stop after a long braking period, and the pad sitcks to the disc.

Also from improper bedding in (NOT the 200 mile pootle about method).

 

[JAY172]

a warped disc/excessive disc run out would normally be felt through the pedal if you cant feel anything maybe the disc surface is contaminated on one area making the efficiency less on one area of the disc so making the overall brake efficiency reading fluctuate.

 

[moggs]

What about anything else like the pressure is being affected in any way. is this possible??

I cant see it being the disc as i would feel it through the pedal and if the surface is contaminated would it be as bad as "excessive" (what MOT station said it was)

Cheers for your help guys