Brake unbalanced problem

[soven]

Car failed wof for a brake problem. According to mechanic, Left rear brake is going into the red straightaway. Handbrake however is fine on both sides. Car has had that same caliper changed to a 2nd hand unit for a wof 2,000kms ago.(not sure if related)

What could cause it?Would air in the system cause that or does it only cause spongy brakes? Master cylinder probable cause?

[sergei]

have you changed rear pads recently, if so did you press the rear piston in or screw it? I assume it is corolla/starlet. If it is celica/corona then the handbrake is separate to normal brake. Anyway it looks like that caliper is semi-siezed.

[soven]

It is an AE82.

Caliper was changed 2000kms ago. I am guessing the last mechanic did a bad job... left rear tyre had to be changed for this wof as well because it was worn down . I think they are related.

[mjrstar]

i had the same problem on my girfriends 99 corolla.I did pads and slave cylinder bleed etc... ..if the problem you have is too much pressure, The problem will almost certainly be the front to rear brake bias valve. i removed it and got it rebuilt. the bias valve will be easy enough to find, probably somewhere on the firewall doen behind the inlet manifold...
Don't forget to give everything a good bleed afterwards.

[Bling]

..if the problem you have is too much pressure, The problem will almost certainly be the front to rear brake bias valve.

I wouldn't be too sure, as I would expect both rear wheels to be affected, but WOF says on left is a problem.



I don't have much experience with brakes, but i'd take the pads off and caliper off and crc and brake clean the caliper and piston and see how it went after that. if still failed i'd then look at spending money

[soven]

Yeah, I was wondering about the bias valve but then the problem is only on the left rear caliper which "goes into red immediately" compared to the others which are fine. Dont think that it is a problem due to improper bleeding either as I think that would just cause a lost of braking power.

Will do what Bzg|Bling suggests firsts. cheers.

[big_boy]

2 points

-1 from memory there dignagly split ant they meaning the bias valve can affect just one rear wheel

-2 keep that CRC miles away from your pads rotors ect breakleen is the only thing for the rotors ect

[mjrstar]

the brake lines on my mrs's 99 corolla does split into 2 seperate lines at the bias valve. thus the l/h side had full unrestricted pressure and the r/h side was geting the correct pressure.