Mot Brake Imblance Advisory At Mot

[T600]

The MR2 was MOT'd today and passed, though not with flying colours as I'd hoped.

I was told that the front brakes only just passed the Imbalance test and the braking system therefore requires adjustment or repair (not the former surely, there's nothing to adjust is there?).

Anyway, this surprised me as the car brakes in a perfectly straight line - I've tried it on a stretch of straight clear road.

And the Measurements section of the Advisory says "RBT Front Brake Imbalance 4%" which doesn't sound like much to me. There's no indication of what would constitute failure, so checked on the web and the only figures I can see say that imbalance on the driven wheels must be less than 25% (which does sound like a lot).

Added to this, there's also a note on the "Visual Safety Report" advising of Brake Drag on the O/S/F brake which I guess is related; perhaps there's a sticking piston.

Does anyone know what the limits are, and what is involved in stripping down the brakes. Is cleaning them likely to help or is it more likely to be a case of new Pads, discs, and/or calipers?

Cheers, Tony

[gazza1286]

The drag on the f/o/s will just be grit/crud build up on the pads. If severe, the pads may have developed a glaze due to overheating and this may have caused the brake imbalance. I'm with you on that fact that if a car pulls up straight then the brakes are OK. The MOT brake test is only carried out on the rolling road and at a very slow speed.

Simple job to remove and clean:

http://www.mr2-tech.com/bgb/mechanical/vol...rake_system.htm

[T600]

The drag on the f/o/s will just be grit/crud build up on the pads. If severe, the pads may have developed a glaze due to overheating and this may have caused the brake imbalance. I'm with you on that fact that if a car pulls up straight then the brakes are OK. The MOT brake test is only carried out on the rolling road and at a very slow speed.

Simple job to remove and clean:

http://www.mr2-tech.com/bgb/mechanical/vol...rake_system.htm

Thanks gazza, that's great info.

I'll probably give them a good clean and check for glazing when I get time.

I also called the dealer back and they say that yes, 4% isn't far out at all and the reason for the wording of the advisory was that they only have certain codes to select on the system. So once they note the fact that Imbalance wasn't zero then they have to use a code, and the only one relevant was the one that implied that the the system had just passed, when in reality they agree that 4% is well within tolerance.

I'll still give them a clean as described though as I guess they'll get worse over time if I don't do anything. Especiall as the car does about 2K per annum.

[Guest MrMojo]

Hi Tony,

Not seen ya around in a bit fella, but.............

When you do it check both sliders are free to move easily, just changed pads in mine recently, bottom slider on o/s/f was seized solid, and n/s/f was not as free as i would of liked, so free'd it off and had to buy new (s/h from breakers) caliper carrier for o/s/f.

HTH,

Mo.

[T600]

Hi.

Good advice thanks, I'll check it out. Trouble is probably not using the car much over the winter, or during the current monsoon weather. I also took it down to the Pod last week on the hope that weather was going to be decent and it was the pits.

Nice to be remembered thanks. Been browsing from time to time, but a few things put me off posting for a while.

Good to be back though and hopefully will get to a few events - bubble or JAE perhaps - and see all the new cars that people have bought while I've been away.

Cheers,

Tony