Brake-Related Problem

[Cobstar]

I wonder if any of you can shed any light on a problem we've got with my RS2.

A week or so back the car started normally and ran through the self check OK. Pulled away from the drive, turned right (applied the brakes lightly at this point) and then within a 10-15yards it felt like the near side rear brake had come on fully of its own accord. Brakes were fully applied and released but on pulling forward it came on again. Had great difficulty turning the car round and limping the 100yards home. The ABS light came on.

Car is currently at the garage. So far, they've had the rear brakes apart and checked pistons and calipers so it isn't the normal corrosion problem with the Porsche calipers. Pads on handbrake have been replaced as they were worn. Cables are free.

Rear diff has been drained as garage advised by local gearbox specialist that there was sometimes a problem with metal getting into fluid. Again no problem. Has also been suggested that gearbox is drained.

Garage have also spoken to the guy who serviced it for previous owner. He couldn't shed any light on problems although he had cleaned up rear calipers etc a couple of years ago when brakes were binding on.

Fault hasn't occurred whilst garage have had car - but isn't that always the way!

Nothing has showed up when garage checked fault codes!

Any ideas?

[GlynRS2]

Tricky one - especially as it appears to have cured itself now it is at the garage.
I wonder whether it may have been the handbrake binding as it first started after the car had been parked up for a while, presumably with the handbrake on. I know the mechanism inside the braking drum can sometimes seize, and there is a repair kit containing the springs and regulator. Now that they have given it a good clean & replaced the handbrake shoes you may find it is ok. Fingers crossed. I think the ABS light would come just if there was any restriction in rotation of the wheel, so that may be a red herring.
I get they occasional squealing from my left rear wheel, especially first thing in the morning. I suspect it may be the handbrake not releasing properly. I was planning to check it soon. The other thought I had was the wheel bearing, but they usually cause a rumble rather than a squeal. I will get on and look at it this weekend in order to try and avoid a scenario like yours.

[scillyisles]

Well at first I thought it might be the handbrake but thinking about it I don't think so - the clue being the fact that the ABS light came on.
Don't forget the ABS system for Audis is more complex than two wheel drive ABS in that it has to be able to cope with four wheel drive. Sounds to me like the ABS system was trying to brake the wheel in question and the system was overloaded ( could be faulty ABS wheel sensor or faulty ABS control unit)

[Jani]

Sounds strange. Only thing that comes to mind is a disintegrated rear brake hose. The way this could cause that is that the interior of the brake hose has disintegrated from outer hose structure. As fluid is flowing back from the pistons, the interior part of the hose blocks return flow. As time passes, fluid pressure is slowly released, hence the wheel is no longer locked. Depending how the hose disintgrates, it can flow OK in one direction, and not in the other. Also it can be erratic, sometimes working OK, others not.

If you haven't had brake hoses changed, might as well do that. Keep us posted if you find the fault.

[Cobstar]

Thanks guys - I'll pass this information on. I want my car back!

[Cobstar]

Conclusion - the problem was handbrake related. Everything seems fine now - just waiting for the handbrake shoes to bed in LOL.

[GlynRS2]

Cobstar,
Do you know exactly what they had to do? Was it just the shoes or did they replace the springs etc?

[Cobstar]

Hi Glyn

Just the shoes and cleaning things up as far as I'm aware. Haven't had the bill yet though.