Brake padel problem (ur)

[ChrisD]

Hello all,

Recently, whilst driving my quattro (ur), I've noticed about an inch of free play/no pressure at the top of the brake pedal.
This does not occur all the time and will then become a very hard pedal.
On a recent journey out, driving in stop/start traffic, I could feel that one of my calipers had locked on (the rear off-side caliper).
You could feel the car dragging, in the o/s rear corner, as you dipped the clutch.

Soooooooooo, I thought, right - this is the problem causing the brake issues. So, I repleced the caliper and thought that would be the end of the problem.

Not so................I still have the same brake pedal feel (initial slack then, rock solid), but no calipers sticking?

I'm sure there's no air in the system and the brake does not feel spongey.

Could this be a Master cyl prob?

Any ideas - sorry to sound a numpty if this is something really simple

Cheers, Chris

[volcano rs]

sounds like brake bomb (brake pressure accumulater sphere )bmw 5 series uses the same one same from euro car parts

[Rusty]

Could also be the servo, the bomb is easy to test (see www.s2cetral.net) so best to start there like Volcano says.

[ChrisD]

Ok.
I thought the bomb was only a reserve? so, when the engine's running, the state of the brake accumulator is not an issue?
Cheers, Chris

[A80Avant]

its more or less the same as i have as a problem now. Check for leaks.

I will be bleeding the brakes and hopefully changing the brake bomb as well