Brake Caliper Piston reset?

[DeadLock]

Hi everyone,

I changed my brake pads today on my A3 8P 2.0TDi. Didn't have the brake caliper windback tool, so used a vice-grips and some leverage to push it back. The thing is I didn't push it ALL the way back, prob was still out a half inch.
When I installed the new pads it was all pretty tight but I just thought to myself it would naturally reset itself when all back and driving.
After I put it all back together the wheel wasn't spinning freely (yes with handbrake off!).
I ran the output tests on VCDS and it did a few ABS tests I think.
Took it for a spin and didn't make any noises or anything, but very tight. I'd be surprised if you could squeeze a pin between the disc and the pad.
On the other side I managed to get the piston in the caliper quite far back and after tightening there was a little bit more room between the disc and the pads.

Please tell me it is normal for it all to be super tight and it will find its own levels through driving it?!

 

[rum4mo]

Using something like vise grips to force the rear pistons back in was not a good idea!

These pistons have a threaded rod passing through/into them and it auto adjusts to keep the handbrake adjustment correct, you MUST only retract them using some method that involves rotating the pistons - ideally a nice cheap piston rewind tool.

 

[DeadLock]

Yes i made sure to rotate them as i pushed, they wound in quite quickly.

 

[audiwaterpump]

Hi everyone,

I changed my brake pads today on my A3 8P 2.0TDi. Didn't have the brake caliper windback tool, so used a vice-grips and some leverage to push it back. The thing is I didn't push it ALL the way back, prob was still out a half inch.
When I installed the new pads it was all pretty tight but I just thought to myself it would naturally reset itself when all back and driving.
After I put it all back together the wheel wasn't spinning freely (yes with handbrake off!).
I ran the output tests on VCDS and it did a few ABS tests I think.
Took it for a spin and didn't make any noises or anything, but very tight. I'd be surprised if you could squeeze a pin between the disc and the pad.
On the other side I managed to get the piston in the caliper quite far back and after tightening there was a little bit more room between the disc and the pads.

Please tell me it is normal for it all to be super tight and it will find its own levels through driving it?!

How did you get on with this?

 

[Retroman]

The smaller TRW calipers fitted to the rear of many A3 and Golfs are renowned for seizing. As a result, companies like GSF sell hundreds of them. When I gave my brakes a good overhaul, I didn't like the feel of one of the rear calipers and decided to change both (around £60 each for new ones). GSF sold me identical OE TRW ones which had a 2-year guarantee but had the VAG Group emblems machined off.

 

[audiwaterpump]

The smaller TRW calipers fitted to the rear of many A3 and Golfs are renowned for seizing. As a result, companies like GSF sell hundreds of them. When I gave my brakes a good overhaul, I didn't like the feel of one of the rear calipers and decided to change both (around £60 each for new ones). GSF sold me identical OE TRW ones which had a 2-year guarantee but had the VAG Group emblems machined off.

Do you know which bit is prone to failure?
The slider pins seizing?
or something else.

 

[Retroman]

It seems to be the piston internals, making the piston difficult to retract

 

[audiwaterpump]

It seems to be the piston internals, making the piston difficult to retract

A bit surprised about that, as it's just a simple piston in a cylinder with a seal.

 

[Retroman]

A bit surprised about that, as it's just a simple piston in a cylinder with a seal.

I don't disagree with you, it does seem odd that these particular VAG/TRW calipers (typically fitted to FWD, manual handbrake models) should be susceptible to seizing. I can only assume it must be either a design issue with the front dust cover or the "wind-in" manual handbrake mechanism at the rear?