Any brake/abs gurus? Audi brakes

attila_

Hi

I am stumped over this issue and wondered if anyone could help.

2 months ago I took my audi a4 (b8) 2009 to my mechanic due to front brakes seized. He reported it was the flexi hoses. So he fitted new hoses, discs and pads and replaced fluid as it cooked.


2 months later I have the same issue but noticeably only on right front. It sticks and when I brake at speed it judders.

Lifted the car and the right wheel was very difficult to move. Whilst left was ok. Took pads off and pushed caliper in. It seemed fine and went in ok. Tried other side and the same. So both calipers didn’t look siezed. Also checked the stainless guide pons and pooked fine.

Put it all back together both sides and right hand side is still tougher to turn compared to left. Brake still getting hot.

I did an abs fault scan and whole car scan and found bo errors.

Any ideas?

arcon5

It won't be abs.

It will be either piston or slider pins. Does the caller move back and forth on the guide pins...

I suspect this was the original fault but pushing piston back and disturbing pins to fit new brakes helped ease it off a bit.

Take out pins completely and inspect them.properly as a first point of call

Gloomendoom

I have a very similar problem with my wife’s car at the moment. No problem with hoses, slide pins or ABS. The caliper piston is a ceramic material and swells and/or distorts slightly with age and can stick in the bore. It’s a known issue. The only solution is to replace the piston or the caliper.

ETA It doesn’t look like Audi used ceramic pistons on the 2009 A4.

Sam_Fallow

attila_ wrote: »

Hi

I am stumped over this issue and wondered if anyone could help.

2 months ago I took my audi a4 (b8) 2009 to my mechanic due to front brakes seized. He reported it was the flexi hoses. So he fitted new hoses, discs and pads and replaced fluid as it cooked.


2 months later I have the same issue but noticeably only on right front. It sticks and when I brake at speed it judders.

HIGHLIGHTED... None of those remedies will fix a sticking brake.

attila_

Thanks all. I will have another look it may be that the high temperatures front the first time round has caused something to warp (pins or piston).

attila_

arcon5 wrote: »

It won't be abs.

Does the caller move back and forth on the guide pins...

Yes i checked this. The pins are stainless with no corossion and looked in good shape. I also though if it was pins one pad would be worn more than the other? As piston would retract but caliper would stay stuck in that position?

thescouselander

OP, can you clarify? You took the brakes apart, reset everything and then put it back together and the wheel was still difficult to turn - correct?

If that's the case it sounds more like bearing trouble to me.

AdrianC

Sam_Fallow wrote: »

HIGHLIGHTED... None of those remedies will fix a sticking brake.

Flexis may well do, if they're delaminating internally and effectively acting as a one-way valve. It does happen...

But I'm also looking sternly at the calipers here.

Muscle750

When its all together and the wheel is hard to turn crack off the bleed valve and see if this releases the wheel if so id say collapsed brake pipe or part stuck caliper. Either ive missed it or you havent said front or rear if its the rear the handbrake is sticking mine did it alot on my a6

attila_

thescouselander wrote: »

OP, can you clarify? You took the brakes apart, reset everything and then put it back together and the wheel was still difficult to turn - correct?

If that's the case it sounds more like bearing trouble to me.

Correct but the wheel (hub) is easy to turn with no pads. I also put a laser heat sensor on either side and one side was reading 30degC and thr other side 100degC which makes me think friction

attila_

Muscle750 wrote: »

When its all together and the wheel is hard to turn crack off the bleed valve and see if this releases the wheel if so id say collapsed brake pipe or part stuck caliper. Either ive missed it or you havent said front or rear if its the rear the handbrake is sticking mine did it alot on my a6

Should have done this. Will do. I’ll do a fluid replacement but I may just buy a caliper they are around £70 new