Nearside Front Caliper Sticking

[Owen341]

Hi everyone,

Im new to the forum.

I have an A4 Avant Quattro b6 1.9 tai quattro with 53000 miles. One gent owner, car possibly been stood for on and off for a while. I'm lead to believe the owner before me lived abroad and drove the car whenever he came back to the UK.

After recently having new discs and pads, I have found that the N/S front calliper is a little sticky and gets very hot after a few miles on an A road drive. It got to the point where after about 5 mins up the motorway the steering wheel began to judder, and even more so after braking.


I took the car to my local mechanic who stripped the callipers, regreased and bled them. Everything seemed to be fine until it happened again with the wobbly steering and worser braking.

With a suspected warped disc (brand new pagid), I opted to go for a new set of discs and a refurbed calliper. I drove the car again for about 10 miles up dual carriage way and a little bit of B roads. I understand that new discs and pads get hot but this was ridiculous compared to the O/S which was luke warm.

The next stage having agreed with my mechanic is to see how they bed in over the weekend, to no avail.
I have looked through the cars history, and have noticed that it has had issues with the same front N/S brakes before. This will be the 3rd calliper it's had.

Has anyone had any similar experiences or could offer a solution?


I have got to the point where having spoke to another mechanic neighbour, to swap out the master cylinder and servo. Ive checked the battery tray which sometimes fills with water and that seems to be clear.

Will the one calliper sticking be caused by a master cylinder/servo fault???

At my wits end with this.

cheers,
Owen

[FrenchAudi]

It seems to me that a brake hose, line, or ABS unit has a blockage in the circuit for that wheel.

As the first, simplest, measure, I suggest changing the brake hose if this wasn't done when the callipers were replaced. One or more blocked hoses may be preventing fluid from returning when the brake pedal is released.

EDIT: I had this problem repeatedly on the rear brakes of the car in my avatar. I had the window open, and when I smelt them cooking again I stopped, and had a suitable spanner ready.
I quickly cracked open a bleed screw, and when fluid squirted out I knew that pressure was trapped in the cylinder.
When I removed the hose I cut it in half, and found that the hole through it was completely invisible.

Loose trash anywhere in the small bore system can have a similar effect. It can get jammed up at a restriction, allowing high pressure fluid to go through it, but stopping or slowing down the flow of low pressure fluid the other way.