Leaking aft caliper

[Pellesin]

Hello everybody!
As the heading mentions I've struggeled with a leak from the L/H rear caliper. Wife had complained about a red brake warning sign in the dash.
The picture shows what I had conserns about.
(for some reason the picture turns upside down when uploading...)

[Pellesin]

To isolate which side from the caliper that was leaking. I parked the car for two days, and drove it to work one day without applying the brake. The plan worked☺ the calipper had dried up.
I jacked up, removed the wheel and applied the brake and voila! 2 seconds and the leak developes as the picture shows.

[Pellesin]

The problem really is a "chain of events" 1.st The cover for the E-brake has cracks, this 2.ndly leads to moisture enterring the area where the axle enters the brake caliper, 3.rdly this causes the axle to corrode as the picture shows. 4.th the corroded axle "chews" the O-ring and causes the caliper to leak.

[Pellesin]

So replacing seals is just a time extension - but its better then the option at the time being.
The housing can be "fixed" with sealant
Getting a long term fix for the axle is a more complicated matter.
Anyway - calipper is now reassembled with new seals - no leaks☺

[Delboy]

You didn't mess about there did you. +++

[CamSteel]

To isolate which side from the caliper that was leaking. I parked the car for two days, and drove it to work one day without applying the brake. The plan worked☺ the calipper had dried up.
I jacked up, removed the wheel and applied the brake and voila! 2 seconds and the leak developes as the picture shows.

It does not matter which side of the caliper you can see the leak from, you need to get that caliper changed, I had to the same thing a month ago and got a exchange unit from fleabay at £175 with a surcharge of £75 for the old one, you should also factor in that you will need someone with the VagCom or similar for the windback on the electronic handbrake.

[Pellesin]

It does not matter which side of the caliper you can see the leak from, you need to get that caliper changed, I had to the same thing a month ago and got a exchange unit from fleabay at £175 with a surcharge of £75 for the old one, you should also factor in that you will need someone with the VagCom or similar for the windback on the electronic handbrake.

I did the windback with my own vagcom. Really straight forward. But thanx for the reminder.+++
I did the isolation procedure to find out where to get the seal set from the "gold smith" (nick name for the local Audi dealer. Same weight to price ratio - hence the name) or from e-bay. Gold smith didn't supply the seal for the input shaft/axle. I'd go for the other if it was the forward side(piston) that leaked. This not being the case I was "forced" to wait for the parts from the UK.
Does anyone know wether the refurbished ones have a new input shaft/axle?
I'll make sure to "confess" when the caliper starts leaking again so that others can learn aswell. (it's not a if but a when)
I hope it will hold up until spring next year - that will buy me some time to figure out a fix that will last a bit longer... :o

[snapdragon]

You did a good job.
I too had a weep there but didn't take out the shaft as the main problem was slipping and insufficient clamping force.
The ones from Eurocarparts are brand new from TRW at about £180 after a £43 core charge is refunded. I thought it would be refurb due to them wanting the old part but it wasn't.

I had a similar problem and tried to fix the old one but the ingress had caused wear and there was too much slop in the swash plate on the shaft causing it to slip when it was clamping. I JB-welded the casing back up and sadly by about the 5th time I put it back on the caliper it cracked again. As someone on here said (quite rightly) there is also a problem with the large o-ring on the caliper that the EPB goes onto becoming a tighter fit due to the aluminium underneath corroding and swelling. I would remove that seal too and give it a good scrape and clean and put some silicone grease on it as when you don't have a crack it will be much tighter!

[Pellesin]

All 3 grooves was filled with old grime. I sand blasted the caliper housing, but only gently scraped the grooves for the piston seal and dust cap. The groove for the seal between the e-brake was incredibly full of crap. As the picture shows the O-ring is forced out of the groove. With the caliper body blasted, and new O-ring greased up with dow 55 O-ring grease it looked awsome:cool: