Any bleeding experts ?

[S2central.net]

I have one problem on the brakes after fitting one new rear caliper. The caliper itself and handbrake mechanism works fine - piston is smooth. I have no leaks.

What I do have is a weird long brake pedal with some sponginess after renewing this caliper and bleeding approx 500cc of fluid through it. The old stuff was mega nasty looking brown stuff.

I used a new tin of DOT4 fluid with an Eezibleed kit - you know the one that uses tyre pressure to force fluid thru the system. Had approx 1.5bar in the tyre. Caliper seemed to bleed just fine but the pedal has never felt as weird.

Brake pedal has been pumped many times with engine running so that I get the rear pistons moving - it actually gave me the RED (!) Alert with the engine running doing that - I was sure I must have had a leak but no sir.

Have I missed a trick here ?
There is no bleed screw on the master cylinder that I can see.

I didn't have any probs during the bleed except having to tighten seals on the bleed kit so that it was airtight. Bit perplexed but maybe it just needs bled thru some more and of course when I renew the other rear caliper I will be doing that. This eezibleed is a bit temperamental - maybe I'll just bleed brakes the traditional way.

Any other ideas from the assembled brake gurus ?

Paul

[quattronutter]

i would re bleed the whole system again,i have found the old fashion way of pumping the pedal and bleeding with an assistant better on some vehicles,did you make sure the rear brake pressure regulator was open?to allow full pressure to the back brakes...

[kwlw]

i would re bleed the whole system again,i have found the old fashion way of pumping the pedal and bleeding with an assistant better on some vehicles,did you make sure the rear brake pressure regulator was open?to allow full pressure to the back brakes...

How to open this regulator? I have heard the same problem on B3 chasis non quattro car. Dunno, how stupid it sounds, but guy cured the problem when he went for a short ride, and did several stops from 20mph to 0 with severe braking. After that he rebled the brakes. I think cause is that regulator. But what is it, and where is it? I have never seen something that you can "open" on a quattro brake system.

Sau

[Corey]

Paul,

Did you rebleed the whole system or just this caliper?

[dan_b]

Paul - you need to make very sure that the Ezibleed cylinder is nicely full and is standing vertically - put it above the master cylinder if you can. There is a chance you can actually draw air in if the nozzle isn't completely and fully covered. Also, you may find that 1.5BAR could be too high.

Secondly, you MUST bleed all four brake calipers. Start with the rear right, then rear left, then front left, then front right. If you have multipots up front, bleed from both nipples on each caliper, outside first. Also, double check the bleed nipples are fully closed after each one.

I would suggest you aim to pull through at least 2-2.5 litres of clean fresh fluid.

I have never had a problem with the Ezibleed myself, and I change my fluid every 12 months. Just make sure you do all 4 brake lines, always starting with the one furthest from the master cylinder.

[S2central.net]

Well I fitted and bled the 2nd rear caliper today (rear left) and the pedal feel is still woefully bad - loads of travel and no bite - despite many pumps of the pedal to push the pistons into place. With the handbrake I can lock both rear wheels - stationary or at speed (declutched of course)... But the pedal feels rubbish - nothing significant happens until the the pedal is much nearer the carpet than normal.

I shouldn't need to bleed the fronts as all quattros have a front rear split and I have not opened the front circuit.

As for th brake pressure regulator - that is non adjustable on the S2 - its not like the older Coupes where you had to trick the regulator into providing more pressure for bleeding.

I have bled a liter of DOT4 thru the rear now (500cc each side) but I guess I just have to try again - might do it the old method this time with someone pressing the middle pedal.

Only question I have is on the brake pads - the factory S8 items are a Textar pad. One of them is coated in a very thing synthetic backing - presumably to stop vibration noise so I put that one to the piston side. The other pad is just a metal backed pad which I put to the outside. I can't imagine that is significant - just asking the question.

[GT500]

Fill your ezy bleed then connect to tyre, then press pedal at the same time.
Also remove bottom caliper to bracket bolt, loosen top bolt, bleed having swung the caliper so the bleed nipple is the highest point.
Sounds like trapped air somewhere, got to be calipers...

[Corey]

Paul,

You need to bleed the whole system when doing any work on it.

After we have done a flush we have an assistant press the brake pedal prior to opening the first nipple and carrying on pushing down until the last nipple has been bled, the theory behind this is that when you take your foot off the pedal you sweep the master cylinder with brand new fluid, works for us.

[CHEN]

I have had this on a 3B before, Spent hours bleeding the rear, but if you put your foot on the brake the rear wheels would still turn. Bleeding all 4 brakes manually improved this a bit, then it just got better by being driven, around 10 miles later it was spot on. Never really understood why, my guess is air trapped in the master, with the power servo running it might help it clear?

[S2central.net]

Paul,

You need to bleed the whole system when doing any work on it.

After we have done a flush we have an assistant press the brake pedal prior to opening the first nipple and carrying on pushing down until the last nipple has been bled, the theory behind this is that when you take your foot off the pedal you sweep the master cylinder with brand new fluid, works for us.

That is my next course of action and I note that the bleeding procedure in the manual for more modern Audis states the use of an assistant to press the pedal during bleeding - or use of of those adjustable clamp things between drivers seat and pedal.

I still don't understand why opening one circuit can affect the other - I'm no brake guru but I've bled lots of cars before and only ever had to bleed the affected circuit before. Confused !

[mcandmar]

Paul, I had a similar issue after fitting new calipers, ditch the easybleed toy and get somebody to help you the old fasioned way. I ended up having to bleed master cyl, and all four corners to get it right again.

Mark.

[waad_uk]

Seen one of these in action. Much much better than the eazy-bleed.

It pulls the fluid through from the nipple. As long as the reservoir is topped up no problems and no mess!

http://www.actron.com/product_detail.php?pid=16292

Plus you end up with a vacuum test tool for all teh vacuum hoses and wastegate diaphram

[S2central.net]

Actually I have a MityVac with a drain bottle - last used it to suck out diesel from a filter. That could work actually... but I need someones leg on the middle pedal !

Cheers,

Paul

[mcandmar]

Never had much luck with them either, i found when you build up a vacume and slack off the bleed nipple it would suck air around it through the screw threads. Never managed to get a constant fluid flow with it.

It did work a treat finding an air leak in my cruise control

[Fat Audi 80]

Stange. I had never bled a car before in my life, I replaced both rear calipers, only bled those calipers (using Ezibleed) and found a rock hard brake pedal afterwards!

Good luck sorting it out.

Cheers,

Steve.