Spongy brake pedal

[Classik]

Be careful with that trim it's very brittle when old. Might be worth warming it up slightly first. Good news is they are still available from Audi / TPS @ £35.

Thanks for the heads-up Bilko, at least one part which doesn't cost an arm & a leg. Seems like Elsa recommends to pull it vertically but haven't yet succeeded to get it out. Why on earth is everything such a pain with this car?

[steve2003rs6]

Hi classik. When I was having a spongy brake problem. Unit 20 suspected a faulty brake booster valve. Have you checked this out ?
This may not be anything to do with your problem but thought I would pass on this info.
Regards Steve.

[Classik]

Hi Steve,

Great minds... Actually I've decided to replace almost all parts : rear calipers, rear discs & pads, master cylinder and since I went that far I also decided to change the mastervac (servo booster) as well, so yeah definitely an excellent recommendation, thanks for this !

At the time of writing, I've already replaced the new servo & master cylinder along with the new rear calipers. Now I just need to find the time to install the rear discs & pads (should have done that when I changed the calipers btw ), and do a proper purge (got a good 6 liters of brake fluid to play with ).



And since there were a few differences between the oem servo (4B3612105C on mine) and the related TRW part (TRW PSA923), I'll try to put together a small tutorial as soon as time allows.

[steve2003rs6]

Please forgive my ignorance. Is the servo booster the same as the brake booster valve.
Basically it is a non return valve. And apparently an absolute pig to get at.
Did not see it on the photos of parts you provided.
Looks like a piece of pipe with the valve inside it.
That’s why I go to garages because I don’t know a lot on car maintenance.
I believe part no 058133753b.
Pm me your phone no and I will send you a photo of it. Regards Steve.

[Classik]

Ha OK you're referring to the pipe that goes from the admission inlet (negative pressure) to the green cap on the mastervac. And yes, I've checked that one too, it's working fine here. Very easy to replace, but could easily lead to an air leak if faulty or not properly fitted... Part 1 or 2 depending if you drive on the right side or on the wrong side of the road..

[steve2003rs6]

Ok buddy. Sounds like you have covered all scenarios.
Good luck brake bleeding
Hope everything turns out ok.

[Classik]

Thank you !

[steve2003rs6]

The diagram above does not look like the part I am mentioning.
Straight piece of plastic pipe with like a tee piece. Several chamfers on each end to push into flexi pipe.

[Classik]

OK 058133753b is actually the jet succion pump, hidden underneath the intake manifolds. Part #1 on the image below. And yes, already changed the 1st of July last year, along with all surrounding non-return valves (#9 #23 #13) Thanks for your interest, appreciated!

[steve2003rs6]

Yes mate that’s the one. All bases covered then.
Regards Steve.

[Classik]

Yes mate that’s the one. All bases covered then.
Regards Steve.

I really hope so, I've already spent quite a lot of time (and money) on the car, hopefully I should be able soon to enjoy it for a long time before it starts falling apart again

[steve2003rs6]

Yes. I think all c5 RS6 owners spend a fair bit of money maintaining their cars.
But oh my. The pleasure they give in return is so rewarding.
Just absolutely love them.
My wife said to me recently.
You think more about that car than you do of me.
I said yes. I spend more money on the car than I do on you !
I think I will live to regret that one.

[Classik]

Some progress on the rear front, bleeding will follow shortly

[Classik]

Just to let you know that bleeding went well, or more precisely it went well as soon as I realised the front calipers have in fact 2 breather valves... One of those stupid newbie mistakes..
Anyway, looks like the car is braking correctly now, which is good news after all this work (=new servo, master cylinder, rear calipers/discs/pads, aviation hoses)

Now I need to change the brake pedal switch (originally 3B0945511A on my car, now replaced by 1K2945511 RDW), as mine must have been broken in the process: the stop lights are always on whatever I do.

So not there yet, but close!

[bilko1]

Have you had the Bilsteins refurbished or are they new?