Brake problems & Brake Servo replacement

[k.alle]

Yeah, i will.

I'm pretty sure now that the servo is the problem.

I believe it's the pressure sensor on the servo that is shouting when i hold the brake, as it cannot build pressure due to the leak.

How much PAS oil should I get, I fiddled with it so many times last summer that I don't have a clue how much the system actually takes

And one should i bleed first?
PAS, or brakes?


Thanks for your help guys, much appreciated.

[Error404]

hydraulics and brakes are separate circuits so it doesn't matter mate

[k.alle]

Yes, i know that much to

My point was if the PAS-system needed to be bled first in order for the lets say pushrod of the servo to function properly when bleeding the brakes, or something.

But sounds good anyways.

How much fluid in the PAS then?
2 Liters ?

[Cullam3n]

There's a little more than 1L but get 2L just in case

[Error404]

I refilled the hydraulic system, then bled the brakes, then bled the hydralic circuit (turn steering lock to lock with engine running)

[k.alle]

2 Liters it is!

Nice to know that there's no secret bleed procedure

You've been a great help guys, will try this one myself next weekend.

Thanks!

[Error404]

good luck!

[Mikes2]

I


[EDIT]

f*ck!
Just saw that there were 2 versions of the brake servo made for the RS2.

First version:
F 8C-R000 001>>
8C-S-000 368
F 8C-S-000 001>>

Second version:
F 8C-S-000 369>>



To witch category does a RS2 -95 with the following numbers belong to?
ZZZ8CZSZ001089


Really need to know this before it's too late!

You need the 2nd version as 8C-S-1089 comes after 8C-S-000 369>>

[SEEMO]

Help!!! Need to replace brake servo

I'm trying to get a used brake servo for my RS2.Looking on german ebay...there are servo pumps for sale.Is this the same as the Brake Servo???
Excuse my ignorance .I would appreciate any help.
Cheers Seemo

[k.alle]

I'm trying to get a used brake servo for my RS2.Looking on german ebay...there are servo pumps for sale.Is this the same as the Brake Servo???
Excuse my ignorance .I would appreciate any help.
Cheers Seemo

No, it's not the same.

The servo pump is the power source for the entire servo system on your car, steering and braking.

The brake servo however is positioned on the firewall, and has the master brake cylinder mounted on it, and connects the master brake cylinder with the brake pedal.

[k.alle]

And a little update on my car:

Changed the servo yesterday, 4hrs of work for the 2 of us.

Well, a long story short, I still have the same braking phenomenon.
We bled the car till my leg fell off me, not a single bubble of air.

Sooo, I will leave it to the Audi dealer to sort my brakes out, they will bleed them like crazy when I leave it for timing belt renewal.

I hope hope hope (!) that it's just air trapped somewhere and that they will bleed it out, even though I then changed the servo for no use.

Well, nothing wrong with having a spare brake servo


I'll post an update when I know more, for future reference.

[Mikes2]

When you replaced the master cylinder, did you bench bleed it off the car ?

I had issues on my Coupe quattro which resulted in brakes going soft over a period of 4-5 weeks of driving. I removed the master cylinder from the car and bled it on a bench using bleed valves and some spare tubing.

Place a bleed valve at each outlet and close them.
Fill the reservoir
Open 1 bleed valve at a time, and push the piston until no more bubbles are seen coming out of the bleed valve. best to secure the master cylinder in a vice to do this.
Repeat for each outlet.
Ensure the fluid level in the reservoir remains topped up

It's been fine since I did this on mine.

[k.alle]

Interesting thought.

But do I really need to bleed it on a bench, wouldn't it be good enough to disconnect the brake lines and install bleed valves when it's on the car?
Given that I have someone who will help me brake/bleed.

It would help with the pushing of the piston.

Perhaps I'll give it a go just before I take it to the shop.

[k.alle]

Update:

I just got the car back from the shop and they have bled it twice with their machine but still spongy pedal.
The first the mechanic said to me was "I'm not happy with the pedal feel"
Although on the way home the pedal seemed OK but not more than that (read a little less spongy).

It seems I'll have to live with this.

This is what's done:

last summer
rebuilt the servo pump
mounted fresh bomb
put Audi's PAS oil in it.

this winter
mounted steel braided brake hoses
sandblasted and painted all brake parts
mounted a stronger parking brake spring
drilled a lube service channel to the parking brake axle
new pads on the rear end
new master brake cylinder
mounted 2nd hand "6k miles" brake servo
bled through approx 3-4 liters of brake fluid


Oh well, at least I have a really good parking brake!

[Knight Rider S4]

I would check piping to brake bomb as you said in some of your first threads the pedal got better when you revved the car ..maybe kink in the pipe after you changing the bomb

And buy a pressure bleeder 35€ and you know you wont draw any air back in the system