Large S2 master cylinder

[Error404]

AFAIK the B6 and later S & RS cars use a 27mm master cylinder, but it is for vacuum servo so probably won't fit. The pedal on my GF's S4 definitely has less travel than my coupe though.

IIRC the OE master cylinder and servo is made by ATE, so perhaps they have a larger one of the same period that will fit?

[Holla]

there is a 26,99mm in a8++, but it doesn't look like it will fit b4's at all...(on the brakebooster)

[re2500]

AFAIK the B6 and later S & RS cars use a 27mm master cylinder, but it is for vacuum servo so probably won't fit. The pedal on my GF's S4 definitely has less travel than my coupe though.

IIRC the OE master cylinder and servo is made by ATE, so perhaps they have a larger one of the same period that will fit?

I think you might be onto something there with the B6 master cylinder. Ive fitted a S2 25.4mm servo onto my vacuum assist setup. I don think it matters what type of assist you have, theyre interchangable. Ive even fitted a S2 cylinder to a MK3 golf, the fitment seems to be the same.

[Error404]

I'll take some pics of the B6 one over the next couple of days

[Holla]

it would be nice if you could write down the partnumbers also!

[Ruhmic]

Different Master cylinder

The different Part Numbers from the RS2 Brake Master cylinder came from the different hydraulic Brake Boosters. The RS2 with the 304x32 Brake disc and the S2 have the "small Brake Booster". The big Brake Kit from the RS2 with the 322x32 have the "big Brake Booster". This system was from construction year 1995 directly fitted in the Factory.
I have shot some photos from the different Brake Boosters.
All Master cylinders for these setup have 25,4mm in Diameter.
The bigger Master cylinder with the 26,99mm came later on the RS6, RS4 or the R8 Models. This systems are with vacuum Brake Boosters and have a completely different Brake Master cylinder. You can see the different Parts in the photos.
With the "big Brake Booster" from the RS2 it is possible to built a setup with the 26,99mm Master cylinder. I have modified some for my R8 Brake setup on the rear that I have built. In the moment I test these Setup in the car.

[Error404]

I am sure that big brake servo is a LHD only part, never seen it on a RHD RS2

[Ruhmic]

Big Brake Booster from RS2

Yes it is only for LHD cars.

[Rocco]

how much it cost this biggermaster cylinder?

[Ruhmic]

Price

Price for the "Big Brake Booster" 815€
Price for the master cylinder that fit to the "Big Brake Booster" 398€
Thats the actual official prices from Audi for this parts

[Rocco]

Price for the "Big Brake Booster" 815€
Price for the master cylinder that fit to the "Big Brake Booster" 398€
Thats the actual official prices from Audi for this parts

Thanks to post it!

So if you want to upgrade master cylinder we've to spend 815+398 €?

Or buying the master alone could work?

Aftermarket masters seems to be far cheaper then true?

[Ruhmic]

Big Brake Booster

The master cylinder from the Big Brake Booster doesn´t fit on the smaller S2 Brake Booster. When you Upgrade your system you must buy the Brake Booster and the master cylinder.
You can buy the master cylinder on the aftermarket, thats cheaper, yes.
The parts were bulit from "ATE"
The Big Brake Booster it´s not available at the aftermarket of my knowledge.
The diameter from the master cylinder is always 25,40mm but the construction are different from the master cylinder. You can see it on the photos that i have posted.

[Rocco]

please could you post here al the items needed for the conversion with their part numbers to make easier someone´s else sopping list?

it would be VERY HELPFUL¡¡