Revisiting "Big" vs "Small" brake master cylinders for RS2

[huksa]

Referring to the old post: http://www.s2forum.com/forum/showthr...ake+booster%22

I was trying to figure out what master cylinder / booster my RS2 originally had.. (My car is a LHD MY1995 RS2 that was built in Oct. 1994.)

Consulting the parts catalog, I've got the following info:

441611021B : F >> 8C-S-000 368 (small cylinder?)
4A0611021C: F 8C-S-000 369 >>* (big one?)

I'd like to know what these series of characters mean (8C-S-000 368 and 8C-S-000 369)

It looks like to me that 8C (Audi 80) S (MY 1995 cars) 000 368 (serial number)..

My wild guess is that RS2s with VIN up until 000 368 have 021B and 000 369 and later cars have 021C?

My VIN is WACZZZ8CZSZ0006**. Could anybody help me find a right part number?

Thanks in advance!

[afen]

I've investigated this for myself, and here's the answer for anybody that's searching for this info:

They are both 25,4mm cylinder, the ony difference is in the ports for the brake lines.

441611021B has M10x1 outlets, and no adapter.
4A0611021C has M12x1 outlets, with adapter to M10x1 - Adapter part no. 8A0614179

Since the 4A0611021C is obsolete and nowhere to be bought new, I've bought the 441611021B and ordered two BrakeQuip BQ40 M10x1-M10x1 adapters, so that I don't have to make new brake lines as well.

The 4A0611021C is also used on the UrS6Plus, which is probably why the reservoir cap is at the back instead of in the middle.

Looks like Audi took whatever they had on the shelves when they built these cars. My 1995 models VIN indicates that I should have the earlier brake system, but I have the 95-96 brake parts.

Older style 441611021B, withouth adapters, reservoir cap in the middle. Note the "edge" at the front of the master cylinder.


Newer style 4A0611021C, with adapters 8A0614179. Note the flat front of the master cylinder, and the reservoir cap at the rear, at an angle.


Here's another photo of the 4A0611021C, with the adapters. Note that the cap on the master cylinder is straight.


From the photos I've seen it looks like older style = centre cap, newer style = rear cap.

[Greg_S]

Thanks for sharing. I have the offset cap on my 93 ABY

[afen]

Thanks for sharing. I have the offset cap on my 93 ABY

It's probably RHD? All the RHD RS2s I saw while investigating had the offset cap, with the cap at the front.

[afen]

And here it's fitted. ATE 441611021B master cylinder, 4A0611301N reservoir, BrakeQuip BQ40 adapters and the original 8A1612099A brake servo.

[afen]

If you're doing this yourself, you probably don't need the BQ40 adapters, you can probably bend the brake pipes a bit to fit them directly to the master cylinder.

[huksa]

Thank you all for the input.
All the info is very important to me as I need to rid the Hyundai master cylinder and vacuum booster of my RS2..
Hell knows why somebody fitted them in it in the first place.

[bartieke210]

Hi, in the old threath you were talking about the big brake booster in the later RS2's. What is exactly the difference between the small one and the big one? Give's it just more assist or is the pedal travel also reduced?

[rxl]

why dont you go with something cheaper and more modern?

[bartieke210]

RXL, on the shell I bought from you is the big booster still fitted. I was planning to use it temperaly on my s2 with the big brakes. But I want to know if it's worth doing al the work to change it.

[rxl]

not realy worth doing all the work if you s2 one is not broken