im trying to guy a brake master cylinder for my S5 90 GTU. Checker auto has a very large collection of different brands and styles.. i know that my brake master cylinder, for some odd reason, is the cast aluminum style brake master that came on turbo II's i believe. It is the only style that has a banjo bolt on the left side. So anyways, i am thinking of going with the rebuilt 15/16ths bendix turbo II aluminum one, or should i go with a 7/8ths? what is the difference? did all GTU come with the cast aluminum like the turbo II or is my car special?

ps: my car had single piston fronts (as all s5 GTU have)(course now its got 4 pot front and vented all around)

thanks

 

anybody have any idea?

 

1/16th of an inch.

 

I know that 15/16ths is 1/16 bigger then 7/8ths! i want to know which BMC to go with..

i have figured this out though..

1. 7/8 or 15/16= internal bore size..
2. 15/16 more then likely only came on turbo
3. bendix remans both have same part number, atleast @ checkerauto, for both there aluminum remans, so it looks like a crap shoot for which i get
4. i would imagine both use same bolt pattern, so it probably cant hurt to get the 15/16, it will atleast make up for the increased hydralic area in with the 4 piston callipers in the front over the stocker singles..

-an expert on 86-91 master cylinders would be very helpful!!!!

 

sorry to be a dick.... lol. Yea man, get the bigger one, it will be useful pushing those 4pots around!

 

There's your answer

 

I believe there were only two sizes for the FC, the single piston caliper models had the 19mm bore, and the 4 postion equipped models had the 21mm bore M/C.
-a

 

The boosters are different between the TII (large MC) and the NA's (smaller MC, even with the 4 pots). With 4 pots and the smaller MC you can still get a really firm pedal and it's not required to go with the larger one, in fact it might not even fit on the NA booster.

 

yes that is my worry, i wish i had a turbo II around to compare and contrast.. i imagine the 15/16ths came with the turbo and larger booster

well i think im gonna go with a 15/16ths just for kicks and in hope that they didnt change enough to use between models, then if it doesnt fit ill return it and go with a 7/8ths or just get a raybestos rebuild kit (which seems pretty high quality to me)..

thanks for help..

and atleast i dont have to deal with the adjustable suspension!

when i changed out the bm cylinder on my GXL a few years back (lot fewer choices for that car) i took a huge monkey wrench, tightened with channel locks, to get that sensor off!