23mm master cylinder, out of what??? Options

[lapuwali]

QUOTE (Britain Smith @ Feb 15 2005, 04:20 PM)

I have Carrera (wide-A) calipers all around and according to that link above the stock set-up was a 20.64mm MC vaccum assisted. Do you think that a 23mm MC would be too large for this set-up when not using vaccum assist? Also, should a proportioning valve be used? -Britain

With A fronts and A rears (I'm assuming this, not the same sizes all round), the split you have is 17:1 front and 13:1 rear with a 23mm MC. This would have fairly heavy pedal. A 19mm would be pretty close, though. A 21mm w/o a servo would probably be spot on. Both might be close enough to be workable, and will come down to your personal preference.

I'm not going to speculate on brake bias, since this is on your unfinished 912, and there's no knowing what your front/rear weight distribution is going to be when you're all finished.

I wonder if a new piston could be machined up to fit a bored out 19mm (3/4") MC. Seals would be interesting, though using 13/16" seals from a Wilwood or other MC might work, which would give 20.62mm. Are rebuild kits for those NLA "21mm" MCs still available? If so, do they include new pistons, or just seals?

[Brett W]

Sorry Mike, didn't mean to jump your shit.

My hats are off the shelf bolt on. Have to drill the lub holes though. With the vented rotor and vented caliper the caliper will need about .75-.100 off the inside mounting ears. I beleive. I need to machine and measure and machine an measure.

The Hat is something like 50 and the rotor is about the same. Calipers are 13 apeice. Haven't priced studs yet.

For the guys running Fuchs or other hub centric wheels then the hat will have to be machined slightly otherwise I am going to turn the ring off all together.

[Jappe914]

Audi RS2 and some Quattros has 23 and 25mm masters. I have Quattro version from -92. It has two different size of pistons. other is 25,5mm and the other is 19,8mm. Bigger is for rear and smaller for front calibers. It's quite hard to use but with 996 monoblocks it is awesome in 914...
(IMG:http://koti.mbnet.fi/ywa/jappe/autot/porsche/paasylinteri1.jpg)

lower part is somekind of pressure balancer between rear and front

[930 914]

I have a 23 mm master and a 19 mm master for sale both are new. they come with the matching pus rod for the pedal.