ttAmerica RoadsterAWD

1. 964 355 305 10

2. 964 355 305 00

3. 928 355 305 02

I'm not getting a whole lot of rear wheel braking support as I get way too much front wheel lockup. I may have to change out the brake regulator for the rear.

thanks, Jaime

Bill Verburg

1. 964 355 305 10 55bar

2. 964 355 305 00 45bar

3. 928 355 305 02 ??

Your problem stems from the 322mm rotor in the front, you already have 30/34 rear pistons and the least aggressive p/v, If you want more rear brake the next step is to remove the p/v .

Indycam

Hiya ttAmerica RoadsterAWD
An adjustable bpv might be a the way to go .
http://www.apracing.com/car/cylinder/pvalves.htm
http://www.hrpworld.com/index.cfm?fo...action=product
http://www.mpbrakes.com/mpfaqvalving.htm

ttAmerica RoadsterAWD

Thanks, Indy. I've considered doing this....might as well as I don't think anything stock will be the ticket for my frankensteined car. I do need to sort out many things being that it's got a 993tt in it. Makes for long hours of wrenching in the garage. I love it!

Jaime

Indycam

"Makes for long hours of wrenching in the garage. I love it!"
You are going to need to spend a bit of time driving that car hard so that you can set up the valve for the best balance , shortest 100-0 . Boo Hoo .

Indycam

Long time ago I was in a car that did a snap 180 because the brakes were not set up right .
Going along a public two lane road , dry , straight level . The brakes were stepped on hard , the rears locked up and the fronts did not . The car went around in a blink . Very scary watching the parked cars and the car in the other lane pass by . Very lucky not to have been killed by "improved" brakes . If you change anything from the highly engineered braking system on the car be very careful in the development and testing . Its easy to create unsafe brakes , unpredictable brakes , dangerous brakes , compromised brakes . Test well away from anything that could be crashed into . Test at slow speeds and slowly increase the speed of the tests .
If you can not improve the braking , go back to stock .

ttAmerica RoadsterAWD

Thanks for the tips. I guess you would want the fronts to lock up just before the rear......how will I be able to tell with ABS??

Jaime

garrett376

not sure... but that's why it's always a good idea to go based on what the Porsche factory has already figured out... I would mimic a setup that they used, to be safe.

Oddjob

The 928 prop. valve is 33bar.

You will know if the rears are locking before the fronts, with or without ABS. Its very unsettling for the car (and the driver...).

Indycam

Hiya ttAmerica RoadsterAWD
"how will I be able to tell with ABS??"
You will need to disable the abs for the development , testing work . If you set up your car with the abs on and the abs covers for the fact that the setup is dangerous , when the abs fails , the abs will no longer cover the flaws . Imagine needing your brakes badly and finding at the worst moment that your abs is not working and that your car is spinning wildly out of control and that you are trying your best to pedal it back but your brakes are not "normal" , that they make things imposable , you put in a control input that should do the trick but it makes things worse .

After the brakes are dialed in for non abs use so that your brakes are safe and predictable you will need to reactivate the abs and redo all the testing so that you can be sure you have good predictable , reliable , efficient etc etc etc brakes .

Document everything you do so that you can prove in court that your nonstandard brakes were non contributory . cya

I know that the engineers at porsche know brakes , suspensions , chassis and how they all interact .
I know they did more brake development work and spent way more money for my 964 brakes ,
than I will ever be able to do and that they did such a good job of it , that my trying to out do them for road use would be .....

ttAmerica RoadsterAWD

Thanks guys, come to think of it, I think the 55bar will be the way to go for me. These are my research results (thank you guys for your help):

60 bar.......C2 Turbo (965 355 305 01)

55bar........993tt (964 355 305 10)X2 units?

55bar........C4, RSA (964 355 305 10)

45bar........C2 (964 355 305 00)

33bar........Turbo Look cars (928 355 305 02)

Guess best thing for me is to find out what front brakes, and rear brake caliper/ piston diameter I have and try to emulate what Porsche has done. At the outset, my car is essentially a 993tt setup with the all wheel drive/engine from the 993tt. But it has 965 front calipers/rotors. Need to find out about the rear. If I do, indeed, have the Turbo Look valve, I can see that I definately need to move up.

Jaime

mcpiaseczny

Reviving an old thread because I'm looking into this as a mod. My car is a C2 with TT brakes, and, AFAIK, the 45 bar proportioning valve.

Has anyone experimented on a C2 to figure out which valve to use in this combination?

drb930

Jamie,

How about this one?

993 355 305 01

Thanks,
Dave

Goughary

The proportioning valve just cuts pressure to the rear. It's cheaper to buy and install a tilton adjustable bias valve and set it how you like.

I have one and will likely install it this spring.

964TT

Remove p/v