ROG100

Chuck,
Yes you do and I know Jim will chime back in with correct number.
Roger

Jim M.

Hi Chuck, I've always run with the 55 bar brake bias valve (stock is 18). With the addition of the bigger rear brakes your actually moving the bias further back. Under very heavy braking the rear would lock up first (not good). So I changed to the 45 bar valve, and all is good again.

IIRC only the US cars came with the 18 bar valve because of the propensity of US drivers to try and sue when they went off the road backwards. The ROW cars had a 33 bar valve. So going from 33 to 55 worked for me until adding the bigger 993TT rear brakes.

atb

Jim, where did you get the 45? I started with the 55 and on the track the fronts locked up with the rears barely engaging. With the 33 that I have in there now, its better but still more bias than I would like. At times, I get too much rear trail braking especially in the wet. The 45 sounds like it would be perfect, I didn't know there was one out there available to us.

mark kibort

theoretically, the more you stand on the front brakes, the less back brakes you will need. I just went to a pagid black racing pad in back, as before I was running just the oranges. I think my new S4 chassis has more rear brake bias it feels too. dont know for sure, but I think the holbert car had the 18bias part dont S4s come with 33 bar stock??

anyway, if I went up on bias, its not hurting me any, in fact, it might be a little better, but I have to be careful under trail braking.

Gary Knox

Adam,
The 45 bar rear bias valve was OE on the 964. I understood from Dave Roberts a few years ago that it is no longer available from Porsche. I have the 45 bar on both my S4 track car (had 55, like Jim, it was too much in a couple of places on specific tracks where braking was required as car passed over a small hill and became unweighted). I posted a "wanted" on the 911 web site, and over a couplel of years two guys have discovered they had their OE 45 bar in the used parts after they had replaced it with a 55 bar on their 964 track cars.

You might try that if the NLA is indeed still the case.

Gary Knox

ROG100

I wonder where Jim bought the 45 from???????????
He fitted one to my car as well.
I will check availablity in the morning.

Jim M.

Hmm, IIRC I got my 45 from that vendor in Double Oak, Texas. Great price and fast delivery. (see signiture line)

Jim M.

Mark, NO, all the U.S.A. S4's, GT's and GTS' came stock with the 18 bar bias valve. The pre-S4's came with a 33 bar but the system is different and the early 33 bar valve will not fit in the 87-95 cars. The ROW 87-95 cars retained the 33 bar system.