For DEs I was running a slightly higher friction pad in the rear than on the front of my 951S. I installed the 5/33 brake bias valve and it is clearly too much rear braking with those same pads. Should I be able to use the same pads in the rear as on the front with the 5/33 bias, or should I go to a lower friction pad in the rear?

 

Run the same compound front and rear.

 

Thanks, I wanted to make sure it still wouldn't be too much in back before I shelled out over $200 for the pads.

 

I run the 5/33 and the same pads front and rear with no problem, but I have an '87, which uses the same size pad for front and rear.

The '89 has more front brake so I would try to get feedback from someone with an '88S or '89.

 

couple of things come to mind
how much are you trail braking, exactly where are they locking up? are they locking up braking straight or if you're still braking at the start of the turn?
Is the car still on stock ride height, stock springs? how much weight transfer is being taken off the rear under hard braking...

 

The car is stock ride height and springs. I do tend to trail brake a little, but it was impossible with the 5/33 valve and higher friction pads in back. Even braking totally straight the rears were locking up when I was braking at the limit with that set up.

 

After talking to a couple of guys who race their 944 S2's & turbo's I decided to keep the stock brake bias valve when I upgraded to the turbo S front brake rotors and calipers on my S2 track car.

The thinking was this is what Porsche used when they built the turbo S's so they should know best.

I have not been dissapointed////

 

I wouldn't disagree with that, however, the question is, best for what? Porsche tends to be conservative with their street cars, which is a very good thing. I'm ok with being less conservative and would like to get that little extra out of the braking system and the car in general, just like I've tried to get rid of some of the understeer that the car had.

 

ABS car here, so I can't say about pads F/R with the proportioning valve. That said, the rake of the car relative to ride height will have an effect. CG + Track + Wheelbase are pretty fixed on the car until you raise/lower one end or the other a bit...

 

This car has ABS, too. What way do you change the rack to leave a little more weight on the rear?

 

By my book, more rake (i.e. rear higher relative to nose) levers the nose down and lightens the rear. Opposite (lower rear end - read no rake or negative rake) reduces the levering of the nose downward and reduces the lightening of the rear end under heavy braking.

I hope this makes sense. Not a suspension engineer by any means, but can definately feel the difference in pitch when changes are made relative to front/rear right heights and the way they rotate the car (pitch and roll) around the CG.

 

FWIW....My 89, 951 S with turbo cup suspension, proper ride height and brake bias valve and Pagid orange F & R works just fine with braking in a straight line or trail braking.

 

Turbo S/89's have the most front brake bias and benefit the most from a 5/33 brake bias valve. You can definitely run the same pads front and rear on an 89 with a 5/33. Without the bias valve you will be underusing the rear brakes.

I would definitely NOT run the 5/33 on an '86 951, however.

 

I have an 86 with 89S front brakes stock rear, no abs, and the 5/33 valve. With stock pads in front and EBS pads in the rear I don't have trouble with the rears during trail braking, but usually do get some inside front wheel lock up.

 

Thanks, all!! I just ordered the same pads for the rear as I have in the front.