jellonailer

I'm running PFC08's on the 964 with big brakes and the bias innards removed. Noticed something recently after switching tires to 275 BFG R1's - my rears chirp every now and then. Certain corners chirp/get a puff of smoke, at threshold braking just from rears. I don't remember having this issue with Nitto NT01's.

Thinking maybe go to PFC01's in front, not sure. Thanks

Bill Verburg

The thing to keep in mind w/ your brake setup is that it is heavily front biased


If you kept the stock rears you are at 2.091 w/o any p/v action, the proportioning valve jumps it to 3.75

If you changed the rears to either 964RS or 993 it goes to 1.713 p/v jumps that to 3.071

On the 964 Cups w/ a setup similar to big red front/993 rear they pull the p/v to get the 1.7

These cars can use a whole bunch more rear brake. 993RS/Cup are 1.426/2.64

The R1 should perform similar to N01,

Given the above I'd suspect an alignment or other issue, perhaps lsd related

tjb616

Bill's braking knowledge never ceases to impress. Always ready to go for threads like these.

OP, would you mind sharing your wheel and fender modification info to fit the 275? I know the 964 Cups ran that size with rolled fenders, but to what degree I've yet to find on paper.

jellonailer

Thanks Bill and TJ.
I am running 993 rears with p/v removed.
As for how I crammed the rears in there:
17x9 ET56mm Fikse Mach V wheels with 8mm of spacer
Fender rolled (actually shot bag and plastic deadblow hammer)
2.5 rear camber, 0.04 toe
Ride height is about 4mm higher - 125mm Front, 227 Rear
Springs are 600F/800R

I will post a picture. Rubbing issue was originally on inside arms so I added 5mm spacer bringing it to 61, then added a couple of mm's for good measure. I mark the tires to watch for rubbing. Good so far.




With Fikse 17's and 225/275 R1's (could be 235's in front cant remember)



With 17" Cup 1's 225/255

jellonailer

The other change I had made was going to Endless RF650 brake fluid from Motul RBF 600 or 660. In my opinion there IS something to the Endless pedal firmness theory - I like it better.

tjb616

Awesome, thank you for the detailed answer. When you say 4mm higher, do you mean than stock, RS, etc?

Thats a lot of tire for a 9" wheel but it looks awesome. If you have a shot from behind I bet it looks pretty rad.

jellonailer

I believe RS is 125/223.
My car has 1 degree rake

TrackDays247.com

Well...when you need brakes give us shout....same brakes on my car :-)

Spyerx

Interesting. I just switched from endless to brembo htc64t and it is similar or firmer than endless. Never used motul brake fluids before. Endless is good. So is the brembo stuff.

jellonailer

I went Endless because HTC64T seemed to hard to find but from what I understood similar to the Endless. So I went that way.
Seems better than both Motuls 600 and 660, and Castrol SRF. Just my subjective experience. Not that I would have said the others were bad by any stretch.