Brake pedal sponginess during track days
10-02-2007, 02:15 PM
#16
Drifting
Then I would go with SRF and I'd mount some holes in your bumper and push cold air there. The A-arm scoops are limited -
The pagids are good pads -
maybe next rebuild calipers and use the ss brake pistons
http://www.esells.com/ecitemlist11.a...7&AIMDID=44409
and TI brake shields
http://www.seinesystems.com/TiBrake-Home.htm
you are right at the edge of thermal capacity - I'd try and incrementally give yourself a little more room for error. Otherwise, a little warmer than normal, better feel for the car and you'll go to brake and the pedal will hit the floor.
Nothing like it to get your attention, especially if you are coming up to a hairpin... you'll have a vertical crease in your seat and you'll need a buddy with a spatula to get you out of your car.
The pagids are good pads -
maybe next rebuild calipers and use the ss brake pistons
http://www.esells.com/ecitemlist11.a...7&AIMDID=44409
and TI brake shields
http://www.seinesystems.com/TiBrake-Home.htm
you are right at the edge of thermal capacity - I'd try and incrementally give yourself a little more room for error. Otherwise, a little warmer than normal, better feel for the car and you'll go to brake and the pedal will hit the floor.
Nothing like it to get your attention, especially if you are coming up to a hairpin... you'll have a vertical crease in your seat and you'll need a buddy with a spatula to get you out of your car.
10-02-2007, 04:19 PM
#17
Addict
Rennlist Member
Rennlist Member
I used to have the same problem and after trying a bunch of different pads, fluids, A-arm scoops, etc, the only real fix came from 930 brakes (Brembo front rotors, 930 rears) and cooling hoses to the front valance. Now I can drive all day (I've done up to 90 min stints) and not have any fade at all. Not a viable solution for PCA stock classed cars (unless they want to move up), but a great solution (and cheaper in the long run) for DE cars.
10-03-2007, 02:13 PM
#18
Rennlist Member
I've never solved it 
I have tried many, many things since that thread, but the fundamental conclusion that I have come to is that the stock brake system on the SC is not up for the task of serious racing/track work. That is my personal experience. I know there are others who don't have a problem and there are others that have a problem worse than mine. In fact, the driver who set all the PCA club racing track records on the East coast this last year in an SC would get so much heat in his brakes that he would melt the calipers to the point where the bores would go out of round. He replaced (not rebuilt) calipers after almost every event.
I have tried just about everything. I have experimented with a brake cooling kit, Motul 600, Castrol SRF, frozen slotted rotors, non-frozen slotted rotors, drilled rotors, stock rotors, PFC 97's, Pagid, master cylinder, etc., etc. Nothing has solved the problem and in some cases it got worse. I went through a stage recently where I was cracking rotors after one day. Right now I am running a brake cooling kit, SRF, Pagid yellow in front and black in the rear and frozen non-drilled, non-slotted rotors with better results but not optimal results.
I have resigned myself to boiling the fluid and changing it after every event. Again, I know of guys running identically prepared G cars who have no problem at all and change their fluid once or twice a season. But, I've been through/replaced every component in the system with no luck.
I have tried many, many things since that thread, but the fundamental conclusion that I have come to is that the stock brake system on the SC is not up for the task of serious racing/track work. That is my personal experience. I know there are others who don't have a problem and there are others that have a problem worse than mine. In fact, the driver who set all the PCA club racing track records on the East coast this last year in an SC would get so much heat in his brakes that he would melt the calipers to the point where the bores would go out of round. He replaced (not rebuilt) calipers after almost every event.
I have tried just about everything. I have experimented with a brake cooling kit, Motul 600, Castrol SRF, frozen slotted rotors, non-frozen slotted rotors, drilled rotors, stock rotors, PFC 97's, Pagid, master cylinder, etc., etc. Nothing has solved the problem and in some cases it got worse. I went through a stage recently where I was cracking rotors after one day. Right now I am running a brake cooling kit, SRF, Pagid yellow in front and black in the rear and frozen non-drilled, non-slotted rotors with better results but not optimal results.
I have resigned myself to boiling the fluid and changing it after every event. Again, I know of guys running identically prepared G cars who have no problem at all and change their fluid once or twice a season. But, I've been through/replaced every component in the system with no luck.
10-09-2007, 11:26 PM
#20
Rennlist Member
I rebuilt my calipers, changed the fluid, lines, and pads. The brakes felt spongy when I tried them. One of the guys on Pelican noticed I said I slid the pads in easily. I thought they would just make up the space the first time I pressed them. He suggested I press the pistons in just enough for the pads to barely slip in. I removed the pads and followed his suggestion. The difference was immediately noticeale. No sponginess and the brakes feel better and stronger than they ever have and they don't drag at all. Nothing like a SC when it's running like it was designed.
Before all this everything was working fine but the lines were corroded, the dust boots were falling apart, everything in there was original. I guess I need to start digging around in the master cylinder? I could try the above suggestion about taking the pads out and pushing the pistons out a little further but I can't see why that would help.
If the master cylinder seals suddenly failed why would all this new hardware cause that? I never bled using the pedal as I'd heard that will cause the seals to be pushed further than they're supposed to be.
BTW I also tried changing my transmission fluid but that fill plug wouldn't budge. I soaked it, hammered on it a little, tried an impact...nothing worked. Probably needs a blow torch which I don't have.
10-10-2007, 08:27 AM
#21
Rennlist Member
Well maybe...
On my 80 SC I installed a Turbo Master Cylinder, rebuilt S calipers and ran Pagid Orange pads with ATE Blue...I did all the other things too:
1. Stainless steel lines,
2. AJ USA brake air scoops
3. Bleeding as necessary
End result,never a brake problem at the track, and I run in the west where it can get plenty hot...I seldom had to bleed brakes over the course of a weekend.
1. Stainless steel lines,
2. AJ USA brake air scoops
3. Bleeding as necessary
End result,never a brake problem at the track, and I run in the west where it can get plenty hot...I seldom had to bleed brakes over the course of a weekend.