Brake help needed on race car
06-08-2010, 06:10 PM
#46
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Hi Mark,
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
06-08-2010, 06:11 PM
#47
Tell us how that goes. Brake feel is everything once you get into the 8/10 of track driving. Right?
06-08-2010, 06:12 PM
#48
Hi Mark,
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
06-08-2010, 06:23 PM
#49
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As others have suggested too, different pad compounds for front and rear could be used to further tune the brakes to your liking.
Good luck,
06-08-2010, 06:25 PM
#50
Rennlist Member
I know Joseph had a dual master set up and went back to the stock stuff.
Hi Mark,
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
06-08-2010, 06:35 PM
#51
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Hi Mark,
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
I used to run a BMW 750 iL (E32) master cylinder on my faster 951's. It is 1 inch and it was a bolt on for an ABS 951. W/O ABS you'll probably need to fool w/plumbing.
It helps a little but the brakes are still a little over boosted.
I HATE the non-assisted brakes like on a 997 cup or GT3R. I would never go the Tilton dual MC route unless I had no other choice.
Chris Cervelli
I will get one and check it out. I totally agree with the 997 brakes. Now the 996 are another story. The best I've ever experienced.
06-08-2010, 06:50 PM
#52
Rennlist Member
He is using pagid blacks in the rear. there is not too many more compounds available with more "bite". Im kind of surprised Mark is running no bias in the rear. You would think he would be getting sidways on turn entry with trail braking, but maybe the proportions of bite with the 14" rotors off sets the small pads and 10" rotors in the rear. I wonder if there is a cylinder volume pressure between the rear and front systems in the stock master. I cant imagine how the same caliper pressure, would not lock the rears up, as in a 1.5g stop, 80% of the cars weight is standing on the front wheels, and 20% is on the rear. if you are threashold braking the fronts, the rears should be locked up in their tracks! 
06-08-2010, 06:54 PM
#53
06-08-2010, 06:56 PM
#54
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He is using pagid blacks in the rear. there is not too many more compounds available with more "bite". Im kind of surprised Mark is running no bias in the rear. You would think he would be getting sidways on turn entry with trail braking, but maybe the proportions of bite with the 14" rotors off sets the small pads and 10" rotors in the rear. I wonder if there is a cylinder volume pressure between the rear and front systems in the stock master. I cant imagine how the same caliper pressure, would not lock the rears up, as in a 1.5g stop, 80% of the cars weight is standing on the front wheels, and 20% is on the rear. if you are threashold braking the fronts, the rears should be locked up in their tracks!
06-08-2010, 06:57 PM
#55
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06-08-2010, 07:51 PM
#56
LOL
06-08-2010, 07:59 PM
#57
Race Director
I could totally see this happening.....at some golf course in Germany....
06-08-2010, 08:29 PM
#58
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Sofa King true.
I have no feel for the unboosted brakes because I have to push so hard. It takes pretty much everything I have to get the car to stop effectively. I am not a small guy either.
On the other hand, the 996 Cup is effortless. I find those a little overboosted and I have a hard time slowing down only a little, like at the Kink at Road America.
Chris Cervelli
06-09-2010, 01:37 AM
#59
I've come to the conclusion that my race car brakes are just to sensative. This weekend I experimented with disconnecting the booster and what I'd really like is someting in between. With the booster connected there just is not enough pedal feel and it is very easy to lock up the brakes. With no boost it is difficult to blip the throttle as it takes so much pedal effort. I was wondering the effect of a smaller booster or a larger master cylinder.
That said I did take first in class and third overall in my 928 this weekend at Fontana. Some new guy in a 2008 RSR got on his radio and asked his crew " what the hell is that car in my mirrors"
That said I did take first in class and third overall in my 928 this weekend at Fontana. Some new guy in a 2008 RSR got on his radio and asked his crew " what the hell is that car in my mirrors"
I had a similar problem with my 1985 with the GTS calipers. They were just too sensitive. It was better for me when I increased the size from the 1985 to the later MC and added an adjustable brake bias.
Greg Phillips
06-09-2010, 06:17 AM
#60
Nordschleife Master
Some kind of regulator between the vacuum and booster might be interesting, by adjusting the vacuum level at the booster I would think the assist could be tuned however you like it.
