C5 brakes
Thread Starter
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
C5 brakes
Somewhere I heard that C4s can run C5 brakes in back to better hold the car on the line when footbraking. Anywone done this. Do 10x15 wheels still fit on the back? Thanks, Willie
Safety Car
Joined: Apr 2011
Posts: 3,660
Likes: 22
I've heard of that but I think the proportioning valve is part of the deal as well.
Another 'fix' you can think about is a brake lock.
Its a simple valve with a handle in the cabin that you flip when you step on the brake. This "locks" the fluid down so the brake is held even after the pedal is released.
For holding the line, I'd set up fronts to be on the lock so the rears could be free to turn...
time it right and you flip the lever to release the front brake and C-Yaaaaaaaaaa ! yer outta there
Another 'fix' you can think about is a brake lock.
Its a simple valve with a handle in the cabin that you flip when you step on the brake. This "locks" the fluid down so the brake is held even after the pedal is released.
For holding the line, I'd set up fronts to be on the lock so the rears could be free to turn...
time it right and you flip the lever to release the front brake and C-Yaaaaaaaaaa ! yer outta there
Thread Starter
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
I've heard of that but I think the proportioning valve is part of the deal as well.
Another 'fix' you can think about is a brake lock.
Its a simple valve with a handle in the cabin that you flip when you step on the brake. This "locks" the fluid down so the brake is held even after the pedal is released.
For holding the line, I'd set up fronts to be on the lock so the rears could be free to turn...
time it right and you flip the lever to release the front brake and C-Yaaaaaaaaaa ! yer outta there
Another 'fix' you can think about is a brake lock.
Its a simple valve with a handle in the cabin that you flip when you step on the brake. This "locks" the fluid down so the brake is held even after the pedal is released.
For holding the line, I'd set up fronts to be on the lock so the rears could be free to turn...
time it right and you flip the lever to release the front brake and C-Yaaaaaaaaaa ! yer outta there
Drifting
Joined: Mar 2009
Posts: 1,253
Likes: 4
From: East Wenatchee (2hours from n e where) WA
A popular RR setup is to use the front J55s on the rear. DRM can make the brackets. They are not listed on the web site. There was a recent thread iirc on the ax rr board. I'll see if I can dig it up.
http://forums.corvetteforum.com/auto...ad-racing.html
http://forums.corvetteforum.com/auto...ad-racing.html
Last edited by Crepitus; Mar 9, 2013 at 03:08 AM.
Thread Starter
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
A popular RR setup is to use the front J55s on the rear. DRM can make the brackets. They are not listed on the web site. There was a recent thread iirc on the ax rr board. I'll see if I can dig it up.
http://forums.corvetteforum.com/auto...ad-racing.html
http://forums.corvetteforum.com/auto...ad-racing.html
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Thread Starter
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
C409 reminded me in a PM about Rossler's transbrake for a 4L60e. I'm going to look into this. I have a friend that uses Rossler's transbrake on his Callaway with a 4l80e. The thing is really slow to release and he is having a heck of a time with reaction times. I think it's the nature of the 4l80e.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
Hey Willie.
Right now, and on most any stock car, the proportioning valve limits pressure to the rear wheel cylinders/calipers. This occurs in a "rising rate" fashion in stock cars so that under light pedal pressure, the rear brakes are doing their "fair share" of the work. As pedal pressure increases however, loads transfer toward the front axle. To prevent rear-wheel lock up, pressure rise rate falls off, as pedal pressure increases. See chart here:
^^This is where you are having the issue; heavy pedal pressure, front wheels skid, rears roll. Not enough rear braking force or friction.
I would never recommend removing the proportioning valve on a street driven vehicle, but since yours is trailered, track-only and massively rear-traction biased, I think it would be O.K. in your case. By removing this valve, you'll have equal pressure rise as you increase pedal pressure, to both the front AND the rear brakes. This is effectively increase your rear brakes' holding power.
Right now, and on most any stock car, the proportioning valve limits pressure to the rear wheel cylinders/calipers. This occurs in a "rising rate" fashion in stock cars so that under light pedal pressure, the rear brakes are doing their "fair share" of the work. As pedal pressure increases however, loads transfer toward the front axle. To prevent rear-wheel lock up, pressure rise rate falls off, as pedal pressure increases. See chart here:
^^This is where you are having the issue; heavy pedal pressure, front wheels skid, rears roll. Not enough rear braking force or friction.
I would never recommend removing the proportioning valve on a street driven vehicle, but since yours is trailered, track-only and massively rear-traction biased, I think it would be O.K. in your case. By removing this valve, you'll have equal pressure rise as you increase pedal pressure, to both the front AND the rear brakes. This is effectively increase your rear brakes' holding power.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
No. Not at all. Rear C5 brake is about the same diameter as early/"base" C4 brakes, but the rear C5 rotor is much thicker, and also has an internal expanding drum/shoe parking brake system. LIKE the "early" C4, but not interchangeable at all.
Caliper is also completely different.
Early front:
C5 Rear:
Caliper is also completely different.
Early front:
C5 Rear:
Thread Starter
Race Director
Joined: Apr 2003
Posts: 17,700
Likes: 1,667
From: moraga ca
Hey Willie.
Right now, and on most any stock car, the proportioning valve limits pressure to the rear wheel cylinders/calipers. This occurs in a "rising rate" fashion in stock cars so that under light pedal pressure, the rear brakes are doing their "fair share" of the work. As pedal pressure increases however, loads transfer toward the front axle. To prevent rear-wheel lock up, pressure rise rate falls off, as pedal pressure increases. See chart here:
^^This is where you are having the issue; heavy pedal pressure, front wheels skid, rears roll. Not enough rear braking force or friction.
I would never recommend removing the proportioning valve on a street driven vehicle, but since yours is trailered, track-only and massively rear-traction biased, I think it would be O.K. in your case. By removing this valve, you'll have equal pressure rise as you increase pedal pressure, to both the front AND the rear brakes. This is effectively increase your rear brakes' holding power.
Right now, and on most any stock car, the proportioning valve limits pressure to the rear wheel cylinders/calipers. This occurs in a "rising rate" fashion in stock cars so that under light pedal pressure, the rear brakes are doing their "fair share" of the work. As pedal pressure increases however, loads transfer toward the front axle. To prevent rear-wheel lock up, pressure rise rate falls off, as pedal pressure increases. See chart here:
^^This is where you are having the issue; heavy pedal pressure, front wheels skid, rears roll. Not enough rear braking force or friction.
I would never recommend removing the proportioning valve on a street driven vehicle, but since yours is trailered, track-only and massively rear-traction biased, I think it would be O.K. in your case. By removing this valve, you'll have equal pressure rise as you increase pedal pressure, to both the front AND the rear brakes. This is effectively increase your rear brakes' holding power.
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
I've never done it, but don't feel that it should be too hard. The valve (as you may already know) is located just below your master cylinder. Removal is straight forward. The front brakes go "straight through" -there is no management of the pressure so simply connecting the MC cylinder front circuit outlet to the lines going to the front brakes with a union would keep the fronts functioning the same.
For the rears, same thing. Seems to me that if you physically remove the PV, re-bend the MC>PV line and rear brake lines to align w/each other and install a female-female union, that would do it -like this...
JEGS
Here, someone has removed their proportioning valve (nothing in the front brakes circuit) and installed an adjustable proportioning valve in the rear circuit....
You could do the same thing, but w/o the adj. prop valve, using a F/F union...
For the rears, same thing. Seems to me that if you physically remove the PV, re-bend the MC>PV line and rear brake lines to align w/each other and install a female-female union, that would do it -like this...
JEGS
Here, someone has removed their proportioning valve (nothing in the front brakes circuit) and installed an adjustable proportioning valve in the rear circuit....
You could do the same thing, but w/o the adj. prop valve, using a F/F union...
Last edited by Tom400CFI; Mar 11, 2013 at 12:30 AM.
Drifting
Joined: Aug 2010
Posts: 1,704
Likes: 8
No. Not at all. Rear C5 brake is about the same diameter as early/"base" C4 brakes, but the rear C5 rotor is much thicker, and also has an internal expanding drum/shoe parking brake system. LIKE the "early" C4, but not interchangeable at all.
Caliper is also completely different.
Early front:
C5 Rear:
Caliper is also completely different.
Early front:
C5 Rear:
Team Owner
Joined: Aug 2004
Posts: 21,543
Likes: 3,216
From: Park City Utah
It increases pressure to the rear, compared to the stock spring.
Say what? Are you asking if you can run the C5 rear rotor on an early C4? If so, then no. Not w/o a lot of custom machine work and "engineering". Anyway, the C5 rotor is not meaningfully larger in diameter than the stock one...only (meaningfully) thicker.
Say what? Are you asking if you can run the C5 rear rotor on an early C4? If so, then no. Not w/o a lot of custom machine work and "engineering". Anyway, the C5 rotor is not meaningfully larger in diameter than the stock one...only (meaningfully) thicker.
Thread Starter
Race Director
Joined: Apr 2003
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From: moraga ca
Le Mans Master
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From: Van Steel Corvettes
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