Brake Upgrade Questions
Thread Starter
Le Mans Master
Joined: Oct 2007
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
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St. Jude Donor '09-'10-'11
Brake Upgrade Questions
I have a 1990 Z51 with the big brake package. I am very slowing acquiring parts (as the budget will allow) for a C5 upgrade in the front. I was thinking of moving the current C4 front calipers to the rear. Would this be too much rear brake?? Has anyone tried this before?
Thanks.
Thanks.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
You probably could move the front calipers to the rear but it would require a custom caliper mounting bracket or some sort of adapter. The size of the pads used in thefront would be too big for the rear rotors so you would need a larger rotor. The size and offset of the rotor hat is different between front and rear (13" J55 fronts and 12" rear) which mandates the adapter bracket.
There would be no provision for a parking brake; the existing rear caliper has the arm for the parking brake cable.
The C4 rear disc is almost the same diameter as the C5 rear disc and the swept area (the total amount of rotor surface the pad rides on) is about the same.
Go with a good performance pad on the rear and get a stiffer brake bias spring to provide a little more braking effort from the rears. Doug Rippie has the C4 spring and the spring doesn't cost a lot of money.
There would be no provision for a parking brake; the existing rear caliper has the arm for the parking brake cable.
The C4 rear disc is almost the same diameter as the C5 rear disc and the swept area (the total amount of rotor surface the pad rides on) is about the same.
Go with a good performance pad on the rear and get a stiffer brake bias spring to provide a little more braking effort from the rears. Doug Rippie has the C4 spring and the spring doesn't cost a lot of money.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thanks. I am willing to make my own adapter brackets. I made aluminum 2 piston calipers from a GMC Envoy work on a 3rd gen Camaro so no problem there. I was just wondering if it would be too much brake force in the rear.
So you say to go with C5 rotors?? Are they thicker to help out with the added force? Would it be better to try and fit a 12" front rotor back there??
As far as the parking brake I don't need one. I do drive this car on the street but I am setting it up for road racing also.
So you say to go with C5 rotors?? Are they thicker to help out with the added force? Would it be better to try and fit a 12" front rotor back there??
As far as the parking brake I don't need one. I do drive this car on the street but I am setting it up for road racing also.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
A lot of work for no benefit. There is ample braking force and heat capacity in the C4 rears for racing. It will probably compromise the master cylinder, pedal travel and bias. Good luck.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
When racing now after only a couple laps my brake pedal feels like mush. I know the C5 fronts will dissipate heat better but are you sure the rears arent contributing?
Melting Slicks
Joined: Jun 2004
Posts: 3,253
Likes: 2
From: Castro Valley CA
Based on my experience of the last 4 years and thirty+ events including Laguna Seca(which is the toughest on brakes) in my 3600#(fuel and driver LT1) the rears are not your problem. A bias spring and race pads are all you need for the rear. Rear rotors will last years and almost never crack(a sign of overheating) and the surface temp pyrometer readings I get are relatively low. Focus on the fronts and proper bias.
Last edited by Sidney004; Aug 14, 2008 at 09:43 PM.
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Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
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From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thank you! That amkes my project a lot easier! What did you do to your fronts?? Wil just moving to C5 brakes be enough?
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
The C6 Z51 has 13.4" rotors correct?? Will these fit inside a 17" ZR1 wheel??
Team Owner
Joined: Dec 1999
Posts: 34,873
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
Do you have any air ducting to the frnt brakes? Getting cool air to the rotors or calipers will help a bunch. What fluid do you use?
Le Mans Master
Joined: Aug 2000
Posts: 8,838
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From: Australia
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
I am working on mocking one up. I currently use the Valvoline DOT 4 stuff. Its good to something like 480 degrees. Its the only thing I can find in part stores.
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thread Starter
Le Mans Master
Joined: Oct 2007
Posts: 9,700
Likes: 3,469
From: Akron Ohio
2025 Corvette of the Year Finalist - Modified
2024 C5 of the Year Winner - Modified
2023 C5 of the Year Finalist - Modified
2022 C5 of the Year Finalist - Modified
St. Jude Donor '09-'10-'11
Thanks. I think this is gonna be the project for this winter. I am now looking for C6 calipers and rotors if anyone has any used at a good price...