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I've been investigating using the Gen1 CTS-V 4 piston fixed brembos on our team's '86 C4 for endurance racing. I dug up this older thread in which Jimson shared his adapter bracket solution: https://www.corvetteforum.com/forums...bos-on-c4.html
Calipers in question:
Jimson's solution from the above thread:
I was wondering if anyone else has successfully used these calipers + the 14inch CTS-V (or smaller) rotors? I have a bracket design mocked up which would change slightly with rotor height.
C7 brembo aren't any more expensive, why bother with those vs the C7's unless you're trying to stay inside a smaller wheel? I think you'd need 18s to run the C7 brakes based on my research.
C7 brembo aren't any more expensive, why bother with those vs the C7's unless you're trying to stay inside a smaller wheel? I think you'd need 18s to run the C7 brakes based on my research.
I should have included some more detail about the race series rules - we're planning to run in the ChampCar endurance series. Calipers are subject to what the rulebook states is a "2x cost rule". Tech takes the autozone list price for a stock replacement caliper and multiplies it by 2x to give you a maximum for your new improved caliper. I have the stock '86 C4 autozone caliper coming in at ~$75 giving me up to $150 per caliper to work with. I was surprised to find these gen1 cts-v calipers for ~$140 each on summitracing. I have seen some people sneak these calipers under a 17" wheel on a smaller 13-13.5" rotor but I think we're leaning toward the 18" wheel with the 14" rotor for better pad contact.
Do you have any references for places we could source cheap C7 brembos? I quickly checked rockauto and they looked to be outside our 2x budget. Thanks!
I have seen full sets on ebay for like 500 pretty often, but they're used. I dunno if that comicates things, as you're probably right about them being over 2x the price new.
im assuming your goal is more ‘pad ‘ surface area?
also, if you try to use these with a 13 or 13.5” rotor(to fit 17” wheels)...im assuming you would need a different bracket
just talking aloud in case I go this route
Yes you're correct, if you use different diameter rotors you will need a different bracket design to move the caliper outward.
The brake pad concern is a bit more complex, and comes from the mismatch between rotor design and pad combo. The ideal situation is to use the rotor from the CTS-V (or 2010 SS camaro since its the same), however the center bore of the rotor would need to be opened up to fit the C4 hub. I think this might be the best route to take.
Other communities doing this swap have found they can use one of the C6 Z51 13.5" rotors which causes the brake pad to hang over the center concavity of that rotor design as it's wear face is too short (52mm from the rockauto spec sheet). The benefit to this combo is you could fit it under a 17" wheel. I'm not convinced that pad contact on the concave face is a good thing, especially for racing where it might build up intense heat. Perhaps it's OK for the street.
Here are pictures of the C4 13" rotor with the brake pad, showing how it would hang over the OD of the rotor as there is no center concavity:
Correct me if I'm wrong, but you mention using a Gen1 CTSV rotor. Didn't they have 6 lug wheels?
Yes you're correct. After reading from other car communities who have done the conversion as well as Jimson above, they use the 2010 Camaro SS rotor which is identical to the 2007 CTS-V rotor except it's 5 lug. Reference part number for the 2010 SS rotor is AC Delco 1771050
We sent off the 1771050 delco rotors to open up the center bore to 70.7mm per the C4's hub. Also ordered longer wheel studs to accommodate different wheel selections. Here are some pics of the adapter bracket for the calipers. We might make another part with tighter clearance holes to take up as much slop as possible.
Last edited by 85'irocz; Nov 10, 2020 at 04:28 PM.
For endurance racing we're thinking they are, for a few reasons. The pads should be quicker to change in the pits vs the floating C5 caliper. We think the pad and rotor wear should be more even with the fixed design. I've heard reports of the C5 caliper spreading under sustained heat and load as well. That being said, some teams have used the C5 caliper with good success. There might be a benefit to total pad area as well and clamping force, but I would need to check those details.
I have similar looking Brembo 4-piston calipers on my 2019 Challenger GT and I have to say that they will pop your eye ***** right out if you look at them hard. It's shocking how fast a 4000# car can slow down. That said, I'm VERY interested to know if these would fit behind sawblades and also if you're considering making these brackets available for others who would want to do this conversion.
I have these brakes on my 05' CTS-V and they work quite well on that 3800lbs car. I've had a close look at the V1 calipers and C6 Z51 calipers and the V1 calipers are for sure a better design and seem sturdier, although C5/C6 brakes do seems to work well on C4's.
Just a quick question for the OP, instead of using a 2010 camaro rotor, could you use a C6 Z06 based rotor? As they are 14in and have the correct hub bore size, if so you would save the machining cost to resize the hub bore.
I have these brakes on my 05' CTS-V and they work quite well on that 3800lbs car. I've had a close look at the V1 calipers and C6 Z51 calipers and the V1 calipers are for sure a better design and seem sturdier, although C5/C6 brakes do seems to work well on C4's.
Just a quick question for the OP, instead of using a 2010 camaro rotor, could you use a C6 Z06 based rotor? As they are 14in and have the correct hub bore size, if so you would save the machining cost to resize the hub bore.
I run C6 Z06 rotors on a few of mine with zero issues.
I would suggest making the bracket more like the right one. That will reduce distance between rotor and mounting point for the caliper.
Thanks JoBy, I have been looking at doing an alternate bracket similar to that, to reduce the moment arm and try to keep the forces in plane between the two mounts. Let me know your thoughts:
I have these brakes on my 05' CTS-V and they work quite well on that 3800lbs car. I've had a close look at the V1 calipers and C6 Z51 calipers and the V1 calipers are for sure a better design and seem sturdier, although C5/C6 brakes do seems to work well on C4's.
Just a quick question for the OP, instead of using a 2010 camaro rotor, could you use a C6 Z06 based rotor? As they are 14in and have the correct hub bore size, if so you would save the machining cost to resize the hub bore.
The reference part I have for C6 Z06 rotors is ACDELCO 18A2535 (let me know if you have a different pn I can check). ACDELCO 18A2535 has less pad height, so the pad would hang over the inside of the rotor just a bit. I've seen others use that rotor with these calipers, however I'm unsure how the pad contact issue would effect durability for a long race. Having that bore be the right size out of the box is nice though.
I have similar looking Brembo 4-piston calipers on my 2019 Challenger GT and I have to say that they will pop your eye ***** right out if you look at them hard. It's shocking how fast a 4000# car can slow down. That said, I'm VERY interested to know if these would fit behind sawblades and also if you're considering making these brackets available for others who would want to do this conversion.
Thats great to hear. Once we have a design nailed down we might be willing to make/sell some of them for others. I'm going to be fitting up a set of 17" C5 Z06 wheels over them soon to see if a spacer would allow it to clear the caliper. I have a hunch we'll need to go with 18" wheels though.
I have similar looking Brembo 4-piston calipers on my 2019 Challenger GT and I have to say that they will pop your eye ***** right out if you look at them hard. It's shocking how fast a 4000# car can slow down. That said, I'm VERY interested to know if these would fit behind sawblades and also if you're considering making these brackets available for others who would want to do this conversion.
The 17" C5 Z06 were not even close to fitting, and a spacer would not have helped. I'm thinking this setup will not clear a set of 17" sawblades either, however if you're able to measure the inner diameter of a sawblade I can check.
Last edited by 85'irocz; Nov 14, 2020 at 01:42 PM.
Thanks JoBy, I have been looking at doing an alternate bracket similar to that, to reduce the moment arm and try to keep the forces in plane between the two mounts. Let me know your thoughts:
Better but i would try to make the bracket thicker to minimize flex. Aiming for about the same thickness as the caliper mounts is probably a good idea.
There are a lot of empty spaces between bolt holes on both caliper and knuckle. In those places I would keep the full thickness of the adapter.
I modified your bracket in windows paint but you get the idea.
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CTS-V gen1 calipers on C4
