c7 to c8 wheels
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The lugs on the C8 will not sit flush with the wheels of a C7 because the chamfer on the wheel are of different angles. As a result the mating surfaces of lugs and wheel will not mate properly. This would create a dangerous situation as there would be a slight wobble and over time will eventually result in a stud failure. Not a safe condition.
Melting Slicks
Joined: Feb 2000
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From: new orleans
Technically the lug pattern is different 120.0 x 5 for the c8, 120.65 x 5 for the c5-c7. As far as the lugs go, there are plenty options for the 14mm with a 19 conical seat, the stock lugs will not work. The c7z front tires stick out about 3mm but they will bolt up. The .65 difference is not a issue, the tolerance between wheel studs is more than that. The fronts due rub on full lock. If you had a good machine shop they could mill 3-4 mm off the the lug face, and re align the holes so you could be perfect 120.0 but it’s a lot of trouble for a wheel known to have problems. I did however use a set of C6z wheels for my track wheels, much better fit. And a 275/325 tire
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From: Lancaster, PA
Technically the lug pattern is different 120.0 x 5 for the c8, 120.65 x 5 for the c5-c7. As far as the lugs go, there are plenty options for the 14mm with a 19 conical seat, the stock lugs will not work. The c7z front tires stick out about 3mm but they will bolt up. The .65 difference is not a issue, the tolerance between wheel studs is more than that. The fronts due rub on full lock. If you had a good machine shop they could mill 3-4 mm off the the lug face, and re align the holes so you could be perfect 120.0 but it’s a lot of trouble for a wheel known to have problems. I did however use a set of C6z wheels for my track wheels, much better fit. And a 275/325 tire
Edit: also would be interested if you need to retorque the lugnuts after a track event.
Last edited by range96; Feb 1, 2021 at 04:47 PM.
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Tadge answered:
Thanks for the question ZR1Bob. Our move to a mid-engine architecture shifted mass rearward so that the Corvette's weight distribution is 40F/60R. We take advantage of that traction with more torque multiplication through our new DCT for improved acceleration. The wheel stud size, pattern, and stud count is based on the needed wheel attachment clamp load to account for vehicle axle load, tire grip and other loads that the wheel-to-bearing joint must endure. These calculations drove us to the M14 wheel stud size for the rear axle. Many generations of Corvettes have used 5 studs on a 4.75 inch diameter bolt circle. It was a very standard pattern for the industry. For this generation we are moving to the metric standard of 5 x 120 mm. This change has nothing to do with the loads, in fact they are very similar patterns. So much so, that some people may try to use wheels designed for one pattern on a bearing with the other. That is very ill-advised. I'm glad this question has been asked because we need to let people know about the potential mismatch problem.
Although not needed for loads, we elected to use the same design on the front axle to keep a common lug nut, similar bearing design, and aesthetics.
Thanks for the question ZR1Bob. Our move to a mid-engine architecture shifted mass rearward so that the Corvette's weight distribution is 40F/60R. We take advantage of that traction with more torque multiplication through our new DCT for improved acceleration. The wheel stud size, pattern, and stud count is based on the needed wheel attachment clamp load to account for vehicle axle load, tire grip and other loads that the wheel-to-bearing joint must endure. These calculations drove us to the M14 wheel stud size for the rear axle. Many generations of Corvettes have used 5 studs on a 4.75 inch diameter bolt circle. It was a very standard pattern for the industry. For this generation we are moving to the metric standard of 5 x 120 mm. This change has nothing to do with the loads, in fact they are very similar patterns. So much so, that some people may try to use wheels designed for one pattern on a bearing with the other. That is very ill-advised. I'm glad this question has been asked because we need to let people know about the potential mismatch problem.
Although not needed for loads, we elected to use the same design on the front axle to keep a common lug nut, similar bearing design, and aesthetics.
Melting Slicks
Joined: Feb 2000
Posts: 3,426
Likes: 568
From: new orleans
Wheels
As measured with a caliper they were all off by 0.13, couldn’t tell by eye but they all tightened down to 140ftlbs and had no vibration. The other issue was the difference in the hub size. The c5-c7 were lug centric. The c8 seems to be both lug and hub centric. If I was Going to continue to use them I would have ordered a centric ring to fit the c6 wheel. Still may do that....
Melting Slicks
Joined: Feb 2000
Posts: 3,426
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From: new orleans
Wheels
I just published findings. Don’t really care what Tadge says. That’s the same Tadge that said the c7 z06 didn’t have an overheating problem....I’ll do my own measurements and come to my own conclusions. And as far as the hubs go, they used what was on the shelf and available and plentiful, the Camaro hub.
Safety Car
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According to Tadge, it is a significant issue. I'll believe the car's chief engineer over someone on the internet.
https://www.midenginecorvetteforum.c...ug-nuts-torque
https://www.midenginecorvetteforum.c...ug-nuts-torque
Melting Slicks
Joined: Feb 2000
Posts: 3,426
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From: new orleans
Different c5, c6, c7, and c8 wheels.....
it’s a car built on assembly line, it’s a great car, but it no way a one off. If you peal the skin off that entire car is bits and pieces of the gm parts bin. Going back to the c5, corvette engineering has to check all the gm parts bins before they can request a custom part. Which is why, the valve spring problem is the same for every gm v8 produced between certain dates. My back up camera went out, yep it’s a caddy part. DCT transmission was a three way deal between fiat, gm and Ford. If you can buy parts for it at autozone, and rock auto.....
it’s a car built on assembly line, it’s a great car, but it no way a one off. If you peal the skin off that entire car is bits and pieces of the gm parts bin. Going back to the c5, corvette engineering has to check all the gm parts bins before they can request a custom part. Which is why, the valve spring problem is the same for every gm v8 produced between certain dates. My back up camera went out, yep it’s a caddy part. DCT transmission was a three way deal between fiat, gm and Ford. If you can buy parts for it at autozone, and rock auto.....
Race Director
Joined: Sep 2016
Posts: 13,180
Likes: 10,527
I just published findings. Don’t really care what Tadge says. That’s the same Tadge that said the c7 z06 didn’t have an overheating problem....I’ll do my own measurements and come to my own conclusions. And as far as the hubs go, they used what was on the shelf and available and plentiful, the Camaro hub.
