92 coupe cowl shake.
Thread Starter
Instructor
Joined: Jun 2011
Posts: 244
Likes: 26
From: Carmel, Indiana
92 coupe cowl shake.
I was informed that to eliminate cowl shake when I take the Targa top off that I can get the cross member from a C-4 convertible and install on my 92 to stiffen the shake.
I guess I'm looking for confirmations that his is a possibility or other methods that can reduce or eliminate the shake.
Thanks in advance.
I guess I'm looking for confirmations that his is a possibility or other methods that can reduce or eliminate the shake.
Thanks in advance.
Melting Slicks
Joined: Oct 2012
Posts: 2,156
Likes: 273
From: Dunedin NZ.
There is or was an alternative to the convertible cross member, it is a kit that was developed by Gordon Killebrew, reading up on this it claims to be superior to the factory system (Killebrew previously worked for GM but I understand they didn't want to pay him royalties for his system). Have a look here -
https://www.google.com/url?sa=t&rct=...wXXyvEpQYyndOT
FWIW I had the roof of my C4 for the first time yesterday to change the weather seal above the drivers door. I must say the car flexes a lot more than I expected plus there is a very unpleasant pulsing of air pressure in the cabin, I understand this can be alleviated by using a spacer that latches the rear hatch open slightly.
https://www.google.com/url?sa=t&rct=...wXXyvEpQYyndOT
FWIW I had the roof of my C4 for the first time yesterday to change the weather seal above the drivers door. I must say the car flexes a lot more than I expected plus there is a very unpleasant pulsing of air pressure in the cabin, I understand this can be alleviated by using a spacer that latches the rear hatch open slightly.
Burning Brakes
Joined: May 2002
Posts: 755
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From: Sierra Foothills, State of Jefferson
You may want to see if you can find a roof brace/ targa truss somewhere. Corvette Central shows one in their downloadable catalog, around page 144. However it is not searchable on their website. maybe a call to them.
These used to be fairly popular, when the C4s were much newer. You may be able to find a used one.
If you read through the history of the C4s, you may find out that they were supposed to have a T-top- which would have included a brace to the windshield header.
However, esthetics won out over function. I took the roof off mine a few times, wasn't worth the compromise.
These used to be fairly popular, when the C4s were much newer. You may be able to find a used one.
If you read through the history of the C4s, you may find out that they were supposed to have a T-top- which would have included a brace to the windshield header.
However, esthetics won out over function. I took the roof off mine a few times, wasn't worth the compromise.
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Last edited by FASTAZU; Jan 8, 2020 at 09:55 AM.
Race Director
Joined: Jan 2012
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From: United States
I have one of these and will not go topless without it.
https://www.corvetteforum.com/forums...e-is-here.html
https://www.corvetteforum.com/forums...e-is-here.html
I also have RD Racing chassis stiffner which is a bolt in 4 point. It helps allot. But the roof brace really makes a difference.
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Melting Slicks
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If you do end up using a factory X-brace, just be aware that you will lose some ground clearance. Boxing in a factory brace would make it even more effective.
Le Mans Master
Joined: May 2005
Posts: 7,359
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From: Central Maryland
Having owned both a coupe and ragtop C4, I can confirm that the coupe gets very loose structurally when the targa panel is removed. And wind turbulence in the cockpit is just awful. I removed the targa on mine once, and almost immediately decided that I'd never do it again.
The factory X-brace under the ragtop car does help quite a bit to stiffen the structure, but there's still a bit of cowl shimmy, most noticeably when the ragtop is down. The X-brace doesn't completely eliminate the jitters. And, as pointed out above, it does cost you around an inch of ground clearance. My car has high-centered many times as a result of the reduced clearance.
Live well,
SJW
The factory X-brace under the ragtop car does help quite a bit to stiffen the structure, but there's still a bit of cowl shimmy, most noticeably when the ragtop is down. The X-brace doesn't completely eliminate the jitters. And, as pointed out above, it does cost you around an inch of ground clearance. My car has high-centered many times as a result of the reduced clearance.
Live well,
SJW
Race Director
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The C4 was never designed to be a ragtop or a Targa. It was then cut into both and it shows. Take the roof off and jack it up. Try to open the door. With my RD Brace, I can now. The aftermarket companys offering roof braces are a God Send..
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Last edited by FASTAZU; Jan 8, 2020 at 09:55 AM.