C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

C4 coilover suspension

 
Old 09-16-2017, 04:29 PM
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waddiejohn
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Default C4 coilover suspension

Can anyone tell me the difference between the "87" and the "88" and later C4's that allow the later cars to run coilover suspensions?
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Old 09-16-2017, 10:03 PM
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1cooldaddyo
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I believe in the earlier cars the "spread" between the legs of the control arms is too narrow to fit a coilover through.
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Old 09-16-2017, 11:06 PM
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Pwnage1337
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There are people who have put coil overs on the 84-87 cars, pretty sure the front just requires reinforcement of the shock tower, and the rears need to be moved forward.

Ld85 has a good thread on it. (pretty sure it was him)
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Old 09-17-2017, 06:51 PM
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the shock towers are wider in the 88 + plus cars,
in the early cars you need to cut out some of the metal to clear the springs and brace the tower.
the pic below is a test fit, the bent metal around the spring and cap was cut out.

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Old 09-19-2017, 07:33 PM
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Mike Holmen
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blackozvet, curious if you have any issues with the top rubber bushing? I was debating in making an more stiff/rigid bushing.

Curious on what springs specs your using? Length and stiffness?

Thanks, looks like a decent upgrade for us C4 guys.
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Old 09-20-2017, 12:09 AM
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blackozvet
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Originally Posted by Mike Holmen View Post
blackozvet, curious if you have any issues with the top rubber bushing? I was debating in making an more stiff/rigid bushing.

Curious on what springs specs your using? Length and stiffness?

Thanks, looks like a decent upgrade for us C4 guys.
I cut the rubber bush that came with the Viking shocks in half and put a half on each side of the steel, has worked ok.

Originally I put 450 lb x 9" springs in to run it on the street.
Had a pair of 600 lb x 8- 1/4" made for track use. at this length the adjuster is half way up the shock thread.
To be honest you cant tell the difference between the spring rates on the street if you set the shocks soft.
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Old 09-20-2017, 12:17 AM
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Originally Posted by blackozvet View Post
the shock towers are wider in the 88 + plus cars,
in the early cars you need to cut out some of the metal to clear the springs and brace the tower.
the pic below is a test fit, the bent metal around the spring and cap was cut out.

This was the info I was looking for. Thank you very much.
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Old 09-20-2017, 11:18 PM
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This is a shot of my '85, you can see where I slightly spread the shock tower to clear the spring. These are Exotic Muscle which I strongly suggest you do NOT buy
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Old 09-21-2017, 01:54 AM
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Originally Posted by Midnight 85 View Post
This is a shot of my '85, you can see where I slightly spread the shock tower to clear the spring. These are Exotic Muscle which I strongly suggest you do NOT buy
I was looking at the set that Corvette Mod's sells. They use QA1 shocks and Hyperco coils. You can pick your spring rates. Initially I was looking at installing these on my 87 convertible but I'm looking at an 89, six speed convertible I found with 75000 miles on it.
I appreciate the response to the thread.
Thank you
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Old 09-21-2017, 02:27 AM
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Yariv
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Hi,
In order to do this coilovers conversion, did you remove the monoleaf?

Thanks.
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Old 09-21-2017, 03:01 AM
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Originally Posted by Yariv View Post
Hi,
In order to do this coilovers conversion, did you remove the monoleaf?

Thanks.
The idea is to get rid of the monoleaf and have a more tuneable suspension.
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Old 09-21-2017, 06:19 AM
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While I really like my coilovers there is one big thing to consider, if a shock or shock mount breaks, you are not going anywhere. The car will drop down on the corner that broke and you will be on a roll back to get it home. While this is a rare occurance, it could happen. That being said, my car has been through 11 states with one broken mount.
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Old 09-21-2017, 12:15 PM
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How are you guys mounting the sway bar? I've heard that the coil over spring might make contact with the sway bar end link attachment.

Has any one have any information the rear coil over set-up?

I want to do both the front/rear on my 85 car this winter.
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Old 09-21-2017, 01:52 PM
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considering the cost of swapping coil overs, I'm guessing you guys that have them are seriously into racing or actually tracking the cars?
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Old 09-21-2017, 03:22 PM
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Another option on converting early cars to coilovers is to use a bracket/mount welded on the top of the shock tower that pushes the coilover out at the top a little.

This is how I did my 84.



Will

Last edited by rklessdriver; 09-21-2017 at 03:24 PM.
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Old 09-21-2017, 06:47 PM
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Originally Posted by rklessdriver View Post
Another option on converting early cars to coilovers is to use a bracket/mount welded on the top of the shock tower that pushes the coilover out at the top a little.

This is how I did my 84.



Will
Rkless, can you provide specs on what coil over (compressed/extended lenghts) and spring specs?

I really like your idea, its a simple fix to the narrow shock tower issue.
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Old 09-21-2017, 06:57 PM
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Originally Posted by Mike Holmen View Post
Rkless, can you provide specs on what coil over (compressed/extended lenghts) and spring specs?

I really like your idea, its a simple fix to the narrow shock tower issue.
and diameter if there is a spec for that. i like the idea as well.
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Old 09-21-2017, 08:20 PM
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rklessdriver
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It is a standard 2.5" OD coilover spring.

Mine is a drag race car so I run a pretty soft spring rate at 350lbs.

The shock is a Viking Double Adjustable. Mine is a custom valved drag racing unit but the off the shelf equillivent Street or RR shock would be PN C217.

The compressed distance of the shock is 10.4"
The extended distance of the shock is 14.3"
The recomended ride height distance of the shock is 12.0"-12.75"

The upper shock mount/bracket is an oval track chassis fabrication piece mfgr'd by places like Kyser Engineering and Pro-Tek and sold thru places like Day Motorsports, PN SM-3180. Just cut it to length, fab an end cover, dress the bottom a little (the top of the factory shock tower is a bit round) and weld it on top of the factory shock tower..... it was very, very easy to fit up.

You will also want to fully weld the factory tower to the frame.... the factory welds are intermitant seam welds and spot welds.....

You may have to trim/grind the sides of the factory tower back a little so the spring will clear the upper A Arm. Stuff varies on these cars.... I needed to trim mine about .150" on the drivers side but not the passenger side.

Hope that helps.
Will
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Old 09-22-2017, 05:09 AM
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Originally Posted by Mike Holmen View Post
How are you guys mounting the sway bar? I've heard that the coil over spring might make contact with the sway bar end link attachment.

Has any one have any information the rear coil over set-up?

I want to do both the front/rear on my 85 car this winter.
the sway bar is awful close to the spring - and the higher the spring rate the fatter the spring !
some people have just bent their tower forward - or you go rod-end like this,





rear coil over's are a whole new ball game - you have to move the locating point inboard and it creates a lot of leverage on that point - I have seen pictures of the alloy hub section that has snapped off !
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Old 09-22-2017, 07:59 AM
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Originally Posted by armybyrd View Post
considering the cost of swapping coil overs, I'm guessing you guys that have them are seriously into racing or actually tracking the cars?
..... ... Aside from car show/my car is better than yours bonus points , if there isn't a serious need (racing or MoBandy) for the investment in coil-overs what is the fascination with doing this conversion ? .....
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