Newbie to C3 with a stupid question

Ozzy · Oct 11, 2009

Has anyone came across any information about grafting C4 front and rear clips to a C3 frame, or adapting a full C4 frame to the C3 body?

The technical fabrication is not a problem for me, I have the resources available to do the deed, just need to know how feasible it is.

My C3 project car is going to be a wide body cnversion so the track width will not be an issue.

Thanks for bearing with me on one of many stupid questions I will be asking.

Twin_Turbo · Oct 11, 2009

Check out 69427s project

http://www.vettemod.com/forum/showthread.php?t=3176

Ozzy · Oct 12, 2009

Twin_Turbo said:
Check out 69427s project

http://www.vettemod.com/forum/showthread.php?t=3176

Awesome project, I read the complete post but never did figure out if he grafted frame sections or modified the C3 frame :confused2:

BBShark · Oct 12, 2009

He modified a C3 frame to accept the C4 suspension. A C4 does not have a traditional frame where you could seperate the body from the frame.

I suppose you could graft the C3 body panels onto a C4 (I know there is sommeone doing this with C2 panels).

Red · Oct 12, 2009

BBShark said:
He modified a C3 frame to accept the C4 suspension. A C4 does not have a traditional frame where you could seperate the body from the frame.

Ozzy isn't alone with his question, I had the same, but never asked. I don't think the question is about the body, but how much of the C-4 frame section is grafted to the C-3 to make it work? Was the entire crossmember section with control arms and steering linkage grafted on? 69427 did an excellent job, but a little vague to follow in this regard. You seem to know, so I'm asking here.

Twin_Turbo · Oct 12, 2009

The C4 uses a front suspension cradle that also has the motor mounts, simplified all you need to do is weld that to a modified C3 front frame and you're done there. For the rear, weld some ears on for the batwing and fabricate a pinion mount like I did on my car.

69427s project is more involves as he narrowed the c4 suspension to fit his body. With a flared car you could use the full C4 track width and still retain the deep rim look without resorting to neg offset/flat wheels that don't look right on a c3 IMO.

Red · Oct 12, 2009

Thanks for clearing that up TT, I have been wondering about how the front suspension adapted, but never though about the back. I prefer my iron dif for drag racing.

69427 · Oct 12, 2009

Red said:
Thanks for clearing that up TT, I have been wondering about how the front suspension adapted, but never though about the back. I prefer my iron dif for drag racing.

FWIW, here's an old picture of the front crossmember when it was first tacked together.

It bolts to the underside of the frame so it is removable in case I wanted to alter the geometry or repair any damage. The inner pivot points are about two inches further in (compared to the C4 crossmember) on each side to make the C4 suspension mimic the C3 trackwidth. I also welded on some tabs to the crossmember to mount the steering rack. The upper A-arms bolt to separate brackets on the top of the frame. This lets me modify/repair the upper geometry separate from the bottom if desired.
I'm using the iron differential housing in the rear. Strong, cheap, and plentiful.

Red · Oct 13, 2009

Thanks for the photo and explanation. You made everything you did both fore and aft look easy and only a good man can do that. I am not familiar with the C-4 susp, but will pay more attention to a buddy's ZR1 next time I'm at the track. What you did to your 69 is a very desirable upgrade, but not a project for the average hobbiest. I'm not a fan of the Dana 44 diff, but what you did combining the C-4 rear susp with the strong iron differential is the best of both worlds. Thanks for sharing your work, it is inspiring!:thumbs:

69427 · Oct 14, 2009

Red said:
Thanks for the photo and explanation. You made everything you did both fore and aft look easy and only a good man can do that. I am not familiar with the C-4 susp, but will pay more attention to a buddy's ZR1 next time I'm at the track. What you did to your 69 is a very desirable upgrade, but not a project for the average hobbiest. I'm not a fan of the Dana 44 diff, but what you did combining the C-4 rear susp with the strong iron differential is the best of both worlds. Thanks for sharing your work, it is inspiring!:thumbs:

Thank you for your kind words.
Mike