General question: how hard is grafting/bolting newer subframes into C3s?


Jul 25, 2019
I'm referring to taking, say, the entire rear subframe and suspension out of a newer car and fabbing up mount points in the c3 frame.
Trynna get some anecdotes and general opinions.
These aren't explicit questions to answer, just things to get your noggin noodling

Do you find it's usually a very painful and unrewarding process? Or is it relatively easy, just time consuming?

Does the final product actually perform as well as you hoped? Or do things not really work right because of the differences introduced?

Is there often a long tail of little issues and annoyances that come with this kind of conversion, or is it a big project with not much else you need to bother with afterwards?

Do you find certain mistakes folks make when doing this kind of thing that was easily avoidable if only they had known some crucial bit of info?

Do you carefully measure things beforehand and do some mock ups to ensure fitment? or do you just sort of slap the two pieces together and throw together a mounting solution?

Would you trust handing something like this off to a shop which specializes in car fabrication, since they have the expertise and tools to do it, or would you MUCH rather do it yourself?
This depends entirely on how confident you are in your ability to fabricate, design and overcome obstacles.

I would build some kind of jig that bolts to your wheel hubs/rotors at ride height to maintain wheel position. Set your new subframe in that jig, and figure out whats in your way and how you are going to attach it to the existing frame rails.
Absolutely need the frame jig. Also an easy way to lower/raise the body onto the the completed chassis to figure out where to clearance the body.
honestly curious how much something like this would cost if given to a shop experienced in classic car fabrication, in California.

is this like a sub $5000 operation? or more like $10k+ just to fab all this up
That's easily 100 hours of work so, if the shop rate is $100/hr., you are looking at $10K+. Add to that building a frame jig, materials, etc.
Revisiting this, a huge boon would be to find someone who already did something like this, so i can borrow their engineering work and then it just becomes a fabrication job

but the problem becomes that a tesla model S motor has to fit into this whole subframe mess in addition to all this, and most modern subrames are very "closed" around the differential
I have been looking at Howe racing chassis slightly used. They pop up pretty reasonable. I think some guys on cf have been using these.

I probably will stick with oem frame and stay old school.
You really don't have to do that. You could use a Detroit Speed setup. Art Morrison makes a subrame rear suspension set but I am not sure how much time you would be trying to get that to work on a stock frame. Don't think it would be worth the effort vs what is already available.
It's not for the newbies. Mine performs fantastically - even competing in national events. I'm not sure my build thread would qualify as a how-to but most of what I did is there... it has a C5 front suspension and a 5th gen Camaro rear suspension. With all of that said, the bigger issue is you must run flares. There's nothing out there that checks all the boxes but fits within the C3 wheel tubs.
One, nice bonus of the Camaro rear is that you gain quite a bit of space between the back seat and where the suspension makes its up bend. Cost - I'd build a rolling frame for 20k.
Thanks for this post. I think your information will help me out with my build.