Any of you guys get into body on frame fabrication in regards to a thirdgen?

The last couple of years I've been doing that for non-thirdgen projects (hot rods, street rods). I've learned a lot about suspension design.

As some of you may know, I do (or did) a lot of Corvette stuff. Built a few frames (C3). Cool thing about those cars is you can fabricate a frame using whatever front and rear suspension you want, and the body just bolts on.

I've kinda thought about the possibility of modifying a thirdgen body to bolt onto a rolling chassis.

Looking for inspiration.

Don't confuse this with putting a thirdgen on a K5 blazer frame. Yes, we did that in high school lol.

 

why would you want to?
stiffness? add a roll cage?

i dont see any benefits for this type of work

 

Third gens are unibodys. There is no body on frame fabrication. Unless you go back a few decades, all the current donor vehicles are also unibody unless you use a truck frame and you need to find one that is the same wheelbase or a frame that can be converted to a different wheelbase. Third gens sit low and putting the body onto any chassis will make it look like a 4x4.

The closest to being a body on frame is to build a tube chassis car. In other discussions, this is not a simple or cheap route to take and if you do decide to go that route, you would be better off finding a car that has had front end damage and start with that instead of converting a drivable street car.

 

It's very difficult to put different front and rear suspension with the existing limitations of the thirdgen chassis.

On other platforms, like the C3, you could buy or fabricate a chassis like this and bolt the body on.

 

It's actually a thing already, I'm asking if any of you guys have done a project like this on a thirdgen. I've done a bunch of Corvettes and some street rods.

https://www.hotrod.com/how-to/first-...olt-in-chassis

 

Looks like a pretty slick setup. A bolt on frame ready to throw big power at it

 

Yup. I love the suspension design too. It's $18k, which is a lot of money but for non-fabrication guys it's a fantastic product.

I'm guessing nobody in here does their own frame fabrication though.. oh well.

 

Yea doesn't appear that way at all. I'd love to pick-up something like this but with any new product you never go out and buy the first ring of things until all the little bugs have been worked out

 

That's what THIS THREAD was about....but I doubt many or any have done this or anything like it. SFC's are the closest thing that I've seen or heard of that anyone has DONE on a 3rd gen.


Love to see pics of something similar for a C4. At one point, I'd day-dreamt about putting ~3" round tube down the middle of the rocker rail and welding it in to the trailing arm panel and the front frame rail "face", right behind the front tire. Experiments flexing the frame by hand, deflated the idea, however.

 

Haven't you done stuff like that on other vehicles? Or am I thinking of Twin-Turbo?

I built another street rod frame on NYE in the shop. Working on the front end right now.

I have thought for years and years why not just fabricate a frame and bolt the thirdgen body to it. I'm glad to see there is a product on the market to shut up all the "that won't work" guys.

I know some of the guys on here love to do the C4 rear ends on these cars, and I think I've seen one C4 front suspension. It is SOOO much easier to fabricate those mounts as part of a frame than it is to retrofit to the existing angles/locations of the thirdgen chassis.

 

Many people don't feel the need to put a full frame under a third gen but that doesn't mean it can't be done.

If you have to ask how to do it, you shouldn't be doing it but with enough time, money and fabrication skills, anything can be done.

 

That must be Maark (TT). I haven't...the most radical thing I've done is the Kart, and that's not that radical.


I totally agree. And you likely end up w/many other benefits: a much stiffer structure. None of the compromises that the C4 suspension has to make (pretty awesome though it is). I also think that if you eliminate the "requirements" and constraints of the stock floor pan, you could end up with more flexibility in seating elevation, ground clearance, exhaust space and more.

 

Instead of focusing on adding a whole frame, why not cut out (at spot welds) existing inner fenders, rails, and other chassis pick-up points to accommodate your desired UCA /LCA front end pick-up points, and alternative arms / fabbed parts?

A subframe unit-body design still has opportunity to be stiffer than a BOF, and it's not like additional reinforcement can't be added to make it moreso.

Sheet with ample formed ridges and other design features can do what's needed. Without making for excess added weight

 

completely with this, too. However....the 3rd gen F-bod's ridges and other design features didn't do it. Or even come close to doing it, IMO. I see the 3rd gen structures/shapes as a liability (space and weight w/o good return), not an asset, to where when comparing Joe's idea, you could do WAY better with that same space and weight, with smartly fabricated parts, replacing the stock parts.

 

I built a 3/4 frame in my AWD build thread and welded it to the car with a new floorpan

It goes from the radiator shroud to the rear LCA pivots

Don't see a reason it couldn't be replicated for any 3rd gen, not necessarily after AWD

 

This is exactly how I did my subframe connectors. I used 2” X .186” wall tube welded along the pinch welds and attached to the control arm pad at the rear and tied into the cowl/firewall at the front. The front frame rails were sectioned and a new rail was inserted, welded, and gussets welded in for my C4 front suspension.

This could very well be done. With all of the work that I had done to modify and reinforce the original frame rails in my car for the C4 SLA/IRS suspension, I could have made a box and tube full frame with custom floor pans and solved a few issues with the stock frame (symmetrical left and right). 427seven did this in the rear when he did his C4 IRS. With a clean sheet you could make the frame in any configuration you like and have room for proper mufflers, engine setback, any suspension, and space for huge tires just to name a few. I wish I could have done this 20 years ago when I started building my car.

 

Exactly my thoughts.

If you're willing to cut the entire floor out, your life gets even better. The floor pan is stamped the way it is for structure. You can cut out a lot of crap that creates obstacles.

I think if you use the rear shock mounts, rear seat belt mounts, and front k-member mounts to attach the body to a new parameter frame similar to how the hot rod shop did, it would work out well.

The unequal four link and watts link rear end is really cool.