Converting Unibody 4th gen to Solid Frame?

[JasonWW]

Here's another idea that's a bit out there. I've been working on variations of this idea for quite a while. At first I wanted to add some square tubing into the factory rails and weld them in solid from wheel to wheel. This was originally going to be like a super sized sub frame connector. It would put all other SFC's to shame, but why stop there?



Why not extend it front and rear like a C5 or C6 frame?



Then you can do all kinds of neat things like flatten the floor boards, connect your roll bar to it, brace your suspension parts to it, ect... It will make the car stiffer and safer. Not to mention freeing up the space that the sheet metal took up.

It may sound crazy, but not any more so than sticking a C5 drivetrain under a C4 body.

[JasonWW]

Didn't folks use to add rear subframes to unibody cars back in the 80's when the Pro Street look was in?

[cnorton]

Most of that work was done in converting my F-body to a Super Stock car. the new frame extends all the way to the rear of the front subframe. Rules requirements for the class prevented completely converting the car to a full-frame configuration. One of the most important considerations for such an operation is keeping the weight down. If you use mild steel tubing you'll have to keep careful tabs on how much weight is going in and how much is coming out.

We used chromemoly round tubing as specified in the NHRA Rulebook for ET's down to 8.50. At the time we built the car it was good to 7.50 but the rules changed a year or so after it was completed. It has narrowed rear frame rails to accommodate the tubs and a full cage system that extends from just behind the radiator to the rear-most crossmember.

[01ssreda4]

i think its a great idea. sounds like a lot of work.

[Wild Willy]

Originally Posted by 01ssreda4

i think its a great idea. sounds like a lot of work.

+1- at least the weight you are adding is down low- I like the idea of strengthing the perimeter- If I got that far into it, I would put the cage/roll bar in, too-

Nice work, if you have time, a shop, and a few $ to spend-

[9sec93]

at a show i saw a 4th gen camaro on a 1st gen frame. im sure it was a good amount of work but it looked nice. it was back-halved but im sure all they bid was channel the underside of the body like the floor board area over the frame. having no strut towers looked nice. it was at the super chevy show in joliet, IL. it was yellow and i have seen it on the internet somewhere before.

[JasonWW]

Originally Posted by 9sec93

at a show i saw a 4th gen camaro on a 1st gen frame. im sure it was a good amount of work but it looked nice. it was back-halved but im sure all they bid was channel the underside of the body like the floor board area over the frame. having no strut towers looked nice. it was at the super chevy show in joliet, IL. it was yellow and i have seen it on the internet somewhere before.

Interesting, if you run across any pics, let me know.

I might pick up a stripped shell (front half anyway) from a junkyard and flip it upside down. Then cut away the stock rails and make new rails that fit nice. Then on my car hold the new rails up to the stock part and trace my cut lines. Cut it out, slide the new rail into place and weld it in. That will at least take care of the front.

[jimmyblue]

If you're not going to be modifying the front suspension then
why not just do like the factory convertible and add layers
from the outside?

I have worked on full-frame cars (GM A-body) and while the
rails are decently stiff in bending, there is really no help for
torsion - that is all taken by the body shell (and being on
rubber mounts, not too stiff). But anyway, while full fore/aft
rails will stiffen the body against sag, they probably will not
make the chassis any better (or not much) for torsion.

The unibody 4th gen, even my 'vert, is well stiffer than the
full-frame 'verts I have had (A and B-body).

[JasonWW]

Every part of the suspension will be modded. I may convert over to short spindles and remove the fender wells.

Look here. Has Anyone Converted to a Short Front Spindle?

I'm stiffening the whole car. I just didn't go into it in this thread.

[FastBlackTA]

Why in the hell would you want to do this?

How much power are you planning on making?

[SuperSlow02]

Originally Posted by 9sec93

at a show i saw a 4th gen camaro on a 1st gen frame. im sure it was a good amount of work but it looked nice. it was back-halved but im sure all they bid was channel the underside of the body like the floor board area over the frame. having no strut towers looked nice. it was at the super chevy show in joliet, IL. it was yellow and i have seen it on the internet somewhere before.

arent 1st gen unibody also...?

[JasonWW]

Originally Posted by FastBlackTA

Why in the hell would you want to do this?

How much power are you planning on making?

It's nothing to do with power. (I would like to build it to hit 200mph, but I don't think I have the money to build that much HP.) Anyway, this car is just a toy to keep me busy. I plan to drop it down to the rockers and keep it drivable. It's going to be what I think is cool.


My concept idea:


A more realistic result that can be driven:

[JasonWW]

Originally Posted by SuperSlow02

arent 1st gen unibody also...?

It has a front and rear sub frame, but they are not connected.

[SuperSlow02]

that would be a unibody..correcto...

[HELLBENTfabrication]

usually when people build something like this they remove the entire floor and existing frame rails. then start from scratch and drop the body on.......why your approaching this like a mad scientist is beyond me

[JasonWW]

Originally Posted by HELLBENTfabrication

usually when people build something like this they remove the entire floor and existing frame rails. then start from scratch and drop the body on.......why your approaching this like a mad scientist is beyond me

Well, I am a mad scientist, but that's beside the point.
I've never seen anybody do this, so I'm just figuring things out as I go along. Who does this type of work? Is there any info online? Any advice would be appreciated.

[01ssreda4]

i like the idea.

[JasonWW]

OK, how's this for an idea? I can hunt around and get a cheap firebird (flooded, blown engine, etc... ). Strip it down to the shell. Then I can brace up the interior so it will hold its shape. Then cut out the front and rear floor pans. I can build a complete frame out of two by four tubing much like the C5 Corvette as well as add a rollbar and extra bracing.

Once it's ready, I can transfer my interior, fenders, hood, doors, rear hatch, front and rear bumper covers, engine/trans, etc... over to the new chassis. This way if I give up halfway through, my original car will still be in one piece. Plus I can still drive it if I want.

Opinions please.

PS.
Could I use a cheap 98+ Firebird?
Would the 93-97 be the same body shell?
Would their k-member be the same as a LS1 Trans Am?

[Black02SLPSS]

all the 98+ fbodys use the same k member, the lt1's had a slightly different k member.

[LS1Formulation]

93-02 use the same body shell, K members are different.