claf

I am an ignorant guest from the C! forum. I have an opportunity ? to buy a '71 4 speed conv with a totally rusted frame. Can someone give me a SIMPLE tutorial on the MAJOR differences in C3 frames ? I know about the bumper problem, how about manual vs automatic ? and single exhaust vs true duals, body mounts etc ? You get the picture. What should I look for , year wise, in a replacement used frame ? Thanks, Bob C

Alan 71

Hi c,
The frames from 68-73 will work fine.
4-Speed cars have the transmission crossmember that's welded in place, while automatic cars have a removable crossmember.
4-Speed cars will have a small bracket welded to the forward left side frame rail for the clutch z-bar to mount to, automatic frames won't have it.
On all these frames the center transmission cross member was set up for dual exhausts.
Good Luck!
Regards,
Alan

PS: … if the frame is so rusted it needs to be replaced what condition is the body 'birdcage', (steel structure) in?

71 Frame


Z-Bar bracket.


Frame rear… note 2 diagonal braces at kick-ups. 68 frames don't have them but they can be added.

bj1k

As Alan said check the birdcage. If the frame is real bad it could have rust in the birdcage. Not always the case but check before you buy. I bought a 69 convertible years ago that had a frame so bad that it broke in half when the body was unbolted and lifted , but the birdcage was perfect . It did need rocker panel supports though. The car only had 63k. miles but sat in a garage for over 20 years with water leaking through the walls and the water laid under the car causing frame rot .

Easy Mike

http://www.71corvette.com/frames.html

claf

Thanks all for your knowledge, however the '71 project is OFF. When pulling the car out of storage from the rear the only thing that moved was the portion of frame from the kick-ups back.

When that part of the frame came out it brought most of the glass with it. Never did check out the birdcage but after seeing what was really under the car I can only assume the worst.

The move destroyed whatever was originally worth saving. Ripped up all the rear suspension, E brake mech, exhaust etc. Car now is basically junk.

Was / is a numbers matching car but bare basic low horsepower no frills conv. Maybe next time. Bob C

Scottd

You didnt miss out on anything. It sounds like this car was a total loss. Splitting in two right before your eyes just saved you 5 years of work and 50K in resto bills.

doorgunner

Thanks for the update......new members need to be aware that some cars need to be closely examined before a purchase/full-price purchase is made.

AllC34Me

I have seen them break at the kickups as well and sad to hear another frame, and maybe whole car, lost to rust. I'm working on one of those now. Good luck with your decision.

parkerracing

I beg to differ, don't think of this as a disaster but rather an opportunity. Look into an aftermarket frame with late model running gear and LS motor/Tremec trans. As others have mentioned, you'll have 50K in a 25K car doing your original plan (and you'll have a car that still runs and drives like a 50 year old car when you're done). That same 50k will get you one of the sexiest body styles that runs and drives like a new car. Which would you prefer?

midigike

Yes, when I doubt you can still go the Restorod route!