Hi all. I am a newbie to the Classic Oldsmobile forum. I have a 1968 Cutlass S convertible. It was my dad's. He has owned it for at least 30 years. I have owned it for 20. years but never had it safetied and licensed. I put it up on the hoist, and the rear frame boxed rails are rusty. They have corroded right through.

Does anyone make replacement rear frame rails for the convertible? If so, are they relatively easy to replace? None of the bigger manufacturers seem to have any.

 

Welcome to CO. I don't think anyone builds frame sections that can be used to repair an existing frame, I think your only options are going to be:
1) Patch what you have
2) Find a doner frame that has not been wrecked in the rear and cut off what you need to replace on your existing frame
3) Replace the entire frame from a less rusty car

Others here have much more experience in this area than I and will probably chime in.

 

No one reproduces frame rails for A-body cars. Good frames aren't that hard to find. What, exactly, are you calling "rear frame boxed rails"? All A-body frames are boxed over the rear axle, but are open channel from there to the back bumper. The non-convertible frames are the same from the rear suspension attach points back, so any 68-72 non-wagon frame is a potential donor. The only part of the convertible frame that is different is the added reinforcement of the straight rail section under the rockers.

 

Thank you very both very much for the information and clarification!. The frame rails over the rear wheels seem to be the only part of the chassis that has rust holes and I would like to replace. I may even have a donor car frame now that I know the rear section is the same.

Convertible middle rails and reinforcement boxes look good. Is there any part of the front frame that is rust prone and I should check while I'm at it??

 

Check where the body mounts, there is a good chance that you need to repair one or more body mount holes

 

I've usually found rust in convertible frames in the box section behind the front wheels, directly below the firewall body mounts.

 

Check on Ebay as an option. There is a junk yard in Arizona that lists a-body frame pieces on Ebay. You would have to cut out a section and weld in the replacement section.

 

Than you all for your replies

Looked on EBay - did find some used frame sections. I have to get my lift clear to have a better look at what I need. (note to self: don't start projects you can't finish quickly).

Presume it would be easier to patch what I have as opposed to cutting out a section. I don't particularly want to remove the body and I haven't done frame repairs before.

I did see: Allstar Performance ALL60085 Frame Repair Plate for GM A-Body/G-Body 27"L. Is this a good fit?

 

From the Allstar Performance website:

 

In order to fix the frame correctly you will almost definitely have to remove the body. Once you do that you're going to find it's worse than you think. The best solution is to remove the body, save the boxed sections from your frame, and have them welded into a hardtop frame..... or find a used convertible frame, which is usually a lot more expensive.

FWIW my 68 convertible frame was rusted at the bottom toward the rear of the boxed sections and almost all the body mounts needed new washers