I have a 53 Chieftain conv with I think a 120 inch wheelbase. I don't have access to any interchangeability manuals and wonder if anyone can tell me what full chassis might fit under the body. Want to upgrade to more modern suspension and drivetrain. Plugged in "120 inch wheelbase" on google but didn't give me any results. Any help would be greatly appreciated.
Greetings! The most important piece of information to keep in mind when attempting a frame swap is not the wheelbase, it's the front and rear track, in other words, the distance between the wheel mounting surfaces. The only late-model chassis out there with anything close to the proper front track is the '79 to 85 G-Body (Monti-Carlo, Buick Regal, Olds Cutlass, ect) , the two door, four door, and wagon frames are basically the same and are too short, the El-Camino frame is too long. If you decide to go this route you'll have to lengthen or shorten a frame to fit, box the side rails, replace the front and rear frame horns and figure out a new floor, which is exactly what I'm doing on my "51 Chevy sedan but my advice to you is to forget about a frame swap, your Olds has an excellent deep channel frame that only needs a front sub-frame and a replacement rear axle to bring it into the 20th century.
Fatman's (maybe others as well) does a Pontiac frame stub so you can put on a mustang, as Junkman suggests mods like that are much easier than a frame swap. Then use a ride tech or simiiar rear kit and you are good to go. Seems more expensive upfront but the chances of completing the job and not getting nickel and dimed to death in the process are better odds. Those Pontiacs frames tend to crack around the front suspension so the stub will eliminate that area and replace with a nice new boxed section. The convertible frame is already beefed up. You can add some plate to the open section, it doesn't have to be super thick to really add strength either.
My 53 has a 68-72 Nova subframe in the front and a 8Inch ford rear Drives great. A friend has a 53 that someone put an entire frame from a late model gm car. It has never gotten finished and seems there are lots of issues. It is very wide, with the stock gm wheels the car sits high and looks as though it will not turn easily. Also remember to get a nova sub that has rear steer, in other words the steering box is behind the crossmember. Any questions I can send photos of mine on my rack so you can see how it went in.
Hey Goat, you might want to Look at the LOW Production numbers of your Ragtop................ But if You Still want to Update the running gear ?? What the Others said about Frt. Clip and later Rear. Photo of your Car wood be Nice, Just Cutious. Good Luck
just swapping a frame might not be a good thing, you have a convertible and unless you get a convertible frame from another car, you have a good chance of the frame bending and the doors not opening over time. your frame has extra stiffeners and stronger crossmembers. I would do a aftermarket frame (spendy), or graft a subframe to the front. (not sure if Fatman or equivalent makes a MII front
A Pontiac frame has a big X in the middle on all the cars. The Convertible has even more reinforcement to keep the body from flexing so you can actually open and close the doors no matter how the car is parked. You have to be just about bat shit insane to think you can stick some late model frame under there and ever keep the door gaps where they're supposed to be. Ever seen a 77-89 GM car frame with the body off? They have some flex in them even with no rot. It's just a C-channel in the middle with no center bracing at all. And they're terribly rot prone. You can put disc brakes on the stock front end with existing kits, go to a ball joint front end using '58 Pontiac parts, and the rear end is leaf spring - there are at least half a dozen rearends that will fit easily, including the 71-81 Camaro/Firebird which will BOLT RIGHT IN with no mods except possibly to fab a lower mount plate with a shock absorber mounting.
Clip it but do not remove the convertible frame,the sedans of that year had a similar looking frame but the convertible X member is much heavier.
Thanks for all the info. Will just do a disc brake upgrade and newer rear end. Just looking for reliability. I know stock is cool too as the car still has the stock straight eight. I will post some pics of the car. The front does not bolt in like the chevy of that year to respond to black 62's question. I have looked up the Fatman kits and Scarebird brake conversions.
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