Body sag
 

Has anyone experienced a body sag when the car is on front jack stands to where the doors will not open freely? My '64 GTO has this problem and I not sure if it's something that can be fixed or if it's life with an old car.

They all do that, once you start supporting that frame and body structure by points on the frame instead of the car sitting on the suspension it’s a normal occurrence.

Same thing but worse with a convertible car, I can’t get the doors open on my Le Mans if I support it under the front frame rails and at the rear suspension mount area. Even that heavy duty boxed frame can’t stop the flexing.

Hardtop cars are worse than post cars in this regard as well.

I had the same problem with my 1965 GTO when it was only 4 years old. I think all the hard tops did it including the "B" bodies.

My father-in-law was an engineer at AO Smith in Milwaukee, where most GM frames were built until the 1970's. He said that the movement or twist on a typical automobile from one corner to the opposite is about 4" as the car travels along a road.

Yes, it's normal for your '64 GTO and all other cars & trucks to deflect noticeably when jacked up by the frame. Watch the wings on the airplane next time you take a flight.

Also, be aware that the windshield and rear window glass play a significant role in keeping the body from flexing. Using butyl tape to secure these windows leaves you with much more flexing. Most auto glass shops will not use butyl tape, but insist on urethane adhesive.

I have a problem with body sag too.

Oh wait, you guys are talking about cars!

LMFAO

I think a lot of it happens from driving over time as well my RAIV w 15k on it is very tight. Jack it up and there’s no flex to the body, never had subframe connectors. I’ve done the same w other birds (I’ve had 21 of them) and had much more flex.
The RAIV car jacks up tight like my turbo car w a 10 pt cage and subframe connectors. It does have alluminum body bushings though and that does help but this is more about twist or sag in the body itself
My convertible on the lift w subframe connectors I can’t open the doors not that you should anyway.

Poly body bushings help a noticeable amount if you care to use them instead of rubber.

I don't think age has a lot to do with it. Those early hard tops are very flexible. Like I said earlier my car was only 4 years old at the time and did it.

Noticed the flex my 65, so while the car was apart for a refresh I boxed the frame. Before it went back togther found a convertable frame so switched every thing over to that frame and is under the car now. Not done yet but expect an improvement. 1966 you could order a heavy duty frame (convert) option on a hardtop.

For what it is worth, when I built my 65 Chevelle 2-door wagon, I used an El Camino frame (boxed like a convertible frame) and used poly body bushings. I could put a jack under the frame just behind the front wheel and it would lift both wheels off the ground on that side at the same time. With a hardtop roof, boxed frame and poly bushings it made the car pretty solid. Don't need some fancy way over priced frame kit to make these cars more stiff.

4" Wow, I guess that makes sense though.

I recall with 68 FB convert I was driving down a smooth road and felt the door gap changing. I have not tried that with my Tempest Convertible.

NOW THATS FUNNY 1111 LOL