Cutlass/Grand Prix frame differences

[87National]

I swapped an 86 grand prix frame under my 86 442. The area of the frame at the #1 body mounts (core support) of the grand prix seems too low. If I try to place a stock body mount on that location.....Its not even close.....there is an uneven door gap to the point where the doors won't even open. It looks like I need an additional 1.5-2" of height at the #1 body mount hole in the gp frame to get the 442 front clip where it needs to be.

I'm aware of the frame difference among wagons, El Caminos, and 2 dr cars. But has anyone seen differences in GP and cutlass frames?

 

[85ss/85gn]

The should be the same. The you sure the Grand Prix is straight and not bent?

 

[87National]

The should be the same. The you sure the Grand Prix is straight and not bent?

I gave it a good inspection prior to the swap, I didn't see any evidence of it ever being in an accident. Also.....the front clip on the grand prix sat good and square on the frame (I bought a complete car as a donor). You would think if the frame was bent, the door gaps would be off or the core support would be jacked.... or something would be wrong.

 

[pagrunt]

This is what I found usimg my Chevy parts books.
Monte Carlo frame p/n: '78 470211, '79 14017671 (must use engine mount 14005699 on '78 models) (used on '78-'81 Buick 09, 69, 87), '80-'81 14013462 (superseded '78 & '79 p/n's) (used on '81 Regal), '82-'88 14103516 (use on '83 Olds W40 Hurst/Olds, '78-87 Pontiac except 35.)
Malibu (19, 27, 69) p/n: '78 461808, '79 14005602 (same note as Monte Carlo), '80 14017667 (must use '80 front park brake cable on earlier models, superseded '79 p/n) (Used on Buick 09, 69, 87), '81 14032514 (superseded '78-'80 p/n's.)
Note body codes:
2 door body: 27, 37, 47, 87
4 door body: 09, 19, 69
station wagon: 35
Looks like the Monte frame would be the one to work on a LeMans. Keep in mind that this is incomplete as I have not cross checked all GM catalogs for our cars.

 

[Streetbu]

My bet is the Grand Prix was in an accident and then repaired during it's life, but the frame never straightened. So the new body panels were bolted on and line to an unsquare frame. That frame is a direct replacement with no modifications required.

 

[pontiacgp]

I replace the frame on my 86 GP for a 81 Regal frame, the only change I had to make was to weld in the addition for the 200 4r transmission support. Other than that the frames were identical.

 

[ck80]

If you put a cab shell onto a bare frame and let it sit the frame sags in the middle... they aren't very stiff.

If you jack the car into the air at the factory jack points just in front of the doors and let the front of the frame sag down in the air, you can counter that arc somewhat. (IF I'm understanding your problem that is....)

 

[87National]

My bet is the Grand Prix was in an accident and then repaired during it's life, but the frame never straightened. So the new body panels were bolted on and line to an unsquare frame. That frame is a direct replacement with no modifications required.

Maybe.......but if the frame was truly bent.......the GP fender to door gap would have been out of whack....or the core support messed up.

 

[87National]

If you put a cab shell onto a bare frame and let it sit the frame sags in the middle... they aren't very stiff.

If you jack the car into the air at the factory jack points just in front of the doors and let the front of the frame sag down in the air, you can counter that arc somewhat. (IF I'm understanding your problem that is....)

The issue is that the #1 body mount point on the frame is too low.....but that got me to thinking...... the car is currently on jack stands placed under the fire wall (pulled the tires off for more clearance when putting the front clip back on) ......maybe the weight of the engine has pulled the frame down 1.5-2". I'll throw the tires back on tomorrow and check it out.