G-Body vs A-Body

[BiGBoY]

Hi, who really know the difference between the A-Body (78 to more or less 81 Regal, Century,Gp,etc.) and the G-Body (81 and up) ??

The reason for this question is that my friend have a frame (in better condition than mine) taken from a Cutlass from the 80s. Its a G-bodied car and mine is a A-bodied one. Is it interchangeable??

Thanks for your help.

 

[GNVAIR]

They were called A bodies up to 1980. G reassigned the A body designation to the front wheel drive Celebritry, Cutlass Ciera, 6000,Century.
As far as using the A body frame.......it will technically work, but from past experiences, the front frame rails are shorter (from front hub center line to the end of the rail).
Someone I know used a 81-88 frame under a 78 and the front rails were too long resulting a drastic relocation of the bumper.
The other issue is the trans cross member mounting bracket for the 2004r is missing on the driver side.
Your best bet would be to look for the correct frame rather than do the swap and find out after the fact.

 

[Ormand]

Frame..

I have a shop manual from Olds I got for a 78 Cutlass Calais (nice car, but the engine was wimpy) and the frame dimensions are the same as those in the Buick book. Not sure if the frames are identical, but I believe they should be close enough for you to use the other frame. Good chance to stiffen it up, put some boxing on some of the open sections, and coat it thoroughly. Good luck! ( I see that Lee posted a reply while I was typing! I guess the bumper mounts must have change, too..)

 

[motorhead]

Your biggest issue is going to be metric (82-88) vs. imperial (78-81) fasteners. From 78-81 there was a slow and confusing conversion to metric fasteners. It is really willy nilly on the 81 model year vehicles... my brother has an '81 Malibu that has some weird issues with its nuts and bolts. Pre-82 is listed as having an .1" shorter wheelbase, as well.

Be cautious and take a lot of measurements before undergoing the swap. And don't throw out your 78-81 nuts and bolts.

 

[tminer]

I thought that the 78-87 (some 88) Regal, Grand Prix, Monte Carlo and Cutlass were G-Bodies and the Malibu, Grand Am, El Camino and Caballero were A-bodies.

Is that not the case?

Tom

 

[b4black]

They are all the same body. Just a name change when the A-body designation followed the FWD platform.

1978/81 A-body
1982/88 G-body



Sometimes the Regal, Cutlass, MC and GP were refered to as A-specials or G-specials.

 

[GNVAIR]

All the 78-87 A/G body cars are what are considered a metric chassis. But GM had a very strange way of phasing in metric fasteners.
78 and 79 models still have 7/16 wheel studs and standard threads on their power steering pumps and steering boxes.
80-88 had 12 mm wheel studs and metric threads throughout the rest of the car. GM also changed the spindles and rotors on the 80-88 cars. No idea why, but the shaft of the spindle is longer. The only areas where you wont find metric is on the engines and earlier transmissions. The later model Buick V6 and all the 200c and 2004r transmissions had metric threads on many accessory holes although many pipe fittings such as trans cooler lines were still standard threads.
I have found that much of the body and frame hardware on the 78 model year vehicles is larger than the 79-88 models.
Back to the original post.
If I were to do such a frame swap I would do this
78-80 cars would get another 78-80 frame
81-88 cars would get another 81-88 frame.
Exceptions to the rule would be the 81-83 Malibu and 81-86 Lemans/Bonneville which could get away with a 78-80 frame since they were still the same. The differences were with the Monte Carlo, Cutlass, Regal and Grand Prix which received longer front rails starting in 81.
Oh yeah! El Caminos uses a different frame than all the other 78-88 A/G bodies since they had a wheel base that was approx 10 inches longer.

 

[motorhead]

Originally posted by GNVAIR
All the 78-87 A/G body cars are what are considered a metric chassis. But GM had a very strange way of phasing in metric fasteners.
78 and 79 models still have 7/16 wheel studs and standard threads on their power steering pumps and steering boxes.
80-88 had 12 mm wheel studs and metric threads throughout the rest of the car. GM also changed the spindles and rotors on the 80-88 cars. No idea why, but the shaft of the spindle is longer. The only areas where you wont find metric is on the engines and earlier transmissions. The later model Buick V6 and all the 200c and 2004r transmissions had metric threads on many accessory holes although many pipe fittings such as trans cooler lines were still standard threads.
I have found that much of the body and frame hardware on the 78 model year vehicles is larger than the 79-88 models.
Back to the original post.
If I were to do such a frame swap I would do this
78-80 cars would get another 78-80 frame
81-88 cars would get another 81-88 frame.
Exceptions to the rule would be the 81-83 Malibu and 81-86 Lemans/Bonneville which could get away with a 78-80 frame since they were still the same. The differences were with the Monte Carlo, Cutlass, Regal and Grand Prix which received longer front rails starting in 81.
Oh yeah! El Caminos uses a different frame than all the other 78-88 A/G bodies since they had a wheel base that was approx 10 inches longer.

Lee gets a cookie for coming up with the specifics! Nice work.

 

[GNVAIR]

Make mine chocolate chip Mike!

 

[BiGBoY]

thanks a lot for all your help guys !!