: Frames Swaps, 1977 to 1992



grant33
07-15-07, 02:56 PM
Are the 1077 to 1992 RWD frame the same and do they interchange? i have a 1979 coupe deville and a 1990 Brougham that seem to be indentical on the underside as far as body mounts, length, width, etc. combining the 79 coupe body and the 90 brougham frame and drivetrain would really move my project along pretty fast, i have the 350 chevy and the tow package in the 1990. any info is greatly appreciated.

77CDV
07-15-07, 03:00 PM
You know, Grant, I do believe it could work. The basic structure of the car stayed the same all the way through. As long as the body mount points line up, I don't see why you couldn't do it. Good luck.

Craig

N0DIH
07-16-07, 02:06 PM
The 93-96 should work as well. I would do a lot of measuing in critical areas to know for sure. See what the Hollander interchange manual shows. You'll need to talk to a boneyard directly on that one.

I highly recommend the 9C1 bushings in all positions if you get into a frame swap. Call Dal for prices.

Wheelman322
07-18-07, 01:44 AM
You may pioneer a new trend for us all. Good luck.
One question...Is the 90 with the 350's body that far gone? That car is worth decent bucks nowadays.

Night Wolf
07-18-07, 03:37 AM
They are pretty much the same...

but keep in mind if you are talking about 2-door vs 4-door.... the 2-doors are usually shorter, by 3-6" or so.... where that length is lost, I dunno. In the case of my '93 Coupe, it was all rear seat leg room... but it may change the size of the frame a bit.

N0DIH
07-18-07, 10:16 AM
My guess is 2dr would lose it in the middle, as the frame ends need to be the same. Maybe an Impala/Caprice/Roadmaster/9C1/9C6 frame would work.

If it will, I might be coming into a 9C1 (read special frame, HD thicker steel, excellent piece!) very soon that might be able to work a good deal on. I need the engine and some other parts (front suspension and rear axle).

Where are you located?

grant33
07-18-07, 08:50 PM
I am in maryland, 15 miles north of baltimore. the 1990 brougham is awesome, midnight blue, with blue interior, 107,000 miles, one owner, an inch thick folder of service records,original window sticker and the 350 tbi chevy and the towing package gears really move the thing. the 79 coupe is awesome to look at, it just drives like the love boat and the 425 is beat. i bought the 90 to have as parts but have really fallen in love with it, but the coupe has an awesome goodfellas look to it. its black with grey interior. the info on the lengths of the the chassis says they are both Wheelbase: 121.5
Overall length: 221.2" , and the body mounts seem to line up. i dunno, it is definetly hard to think about trashing the 90. thanks for the input on the swap. one more question, is the bolt pattern on the rims the same for these cars? it starts to list it in millimeters instead of inches after a certain year, but it sems like they all interchange.

77CDV
07-18-07, 08:58 PM
They are pretty much the same...

but keep in mind if you are talking about 2-door vs 4-door.... the 2-doors are usually shorter, by 3-6" or so.... where that length is lost, I dunno. In the case of my '93 Coupe, it was all rear seat leg room... but it may change the size of the frame a bit.
But, Rick, he's talking about the C/D body RWD cars, not the downsized FWD C cars. With the RWD cars, the 2 and 4 door models were the same length: 221". The only difference is that the coupe was like a 1/2" lower, owing to the different roofline I think.

With the FWD cars, you're right, the 2 door model was shorter than the 4 door.

77CDV
07-18-07, 09:12 PM
I am in maryland, 15 miles north of baltimore. the 1990 brougham is awesome, midnight blue, with blue interior, 107,000 miles, one owner, an inch thick folder of service records,original window sticker and the 350 tbi chevy and the towing package gears really move the thing. the 79 coupe is awesome to look at, it just drives like the love boat and the 425 is beat. i bought the 90 to have as parts but have really fallen in love with it, but the coupe has an awesome goodfellas look to it. its black with grey interior. the info on the lengths of the the chassis says they are both Wheelbase: 121.5
Overall length: 221.2" , and the body mounts seem to line up. i dunno, it is definetly hard to think about trashing the 90. thanks for the input on the swap. one more question, is the bolt pattern on the rims the same for these cars? it starts to list it in millimeters instead of inches after a certain year, but it sems like they all interchange.
The bolt pattern is the same, I think, with 5 bolts in a pentagonal pattern, but the bolt size may be different. The 79 uses 1/2" nuts and bolts, later C/D body models may retain the same or use the closest metric equivalent. As far as the bolt circle diameter, it should be a contant 5" through the life of the chassis.

N0DIH
07-18-07, 11:35 PM
My 94 uses 12mm bolts, my 80 axle uses 1/2", so I have a hybrid lug nut that has metric taper with a English thread....

What is the coupe wheelbase? I thought it was shorter.... What was the last year of the Coupe?

Night Wolf
07-19-07, 12:17 AM
But, Rick, he's talking about the C/D body RWD cars, not the downsized FWD C cars. With the RWD cars, the 2 and 4 door models were the same length: 221". The only difference is that the coupe was like a 1/2" lower, owing to the different roofline I think.

With the FWD cars, you're right, the 2 door model was shorter than the 4 door.

I was using the FWD car as an example, but i thought the RWD cars were the same.

77CDV
07-21-07, 02:22 AM
Nope, RWD coupes and sedans are the same length and wb.

N0DIH
07-21-07, 09:52 AM
I would strive for a 94-96 frame, as it was the last of the big car frames.

Regardless of what frame you get, (and this is a upgrade tip that is noticeable for all 71-96 owners) ensure that the frame to crossmember braces are in place. They are often removed and not reinstalled, or in some cars, just not installed. All of the 1970-1981 F-Body, 1971-1976 B/C/D Body, 1973-1977 A/G Body and 1977-1996 B/D body are setup for these.

Now, there is 2 braces, get the larger of the 2. One connects the frame to the lower control arm mount, and the other connects the frame to the lower control arm to the cross member. That is the one you want. In 1994-1996 it was welded in. In previous years (not sure all of which) it was bolt in. And on some cars needed to be removed to replace the oil filter or to install headers, so people just whacked them out. Junkyards often cut them out with a torch so they are junk there to.

But you will see a handling and overall stiffness improvement with these braces in place. It will improve ride and stability as well. HIGHLY recommended. Best place to find is the Trans AM's and Z28's, IF they still have them...