ChrisMiami

I just bought the frame restoration guide in the books & manuals section, and I was curious why the title says 69-72. It has been my belief that the frame didn't change substantially until 1975, which would make the book apply to 69-74.

Other than the age of the welds, what are the differences between a 69 frame & 74 frame?

Thanks,
Chris

js292

I beleive 73 & 74 had a different front section for mounting the absorbtion bumper thingy's

427basketcase

I believe that the body mounts were different too; the early cars were a solid aluminum, and later were rubber, so the mounting tabs might be a little different.

67-73-76

69-72 are the same and will interchange.

73 is a one year only frame. The crossmember at the very back is the same as the 69-72. The body mounts are a different height to account for the rubber body mount cushions. 69-72 did not use rubber body mounts. The front frame horns are drilled different for the crash bar on the rubber bumper 73.

74 is also a one year only frame. The front frame horns are the same as 73. The body mounts are the same as the 73. The cross member at the very back is different than the chrome bumber 69-73 cars. The 74 had a rubber rear bumper and it mounted to the frame different.

stpman

The rear crossmember is the same the last 14" of each frame rail is different for the 1 year only 5 Mph bumper.

js292

Do you know what the height difference is? I'm using a 70 frame and a 74 birdcage.

67-73-76

The crossmember thats closest to the license plate is different on the 74 cars. Its shaped different at the ends where its welded to the side rails.

72LS1Vette

I was under the impression that the body mounts were changed substantially for 73 but someone corrected me in a thread a couple of weeks ago. I went back and checked the engineering drawings for both styles of frame and the difference in mounts is on the order of 1/16" to 1/8" which is easily compensated for with shims. I think what really happened is the rubber body mounts just made the car sit a little higher off the frame. Poly mounts wouls probably sit ecen higher. The rear of the 74 frame is similar to the 73 with extra plates welded on for the 74 rear bumper. 75-up had a new rear section that is quite different from the earlier frames.

I have a 73 frame that I'm using for my 72 so I will know shortly if the front holes are different, but I think I'm just going to use solid mounts again to keep the body as close to the frame as possible. I'm probably going to have ride height issues anyway with an aluminum engine.



Rick B.

ChrisMiami

Where does one get 'engineering drawings'?
Anyone have pictures to share of these differences?
Any reference sources for exact details?
Anyone have a contact at NCRA who might have docs?

I only ask because I bought a 69 body and a 74 frame (not yet in possession or ya, I'd just look at it). If I'm SOL in mating them, it'd be nice to know...

Thanks again!
Chris

stpman

are you talking about the rod guide thats welded to the end of the crossmember?

72LS1Vette

Look up member BarryK. He has a website with the drawings for the 2 different frame styles. I'm not sure myself about the front frame rails, but this weekend I can take off one of the 72 body plates that mount to the frame and see if it matches up to the 73 frame rails. As far as I know the rear of the 74 frame can be easily modified to work with your 69.



Rick B.

davetr

im looking at a 74 frame to use in my 72, what kind of problems am I looking at ??

Easy Mike

http://www.71corvette.com/frames.html

Mike Ward

Read the entire thread...................

davetr

cool read thank you

tracdogg2

I've measured the height of the body mount brackets on 69-74 frames and have not found any difference in height. The 74 frame has two plates and two hoops welded at the rear corners. They can be removed to work on 69-73.
Mike

davetr

thank you mike

tracdogg2

You're welcome Dave,
If you have any specific questions I have in my shop (at this time)
3 73's, 2 74's, 2 71's, and a 69.
Mike

loup68

I have a GM replacement frame on my 68 coupe. It was listed as fitting 1968-1974. As Trackdogg2 has said, only the outer corners had different add on's, that I removed. My car was twenty years old at the time, and I found out that three months later they were discontinued!!! I really got lucky. Lou.

davetr

mike, wow nice line up