Frames and rear end locating holes

[Fran Preve]

The was/is another thread that was into this but got off topic. I had a couple of thoughts on this.

a) how many frames were interchangeable in the years your talking about?. Which were the same, which were different (I'm assuming the convertible was beefed). Knowing GM I don't think they would store a whole bunch of different frames on the line when they could use 2 or three on all body styles.

b) the Chevrolet was an "h" body, taking Poniac as one example, could Chevy/Pontiac use, basically, the same frame. Except for one or two small brackets or holes, as in Pontiac uses'm and Chevy don't. It's cheaper to mass produce ten's of thousands of frames with what would be a very small added cost than thousands with individual small brackets and/or holes. Remember, back then Chevy and Pontiac were building over a million full size cars a year. Yes, the wheel bases would change the frames in some cases.

Anyway, I've found people get all wound up over some of these things, GM did things that may not made sense to people today, but back then it was ultimate cost and inventory control, not whether each (frame for example) had an EXTRA hole or bracket. If the frame has the hole where it was supposed to be for YOUR car anything else is immaterial.

Don't know. Just sayin'. Take it from there.

[walkerheaders]

whew............i got dizzy tryin to read all that.
i think i follow your point fran, the only problem with your theory is that, only chevy had the X frame under the "B" body cars.
the other brands were smart enough to avoid the hourglass shape and go with the full perimeter style.
from what we can tell, the X frame fit all B bodys except convert. so your multiple hole theory holds water in most instances.......but this is a different application. this double hole delemma seems to apply mostly to the super/sport cars.
yes the double hole bracket discussion is silly, i'm sorry i mentioned it since there seems to be no pattern to it's use application on the vehicles. glad to know your still on the ball just the same. it's when you get quiet on us..........i start to worry.

[Fran Preve]

Walkerheaders: Like I said, I don't know I just had a thought maybe. GM works in funny ways, sometimes they'll add something (bracket/hole) to EVERYTHING because in the long run it's more cost effective or more makes inventory more easily controlled. I usually won't post to a thread like the frame one because frankly I know/care little about them, it was only a thought.

[MK IISS]

Bob: You said only the Chevy had the X frame, but didn't the '58 Pontiac Bonneville also have the same type of frame? I know some of the other GM cars are different. I looked at a friend's '59 Olds Super 88 the other day. Apparently the '59 Olds still had leaf springs in the rear. I thought all the GM cars after '57 had coils. So all these years my assumption was incorrect.

[Fran Preve]

Maybe that's the thing. Coils under X frame, leafs under perimeter. I don't think this question has been answered yet (x only under Chevy 58-64).

[gearhead409]

Usa frames. there were three companies making frames for our cars back then. A.O. Smith frame ( 2pc. tunnel plate bottom with welded channel rails). Budd frame ( 1 pc. tunel plate bottom with welded channel rails). and Chevrolet frame ( 1 pc. tunnel plate bottom with tube rails). these were used under all pass. cars except convertibles. the droptops used a channel type fame with very heavy welded plates above and below the rails, also had 4 extra body mounts at floorpans. all frames are pretty much the same except the rear axle and rear bumper crossmembers in the 58,59 and 60 models. and the bumper cossmember in the 61 model.

[Mr.Jimmy]

Also.....there is a difference in body mount holes.....I learned this that a 60 is different than a 62 63 and 64. I forget which way one goes, but one has a larger hole for the pucks than the other, so when one swaps frames, they have to ream the holes out.

What was the Canadian Pontiac 409 car? Did they use the X frame? Just a thought.

[CDNpontiac409guy]

What was the Canadian Pontiac 409 car? Did they use the X frame? Just a thought.

I guess that would be a question for me, Mr Jimmy :p

All Chevrolet. The complete chassis, engine, trans, diff, fuel tank & system, floor boards and braces, complete trunk floor, firewall, complete steering system..including column, radiator, and a few other items... ALL Chevrolet.

Here's a link to an article that I wrote a couple years ago on the subject:

http://www.bruneauperformance.ca/lgcartical.html

I know... Everytime somebody poses a question on this subject... I "over answer" :doh :p

[Fran Preve]

I for one appreciate "over answers".

[dq409]

Here`s someting that Verne Frantz sent me in regards to this subject,,,

Gearhead has the frame issues straightened out very well. (pun intended) The Chevrolet frame is what we call the "box" frame. The A.O. Smith frame "is" the convertible frame, with it's associated extra reinforcements. There is no such thing as a "409" frame either. The different types of frames arrived at the plants in batches, so every car (other than convertibles) got whichever frame last arrived, then the next batch was delivered and each car got that type frame, and on and on.
I don't know if any of this helps or not.
take care,
Verne

[BC409]

Bob: You said only the Chevy had the X frame, but didn't the '58 Pontiac Bonneville also have the same type of frame? I know some of the other GM cars are different. I looked at a friend's '59 Olds Super 88 the other day. Apparently the '59 Olds still had leaf springs in the rear. I thought all the GM cars after '57 had coils. So all these years my assumption was incorrect.
you are correct about 58 bonneville.i recently did some resto work on a 58 bonny rolling chassis an it is definetly an x frame.

[MK IISS]

BC: Thanks for your info on the Pontiac. I had a '58 a long time ago, remembered it had rear coil springs but couldn't remember the frame. I did some research on some of the other GM cars and found Buicks and Cadillacs had rear coil springs long before the '58 X frames. Oldsmobiles, for some reason, were hold outs and used rear leaf springs thru at least 1961.

[MK IISS]

Not that it really matters because this is a Chevy site but new info leads me to believe '57 and earlier Cadillacs had leaf springs, went to the X frame and coils in '58. Buicks switched to rear coils in the late 30s, don't know if they used the X frame in '58.

[walkerheaders]

Alot of those early cars used a "ladder style" frame. narrow like a pickup truck, yet with an "X" riveted in the center. there are oblong slots in the x members for the exhaust to pass thru. our 56 caddy is this way and has leaf springs.
we were originally discussing the use of an "hourglass" "X" frame.
I may have spoke out of turn regarding the use of the true x frame being used under the other GM 59-64 cars. I did'nt think they did. next time i'm at the yard i will tally this up.
those of you who also have a 62-64 pontiac, olds or buick, what syle frame is under them?

[MK IISS]

I guess my last post got bumped. I said that after more research on the web I found that '57 and earlier Cadillacs appear to have leaf springs. I'm assuming the '58 Cadillacs used the X frame similar to Chevrolet because they had rear coils. I have a '59 Cadillac ad which shows a painted up Cadillac chassis/frame with engine/trans-driveline, steering column and wheels/tires. The frame is a big version of the Chevrolet X frame with no side rails. I also found that Buicks had rear coil springs starting in the late 30s. I don't know if they used the X frame starting with the 58s. I still wonder why Oldsmobile retained the ladder type frame and leaf springs until at least 1962.

[Fran Preve]

Then my point still stands, maybe. If the frame was identical is it possible when the wheel base is the same did GM use a "common" frame rather than make dozens of different ones?. I still contend GM would do something like this for stocking reasons. Only a thought as to why there may have been extra brackets or holes.