frame swap for a 4x4

[prg machine]

I am told that a GMC 2wd frame can be converted to a 4x4 by using the front spring hangers from a K truck and a front crossmember????

Does anyone know for sure how this is done?

[Longhorn Man]

I'll move this to the 4X4 section. They can probably tell you every little tidbit you need to know.
With that being said... I *THINK* it can be done, and probably takes what you listed, and then the 4X4 steering gear box and a few other odds and ends.

[prg machine]

yea, I posted around in frame and suspension and the 4x4 forum and here also hoping for attention.

does the steering box bolt to the 2wd frame without trouble?? I never thought there would be a difference. I have everything on my K truck to swap over. I straightened the frame as best I could but it still favors pulling slightly right, just enough that I know it and wish it didn't. For now the truck is used minimaly and only short distances. Someday I would like to swap.........................or find a shortbed frame!!!!!!!!

[sweet70beast]

I know a guy that did just that. He told me that other than a few minor things it is basicly a bolt in, all the holes are already there. I didn't see the before but I did see the after and you'd never know it was a conversion. I've got my eye on a 71 Chev with rear leaf springs and if I can get my hands on it I will do a conversion to it.

[GMCMAX]

All the holes aren't there, but it's not hard to drill the ones that aren't. If the 2wd frame has rear leaf, you're a step ahead. One of the PITA things on my 68 was flattening out the dimples in the front where the e-brake cables go through. The other was that the 2wd rear end spring hangers are shorter and it took a 4" block to make it sit level with the stock 4X4 front springs.
The 4X4 power steering box bolted right up on mine.

[prg machine]

and is there any difference in the 3/4 ton to the 1/2 ton frames in consi9dering this swap????

[Dieselwrencher]

Like mentioned all the holes are not there. Mainly for the shackle mount for the front spring. I am in the process of doing this to my 72 longhorn. When i get it far enough I will post up pics and info. I am planning on cutting the part of the frame where the e brake knotches are and installing a flat piece of steel there so it looks factory. I may even replace the rear spring hanger because I am using 6" lift springs in the front and if I don't replace that hanger, I will need a 10" block. LOL I think the biggest difference in the frames, is the 1/2 frame rail heighth is shorter than the 3/4. But I am not 100% on that.

[Dieselwrencher]

And another thing, you will need the bumper brackets from the 4wd truck in the front because 2wd and 4wd are different.

[maximum destruction]

Originally Posted by Dieselwrencher

Like mentioned all the holes are not there. Mainly for the shackle mount for the front spring. I am in the process of doing this to my 72 longhorn. When i get it far enough I will post up pics and info. I am planning on cutting the part of the frame where the e brake knotches are and installing a flat piece of steel there so it looks factory. I may even replace the rear spring hanger because I am using 6" lift springs in the front and if I don't replace that hanger, I will need a 10" block. LOL I think the biggest difference in the frames, is the 1/2 frame rail heighth is shorter than the 3/4. But I am not 100% on that.

actually, the 1/2 ton & 3/4 ton frame heights are the same, as well as some 1 tons. the rails are indeed taller on 1 tons that were designated for dumps, box trucks, ambulances & military cucv's.

[prg machine]

so 1/2 ton and 3/4 ton frames were the same dimensions and material strength?

[Jtrux]

Interesting thread, I have a 69 chevy parts truck with rear springs, might have a new project after all.

[maximum destruction]

Originally Posted by prg machine

so 1/2 ton and 3/4 ton frames were the same dimensions and material strength?

as far as i know, the 1/2 & 3/4 trucks, blazers, & suburbans use the same thickness in the steel. 1 tons are thicker & as i said before, depending on their intended use, some had a physically taller rail. however, i don't remember the time span when gm changed the steel in their frames. i believe late 70's or early 80's.? maybe someone else here can pinpoint that for u.

[prg machine]

okay, I have located a 1/2 ton longbed frame from a chevy with the rear leafs. The guy thinks that the 1/2 ton might have a slightly narrower, like 1 inch per side or so, set up in the rear spring hangers or the rails themselves, than the 3/4 tons?????


I guess the problem is putting the 3/4 axles under the 1/2 ton frames in the rear.

anyone know anything about this fact???

[padresag]

4 x 4 frame is 1" higher than a 2 x 4 frame in the trans-t/c area
ron

[Dieselwrencher]

I am going to measure this blazer 4x4 frame I have and the longhorn frame I have to compare. I never have done it, the 3/4 tons just look bigger in the frame area I guess?

[padresag]

measuring your blazer frame and your longhorn frame is going to tell you what?
I do have a suburban 2 x 4 frame and my panel 4 x4 frame and the 4 x 4 is 1" deeper. mine are same year , same w/b
ron

[prg machine]

so what about the width at the rear spring hanger area????

[padresag]

don't know. best thing to do is find the chassis in question which is opposite what you have and measure it for yourself; then you know exactly what the differences for. you will get a variety of answers on these boards. always confirm what you need to know and that will alleviate any foreseeable problems
ron

[manimal]

look for grendel he has done this and posted the whole build up. AWESOME work he's done. Good Luck
-Lance

[GMCMAX]

Dang, sorry, it's for 73-87.......... thought I had another link for ours, but can't find it.
Check this link from Chuck's Chevy pages, it gives frame dimensions
http://www.chuckschevytruckpages.com/framespecs.html

[Dieselwrencher]

Originally Posted by padresag

measuring your blazer frame and your longhorn frame is going to tell you what?I do have a suburban 2 x 4 frame and my panel 4 x4 frame and the 4 x 4 is 1" deeper. mine are same year , same w/b
ron

It will tell me that a 4x4 1/2 ton frame is different than a 2x4 3/4 ton frame. This is what I found in my measurements.
These measurements were taken from top to bottom of frame flanges. And both frames were 1/4" thick. The Bold is for the longhorn to try to see the difference in the post.

1972 Blazer 4x4 1/2 ton 1972 Chevy Longhorn 3/4 ton 2x4
6 1/8" tall behind front cab mount 7 5/8" tall behind front cab mount 1 1/2" difference
4 1/2" Tall above rear axle 5" Tall above rear axle 1" difference

Rear Spring Hangers On Frame
Front Front
10" 5 1/2" 4 1/2" difference
Rear Rear
7 1/4" 7 1/4" Same

So what this shows me is that the frames are different from 1/2 ton to 3/4 ton. Now this could be different with the 2wd coil spring rear suspension trucks. But not with the leaf spring 3/4 ton trucks. Basically the 2wd 3/4 ton frame I have is the same as a 4wd frame almost. Since some holes are different up front I realize they are different. But that shows a comparrison on frame heighth.

And for the rear leaf spring hangers. I had it backwards. Everyone told me the rear hanger was longer on the 4wd's than the 2wd's. Well in reality it is the front hanger that is almost 4 1/2" longer than the 2wd one. That is a big difference. And the rear ones are the same.

[prg machine]

http://www.chuckschevytruckpages.com/framespecs.html

the "S" dimensions don't make any scence to me for longbed/shortbed trucks................??????????

[padresag]

Originally Posted by Dieselwrencher

It will tell me that a 4x4 1/2 ton frame is different than a 2x4 3/4 ton frame. This is what I found in my measurements.
These measurements were taken from top to bottom of frame flanges. And both frames were 1/4" thick. The Bold is for the longhorn to try to see the difference in the post.

1972 Blazer 4x4 1/2 ton 1972 Chevy Longhorn 3/4 ton 2x4
6 1/8" tall behind front cab mount 7 5/8" tall behind front cab mount 1 1/2" difference
4 1/2" Tall above rear axle 5" Tall above rear axle 1" difference

Rear Spring Hangers On Frame
Front Front
10" 5 1/2" 4 1/2" difference
Rear Rear
7 1/4" 7 1/4" Same

So what this shows me is that the frames are different from 1/2 ton to 3/4 ton. Now this could be different with the 2wd coil spring rear suspension trucks. But not with the leaf spring 3/4 ton trucks. Basically the 2wd 3/4 ton frame I have is the same as a 4wd frame almost. Since some holes are different up front I realize they are different. But that shows a comparrison on frame heighth.

And for the rear leaf spring hangers. I had it backwards. Everyone told me the rear hanger was longer on the 4wd's than the 2wd's. Well in reality it is the front hanger that is almost 4 1/2" longer than the 2wd one. That is a big difference. And the rear ones are the same.

what I can't understand is trying to figure out a comparison between a blazer chassis to a 3/4 ton chassis,.I can see comparing a 127" w/b 1/2t 2 x 4 chassis to a 127" w/b 3/4t 4 x 4 to see what the differences are other than crossmembers and suspension orientation.
ron

[Jtrux]

Originally Posted by padresag

what I can't understand is trying to figure out a comparison between a blazer chassis to a 3/4 ton chassis,.I can see comparing a 127" w/b 1/2t 2 x 4 chassis to a 127" w/b 3/4t 4 x 4 to see what the differences are other than crossmembers and suspension orientation.
ron

It's because it's what he has, the comparison is between a 1/2 ton and 3/4 ton more specifically 1/2 ton 4x4 to 3/4 ton 2x4.

[prg machine]

what the.............?????


can't believe how many variations of the same thing we can come up with here.


sounds like the 4x4 frame is a little taller at the transfer case area....................and since anything can be done..................the 2wd rear leaf sprung longbed truck frame will work for a 4x4 conversion.

I think!