Leaf to trailing arms how to ?

[warriorsimi]

Can I get some help on what is needed to swap from leafs to trailing arms for my 72 GMC with 5 x5 lug pattern.thanks in advance.

[GR8-68]

Quite a bit, crossmember where trailing arms attach, trailing arms, drive shaft, rear axle housing, tracking bar, tracking bar frame bracket, coil spring frame perches, coil springs, shock mounting crossmember, and time and knowledge to get it back together. I believe I thought of it all.

[notsolo]

If you are going to go with original parts find a donor truck with trailing arm cross member trailing arms and springs, axle with correct welded mount. You will need to build spring perches for the frame. Frame on a leaf spring truck were straight, trailing arm trucks the frame bows out where the spring mounts.

[GR8-68]

Oh wow ! Didn't know that. Better off finding the whole frame to swap out

[warriorsimi]

Wow that is a lot of work thanks for the replies I think my only option is a four link set up so I can keep my axle with the 5 lug.

[Jeff's bowtie's]

Leaf spring 2 wheel drive and coil spring frames have the same bowed out frame rails the 4 wd are straight frames and C/30 leaf frames are straight

[schwoch1]

Originally Posted by Jeff's bowtie's

Leaf spring 2 wheel drive and coil spring frames have the same bowed out frame rails the 4 wd are straight frames and C/30 leaf frames are straight

I was just going to say the same thing. I converted my '71 GMC to coils in the rear and other than the trailing arms and all the hardware, the crossmember was there and the frame was bowed in the right spots to accept the springs!!!

Mike

[warriorsimi]

The spring mounts do not matter cause I am bagging it.the only thing I am concerned about is the pan hard mount on the frame and keeping the 5 lug.can I swap axle shafts from 6 lug to 5 lug?

[StingRay]

There is a 6 lug housing from the 1970 model year that will accept either 70 6 lug or 71 up 5 lug. Those 70 6 lug will swap up years as well. Earlier housings are too short for later axles and require an aftermarket axle or re-machining of the originals.

[warriorsimi]

Thanks for the info ,glad I joined the forum there sure is a lot of knowledgable forks here.

[jr1966]

Is there a problem if you just want to swap the complete axle housings only from a leaf truck to a trailing arm truck ?
Thanks

[GASoline71]

The rear brake lines are routed completely different too.

Gary

[suprachrgd82]

Have a look at this. It's a reasonable compromise to a full axle swap.

https://www.youtube.com/watch?v=vS_5xwt1_io

[jr1966]

Originally Posted by GR8-68

Quite a bit, crossmember where trailing arms attach, trailing arms, drive shaft, rear axle housing, tracking bar, tracking bar frame bracket, coil spring frame perches, coil springs, shock mounting crossmember, and time and knowledge to get it back together. I believe I thought of it all.

Why do you have to change drive shaft in this swap ? and if the truck is a trailing arm truck what needs to be done to adapt a leaf spring axle to the trailing arms ? I am needing to do this also
Thanks Good info here for a new to trucks guy

[bsampson]

Originally Posted by jr1966

... and if the truck is a trailing arm truck what needs to be done to adapt a leaf spring axle to the trailing arms ? I am needing to do this also

I don't know on the driveshaft. Maybe a slightly different length?

A leaf spring axle would be missing the correct saddles and a panhard mounting location.

This looks to be a pretty complete kit:
https://www.performanceonline.com/19...onversion-Kit/

[jr1966]

That looks like a good start on the changeover. Hope the driveshaft is the same but the frame I am using from has one I think.
Thanks