Post Mount to Later FSJ Leaf Spring Conversion

[Harry Dawg]

Hey Y'all.
Just getting into fabrication and FSJ's and am looking for some advice.
I currently have a 1969 J3000 that needs some suspension work.

The current post mount leaf springs are flat, and I am looking to swap them out for the style used on the J10's.
I hav attached some pictures of the current springs for reference.

What are my options here? Do I just weld new spring hangars and relocate the spring perches on the axle?
What about the front steering? The parts are so outdated and there is very little information out there, so thanks for any input.

PS. The front axle is a Dana 44 Closed Knuckle, so I would think that I might want to swap it out for an open knuckle from the later models to make the swap easier?

[Yeller]

Welcome to FSJN!

I'm going through some of the same things currently on my 70' J2000. I'm a bit more of a make it even more modern guy, already did 63" Chevy rear springs and have an open knuckle 44 going in on coil springs. I'm following to see what the other responses are.

[Harry Dawg]

Thanks Yeller!
Glad to be here. Do you think you can lend me some technical advice on a swap like this?
What was the process for swapping in the Chevy springs? I am kind of a novice when it comes to how to setup suspension/ obtaining proper geometry.
I have heard all sorts of stuff about shimming the axle, relocating hangars etc., but what was your experience with the 63" Chevy Leafs?
Chevy springs seem like the ideal candidate for the swap price wise. How much lift did you get?
Is this an option for the front as well?

[Eldog22]

I did a full chevy swap on my wagoneer. D44s front an rear.
Process was pretty straightforward

[Yeller]

I got 2” of lift that I was after. Here’s what I’ve been up to.

https://www.fsjnetwork.com/forum/viewt ... 12&t=21395

[rocklaurence]

Phils67 did a upgrade to remove the Post mounts. He used Rocklaurence FSSR -kit and Ebay rear brackets to mount the new springs. He has the project URL here on site.

[Harry Dawg]

Thanks for everyones input.
After much consideration I decided to go with the 4" lift from Hell Creek Suspensions.
It wasn't exactly what I wanted, but due to time and space limitations it seems like the best choice.

[Phils67]

Phils67 did a upgrade to remove the Post mounts. He used Rocklaurence FSSR -kit and Ebay rear brackets to mount the new springs. He has the project URL here on site.

Sure did and it rides better than it ever has. Was fairly inexpensive to do as well. It's all bolt on, just get some good drill bits. Removing the post mounts is kind of a pain but not impossible. My front ones I didn't even remove and it's been over a year now. Gave me around 2-2.5" of lift I'd estimate. I wasn't a fan of the hell creek kit so I removed it for this setup. Some guys have had good luck with it but I didn't unfortunately. I'll try ro go back and find my build link and post it, then if you ever decide to revert back or go a different route at least you'll be able to find it

[Phils67]

https://www.fsjnetwork.com/forum/viewto ... 12&t=18528

[Harry Dawg]

Nice Job Phils67!
This is a great write up and I will be saving this gold mine of info for use at a later time.
After reading your swap guide I am glad that I went with the Hell Creek kit for the time being, and it sounds like that was what you ran before swapping in the box mount springs. I am just going to stick with the original axle and steering for now until I break something and am forced to swap it out.

[Phils67]

Nice Job Phils67!
This is a great write up and I will be saving this gold mine of info for use at a later time.
After reading your swap guide I am glad that I went with the Hell Creek kit for the time being, and it sounds like that was what you ran before swapping in the box mount springs. I am just going to stick with the original axle and steering for now until I break something and am forced to swap it out.

Thanks. Alot of head scratching (and banging) measuring, and trial and (mostly) error went into that. It isn't perfect by any means but is 1000% better in my opinion for streetability. If I was building it for mostly offroad/rock crawling I'd keep the shackle at the front but this doesn't see much if any of that. Mostly road driving. The Hell Creek will work with your original differentials but not with my setup. You'd need new springs again. If you go with later model j10 or j20 differentials then my setup should work on any early truck with post mounts. If you ever need measurements other than what I posted or anything like that feel free to ask and I'll provide them. Good luck

[backroadin']

The parts are still available to rebuild or refurbish that closed knuckle front end if need be, too.

I went with chevy springs to lift the rear of my wag. The chevy swap (which should be 52" springs for you - there are two lenghts of chevy rear springs in the years involved with this swap - make sure you are getting the 52" ones if you ever upgrade this way from your current lift) just involves swaping out the eye bushings on the post end. Here's some links with spring length and bushing sizes for future reference:

http://www.ifsja.org/forums/vb/showthread.php?t=66430
http://www.ifsja.org/forums/vb/showthread.php?t=73856

For more reading, search "post mount lift" here or at ifsja. Best of luck with the truck!