47-55.1 47-54 1/2 ton leaf spring kit in a 3/4 ton

[68c10owner]

I know the 3/4 ton frames are narrower than the 1/2 frames but other than the shock mount crossmember, is there any reason the kits wouldnt physically bolt up to a 3/4 ton? The springs mount at an angle for the 1/2 ton and would be more parallel on a 3/4 ton. Im just trying to figure out how I could make a kit like this work.

Before Im asked, I do not have a truck yet. Im still searching but 1/2 prices are ridiculous near me and 3/4 ton prices are easier to swallow. The truck will be a driver and not used to tow or haul.

1947-54 Chevy 3100 1/2-Ton Pickup Rear Suspension Kit, 4-in Drop https://share.google/RdMI6cTpi31xbOoAu

[nvrdone]

I'm not familiar with the difference between a 1/2 & 3/4 ton frame other than to know that the 1/2 ton tapers and the 3/4 ton is straight. also that the 1/2 ton springs mount under the frame rail & the 3/4 ton mount out side of the frame.
Having said that I don't see why you could not find some mounts that would let you mount the 1/2 ton springs. It would take some measuring and maybe some custom fabrication.
I would be contacting some of our vendors that sell spring kits and ask questions.
The other possibility might be a 4 link setup.
Good luck on this one

[dsraven]

if the supplier doesn't know, and you are just trying to hang some softer springs, you could simply use SOME springs from the 3/4 ton pack and not ALL springs.
there will be a spring pack bolt that goes through the pack and holds it all together. remove that bolt, thin the pack some to what you think you will need, then install a new bolt to make a tight pack again.
or you could get a new 1/2 ton pack and make/move the hangers. i suggest to mark the frame at the axle centerline before you start so you get it back where it needs to go
will you be using the stock torque tube rear axle in your build? if not, then you will need to change the rear spring to axle mounting to a more modern open driveline style, where the axle is tied to the springs solidly.
a factory assembly manual will have drawings of the different models of trucks and will show dimensions that could be compared between models. you also may find some dimensions in this link that has manuals from models of different years of chevy cars and trucks

https://chevy.oldcarmanualproject.co...esto/56134.htm

[68c10owner]

Originally Posted by nvrdone

I'm not familiar with the difference between a 1/2 & 3/4 ton frame other than to know that the 1/2 ton tapers and the 3/4 ton is straight. also that the 1/2 ton springs mount under the frame rail & the 3/4 ton mount out side of the frame.
Having said that I don't see why you could not find some mounts that would let you mount the 1/2 ton springs. It would take some measuring and maybe some custom fabrication.
I would be contacting some of our vendors that sell spring kits and ask questions.
The other possibility might be a 4 link setup.
Good luck on this one

While I knew of the frame differences, I was not aware of the spring mounting differences. So I appreciate that bit of info. Ive heard the 3/4 ton frames are thicker metal as well and possibly a taller rail. Im not opposed to a 4 link but I just wanted to keep it simple since its just going to be a driver with a fairly mild sbc.

[68c10owner]

Originally Posted by dsraven

if the supplier doesn't know, and you are just trying to hang some softer springs, you could simply use SOME springs from the 3/4 ton pack and not ALL springs.
there will be a spring pack bolt that goes through the pack and holds it all together. remove that bolt, thin the pack some to what you think you will need, then install a new bolt to make a tight pack again.
or you could get a new 1/2 ton pack and make/move the hangers. i suggest to mark the frame at the axle centerline before you start so you get it back where it needs to go
will you be using the stock torque tube rear axle in your build? if not, then you will need to change the rear spring to axle mounting to a more modern open driveline style, where the axle is tied to the springs solidly.
a factory assembly manual will have drawings of the different models of trucks and will show dimensions that could be compared between models. you also may find some dimensions in this link that has manuals from models of different years of chevy cars and trucks

https://chevy.oldcarmanualproject.co...esto/56134.htm

I will not be using anything stock from the drivetrain. SBC/auto and either a 8.8 sor ab9" rearend. I wanted to use this kit specifically because they are lowered leafs. I dont want to use stock leafs at all. It will probably just be easier to do a 4 link and coil overs but I just want to keep it simple. Its not going to be used to tow, haul or race. Just a driver. I just want to do it low buck.

[51 3600]

Like you, on my 3600 I wanted to keep the rear suspension simple with leaf springs but not endure the stiff stock springs. The main problem to solve was to find springs of the right length that when mounted for proper axle location, were not too long to interfere with the running board brackets. Most modern springs were too long. I ended up with Jeep Wrangler springs which are very close to stock spring length so mount in just about the same location as stock. But since the Jeep springs were 2.5" wide I had to make new spring hangers/mounts. Jeep springs should be adequate for my purposes but if too soft I can add a leaf. Truck is not on the road yet so I can't give you an actual ride report.

[68c10owner]

Originally Posted by 51 3600

Like you, on my 3600 I wanted to keep the rear suspension simple with leaf springs but not endure the stiff stock springs. The main problem to solve was to find springs of the right length that when mounted for proper axle location, were not too long to interfere with the running board brackets. Most modern springs were too long. I ended up with Jeep Wrangler springs which are very close to stock spring length so mount in just about the same location as stock. But since the Jeep springs were 2.5" wide I had to make new spring hangers/mounts. Jeep springs should be adequate for my purposes but if too soft I can add a leaf. Truck is not on the road yet so I can't give you an actual ride report.

Attachment 2435766

I didnt really get too far into my plan but Im going to shorten a 3600 truck down to a 3100 wheelbase. And I wanted to use the leaf spring kit i linked to but I didnt know until this morning that the leafs mounted outboard of the rails instead of under them like the 3100 trucks. I can make new brackets I suppose but I may just end up doing a 4 link to make it easier. I guess I could look and see if some different year shackles and hangers could be modified to work. Hopefully Ill have a truck in front of me soon so I can see exactly what obstacles I'll have

[leegreen]

"doing a 4 link to make it easier."
Not sure that installing a 4 link is easier than installing new leaf mounts. Or cheaper

You need to figure out what bolt pattern you want and what front suspension. What wheels and tires and offset. Then source a rear axle of correct bolt pattern and length.
Then look at clearance between frame rails and wheels to decide where you want the springs

get some wrecker springs from jeep, s10 (something on the smaller side), and a universal hanger / shackle weld on kit of the correct spring width off ebay and most likely a new set of weld on axle spring perches

If that much fabrication is discouraging, you could turn to a local spring shop to modify/replace your original springs. You still need to find an axle and most likely get new perches welded onto it

[68c10owner]

Originally Posted by leegreen

"doing a 4 link to make it easier."
Not sure that installing a 4 link is easier than installing new leaf mounts. Or cheaper

You need to figure out what bolt pattern you want and what front suspension. What wheels and tires and offset. Then source a rear axle of correct bolt pattern and length.
Then look at clearance between frame rails and wheels to decide where you want the springs

get some wrecker springs from jeep, s10 (something on the smaller side), and a universal hanger / shackle weld on kit of the correct spring width off ebay and most likely a new set of weld on axle spring perches

If that much fabrication is discouraging, you could turn to a local spring shop to modify/replace your original springs. You still need to find an axle and most likely get new perches welded onto it

Slow down now. I didnt list every detail but I already know what front suspension and bolt pattern Im going to use.

I just wanted to know about this specific leaf spring kit. A 4 link kit isnt that much more, at least the ones Im looking at. And if I have to fab up mounts anyway its just as easy to do a 4 link. It will be more expensive over all because Ill need coil overs.

Fabrication doesnt scare me. I have the skills needed. But what I dont have is an actual truck in fr9jt of me to work the problem. I like to have a plan ready so that when I grab the project ai know exactly where to start instead of letting it just sit until I figure it out

[mr48chev]

I looked for spring kits for TF trucks last night as the rear sectrons of AD 3/4 ton and TF truck frames are within fractions of an inch of each other but didn't come up with anything that said "share this"

[68c10owner]

Originally Posted by mr48chev

I looked for spring kits for TF trucks last night as the rear sectrons of AD 3/4 ton and TF truck frames are within fractions of an inch of each other but didn't come up with anything that said "share this"

This is the closest thing I see for the TF trucks

TCI 1955-59 Chevy Pickup Rear Leaf Spring Kit https://share.google/0RXaebDoWMirjrMn9

[dsraven]

leafs and hangers from a production truck wouild possibly be an option. choose a truck that is approx the same weight as your project. possibly a ford ranger? spring hanger kits can be found on amazon and spring dimensions can be found online as well.
if you want a 4 link kit for reasonable costs check out welder's series. they're Canadian so your USD goes further

[57tailgater]

You may be able to use this websites to find dimensions for various springs for comparison:
https://www.generalspringkc.com/ or https://www.eatondetroitspring.com/

[dsraven]

if going the 4 link direction, would you choose a cross bar rod similar to the TCI version or a panhard bar style? personally, i prefer the panhard bar method, using a long bar for less side to side movement as the axle goes through it's suspension travel. the cross bar style seems to take a lot of space where driveline, exhaust, etc needs to share that space
I would still, however, recommend a leaf spring set up for less work and figuring. a 4 link locates the axle but, in order to get a 4 link to work properly for traction, there are angles to consider. you should possibly check out a few 4 link and suspension theory websites before you commit. if set up right a 4 link attempts to lift the vehicle, and in doing that, it plants the tires for best traction. there are differences with parallel compared to non parallel bars, etc. some 4x4 sites explain things like that pretty well, in lay,an's terms. there are apps and online calculators as well. there are also 3 link set ups that work well as do some set ups that use the geometry from some gm cars, where there are longer lower bars paralell to the frame, and shorter upper bars, more centrally located, that are placed at an angle to the frame.

https://www.crawlpedia.com/4_link_suspension.htm

[mr48chev]

Paralllel 4 links need a Panhard bar while triangulated 4 links don't.

Here is a link to check out.

[dsraven]

good drawings MR48. explains it well. panhard bar needs to be level at ride height and as long as possible to help with side to side movement of the axle as suspension travels up and down. there needs to be tire clearance built in as well, for the minimal side to side movement that is inevitable due to geometry of the system
if the rear axle is sourced from the right car there could be mounts built in for the triangulated 4 link set up. gm G and A body cars had that setup if you google it for pics etc.