leaf spring question.

gwizz

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just got a set of nationals have some questions about the bushings. the spring eyelets are very very tiny. wondering what you guys run? derlin? nothing and a big ass bolt? poly or wut??
i want to use at least a 9/16 bolt, these appear to be 3/4-7/8 hole ish. so not much room for bushing material. who should i call to see if they have stuff for these springs? auto fab?

are there any rules for making a leaf set up for something that cycles more than 14". does it need to be spring under or is that done strictly for bump up and handling? besides how everything mounts with out over arching at bump what dictates spring under vs spring over? ideally im thinking tension shackle with bronco style 2 link traction bars for spring over cause i know it can take the torq.

any one put real power through a spring under using a little mack style traction bar on the top? i just cant see spring under workign with out hop or not destroying hte springs even with a traction bar.

any pictures or links to threads with a good leaf build would be appreciated.
 

BTFfabrication

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I’ve built both spring under and spring over set ups with trac bars on top of the axle and below the axle; both worked well. They just take a bit of setup time, or they will bind pretty quickly. As for the bushings use a poly bushing with a metal sleeve for the size bolt you want. Sounds like a small eyelet but poly bushings come in all sorts of dimensions. We used to have a local “off-road” shop that had a wall of bins full of different size bushings.
 

Bert is my name

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All the class 8 trucks in the 70s and 80s ran spring under nationals. To answer your question yes "real power" was put to the ground using spring under.
 

gwizz

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I’ve built both spring under and spring over set ups with trac bars on top of the axle and below the axle; both worked well. They just take a bit of setup time, or they will bind pretty quickly. As for the bushings use a poly bushing with a metal sleeve for the size bolt you want. Sounds like a small eyelet but poly bushings come in all sorts of dimensions. We used to have a local “off-road” shop that had a wall of bins full of different size bushings.
the under axle traction bars are fairly strait forward, as far as over axle/over spring, whats easier? three link wishbone deal on top of the axle? or two link over each spring clearing the shocks as best as possible?
 

BTFfabrication

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the under axle traction bars are fairly strait forward, as far as over axle/over spring, whats easier? three link wishbone deal on top of the axle? or two link over each spring clearing the shocks as best as possible?

I personally like the top link better, more out of the way,not down low where they get smacked by rocks and stuff. Also higher up on the top of the pumpkin controls pinion/wheel hop better. And you have 1 less heim or pivot.
 

Fifty

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I guess it is just going from a crap stock 4 leaf leaf spring over to a 10 leaf spring under. But the wrap has been significantly reduced.

It was my understanding that going to a spring under will reduce the wrap likelihood
 

Bert is my name

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You can have an anti wrap leaf added to the front of the leaf pack. Basically a half leaf that sits on top of the front portion of the spring.
 

Bert is my name

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The axle has a harder time placing leverage on the spring in spring under setups. So traction bars may not be needed. I've also seen four links with leaf springs that use a double shackle arrangement but that was on a rock crawler .
 

gwizz

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Mine is just a regular leaf I think.
i will attach pictures of my current set up. probably going to do the same just on a larger scale.
The axle has a harder time placing leverage on the spring in spring under setups. So traction bars may not be needed. I've also seen four links with leaf springs that use a double shackle arrangement but that was on a rock crawler .
i already have the bars was just nerding out on spring over or under and how a traction bar on spring under compresses the spring eyelet under traction. i definatly need or want them, much better sway control, and i can plant power in turns.
i have a 250horse cummins probably conservatively doing 5-600ftlbs. IMG_2762.JPGIMG_3085.JPG
 

jon coleman

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The axle has a harder time placing leverage on the spring in spring under setups. So traction bars may not be needed. I've also seen four links with leaf springs that use a double shackle arrangement but that was on a rock crawler .
seen that w- 3 link, but shackles were hiem'ed for maxx articulatation
 
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