Moving leaf springs inboard?

TheBac

TheBac

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As the title states, Im contemplating moving the springs inboard the frame on the 1/2 ton so-as to gain room for larger rear tires. I am looking for advice/opinion from guys who know suspensions far better than I (cough cough James cough cough) on what pitfalls I may run into by doing this.
Keep in mind that I am only using 2 leaves of the springs and they will essentially be locators for the rear axle, as I am going to run adjustable coilovers for suspension.

The way things are measuring out, the springs will end up above that flat platform next to the existing spring perches on the 9.5" 14 bolt, so they'll be about 6" inboard from where they are now. This will neccesitate removing the existing shock mounts and moving them inboard between the springs and diff, but that was something I was planning anyway. I plan on using some sort of rear stabilizer bar to help regain some of the lost handling, while either running my Caltracs (as from what Ive read it seems they would still work in this configuration) or a ladder bar of some kind.

I just wonder if it make the truck unstable as far as drag racing? In my reading, I find that this is a common change made by Mopar and Chevy owners to gain wheel well width for their cars, but we're talking a 4500lbs truck, not a 3000lb car.

I appreciate any insight.
 
TheBac

TheBac

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I almost forgot, as far as mounting the springs, I am running a lowering hanger on the front, and either drop shackles or sliders on the rear. The front hangers will simply be swapped side-to-side, with the frame boxed and DOM tubing between the inner and outer frame rails for the bolts to run thru. There would be a new crossmember run just in front of the new hangers, which would take the place of the rusted out old one (that used to be the rear fuel tank hanger).
The rear will have the crossmember removed from between the spring mounts and moved to the very back to the frame, since Im running a rollpan instead of a bumper.

BTW, YES a four-link is a possibility, provided I can find tubes large enough to survive behind a Duramax, and if I could get Rick to create some of those exceptionally nice brackets he posted a picture of years ago, but for a 3-3/8" axle tube :poke:....:hehe:
Only problem with that is then Im kind of a "man without a country" as far as what class to race in if I go that route.
 
thunder550

thunder550

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Tom, I am only running 2 leaves on my half ton and it's plenty to support the weight of the truck's rear end. I think running 2 leafs as well as a coilover would be too much, unless you are swapping in leafs from a lighter vehicle.
 
Chevy1925

Chevy1925

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Putting the springs inboard allows the axle/wheels to put more leverage on the springs in a cornering environment and induce more body roll. Obviously your not going for corners lol. I would certainly run them inboard ONLY if your trying to runs tire under that bed you couldn't fit normally. That's pretty much all your gaining.

Is there a tire your after Tom? One that's not going to fit normally? It's much easier to weld on some new spring pads and leave the old ones in place than to remount all those hangers. Plus if you decide to move them inboard, the old stock plates are there and ready.

I wouldn't run a coil over on the rear. At least not right away. Initially, you just want the spring there to support the vehicle to the proper ride height. This means it should take 1-2" of spring preload to get that desired height. Being you have leafs already that will increase at spring rates different than what a coil spring will, it may cause you to have a hard time getting the back end to work right. A single leaf, pan hard bar, and sway bar as well as the coil overs would work better but a 4 link would be best and the most work to get to work for your truck.

I'm also not sure how caltracs will do on a single spring that has next to no preload in it as it's not supporting the weight of the vehicle. I have not looked into that at all. It may work but may need a lot of preload in the bars.

If it were me, here is what I would do. Figure out the tires you want to run and wheel off set. This obviously will determine how much tire will stick out the fender or not and where you need to mount the springs. If you can leave them outboard, leave them and just weld new spring perches on the axle and leave the stock ones in the axle. Leave the two springs on if ride height is where you want or use lowing hangers to get you down where you want. Buy double adjustable rear coilover shocks but no springs. This way you have the shock should you want to try a single spring and springs on the coil overs. A pan hard bar is a good idea to keep the rear end from walking around.

If you need to move the springs inboard, run the two springs, mount hangers so your at the right ride height you want, buy the double adjustable shocks without springs but look into the idea of an adjustable sway bar. At launch, with diesel torque, it will twist the chassis up when you get launching close to perfect and cause you to pull one way or the other. The sway bar will help eliminate it.

So basically, I can't tell you what the best way is for your setup but what i listed out is a good process of elimination.
 
TheBac

TheBac

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Chevy1925 said:
Putting the springs inboard allows the axle/wheels to put more leverage on the springs in a cornering environment and induce more body roll. You are correct. Obviously your not going for corners lol. Again, correct. :) I would certainly run them inboard ONLY if your trying to runs tire under that bed you couldn't fit normally. That's pretty much all your gaining. This is why I am asking.

Is there a tire your after Tom? One that's not going to fit normally? 13.0/16 M&H, but the kicker is Im exploring widening a couple PY0s for them. It's much easier to weld on some new spring pads and leave the old ones in place than to remount all those hangers. Plus if you decide to move them inboard, the old stock plates are there and ready. Ok, I didnt quite understand this. I was planning new plates...the old ones wouldnt be reusable.

I wouldn't run a coil over on the rear. At least not right away. Initially, you just want the spring there to support the vehicle to the proper ride height. This means it should take 1-2" of spring preload to get that desired height. I misspoke myself. I agree with just using a double adjustable coilover shock w/o the springs. Being you have leafs already that will increase at spring rates different than what a coil spring will, it may cause you to have a hard time getting the back end to work right. A single leaf, pan hard bar, and sway bar as well as the coil overs would work better but a 4 link would be best and the most work to get to work for your truck. I would agree, but asking about what dia 4-link bars, rod ends, mounts, etc....is another entire thread. :)

I'm also not sure how caltracs will do on a single spring that has next to no preload in it as it's not supporting the weight of the vehicle. I have not looked into that at all. It may work but may need a lot of preload in the bars. My thinking was to use the Caltracs the same as they do when using their split mono leaf.

If it were me, here is what I would do. Figure out the tires you want to run and wheel off set. This obviously will determine how much tire will stick out the fender or not and where you need to mount the springs. If you can leave them outboard, leave them and just weld new spring perches on the axle and leave the stock ones in the axle. Leave the two springs on if ride height is where you want or use lowing hangers to get you down where you want. Buy double adjustable rear coilover shocks but no springs. This way you have the shock should you want to try a single spring and springs on the coil overs. A pan hard bar is a good idea to keep the rear end from walking around.

If you need to move the springs inboard, run the two springs, mount hangers so your at the right ride height you want, buy the double adjustable shocks without springs but look into the idea of an adjustable sway bar. At launch, with diesel torque, it will twist the chassis up when you get launching close to perfect and cause you to pull one way or the other. The sway bar will help eliminate it. Yep. I agree.

So basically, I can't tell you what the best way is for your setup but what i listed out is a good process of elimination.
Click to expand...

If the rear of the truck is lowered where I think it will be, the "normal" wheel/tire setup will run into the fender lip. I really need to go back and reread what Brandon used to run on his CC 2wd.

Thank you James. You too, A.J. and Sean. Appreciate your insight and advice.
 
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Chevy1925

Chevy1925

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TheBac said:
If the rear of the truck is lowered where I think it will be, the "normal" wheel/tire setup will run into the fender lip. I really need to go back and reread what Brandon used to run on his CC 2wd.

Thank you James. You too, A.J. and Sean. Appreciate your insight and advice.
Click to expand...

what i mean by old plates is "assuming" the perch angle is where you want the pinion angle to be, leave them on the axle while you keep the springs out board so when you go in board, you dont have to setup spring perches again. But im betting they are not at the correct angle if you are wanting to cut them off.
 
TheBac

TheBac

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There's no way I could swing that, Russ. Thats why the 1/2 ton build is going so slow....money and time.

But thanks to you and Chris for your advice.
 
TheBac

TheBac

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duramaxzak said:
Have you thought about just narrowing the factory frame rail and leaving the leaf springs on the outside?
Click to expand...
Not really. IMO that would add a lot of work to get the same thing.



Russ, the kids and I went to the big car show in the town I deliver last Thurs. They both said they want to see the red truck in the show next year. I told them Id need a lot of help to do it and it will take time. So, we'll see.
I finally figured out the front suspension. Adjustable ball joints are my friend. Everything else fits and works as if it was OEM.
Now on to the back half.
 
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