Re-drilling leaf spring perch to move axle back

[Whoaa]

There has been some discussion in other various threads about drilling a new hole in the leaf spring perch to move the axle housing back a little bit. However I'm still unclear of exactly what all this may change.

From what I understand, the basic idea is to move the rear end housing, rearward about 3/4"+, by driling a new hole forward of the factory hole for the leaf spring centering pin to align with. By moving the rear end housing back it better center's the rear end in the fender -on mine (5.5" lift & unloaded springs) when I measure from the center of the drum to the closest inner fender sheet metal rearward I get 28", when I pull this same measurment from the center of the drum to the closest inner fender sheet metal forward I get 26". So in theory, if I move the rear end housing back 1" it will be better centered in the fender and should give me 27" forward and rearward for this V measurement I made...advatangous for big tires & flexy suspension, and minimum trimming on the inner fender sheet metal.


For example; by redrilling the hole to a different location the leaf spring pack is no longer centered on the axle housing, what does this mean? What all should I consider when thinking about this, advantageous, disadvatageous? Strenght?

Right now I have factory leaf spring perch's, they are about 4 3/8" long. I'm using 11 pack Spring's, 7/16" centering pin, 6* shims, extreme duty U bolts and top plate. It makes sense that longer perch's http://www.wildhorses4x4.com/product/Anti-Wrap_Leaf_Spring_Perches would offer more strenght and mounting surface....I'm just having a hard time with the center of the spring not being centered on the diff housing....

 

[bax]

I did it on my build. You cant go too farback if you have a 23 gallon gas tank. The rear will hit it. I did it to help out my rear drive angle. My fenders are cut so the centering thing was not an issue. use good u bolts. nice looking welds. also dont put jackstands on concrete blocks that way. Turn them the other way and find a board to put on top of the block. The block is not very strong in that position and can break very easy.

 

[AxlesUp]

one of my friends died like that a decade or so ago. damn blocks crumbled and dropped the car on him. it was late at night and he was alone.

i did a toyota like that. it never caused me any grief, but it does put more stress on the spring pads and u-bolts.

 

[ILikeBond]

FWIW, I did a write-up of my axle push starting at post #22 of this thread.

 

[MyOriginal66]

I had the same concern so I bought the ones from ruff stuff. Super heavy duty, longer and pre-drilled. The rear end shop that's doing the work (and has been in business for 30 plus years) wanted to know where I bought them so he could start using them in some of thier axle builds. Bought the whole kits with the heavy duty, pre drilled plates as well.

 

[DirtDonk]

I don't know all the dynamic characteristics of the change, but there are many factory offerings with offset pins in the springs themselves. GM was known to do this on some trucks. I'm sure others did as well.

It probably does change the way a spring works, but I doubt that it's a radical change. So whether or not it's a "bad" change (from stock) the bad probably isn't all that bad enough to outweigh whatever benefit you're trying to achieve.
That's pure conjecture though, as like I said, I don't know what it does to the dynamics of the suspension at that point.

Paul

 

[welndmn]

It's very common, but I would not drill the stock perch, just buy a new perch that has the multiple holes for adjustment.

 

[.94 OR]

I'm gearing up to do this "move" on mine.

I have a different housing that I will be putting in. Should I cut the stock perches off, then assemble everything loose and tighten up when I get it where I want it and then tack the perches to the axle? If so, what pinion to driveline angle should I be targeting at ride height?

I currently have the 6* shim which I wouldn't mind eliminating as I'm not sure it is the ideal angle on the pinion anyway.

Planning to buy the longer perches and beefier top plates with the multiple holes already drilled.

 

[tirewater]

Yikes, cinder blocks can't take much weight on their side like that. Please consider eliminating them or orienting them up and using a plate or heavy duty piece of wood across them.

one of my friends died like that a decade or so ago. damn blocks crumbled and dropped the car on him. it was late at night and he was alone.

 

[ransil]

I'm gearing up to do this "move" on mine.

I have a different housing that I will be putting in. Should I cut the stock perches off, then assemble everything loose and tighten up when I get it where I want it and then tack the perches to the axle? If so, what pinion to driveline angle should I be targeting at ride height?

I currently have the 6* shim which I wouldn't mind eliminating as I'm not sure it is the ideal angle on the pinion anyway.

Planning to buy the longer perches and beefier top plates with the multiple holes already drilled.

get rid of the shims and set the new brackets on with full weight on the perches, then weld perches on once you get everything set.

there is a couple of websites that tell you how to set up the pinion angle, make sure you use the one for a double cardan joint.
short version is set the pinion 2 degrees pointing down, but double check that it from memory and i cant remember shit anymore.

 

[Broncobowsher]

First, GET RID OF THE CINDER BLOCKS! Not soon, or the next time you want to move the jackstands, before you go near under that ting again. Even worse you have them lined up in the weakest possible way.

PSA over,

Redrilling the hole has been done and works. Also have to do the spring plate on top. Watch for clearance. That 23 gallon tank clearance is what stopped me.

 

[Geniusloerts]

First, GET RID OF THE CINDER BLOCKS! Not soon, or the next time you want to move the jackstands, before you go near under that ting again. Even worse you have them lined up in the weakest possible way.

PSA over,

Redrilling the hole has been done and works. Also have to do the spring plate on top. Watch for clearance. That 23 gallon tank clearance is what stopped me.

I sure hope it’s not on cinder blocks 4 years later...


Sent from my iPhone using Tapatalk

 

[Broncobowsher]

One of the times I didn't look at the original date.

 

[Jamie Chriss]

I am super happy with these perches! Ez PZ

 

[.94 OR]

I am super happy with these perches! Ez PZ

Did you get the mounts and the top plates from the same vendor?