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What's the best way to move rear axle back 3 inches?

blowedupmotor87

blowedupmotor87

1/2 ton status
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I bought my 87 GMC Jimmy with an ORD rear shackle flip already on it. I like the height but, I want my rear wheels to be centered in the wheel wells better. To my eye it looks rather strange with its slightly shorter wheelbase and slightly longer rear overhang as a result of the shackle flip. I realize that the rear axle is going to move back somewhat as the suspension flexes but, I would rather just cut a bit off the of the wheel well openings than have to run a shorter wheelbase.
My questions:
1.Is this wheelbase shortening normal with a shackle flip? It seems that it would be due to the change in the angle of the springs but...?
2.Is the (centering?) pin actually in the center of the spring or can it be moved? or a zero rate used?
3.Can longer rear springs be used (relocated the rear shackles but retaining the front spring mounts)? (I do not want to run 64's, I desire the rear axle to move back about 3 inches not the 10 or so inches that a 64's swap seems to yield)
4.Would longer rear springs (if they are the best answer) be something readily available or would they have to be a complete custom leaf pack?
5.Is the frame consistent enough in shape to make a rearward move of the shackle mounts of about 6 inches possible w/o major modification to shackle hangers or frame?
6. Would swapping sides on the shackle mounts, 56's and zero rates be enough and would that be a pretty bulletproof combo?
As I have said I would like to have the rear axle moved back approx 3" to better center the rear wheels and to not be running a shorter than stock wheelbase. If I have to cut the wheelwells/get a different fuel tank/relocate shackle mounts/get a different hitch (any other problems y'all can think of?) I am actually okay with this. I want to run a 14BFF approx. 4" lift and cut the fenders accordingly to fit 37"s and do not want to cut them wrong now because my rear wheels are in a funky spot. Also, even if getting there is complicated, I want the final result to be as bulletproof as possible with as few complicated things (no blocks, sketchy spring pack/perch mods, etc) to fail as possible.
I will attach a pic to show the problem. I apologize for the fact that this is probably a repost but, I couldn't find a post by searching that adequately answered my questions, if y'all know of one, I would definately appreciate a link! Thank you everybody!
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If you want the axle back in it's original location (still sits forward of center a bit) then turn your springs around and that will move it back 1". If you still want more then you can add a zero rate and get another 1-1.5" but that will also add 1" to height.
 
4X4HIGH, thanks for the response! A 1" lift from zero rates would be fine as I am going to be getting a 1" lift up front due to a dana 60 swap anyway. Are there any problems associated with using Zero rates to move the axle back? Like, does the axle being further back on the same springs cause any weird axle wrap, ride quality compromises, or odd spring deformation over time? If there ar none of those penalties, maybe I will add some zero rates (along with turning the springs around) sounds like that combo might just put the axle right where I want it and fo a lot less $$$ than I originally thought I'd be looking at to move it back! Thanks!:D
 
There are no ill effects of moving the axle back with zero rates. The only thing you'll have to do is to drill a new hole in the spring plate for the center pin to go into. I have a 4" rear spring and a 4" shackle flip and i only turned my springs around and it looks pretty good.
 
Cool deal! I am definately going to try turning my springs around before anything else, sounds like this is going to be a lot simpler than I had expected, which is always a good thing, thanks!:waytogo: Oh yeah, does turning around the springs effect pinion angle at all? Like will I need to run shims or anything?
 
The axle will end up on a different part of the arch of the spring but not enough to notice anything. Flip the springs around and i think you'll be happy.
 
just a quick question. why is fliping end for end on 52" springs going to move the axle back? 52" springs are even spaced not offset. :eek1:

unless you are thinking of a diffrent style spring pack. just want to make sure.
 
My superlift rear 52" springs do not have a centered pin, they are offset by 1".
 
I hope my springs have offset center posts so this will work, they are stock springs though (I think). Might have to look into a more complicated solution if they aren't offset 'cause I don't think the 1.5" from zero rates will be enough of a difference. Well, I guess I will just have to take a look at my spring packs (right now I am 1000 miles away from the Jimmy visiting friends in TX). Thanks for all the info y'all!
 
blowedupmotor87 said:
I hope my springs have offset center posts so this will work, they are stock springs though (I think). Might have to look into a more complicated solution if they aren't offset 'cause I don't think the 1.5" from zero rates will be enough of a difference. Well, I guess I will just have to take a look at my spring packs (right now I am 1000 miles away from the Jimmy visiting friends in TX). Thanks for all the info y'all!
Click to expand...

If you have stock springs, they are centered,to get a few inches back a\with stock springs your best bet is the 56 inch springs, and swap the shackle flip side to side, you should get close to 4" since they are a 52" spring with an extra 4" on one side.
And if you get it from a 3/4 ton HD you will probably also end up with an extra inch of lift.
 
imiceman44,
Thanks for the info on the 56" spring swap! Do have a question though, wouldn't the ride be pretty harsh with 3/4 ton springs? Would you have a suggestion to soften the ride (maybe removing leave(s))? Or is it not a problem? Also, will swapping the shackle flip brackets side to side work with ORD brackets? The 1" extra lift would be cool since I plan on swapping in a Dana 60 up front eventually anyway so that'll add almost an inch to the front. Thanks for the info!
 
blowedupmotor87 said:
imiceman44,
Thanks for the info on the 56" spring swap! Do have a question though, wouldn't the ride be pretty harsh with 3/4 ton springs? Would you have a suggestion to soften the ride (maybe removing leave(s))? Or is it not a problem? Also, will swapping the shackle flip brackets side to side work with ORD brackets? The 1" extra lift would be cool since I plan on swapping in a Dana 60 up front eventually anyway so that'll add almost an inch to the front. Thanks for the info!
Click to expand...

It depends where you get your spring.
My 84 3/4 ton long bed rides smoother than any 1/2 ton 70's truck or blazer I ever drove, even empty it rides like a car not a truck.
I think the mid eighty's got smoother riding springs until they switched to 63's when they had even more smoothing.
The ORD brakets will accomodate the 56" springs if swapped side to side.
You will notice if you look at them that they are not centered, froward they are good for the 52" and backwards they are good for the 56"
 
i have 56"s in backwards with ORD flip brackets. and i still had to move the brackets 3" back. the springs are from an 85' crew cab dually 2wd. I removed the the upper and lower overloads, and the 2 small bottom leaves. they might be a bit soft for my tall truck but other than some leaning in the corners they are great. An improvement over the modified 52s that where in there for sure. I recently cut the tops out of the spring clamps too so now they droop even more but the leaves don't get all twisted from each other.
 
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