Author Topic: DIY Rear Axle Alignment - not adjustable - it is now  (Read 10608 times)

Offline Thundergun

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DIY Rear Axle Alignment - not adjustable - it is now
« on: August 31, 2015, 10:20:15 pm »
Hey again everyone.

Okay so my 85 k10 short bed. It was hit while parked on the drivers side rear tire. it bent the axle. and the frame slightly. I got new axle (with posi!) I had a body shop measure the 'diamond-ing' of the frame and they said it was a little out of spec, but not much, and if i don't notice it don't worry about it. I've driven it a bit, don't really notice it, cuz honestly the font tie rod ends have a little play causing the steering to be out of alignment anyways.

But the rear axle needs a small amount of alignment; i measured the distance between the front and rear axles; one distance between axles on the drivers side and one on the passenger side. The distance on the drivers side was less than the distance on the passenger side. (which makes sense, the left rear tire was hit bending that part of the axle fwd) So the axles are not parallel as they should be. The difference was only about 1/2"

Buuut this bothers me and i'd like to correct it. So im thinking of a way to correct it and realign the rear axle; move the rear left block back about 3/8"  toward the rear (drivers side where the axle got moved forward). (not a full 1/2" cuz as i move the rear left back, this will also move the rear right forward).

I know this sounds crazy. not saying im going to do it. Just wanted to throw it out there and see what people think. And why this is not
a good idea.

How? The block locks into place under the leaf via a vertical bolt and nut thru the leaf. i propose to drill a hole thru the spring 3/8" aft of the bolt and re-position the bolt in the new hole,

Consequences? well the pay load in the bed will no longer be supported by the intended part of the spring, but i don't think 3/8" will have much of an effect, plus i never intend to load the truck to it's max capacity. the new hole in the spring will also be a stress concentration, but im not worried about that.
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline Greybeard

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #1 on: September 03, 2015, 12:32:51 pm »
Bad idea only because you will never drill a hole in those springs without removing them and taking them to a machine shop. If that truck is only out by a 1/2 inch that frame shop should be able to pull it back easy enough, a Chevy frame is pretty limber. Besides, if it moved the rear suspension that much then the body mount bolts, the engine, tranny and transfer case mounts, the front and rear bumper mounts and cross-members are now all under stress. If just the spring mount was tweaked then replace it. If the frame was bent in jack it apart. Or...

Go to your friendly local welding shop and have them build you a set of zero rate 'springs' with the offset you want. Keep the center pin where it is in the spring pack. Use a new center pin in the block at the location you need it to be to fit into the axles locator hole. Gotta make two though to keep the truck level side to side. You will likely have to take all the misalignment out on one side instead of splitting it side to side due to the diameter of the center pins nuts. First it might be worth your while to remove that side from the spring and put the axle where it is square again with the front and find out for certain how much to move it.

My personal opinion is to use new u-bolts, nuts, and washers regardless of how you do it, $40-$50 is cheap insurance as opposed to having an over-stretched u-bolt break during a panic stop.

This page should give you an idea of what I mean. The ones they sell won't work for your problem.
http://offroaddesign.com/catalog/Zero%20Rate%20Instructions.pdf

FWIW- The only thing you will notice while drive it is a dog leg effect anyway. 1/2" out of alignment isn't very bad. It won't hurt the tires, might see the passenger side of the truck in side mirror more than the drivers side. Personally, I don't think I'd bother with it.
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Offline roundhouse

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #2 on: September 03, 2015, 03:44:42 pm »
I think that someone' makes a one inch lift block that has an adjustable hole

The center hole is on a threaded rod and track that's adjustable


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Offline Irish_Alley

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #3 on: September 03, 2015, 08:21:18 pm »
think about it logically. if youre only out of square .5" you have to move one side .25" in order to square it up. if you drill a 3/8s hole for the spring bolt you will just be oblonging the hole and it will just move around freely. fix it right or dont do anything at all cause you will just cause more problems
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

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Offline Greybeard

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #4 on: September 03, 2015, 08:48:37 pm »
think about it logically. if youre only out of square .5" you have to move one side .25" in order to square it up. if you drill a 3/8s hole for the spring bolt you will just be oblonging the hole and it will just move around freely. fix it right or dont do anything at all cause you will just cause more problems

Dang! I hate logic when I didn't think of it... ;)
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Offline Irish_Alley

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #5 on: September 03, 2015, 10:17:31 pm »
think about it logically. if youre only out of square .5" you have to move one side .25" in order to square it up. if you drill a 3/8s hole for the spring bolt you will just be oblonging the hole and it will just move around freely. fix it right or dont do anything at all cause you will just cause more problems
Dang! I hate logic when I didn't think of it... ;)
na i was just adding to your logic lol
« Last Edit: September 04, 2015, 07:28:55 pm by Irish_Alley »
If you can’t tell yourself the truth, who can you tell it to?~Irish_Alley

When you have eliminated the impossible, whatever remains, however improbable, must be the truth ~Sherlock Holmes

Offline Thundergun

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #6 on: September 04, 2015, 03:07:46 pm »
Thanks everyone for the help! All great info.

A body shop said they could striaghten it the frame out for less than $500, which doesn't sound too bad. THey also said if you don't notice it, don't worry about it.

So i think you guys have put my mind at ease. I was worried this was a big deal but it sounds like it's not.

I did notice the rear shackle appears to be pushed more fwd than on the drivers side than the passenger side, which would cause my problem? So maybe a new shackle could be a fix.

I'll keep you guys posted. thanks again!
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline Thundergun

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #7 on: September 04, 2015, 03:10:48 pm »
I think that someone' makes a one inch lift block that has an adjustable hole

The center hole is on a threaded rod and track that's adjustable


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That's exactly what i need. I'll google it. If anything comes to mind let me know. THanks! 
« Last Edit: September 04, 2015, 03:13:23 pm by Thundergun »
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline Thundergun

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #8 on: September 04, 2015, 03:11:19 pm »
think about it logically. if youre only out of square .5" you have to move one side .25" in order to square it up. if you drill a 3/8s hole for the spring bolt you will just be oblonging the hole and it will just move around freely. fix it right or dont do anything at all cause you will just cause more problems

Yes, you are correct, on all points. I won't be drilling a hole. As suggested above, there are much better options. That was just what made a little sense to me, a noob. Thanks tho!
« Last Edit: September 04, 2015, 03:12:50 pm by Thundergun »
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline Thundergun

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #9 on: September 04, 2015, 03:14:07 pm »
Bad idea only because you will never drill a hole in those springs without removing them and taking them to a machine shop. If that truck is only out by a 1/2 inch that frame shop should be able to pull it back easy enough, a Chevy frame is pretty limber. Besides, if it moved the rear suspension that much then the body mount bolts, the engine, tranny and transfer case mounts, the front and rear bumper mounts and cross-members are now all under stress. If just the spring mount was tweaked then replace it. If the frame was bent in jack it apart. Or...

Go to your friendly local welding shop and have them build you a set of zero rate 'springs' with the offset you want. Keep the center pin where it is in the spring pack. Use a new center pin in the block at the location you need it to be to fit into the axles locator hole. Gotta make two though to keep the truck level side to side. You will likely have to take all the misalignment out on one side instead of splitting it side to side due to the diameter of the center pins nuts. First it might be worth your while to remove that side from the spring and put the axle where it is square again with the front and find out for certain how much to move it.

My personal opinion is to use new u-bolts, nuts, and washers regardless of how you do it, $40-$50 is cheap insurance as opposed to having an over-stretched u-bolt break during a panic stop.

This page should give you an idea of what I mean. The ones they sell won't work for your problem.
http://offroaddesign.com/catalog/Zero%20Rate%20Instructions.pdf

FWIW- The only thing you will notice while drive it is a dog leg effect anyway. 1/2" out of alignment isn't very bad. It won't hurt the tires, might see the passenger side of the truck in side mirror more than the drivers side. Personally, I don't think I'd bother with it.

Thanks a ton for the info! Your completely right about trying to drill a hole through the spring - i would need a shop to do it. your other options are even better tho. I think i'll go with your last advice and just ignore it! i was a little worried that it's eating up the tires but it sounds like it won't. I'll look more into your 'zero rate springs' suggestion - i don't know what that is, i'll have to re-read your post a few times, but it sounds interesting. Thanks again.
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline roundhouse

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #10 on: September 05, 2015, 08:16:04 am »
Might be a bent spring or squished bushing

I'd install new leaf springs and bushings and measure it again
Also.  Check the axle tube itself , make sure it's not bent

Get a helper and pull a string across the axle and measure carefully


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Offline roundhouse

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #11 on: September 07, 2015, 08:33:41 pm »

I think that someone' makes a one inch lift block that has an adjustable hole

The center hole is on a threaded rod and track that's adjustable


Sent from my iPhone using Tapatalk

That's exactly what i need. I'll google it. If anything comes to mind let me know. THanks!



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Offline Thundergun

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #12 on: September 08, 2015, 03:08:10 pm »

I think that someone' makes a one inch lift block that has an adjustable hole

The center hole is on a threaded rod and track that's adjustable


Sent from my iPhone using Tapatalk

That's exactly what i need. I'll google it. If anything comes to mind let me know. THanks!



Wow, that's exactly what i need ... but i don't know if that will work. The current lift blocks i have are not a perfect square block. The top of the block, where the nipple is located, is not flat - it's actually angled up slightly. I'll look into the product that you recommended tho. Thanks a ton!!
1985 K10 Shortbed, 6" Superlift, 33x12.5x15" tires, 100% bad, '87 fuel injected 350 (i think)

Offline Greybeard

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Re: DIY Rear Axle Alignment - not adjustable - it is now
« Reply #13 on: September 08, 2015, 08:49:53 pm »
That block looks scary. Aluminum? On a four wheel drive truck? Solid maybe, hollowed out with a bolt threaded through it holding the center pin, maybe a little less. Since these are intended as lowering blocks it might be a great idea to call the manufacturers and find out whether they suggest them as lift blocks. That is the reason they have no angle to them. They are designed as spring-under components. Those don't carry the same compression loads that a spring-over does although it appears that the rotational forces might be similar. A spring under relies entirely on the u-bolts for support and rotational resistance whereas the spring over only relies on the u-bolts for rotational and clamping forces (plus the normal axle location forces for both). If they think they are safe for this application, go for it. But you will likely need an angle wedge to get the driveline angle back. Stacking blocks is illegal BTW. That is why they invented the cheater block, otherwise known as a zero-rate spring. The wedge is not considered a block if that was confusing but they are not the best choice in the end because they can be squirted out.
I am what I am and I ain't no more!