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Old 05-09-2017, 10:23 PM   #1
mister.freeze
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Rear axle alignment

A while ago I ran across a thread about leaf springs not having all the leaves lined up side-to-side. The consensus seemed to be this was not a problem as long as everything was tight and functioned.

Yesterday, I had a front end alignment hoping to correct a mild but definite pull to the right. Caster was ok, no changes made to camber, and a little bit of toe was adjusted, but the pull remained.

So today, i took some measurements to find the right rear tire 7/8" further forward than the left. It's the wheel with the misaligned leaves too. Does this mean the nipple or pin keeping everything lined up is broken? I hope not... if I loosen up the u-bolts, tap the axle aft, and re-tighten, am I good to go? Thanks in advance for any input.
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Old 05-09-2017, 10:42 PM   #2
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Re: Rear axle alignment

Sounds like you need to check the centering pins in the rear springs. Not a bad job and you can get them from a spring shop.
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Old 05-10-2017, 08:42 AM   #3
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Re: Rear axle alignment

Even if the pins are in good shape, you may have to slot the mounting holes a bit. My Blazer had low miles and even though everything in the suspension was in perfect shape, I still had to elongate the locating hole on one of the front axle perches because I had a 3/8 difference side to side.
7/8 does sound excessive. I would take some measurements from static holes in the frame to see where you're getting this variation. Don't worry too much if you have to grind here and there to get everything squared up. Unfortunately, back in the early 70's, these trucks were slapped together and had huge tolerance variations.
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Old 05-10-2017, 10:04 AM   #4
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Re: Rear axle alignment

Good to know. Unfortunately, this is a fairly new problem, so I suspect a broken pin. In the pics, you can see a rust spot just to the right of the forward u-bolt that looks like where the bolt used to be. It's also 7/8" from the bolt itself. I took several measurements fore and aft from the u-bolts to fixed points on the frame and got that 7/8" variance.
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Old 05-10-2017, 10:05 AM   #5
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Re: Rear axle alignment

Do I have to get a pin to match my spring or are they generic? (3/4 Skyjacker springs)
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Old 05-10-2017, 10:44 AM   #6
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Re: Rear axle alignment

Quote:
Originally Posted by mister.freeze View Post
Do I have to get a pin to match my spring or are they generic? (3/4 Skyjacker springs)
Should be just a 3/8 center pin. I've made them in the out of regular 3/8 bolts in a pinch.
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Old 05-10-2017, 10:51 AM   #7
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Re: Rear axle alignment

Lowes has a hardend allen bolt with a little fitting that works great
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Old 05-10-2017, 10:58 AM   #8
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Re: Rear axle alignment

Quote:
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Lowes has a hardend allen bolt with a little fitting that works great
I agree !! Over the years, that's all I ever used.
Ask for a 3/8-16 Socket Head Cap Screw (SHCS). These are grade 8


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Old 05-14-2017, 05:42 PM   #9
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Re: Rear axle alignment

Set that into the spring perch (upside down?) and reassemble? Any reason not to add a nut?
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Old 05-18-2017, 12:13 AM   #10
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Re: Rear axle alignment

Quote:
Originally Posted by hemi43 View Post
I agree !! Over the years, that's all I ever used.
Ask for a 3/8-16 Socket Head Cap Screw (SHCS). These are grade 8


How long of a bolt do I need? Will I need to disconnect a shock as well?
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Old 05-18-2017, 10:37 PM   #11
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Re: Rear axle alignment

You can get the spring tie bolt from a parts house or spring shop I have replaced these before.
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Old 05-18-2017, 10:50 PM   #12
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Re: Rear axle alignment

To get the lift I need, I'm going to have to use a forklift on the back bumper. Do I need to disconnect the shock from the side I'm working on? After loosening up the u-bolts and lifting the spring off the axle, will the old pin (pieces) just fall out?
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Old 05-19-2017, 10:36 AM   #13
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Re: Rear axle alignment

As far as the old bolt pieces falling out you might get lucky might not it has gone both ways for me. Yes I would take the shock loose so it does not limit your axle droop. Use a c clamp or duck tape to hold the springs together since the tie bolt is broke also makes it easy to install the new bolt since you are not having to compress the springs back together. I also noticed you have a small spacer under your main helper spring that could have kept the head of the tie bolt from falling into the alignment hole on the axle. Had this happen once too.

Last edited by 72k5ls; 05-19-2017 at 10:39 AM. Reason: more text
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Old 05-19-2017, 11:07 AM   #14
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Re: Rear axle alignment

good advice! I just looked and there is in fact a nut on top. Didn't know that was there. I'll give it a tug with pliers in a while just to see if it's willing to come out and to confirm that's my problem. I'm guessing a 3 or 4" bolt is what I need? It's a 3/4 ton spring...
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Old 05-19-2017, 04:33 PM   #15
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Re: Rear axle alignment

You should not have to change the bolt if all the problem is the spacer you have under the helper spring.
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Old 05-21-2017, 11:22 AM   #16
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Re: Rear axle alignment

Well, crap. That wasn't the problem (see first pic). Pin is solid, lined up, and fits the spring perch. Turns out 1 spring is longer in front than the oter, meaning this is not why the truck pulls to the right. It also meeans I've been driving sideways for a long time!
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Old 05-21-2017, 11:33 AM   #17
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Re: Rear axle alignment

If the spring was installed backwards you will see that to had that happen the springs had no directional markers for installation so it was possible to install wrong. Try turning that spring around and see what happens.
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Old 05-21-2017, 11:52 AM   #18
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Re: Rear axle alignment

I thought of that and checked, but it looks different on the back than the front. I'll do some more measuring to see. Also will check to make sure a front spring is not on the rear.
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Old 05-21-2017, 12:10 PM   #19
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Re: Rear axle alignment

Front springs will not interchange to back. The axle centering pin may be offset on your springs you can check by measuring from the center of the bushing to the center of the pin need to do this front and back on the spring. Front springs do not have the big helper spring.

Last edited by 72k5ls; 05-21-2017 at 12:11 PM. Reason: more text
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Old 05-21-2017, 12:42 PM   #20
mister.freeze
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Re: Rear axle alignment

Well, the springs are marked, and installed according to the markings. However, measurements tell a different tale. Which one should be flipped? Should they be longer in the front or back?
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Old 05-21-2017, 09:20 PM   #21
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Re: Rear axle alignment

Long length of spring to front.
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Old 07-19-2017, 01:24 AM   #22
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Re: Rear axle alignment

WTF spamer.
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