71 Burb with a leaning problem

[DBear]

Ok....I have been working on this tank for some time. Just started buttoning up the 3/4 ton axle swap and the DAMN thing is lower by a 1 1/4 on the drivers side. I first thought it was the springs so I swapped them out with a set of skyjacker lift springs....and still the same problem. When I set the skyjacker springs on the axle, and the axle was sitting on jack stands, it was level! When I put the tires on and lowered them to the ground, the burb then had the lean of 1 1/4" to the drivers side again.

I have checked the following :

Tire pressure
Body mounts
Spring bushings etc...

I checked the front of the frame and it was level....and pretty sure frame isn't tweaked because I don't remember if ever leaning at all.

this one has me stumped....please help if u can!!!
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[argonaut]

Two different length shackles??

[DBear]

Yeah....measured those and they are same size. This is the weirdest thing I have experienced with this rig for sure

[argonaut]

It is weird. so with the new springs mounted and the axle mounted, but axle on jack stands, it was level? Are you sure both jack stands were extended the same amount? can you simulate this by putting it back up on jack stands? is one of your tires mistakenly a smaller size!?!?!

Is the rear axle a 14 bolt, eaton or dana 60? Did you relocate the spring perches inward to 40"? Or did you convert to later model wider hangers at 42.5"?

[cdowns]

normal chevy lean they all do it to some extant the harder they were used the greater the lean

[DBear]

Originally Posted by argonaut

It is weird. so with the new springs mounted and the axle mounted, but axle on jack stands, it was level? Are you sure both jack stands were extended the same amount? can you simulate this by putting it back up on jack stands? is one of your tires mistakenly a smaller size!?!?!

Is the rear axle a 14 bolt, eaton or dana 60? Did you relocate the spring perches inward to 40.5"? Or did you convert to later model wider hangers at 42.5"?

when I had it up on jack stands....and unfortunately they were even /level, the burb sat level. The 14 bolt came out of a 3/4 ton which the perches line up. The tires measured the same as well

[Bladeboy1998]

Originally Posted by cdowns

normal chevy lean they all do it to some extant the harder they were used the greater the lean

This

I forget who it is (has the polar bear suburban) I think it was his build thread he talked about the chevy lean.

[argonaut]

With good body mount bushings, springs, spring bushings and shackles, there is no reason a truck should lean. At least not as mush as 1"+. Unless it is actually weighted heavier on one side, or something is on the chassis is bent.

If it sat level on the jack stands then the only remaining factors are the wheels and tires.

The other puzzling thing to me is that there is no factory 3/4 ton truck (or 1 ton for that matter) with a 14 bolt that has the the same spring perch distance as a 71.

[71blksuper4x4]

Originally Posted by argonaut

With good body mount bushings, springs, spring bushings and shackles, there is no reason a truck should lean. At least not as mush as 1"+. Unless it is actually weighted heavier on one side, or something is on the chassis is bent.

If it sat level on the jack stands then the only remaining factors are the wheels and tires.

The other puzzling thing to me is that there is no factory 3/4 ton truck (or 1 ton for that matter) with a 14 bolt that has the the same spring perch distance as a 71.

The cab & chassis 1 tons drw have the same perch distance as the 72 body style.

['63GENIII]

My '63 leans about the same amount but on the passenger side. The only difference is that the front shackle on the passenger side has a little more angle. By a little Im talking within 5 degrees of the drivers side. Its driven me crazy for the last 8 years! In two weeks, Im swapping in a set of 52" springs into the front and at that time, I will make sure that the new rear shackle eyes and front spring hangers are in identical places. I can't tell you how many times Ive measured my frame with a straight edge and plumb bob only to come to the conclusion that the hanger was installed just a little off at the factory. Not sure if this is what you have going on with yours as well but its free to take a tape measure and look.

[bilfman]

Could be a bent frame , hate to bring that option up. I had the same issue on a prior resto, needed a tweak on a frame machine to fix it.

[Mr. D]

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[Mr. D]

Check the spindles. One may have 1" drop.
Just a thought.
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[swamp rat]

My thought is binding suspension, did you lower the driver side last with a floor jack? did you torque the U bolts up in the air or on the ground?

[argonaut]

Originally Posted by 71blksuper4x4

The cab & chassis 1 tons drw have the same perch distance as the 72 body style.

My 83 1 ton perches measured 40.5". My 73 3/4 ton measured 42.5". My 64, 66 and 70 axles measure 40". This is measured by hanging a plumb bob from each spring perch centerline to a flat level surface and measuring between them. To be fair, I never measured an axle from a cab & chassis truck.

I dont mean to steer this off topic; the reason I bring this up is because if the OP has a 1 ton axle with 40.5" spacing installed on 40" wide hangers then spring bind could be causing some problems, whether they are causing the lean or not.

[argonaut]

Another thought: measure your springs from each end to to center pin. My 52" long tuff country 4" lift rear springs had slightly offset spring pins so I had to be sure to have both oriented the same.

[special-K]

Just throwing this out there since no one has mentioned it... Could the frame be cracked at the steering box? What surface is the truck on when measuring?

The last suggestions by argonaut could make a difference.

[Mr. D]

One thing for sure, this is not your usual problem. Very odd.
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[Mr. D]

Did you ever find out what the problem was?