Tracking issues on '72 4x4

[joeydurango]

After looking for a long time, just found a '72 SWB 4x4. Drove seven hours to check it out, made the call, drove it back home. Drives good, needs some front end/steering work (play in the system), but it does drive straight. Frame looks good (considering it's 40 years old) to my eye, although I'm not a trained auto mechanic.

The one issue that stood out when deciding whether to purchase or not was tracking. Drove it through a bit of sand in a straight line, and checked out the tracks. Driver's side, front and rear tires are on the same track. Passenger side, the rear tire rides a few inches inboard of the front. The rear axles on the SWB 4x4 are shorter than the front, I believe, so it appears that the rear axle is shifted to the driver's side a bit. Tricky, though:

-The cab and bed are straight, aligned well, and other than the bed being *slightly* tilted to one side (something I've seen on several of these trucks), everything looks good. Cab and bed being mounted to the frame, it makes me think the frame is straight, and there's no frame damage I've seen.
-The wheels are all the same (although I'm not sure whether the rally wheels were made in a bunch of different offsets - they look the same).
-The tires are all the same.
-The rear tires have a good bit of wear and the wear is even.
-It drives nice and straight.
-Rear axle looks good.
-Rear axle halves measure out the same from leaf to drum.
-Suspension looks good to my eye - but since it's the only thing between the frame and the axle, I'm wondering if I'm missing something.

Sighting down either side, the front tires sit equally (lateral position) in the fender wells. The rear tires do not - the passenger side is inboard, confirming what I saw in the sand. Anyone have similar issues or have ideas on what might be going on? If it's something really odd, I'll have my shop diagnose, but just curious if it's a known issue on these.

Even if it is something odd, I'm not too worried - the previous, older fellow who had the truck had driven it since 1992-ish and never noticed a thing.

[cleszkie]

I can confirm that the Dana 44 front axles have a wider track width than the rear 12 bolts in the 4x4 trucks and blazers. However I don't know why your rear axle is not centered if there is no apparent damage in either the frame or body. Have you checked to see that the backspacing/width is the same for all the rims? If you have one rim on the back that has more backspacing or is narrower, it will appear as you are describing.

[joeydurango]

I did look at the backspacing. Didn't think to look at overall width, I'll check that out too! I'd love if it were a forehead-smack stupid-simple thing like that.

I was curious if it's possible for the leaf springs to be offset to one side somehow. I don't see how - they both appear to be perpendicular to the ground and parallel to one another, and mounted correctly - but someone mentioned that as a possibility, so I was throwing this out there to see if anyone else had the same issue.

[Fitz]

Originally Posted by joeydurango

The rear axles on the SWB 4x4 are shorter than the front, I believe, so it appears that the rear axle is shifted to the driver's side a bit. Tricky, though:

--The rear tires have a good bit of wear and the wear is even.
-It drives nice and straight.
-Rear axle looks good.
-Rear axle halves measure out the same from leaf to drum.
-Suspension looks good to my eye - but since it's the only thing between the frame and the axle, I'm wondering if I'm missing something.

Sighting down either side, the front tires sit equally (lateral position) in the fender wells. The rear tires do not - the passenger side is inboard, confirming what I saw in the sand. Anyone have similar issues or have ideas on what might be going on? If it's something really odd, I'll have my shop diagnose, but just curious if it's a known issue on these.

Even if it is something odd, I'm not too worried - the previous, older fellow who had the truck had driven it since 1992-ish and never noticed a thing.

If only the passenger side is inboard, the axle is indeed shifted to the drivers side. The last person who had the truck apart probably sighted the drivers side to be dead even and let it go. To correct it measure the axle width from wheel flange to wheel flange in the rear. Subtract that distance from the same measurement in the front and divide the result by two. That is how far the DRIVERS side must move toward the passenger side to make the track correct. You must measure this with the truck at ride height and all four wheels loaded.

[tlcrz1972]

Here is my guess, yes the front and rear axles are different widths, don't sweat that.

It sounds as if the truck is dog walking just a little bit, beings the one rear tire is in line with the front tire.

The best way to verify if it is dog-walking is to have someone drive it and you follow behind it on a straight section of road. And just use your eye looking down the body and look at the tires and how they are tracking.and then vice versa look down the edge of the tires and watch the body. If something is out of wack it'll be apparent from that view.

Now how to fix that ask someone with more experience, It could be suspension bushings, maybe the primary leafspring is bent somehow.
Maybe the locator pins in the springpacks locating the axle mounting pads are missing.

Good luck in your search.

Originally Posted by joeydurango

I did look at the backspacing. Didn't think to look at overall width, I'll check that out too! I'd love if it were a forehead-smack stupid-simple thing like that.

I was curious if it's possible for the leaf springs to be offset to one side somehow. I don't see how - they both appear to be perpendicular to the ground and parallel to one another, and mounted correctly - but someone mentioned that as a possibility, so I was throwing this out there to see if anyone else had the same issue.

[joeydurango]

Sure, that all makes sense. I figured it was off to the driver's side, and I have driven behind the truck on straight highway and although slight, it is visible. But I'm not positive what is causing it - wheel differences could accentuate the problem, but since the rear axle is shorter than the front and the driver's side all lines up, it's gotta be off regardless of wheels alone. It's just tricky since the frame/body appear to be totally fine.

Can the leaf placement on the rear axle be moved laterally? Possibly as simple as moving the U-brackets a bit to the drivers side? Or are those spring perches welded to the axle?

Thanks for the info everyone, and for helping out a forum newbie!

[hamjet]

Also make sure the spring center bolt is directly over the center of the axle, sometimes its possible for the center bolt to shear off in the axle spring pad if the u-bolts were a little loose or abuse. I worked at a spring shop many years ago and any dogtracking could be that, broken main leaf, etc. also while your'e under there, measure from the front hanger eye to the axle on both sides. you never know..

[Kennuck]

Originally Posted by tlcrz1972

Maybe the locator pins in the springpacks locating the axle mounting pads are missing.

I used to work for the company that made these springs back in the day. I can tell you this is not unusual. The center bolt location does determine the track of the truck. When these springs were made the tolerance wasn't that tight and the distance from the spring main eye to the centerbolt can vary from spring to spring. It could be a missing or sheared off locating head on the centerbolt or simply manufacturing variation. If it bothers you, you could check the centerbolt distance and if they are different get a pair of matched springs.

[hamjet]

"Sighting down either side, the front tires sit equally (lateral position) in the fender wells. The rear tires do not - the passenger side is inboard" Sorry, I missed this part...

[joeydurango]

Originally Posted by Kennuck

I used to work for the company that made these springs back in the day. I can tell you this is not unusual. The center bolt location does determine the track of the truck. When these springs were made the tolerance wasn't that tight and the distance from the spring main eye to the centerbolt can vary from spring to spring. It could be a missing or sheared off locating head on the centerbolt or simply manufacturing variation. If it bothers you, you could check the centerbolt distance and if they are different get a pair of matched springs.

That's super helpful. Thanks! It doesn't particularly bother me so long as nothing's broken. If it is manufacturing variation, nothing's broken, and it drives straight, is there any reason to worry about it?

[Kennuck]

If it is just manufacturing variation I wouldn't be concerned about it. However I would have a good at the springs to make sure there are not any broken leafs, loose U bolts etc. just to be on the safe side.

[burnin oil]

Could be the bolt that holts the springs together has been changed. My spring packs bolt was alot larger than what I have seen on other springs. It may just be a sloppy fit with the locator. You may be able to loosen the U bolts and get it closer. FYI, I have never seen an old 4x4 that the frame was not tweaked on somewhere. Usually at the steering box or the mid point. Not a big deal as long as it is not cracked and everything tracks well. It can make it fun to pull the crossmember or reinstall.