Front and rear wheels not inline?

[Konnor S]

Recently bought a 72 620 that I’ve been messing with, it has a pretty bad alignment issue where if you let go of the wheel it pulls sharply to the right. While I was adjusting the steering box this morning I noticed that the front wheels were offset differently compared to the fenders. The front right wheel sticks out around half an inch past the fender line while the front left wheel is about an inch inside the fender line. I also checked the rear and it’s the same thing but opposite. (Rear left sticks out to fender line and rear right is inside fender line) I should just need to move the rear axle over to fix the rear issue, but how would I fix the front offset problem? Maybe that would help with the alignment issue as well.

[Bleach]

Is there any slop in your steering? If you feel there is a loose or 'dead' spot while steering then that is normally a worn out idler arm.

Installing a new idler arm is the first step to getting good steering and alignment up front.

 

Your older version of the 620 has kingpin suspension up front. Those can wear out and cause the hub to rest inward at an angle which adds negative camber. I suppose that could be what you are observing on the wheel to fender position.

 

I would suggest you inspect every bushing up front and try to determine if the kingpins are in good condition or not. Replace what you can based on availability and cost. Tie rod ends are also part of that inspection. Once complete, I would also look at the rear springs for any slop. I've never replaced bushings in the back so I'm not sure if they exist.

 

If you've done everything as well as you can, set the front ride height to what you want using the torsion bar adjustment. Then take it in to get an alignment. They'll only be able to adjust the front toe but that will help.

 

Another item to look at is wheel offset. Maybe pull all four wheels off and do some measurements. Perhaps two wheel have a different offset than the other two. If so, install the two wheels that set further out on the rear axle.

[datzenmike]

Adjusting the box may only remove a little play in the steering wheel. 

 

You will need to look at all the ball joints in the steering and replace if needed an don't forget to check the play in the idler arm! Set ride height to stock and get the king pins in order or an alignment is a waste of time.

 

Must have miss matched rims.

 

Get aligned. The shop will tell you if the frame is bent or rusted out. If everything checks out and still front right/rear left is sticking out oval the holes on the frame and move the cab and box. 

[Crashtd420]

18 hours ago, Konnor S said:

Recently bought a 72 620 that I’ve been messing with, it has a pretty bad alignment issue where if you let go of the wheel it pulls sharply to the right. While I was adjusting the steering box this morning I noticed that the front wheels were offset differently compared to the fenders. The front right wheel sticks out around half an inch past the fender line while the front left wheel is about an inch inside the fender line. I also checked the rear and it’s the same thing but opposite. (Rear left sticks out to fender line and rear right is inside fender line) I should just need to move the rear axle over to fix the rear issue, but how would I fix the front offset problem? Maybe that would help with the alignment issue as well.

 

Start with something easy... take all 4 wheels off and check back spacing...

My guess is you have 2 rims with one back spacing and 2 that are another....

Put the narrower matched set up front and the wider in the rear....

 

You could even do a quick alignment check with a tape measure.... there are methods out there... just need to look.... might not be perfect but it will tell you if it's close or far out....

 

You could also take some comparisons measurements from the frame to the body from one side to the other to see if the cab and box is centered on the frame.....

 

You could even measure from the centerline of the wheels to a spot on the frame...

 

I'm thinking you should stumble on something pretty obvious.... 1/2 inch from one side to the other should jump out at you when you find the reason..

[datzenmike]

Occam's razor or the Law of Parsimony. Simplest answer is likely correct. Look at the rims. Tires may also be miss matched with two being wider.

[Stoffregen Motorsports]

One possibility is that the rear axle is out of alignment. It could have been in an accident and a leaf spring got bent. Or a leaf spring mounting bracket got bent. Or the u-bolts could be loose. There's also the possibility that this 40 year old truck has been hacked on by previous owners. Mixing-matching parts or just hack repairs.

 

I suspect the wheels are not all the same. Check that first.

 

Also have a look at the body and bed mounting bolts, bushings and frame brackets. If any of those bolts were ever removed, it could be that the body shifted on the mounting points.

 

Do you have a pic of the truck?

[victhewhimpykid]

Like others have stated, start by checking the wheel width and back spacing making sure all are the same specs. You can also measure the hub face distance to the frame and see if those are off. 

[EDM620]

On 6/15/2023 at 9:58 AM, Stoffregen Motorsports said:

One possibility is that the rear axle is out of alignment

Actually pretty common on lots of trucks due to overloading and general abuse. The rear axle no longer follows the front axle - it "dog tracks". A few ways to check it out. have someone drive it in a straight line and you follow behind. Can you see both wheels on one side but only the rear on the other? Wet road or dusty and look for the tracks being offset to one side only. Come to a full stop where you're travelling in a STRAIGHT line and grab your tape measure, measure from center to center front wheel to rear wheel both sides - they should match.

[datzenmike]

A parallelogram will be off set but measure the same distance front to back on both sides. 

[Stoffregen Motorsports]

We call it a crab walk here in the lower 48.

[abbylind]

Looks like a 3 legged dog runnin down the road.....