The Stovebolt Site Forums The Shop Area Paint and Body Shop Leveling a frame?

Ok, I was hesitant to ask this question but can’t find it in the factory manual. I am wanting to level my frame (1950 1/2 ton) on jack stands but what portions of the frame are on the same plane and should equally distant to the ground?
The only section that appears along the same plane to me is the frame under the cab but I’m not certain. Any information is greatly appreciated.

Thanks,
Eric

Eric,

On my '51-3100 I use the frame area just behind the cab as a reference point for front to back and the cross member just behind the cab as a reference point for side to side. It has worked well for me.

Coarseness,
For the front do you also just use a few inches in front of the cab as well?

The frame should be straight from right near the front brake line mounts on either side back to the front hanger for the rear springs. Whether it's level will depend on the springs and wheels on a completed truck.

"Leveling the frame" on jack stands is a little tricky and more work than is seems. I am assuming the body and suspension is still attached.
If a long level shows the same bubble on the floor as the bubble on the frame, while truck is sitting on it's tires, you could assume the frame is level and suspension is equally sagging. Tires have same pressure. That may not happen. That would be a macro measurement. You seem to want a micro measurement.

What is your goal? Are you getting ready to do a modification? What is the purpose of "leveling the frame" on jack stands? If you just wanted to know if the truck was level'ish, that's easier. It was never dead nuts level when new. Give us a little more info/what's on your mind, then we can go hog wild.

Some of the comments seem to be more like parallel or racking checks, not setting a frame level on jack stands.

Also, the suspension would be out of the equation for leveling the frame on jack stands.

The wheels and suspension are on but only the cab is in place. I’m wanting to level to the frame so I can fit check the doors then proceed to replace parts of the floor, inner and outer cowls.
Tonight I placed the rear on jacks then brought the front up so the frame in front of the cab was level with the rear. Actually the same distance from the ground. I also checked the frame about six inches behind the cab and all three were about the same height when checked from the ground to the top of the frame. Ugh, Now I realize I don’t know how level my garage floor is, doh!!
I should be able to take a long straight edge and check the floor for level and compensate for any difference shouldn’t I?

Thanks for the feedback!

"Fit check the doors? Why not leave the truck on the tires and get the doors to fit. Then cross brace the cab so there is no movement when patches are welded in. The truck will be sitting on the tires when you drive it. You could introduce some kind of twist up on jack stands due to cab mount rubber and frame twist/sag/suspension stance. Then when you let it down on the suspension, all goes south.
Wait awhile for MNSmith, 52Carl (they are both real nosey on here) and there are other experts to advise now that we know what you are doing. Better wait. What you are doing has been done many, many times by members.

Bartamos,
The doors have been off for sometime and the cab has been on and off several times. My thinking was to level the frame and get the front and rear cab mounts installed then fit the doors. I have seen where some people don’t necessarily brace but install the door several times as fit checks to make sure nothing has moved and they have no bracing in the way.
Either way I need to get my doors back on to check fit before proceeding with repairs.
Thanks for the input and I look forward to hearing from the others as well.

Bracing depends and how much/what size floor is replaced and if the floor supports are cut. Kevin H. was just doing cowls so he knows about them. See this. These are the guys I was mentioning.
Put the cab on the frame with new mounts and then do your thing.

Whenever I do frame work, I never consider the floor. I either make a level surface or level the frame by bubble. Most of the time, that includes setting jack stands at the same height, then shimming between the frame and the jack stand where necessary. Way back when, I put the Suburban on jack stands. My current project, the Model A, is on a level frame building jig. Which actually works out better as you don't having to worry about kicking jack stands around or knocking shims off, even though they are taped in place.

If you are only concerned with how the cab and frame will end up with a proper fit to each other so that you can make accurate repairs to the cab, you do not need to do any level checks to the frame. If the frame had ever been in a collision hard enough to upset where the cab mounts up, you would know it right away.

I agree with Bartamos, Carl and Mark.

As long as the frame isn't' twisted or severely bent, it's the reference for the cab floor. I'm doing my repairs off the frame. The door frames were still intact when I took them off (rockers, etc. still connected, so I put bracing on them before removing the rockers to maintain the door fit. I put the cab on a rotisserie so I didn't have to do the work laying on my back. Here is how I did that. The rotisserie provides some door frame bracing as well.

Making sure the doors fit correctly is the first step, then bracing so that alignment isn't affected, whether on the frame or off.

Good luck with your repairs.

I have managed to level the frame using shims and jack stands to about a tolerance of 1/8” ish. I have installed the front mounts and they are slightly thicker than spec but I figure the new rubber spacer will give and get there eventually. The rear cab shackles on the other hand are not working out.
Prior to installing the shackles I had wood between the rear support and frame and the back panel looked nice and even from behind the cab. After installing the rear shackles the passenger side sits about a 1/4 inch higher than the drivers side . I removed all shims between the shackle and floor on the drivers side and it was still uneven. I even moved them all to the drivers side which is about 1/4 inch thick and it was much closer the cab was now off center.
I released the upper fasteners that go from the shackle to the floor, lifted the cab, re-centered it and installed the blocks again. The blocks give it the correct gap based on what’s in the factory manual. I noticed that the driver side of the cab place there is a lot of weight on the block where as the passenger side is relatively light and easier to lift.

I then tried to line up the holes between the shackle and floor and noticed the driver’s side shackle holes were slightly out board of the cab holes. So if the cab was raised more they should line up. On the passenger side the shackle holes are about 3/8” out board of the cab holes and in order to line them up the cab must be significantly raised on this side which in turn also seems to push the cab over to the driver’s side.
I did look closely at both shackles and they are identical except one is left and the other right.

Sorry for the lengthy explanation I tried to get out all the details.
Any assistance is appreciated.

Thank you!

Thanks 52Carl,
That is good to hear. I seem to be having an issue with my rear mounts and have posted the the problem above. Would you mind giving it a read and let me know what you think?

Eric