Stumped on stance

[71CHEVYSHORTBED402]

Today I tightened up my cab mounts for permanent. This is the first I measured from the floor and ceiling to the cab in places, such as the rocker, bolt holes and gutter, and the LH cab sits about a 1/2" lower than the RH side. I checked the floor, it's mostly level. All hardware and torque settings match side to side.

To add to the mystery, a level on the cab side to side is good, everything is spot on or ever so much leaning to the LH side.

And to add more to the mystery, the bed is level, but I had to shim its front LH corner 1/8th" to match the cab body line, while the RH front corner was raised just a 1/16th. The opposite a guy would expect, because the RH cab sits higher.

Has anyone noticed anything like that before? I know GMs stuff wasn't perfect, but 1/2" off yet mostly level, what the?

[pjmoreland]

Based on your two photos of the level on the cab, it looks to me like the bubbles are floating toward the LH side, indicating the RH side is lower. That would agree with your measurements. Am I seeing that correctly? The bubble on that short of a level wouldn't have to be off that far to indicate 1/2" way over at the side of the cab.

[71CHEVYSHORTBED402]

Originally Posted by pjmoreland

Based on your two photos of the level on the cab, it looks to me like the bubbles are floating toward the LH side, indicating the RH side is lower. That would agree with your measurements. Am I seeing that correctly? The bubble on that short of a level wouldn't have to be off that far to indicate 1/2" way over at the side of the cab.

The LH side is actually lower.

Yet........I had to raise the LH bed more to match the cab, yikes In other terms, imagine if I raised the LH side of the cab only to raise the bed even further.

I don't get it.

If you were to take a 6-7 foot straight edge for instance, and dropped one end 1/2", then a level would show way off. Yet this shows mostly level........Hmm!

[pjmoreland]

Originally Posted by 71CHEVYSHORTBED402

The LH side is actually lower.

Yet........I had to raise the LH bed more to match the cab, yikes

This is confusing

[pjmoreland]

Are the door opening heights (top of rocker to underside of gutter) the same on left and right?

[71CHEVYSHORTBED402]

Originally Posted by pjmoreland

This is confusing

Welcome to my world. It's like a table with legs of unequal lengths but the table is level

Yes, rockers to gutter is the same on both sides.

[pjmoreland]

Is the distance from the frame rail to the garage floor under the cab the same on both sides?

[71CHEVYSHORTBED402]

Originally Posted by pjmoreland

Is the distance from the frame rail to the garage floor under the cab the same on both sides?

When it warms up I'm going to check the tires and measure all the rails & mounts. Either way I'm stuck with it, imagine raising one side, then the bed has to be lifted another 1/2" and everything is off kilter. 1/2", I'd expect to have seen a problem already.

At the end of the day it's level. Only thing off more than I'd like is the LH rocker which is a 16th or so high in front. All considered, it's probably going to be easier to close the door I installed the old 1/8ish shims in front, though I may replace the LH side with shorter one.

I don't want to raise the LH rear cab anymore, the front LH bed is already shimmed 1/8". Very odd right, the RH cab sits higher yet the RH bed was only 1/16" too low.

[pjmoreland]

Having the line on the back of the cab lining up with the bed, and the bed lining up with the bumper will be the most important, in my opinion, since that's what you'll notice when looking at it. Hopefully the 1/2" discrepancy doesn't cause issues with the front clip and front bumper.

When I first bought my truck, the two sides were different heights by over an inch. It was very easy to see. Turns out one of the lower control arms was bent and binding, causing the suspension to ride at uneven heights. it looked like the control arm had been smashed into something at some point. I replaced that control arm and rebuilt the suspension, and now it's nice and even.

[Palf70Step]

As mentioned check the frame for being side to side level. Also, is it new springs at all 4 corners? If not it may be one spring is weaker/sagging more than the other. I have had to shim cabs in the past on one side to get them level, so that is not uncommon. But, before you do try and isolate what is causing the unevenness. My guess is a suspension issue.

[HO455]

It may be time to check the frame for a twist or bent rail one one end. My Burban has a bend in the right rear frame rail. I ended up having to shim the two right rear body mounts to get things to sit properly.

[71CHEVYSHORTBED402]

Here are my measurements, figure they're within say 1/10" plus/minus - ish:

Cold floor to frame rail directly under front cab mount: RH 11.8", LH 11.7"

Here you go, floor to front cab mount: RH 15.6, LH 15.1"

Front cab mount shims to top of upper cushion 1.25" each

Cab floor to cab rail above front mount: 1.9" each.

Here you go again, floor to rear cab mount: RH 18.1, LH 17.6"

So yeah, the cab mounts differ, higher on the RH side by approx. 1/2", yet somehow the cab and bed are level. How's that possible, couldn't tell you. 28 years after I bought the truck forensics says it was t-boned on the RH side.....Whooops. But we only had to deal with the door to the tune of 5 hours labor a piece. I know the RH cab rail had some work, but it's right, and the rocker was replaced. Other than that nothing remarkable to note. All new suspension.

GM didn't rivet these perfect. My leaf spring hangers can attest to it. The RH front cab mount is riveted higher than the LH side, but not by a goliath 1/2". Think I'll roll up the C20 onto the driveway, see if it's off too, though the suspension is old. Edit: Well that's discouraging, C20 is equal on all sides, I restored the wrong truck

STUMPED on stance. Mounts 1/2" higher yet the cabs level, hmm. You'd think the frame rails were bent, but they're the same height on both sides.

[pjmoreland]

The top of the "A" pillar on my truck sits about 1/4" lower than the rest of the gutter/upper door opening. They smooshed the gutter to make it sort of line up. This poorly positioned pillar makes the distance from the gutter to the rocker panel (my rockers are original) too small at the front for the door to fit in there correctly. I had to install my door lower in the front than I wanted to, so it was a compromise between keeping the window frame from hitting the gutter and having the cab body lines inline with the door body lines at the rear. Most people probably wouldn't notice, but I do. I contemplated shaving down the top of the door a bit to make it fit better, but I couldn't bring myself to do that. Anyway, my impression is that these cabs don't seem to have been put together with a high level of precision.

I wonder if GM ever set certain poorly fitting components aside until a compensating mating component came along. If they did, then maybe they matched your chassis and cab together in a way that resulted in a level cab. This is 100% conjecture on my part.

There are a couple of rivets on my truck that are smashed sideways and spilling out of the hole. They seem to be functionally sound at least.

[71CHEVYSHORTBED402]

Originally Posted by pjmoreland

The top of the "A" pillar on my truck sits about 1/4" lower than the rest of the gutter/upper door opening. They smooshed the gutter to make it sort of line up. This poorly positioned pillar makes the distance from the gutter to the rocker panel (my rockers are original) too small at the front for the door to fit in there correctly. I had to install my door lower in the front than I wanted to, so it was a compromise between keeping the window frame from hitting the gutter and having the cab body lines inline with the door body lines at the rear. Most people probably wouldn't notice, but I do. I contemplated shaving down the top of the door a bit to make it fit better, but I couldn't bring myself to do that. Anyway, my impression is that these cabs don't seem to have been put together with a high level of precision.

I wonder if GM ever set certain poorly fitting components aside until a compensating mating component came along. If they did, then maybe they matched your chassis and cab together in a way that resulted in a level cab. This is 100% conjecture on my part.

There are a couple of rivets on my truck that are smashed sideways and spilling out of the hole. They seem to be functionally sound at least.

Seems possible. I wonder if it was jacked up when it was t-boned though. Still doesn't explain why the cab's level without lifting anything, I seriously doubt they went into that kind of detail with the "Maco" paint job & cheap body work, though they did a nice job with the rocker.

[Grumpy old man]

I think you've officially lost your mind measuring to the 1/10 of an inch You should probably tear it all apart and have it zeroed on a frame machine .

The men in the white coats should be on alert , What's going to happen when you fill it with gas and sit in the drivers seat ? everything's going to change ? I'd pay your neighbor a $100.00 to walk over and ask if it's crooked and send me the video of your response .

[71CHEVYSHORTBED402]

Originally Posted by Grumpy old man

I think you've officially lost your mind measuring to the 1/10 of an inch You should probably tear it all apart and have it zeroed on a frame machine .

The men in the white coats should be on alert , What's going to happen when you fill it with gas and sit in the drivers seat ? everything's going to change ? I'd pay your neighbor a $100.00 to walk over and ask if it's crooked and send me the video of your response .

Sadly true

[HO455]

Originally Posted by 71CHEVYSHORTBED402

Think I'll roll up the C20 onto the driveway, see if it's off too, though the suspension is old. Edit: Well that's discouraging, C20 is equal on all sides, I restored the wrong truck

My Burban has a similar misaligned panel issue that pjmoreland talked about. On the drivers side where the roof meets the drip rail and the windshield frame the pieces are poorly fit together. The most noticeable result is the drip channel is almost flush with the top of the drip rail. The not so noticeable items was the top of the windshield frame was more than 1/8" proud of the A pillar it was supposed to be flush with. As part of these misaligned pieces the door frame hits the A pillar if the body lines are properly lined up.

My assumption about the assembly of truck cabs is that they had some jigs that held key components together (Like the windshield frame or door frames.) and all the rest of the pieces were massaged into place and welded together as quickly as possible.

[71CHEVYSHORTBED402]

Here are the body alignment issues after a half a day's work on just that door. Mostly the pillar was bent in. Two of us, I was there for moral support We're going to try and drop the door and fender by two hairs & one respectively.

[toolboxchev]

Here is some information you may not like. Had my C20 appraised after a rear end accident. One side of the rear is now almost 3/4 of an inch off.

Inspector gave me some line of BS about how they could be as much as 1/2 off from the factory. One could not really notice it going down the road.

How perfect do you want, and how much time, effort and money would it take to get to the desired point. Looking at your past posts you have done a dam good job on everything I have seen.

One other thing is how much tooling do you have access to as Grumpy has mentioned.

[71CHEVYSHORTBED402]

Originally Posted by toolboxchev

Here is some information you may not like. Had my C20 appraised after a rear end accident. One side of the rear is now almost 3/4 of an inch off.

Inspector gave me some line of BS about how they could be as much as 1/2 off from the factory. One could not really notice it going down the road.

How perfect do you want, and how much time, effort and money would it take to get to the desired point. Looking at your past posts you have done a dam good job on everything I have seen.

One other thing is how much tooling do you have access to as Grumpy has mentioned.

I'm doing exactly nothing about it The cab and bed are level. I suspect the difference is in the floor board. Like I mentioned before, the rails matched and the cab (corrected) rails on the mounts as well. Have to make up the difference somehow, that leaves the floor and yep leans left, while everything above it is level Equal hardware and torque. So unless I'm wrong, probably am, the floor is off. Had to be factory IMO, since after all, the cab mount surfaces are unequal with factory rivets, and the frame rails are equal.

Thanks for the props, I really try but often frustrating, especially this end. I want to get her done already.