Have you been driving a crooked truck?

[Boog]

Originally Posted by Swar

This is the strangest part, the owner before me had cut the frame, but I don't know why.
This is an original swb frame, the trailing arm cross member is riveted in from factory.
Someone cut the frame and possibly added the rear end from a different truck.
I've been driving this thing for 12 years now and never had a problem, it feels straight as an arrow going down the highway.
It wasn't until I started measuring things and did the string method that I found these problems, so I guess I have some work to do.
Oh yeah, and my bed is out of square by an inch, so yes I have been driving a crooked truck.

If this is an original short wheel base frame and has been cut it just might have been done so to replace the back half due to an accident and the frame may have been bent further forward or the replacement rear half may not have been measured out properly before welding. Follow Jim's instructions on how to cross measure to make sure the frame is square.

[stsalvage]

We call that in the C30-C60 truck dog leggin it its fun to watch but very bad to have CHP pulling you over means your rear end has loosen up or you have something Broken

[iowarust]

Those are some good looking tires, care to share the brand and the white wall width??

[Steeveedee]

I don't use string. The factory service manual shows how to measure at the trammel points and gives dimensions and tolerances. Too many things may have been done in the intervening years. In your case, somebody welded it up who-knows-how, so that makes it tough.

[swamp rat]

I believe this is the post Hugger6933 is talking about..

http://67-72chevytrucks.com/vboard/s...91&postcount=9

Whole thread..

http://67-72chevytrucks.com/vboard/index.php
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[Swar]

Originally Posted by iowarust

Those are some good looking tires, care to share the brand and the white wall width??

Yea, they're used tires that I painted. 255/70R16 Thanks, I guess I did a pretty good job.

I appreciate all the input from everyone. I didn't have time to do anything last night, but I'm going to set up the string on 4 points and start X measuring the frame.
The X method is pretty simple actually, I measured the bed before all this and found it's about an inch out of square.
I might take it off to get to the frame better.

[Lmac]

Originally Posted by DBK81

I don't dare try this on my vehicle, ignorance is bliss hahaha

Roger That!!

[clemsonteg]

Any updates?

[Swar]

Yes! updates:

I measured my wheel base and it is not the same on both sides!
114 inches on the driver's side and 115 on the right.

I X measured the frame in several spots, so far the front half of the frame is good.
I set up the string on 4 points and the measurements were all matching up.
The problem lies in the rear of the truck, something is causing the rear to be crooked. Most likely the frame when they cut it.
This sketch explains what's going on. Obviously it's exaggerated to see the problem, but it explains why the string was not lining up when it was wrapped behind the rear wheels.
I'm going to take the bed off to get to everything and see what the hell is going on!

[snipescastle2]

Could your axle tubes be bent? Or mounting pads welded on crooked? These trailing arms are known for "splitting apart" wonder if the u bolts might have shifted causing it dog track?
Ben

[Swar]

I'm going to look at all of that once I get the bed out of the way.
There's a crap load of power going to the wheels, it wouldn't surprise me if something isn't holding up to it.

[67ChevyRedneck]

Twisted frame or bent trailing arm?

It looks like your arms/frame are in great condition for your location.

Removing the bed is dedication!

If it wasn't damaging tires, I'd turn up the radio and drive on!

[Swar]

Originally Posted by 67ChevyRedneck

Twisted frame or bent trailing arm?

It looks like your arms/frame are in great condition for your location.

Removing the bed is dedication!

If it wasn't damaging tires, I'd turn up the radio and drive on!

Removing the bed is the easy part. Once it's off, I'll find out.

I spray everything down with WD-40, it saved the frame's life.

I wish I didn't have to rip it apart, but that inch difference on the wb bugs me, as well as the bed that's out of square.

I'm hell bent on fixing this.

[Swar]

Update:

Taking the bed off helped a lot. I X measured the back half of the frame, it seems to be off a bit. It looks like it's tweaked to the left.
So I adjusted the track bar way out to the right and bam! Wheel base matches up on both sides and wheels line up on the string.
I was mistaken before about the track width. The front wheels are tracked slightly wider than the rear. I thought it was the other way around because the strings were not giving me an accurate reading.

Note the frame in relation to the U bolts, way off center.

[88Stanger]

good info, thanks

[Boog]

I think you are maybe confused by the terms. "Wheel base" is measured from the centerline of the front wheel to the centerline of the rear wheel.
Adjusting the track bar does nothing to affect the wheel base. It will center the rear wheels right to left behind the front wheels though. Adjusting the rear track.
Were either of those rear tires very close to the fenders before you removed the bed and made this adjustment?

[Swar]

I'm going to have to disagree with you.
The trailing arms angle into the center of the truck.
Moving the rear end side to side, as far as you can, it almost acts like a pendulum.
My wheel base was 114" on the driver's side and 115" on the right.
As I moved the rear to the right, those number became equal.
They are now both 114.5"

[Boog]

I should probably have said "little change to the wheelbase". So now your rear end is offset more to the right than left. Is that right tire going to clear the fender ok?

[kehstr]

Originally Posted by Boog

I should probably have said "little change to the wheelbase". So now your rear end is offset more to the right than left. Is that right tire going to clear the fender ok?

not only that, but also will the wheels look good inside the fenders once he puts the bed back on?

[Swar]

Well, I guess we're going to find out!

I'm going to gamble and say I might have a lot of work ahead of me.

[Boog]

We'll certainly hope not. You saved the beginning measurements in case you have to put it back, right?
What kind of motorvation is underhood?

[Swar]

Doesn't matter because all 4 wheels lining up is more important than where the frame sits on the rear end.

It's got a worked 350, cam, heads, dual quads and a 4 speed, no posi yet.

Engine and more pics here:

http://67-72chevytrucks.com/vboard/s...d.php?t=664085

[snipescastle2]

Originally Posted by snipescastle2

When I changed rear ends on Mine, I used a 12 bolt posi rear end out of a '64 C10, basically the same rear end, except the track bar was different. Which necessitated fabricating a new track bar. I had replaced the bushings in my control arms while it was apart as well. It wasn't until after I bolted on my bed that it was evident my tires were not centered in the wheel wells/ chassis.
Since I made my track bar adjustable, it was easy to center the wheels, maybe that is the problem you are having now that it's lowered?
Ben

I love it when I'm right.....just sayin'

[Swar]

What you're saying is correct, but if the frame is crooked, it's not possible to center it on the rear wheels and align them with the front.
In my case, it's one or the other.
Center the frame on the rear end and have the wheels not line up, or line up all 4 wheels and have the frame off center. I can't have both.

[cheyennesr]

hope yours a easy fix . i lined my bed up with back of cab even gap and looked at wheels in center of the wheel wheel and checked wheel base mine is shorter by 1/2 inch on the driver side . but where mine is off and why im still checking .good luck and thanks for sharing