Bed Alignment

[Dashman]

I had the bed raised on my Dad's '72 to straighten the rear frame rails from a bad bumper strike many years ago. Before I raised it, it was crooked more to the left. First, I inserted the middle bolts, then I inserted the two front bolts.
One rear bolt is spot on, and the other is very near. Now that I lowered it and inserted bolts to secure, I have it nearly corrected.

Left Side Alignment:
Right Side Alignment:
Front Right Side Hole:
Front Left Side Hole:

I was about to ream the holes when I read someone's post here that the cab mounts can affect the bed alignment.

Front Left Cab Mount:

Is it possible to shift the cab over to the right, so that the bed will align without having to ream out the holes? Is there about 1/4" lateral play in the cab mounts? I'll have to install new radiator supports at the same time, correct? ...and shim the radiator supports so the fenders align with the doors? Do I need to loosen everything, or just the radiator mounts? Thank you!

*Edit: I measured the cab to frame, Left side: 17-1/4". Right Side: 16-3/4"

[Sheepdip]

Just looking at the pic's I would definitely replace cab and core mounts first then work it all out together.

[Casper42]

it's my understanding from body shop persons, some in this group, that there is play in the cab to be shifted as needed - I just can't say how much. 1/4" seems like it would be about the max. I would suggest loosening all six mounts, but while you're at it, just replace all those rubber mounts. You'll appreciate it afterwards and it will ride better for sure. Just keep in mind, 50+ years ago the manufactures probably used a "five or ten foot rule" about getting things lines up. Ones that you see today that look perfect was by chance, or someone put in work recently.

[Dashman]

I'm hoping that it shifted 1/4" left on it's own, and will go back to center. I thought I was close to starting after a complete drivetrain upgrade, but a monkey wrench got thrown into my plans. I left the bed loose, and ordered a set of rubber bushings. I already loosened all the nuts and bolts, and just have to break the welds on the bolt heads in the cab. I'm thinking I'll go back and forth with the floor jack to all (6) positions to raise it in 1/4" increments. My concern is that I'll put some sort of stress into the front fenders.

[Keith Seymore]

Originally Posted by Casper42

Just keep in mind, 50+ years ago the manufactures probably used a "five or ten foot rule" about getting things lines up. Ones that you see today that look perfect was by chance, or someone put in work recently.

We set the bed on, jiggled it to get the bolts to drop through the frame, and tightened it down.

I watched my guys do about 900,000 of 'em that way.

K

[zicc1835]

Originally Posted by Keith Seymore

We set the bed on, jiggled it to get the bolts to drop through the frame, and tightened it down.

I watched my guys do about 900,000 of 'em that way.

K

[Dashman]

It's a PIA to break the welds on the front cab bolts under sound deadening material, floor mat, and carpet. It makes it difficult not to damage the sheet metal. It's a floor liner completely off sort of event to do right. I don't know why GM didn't weld the same square hole washer that they used at the radiator support. A Dremel with a grinding wheel can do it, if you position it over the bolt head. Otherwise, at a slight angle you're missing some weld down in the corner.

I raised each point of the body and inserted 1/4" pieces of steel, and followed up for a total of 1/2" on points 1 and 2. Then I raised point 3 what it need to get the new bushing in. I didn't want to tweak the fenders in anyway.

Once I got the bushings in place on both sides, then worked on pushing the cab over on the frame. I raised one corner of the cab to reduce the friction, then I used a 2x4 and wood shims. For the rear, I used a 2x4 and shims, but also a pipe clamp setup above the frame to push the wood block. It was pivoting in above the frame and not working like the shims in the front, so the pipe clamp pushed it over. I had to go over the 3 rows of bushings twice because the cab pivots, and changes what you previously moved. I had to use a plumb bob because the passenger side flanges at the bottom of the cab are smashed. I had 22" on the driver side after the initial move.

Stupid kit assumes all your bolts will be bad, but doesn't come with new sleeves??? Don't be like me, get the kit with bolts and sleeves. ...or at least sleeves if you know your bolts are ok, or with just the 9/16 bolts considering you have to grind the weld off them.

I had to push the bed back to the right to match the new position of the cab, and I could hear the bolts drop in. I may have 1/16" that I can get from the cab when my sleeves arrive and I'm ready to bolt it down. The front fender is also lining up perfect. The buck 80 me could shove that over manually, hahaha. Where my passenger door could close with a finger swing, it's now jacked up, and my hood really needs adjustment.

[Casper42]

My Atlanta built '72 didn't have the spot welds on those front cab bolts. Not sure why any were done that way as it was an easy peezy one-person job. BTW, if you haven't already, you might need additional washers to get your body to line up nicely, as it sounds like you might still be waiting on those crush sleeves. I had to add two washers on my rear cab.

[Dashman]

I didn't find just a sleeve kit, so I opted to cut my own from stock. I used (2) 1 x 5 x 0.120" for the rear cab, (2) 7/8 x 2.25 x 0.095" for the front cab, and (2) 3/4 x 1.75 x 0.083" for the radiator support/front fender. These dimensions are applicable to C/20, C30, and K series trucks. I sprayed them with a primer before installing.

I was about to install and move on, when I noticed that the left frame rail was more rearward than the right making the right rail more forward at the front as evidenced by the bumper to grill distance.

[Dashman]

I guess I was gluten for more punishment for my transgressions against this truck as a teenager (hahaha) that I sought to pull the left frame rail. The previous photo with the 1/4" steel piece doesn't show it, but the difference was 5/16". The truck is on jack stands in the front, and I didn't want to wait to drive it to a frame shop. Sorry, I don't have during and after photos, but I'll briefly describe my process. I loosened all the cross member bolts. I set up a gooseneck flat bed with the kingpin against the right front rail, and then used a chain screw tensioning binder to pull the left frame rail. During the process I could see that the bolts were holding back the displacement, so I removed the bolts on the left side. I got the left rail to square in the back, but it looked like it was more forward than the right in the front. I think it was the truck's weight on the front springs that caused the left rail to shift backwards again. It stayed with 1/8" difference in the frame rails at the rear. However, the front rails really matched up well.

The next morning I noticed that now it was the cab that was out of square as though the cab was forward on the right rail. I measured a 1" gap between the cab and bed on the left, but it was 1-1/4" on the right. I set up a vise grip, ratchet strap, and floor jack to pull the cab backwards. I used a 4x6 to spread the load on the floor support Z channel, and clamped the vise grips on the same channel. During the process I could step on the strap and it would move the cab. The front just got pulled along for the ride. No fenders were harmed during this process, hahaha. I settled on a cab to bed clearance of 15/16" on both sides as shown in the attached photo even though it's deceiving.

After that I went to work on reinstalling the bolts into the rear cross member. It's tweaked, so I used a pipe clamp to pull and push it to get the holes lined up. If there's a procedure, it should be the upper bolts first, just sayin'. I'll get the engine cross member bolts soon.