Riddle me this.......cab question

[sdailey]

In doing some work on the cab of my '69 this weekend I noticed a bow on the back of the cab. In the pictures below you can see the rear window pinch weld bow out at least a 1/4". The top of the window opening has an ever so slight bow. Is this normal??? There is no obvious damage to this area of the cab. I've never noticed it before and I don't have another cab to compare it to.

Thoughts????

[YBNORML]

I just went out and looked at mine, it is straight as an arrow.
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[pat 70/71]

I think is is normal for our trucks or any product made by gm. It's always plus or minus 5/16 on tolerance's across the board. I would recommend blocking it as straight as you can and call it even. Don't stress on how bowed it is no one will see it but you when it's done. Cheers, Pat
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[Sammy]

No freaking way that rolled out like that. Just can't see that happening. 5/16th tolerance on panel gaps, yes. But not on a bow there. My dad had a body repair shop cut a later '75 model cab below the windshield and under the rear window from a dropped tree mashed to the seat on the cab and when he was done you couldn't tell it even if you knew it.

[64fleetside]

I've run into the same thing on a '64, with no sign of any damage at all. Monday or Friday unit, IMO.

[68gmsee]

Wouldn't that bow affect the rear windshield? Does the top of the opening match?

Seems to me a good shop could reshape that with some type of hydraulic fixture???

[sdailey]

Thanks for the replies. I've been around other bare cabs before and have never noticed this bow before, never thought to look I guess. My cab is currently sitting on a dolly high enough for this area to catch my eye. The top pinch weld is nearly straight, but not perfect. There is no obvious damage inside the cab or on the back panel.

Here's a shot of the back panel.

[pat 70/71]

We all need to remember our trucks were built to be trucks ( tractors with doors) like it or not they were put together as fast as possible. From one stamping plant to another it would be common for the dies to just plan wear out of the initial tolerance. I have owned my fair share of these trucks and have never seen the top of a door to cab reveal even close to correct on a stock truck. My dads truck, bought new, loaded70 3/4 ton had a cab with a bow across the belt line area of1/4" inward . (Never been hit) cheers, Pat
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[PanelDeland]

Another possibility is that after 40 years the window has been replaced and the bend was done then.It probably isn't out enough to notice when the window and seal are in place.

[68gmsee]

Originally Posted by pat 70/71

We all need to remember our trucks were built to be trucks ( tractors with doors) like it or not they were put together as fast as possible. From one stamping plant to another it would be common for the dies to just plan wear out of the initial tolerance. I have owned my fair share of these trucks and have never seen the top of a door to cab reveal even close to correct on a stock truck. My dads truck, bought new, loaded70 3/4 ton had a cab with a bow across the belt line area of1/4" inward . (Never been hit) cheers, Pat
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Granted that's true, but the gap on his truck looks to be more than 1/4"-maybe 1/2" or more. The concern would be the stress put on the rear window glass. If the top is pretty close to straight, I would think a fixture of some sort could press this back to being fairly straight. At least that would be my guess.

[68gmsee]

Originally Posted by PanelDeland

Another possibility is that after 40 years the window has been replaced and the bend was done then.It probably isn't out enough to notice when the window and seal are in place.

This is probably a good explanation. Sometome ago I was watching a window repair guy replacing a windshield on a truck. He was sitting on the seat and with his feet pushing and kicking the windshield out from the inside. Maybe they did the same on this one??

[Vintage Windmills]

Curious how common this is. I will try to check some of the cabs here.

[sdailey]

Some interesting opinions here.

The cab actually had glass installed when I brought it home.

[68gmsee]

I like that cab. Sure wish I could find one over here in good condition.

I curious also if other trucks are bowed so checked my 68 and it's straight. I will check my 69 later in the week since it's not here.

btw: since you mention the truck had glass already and you didn't bow it by removing it, then it may have been done sometime ago. After 44 years who knows.

[Wookiee]

I know in my truck I drive with the seat all the way back and it contacts the cab here. Get a big enough guy in the middle wearing his seatbelt in an accident and I could see where this could happen without breaking the window. I have a hard time believing this damage was done while replacing the rear window. The rear comes out a whole lot easier than the front. When they are broken the glass is in a million tiny pieces and the rubber comes right out and installation is pulling in.My vote is for the seat pushing below the pinch weld.

[sdailey]

Like some of you, I don't think this was done by replacing the window. I removed the glass from the cab myself back before I had it blasted. I cut the weatherstripping on the back glass and it popped right out with no issues. My blaster does cabs and tons of other car parts, so I don't think he would've damaged it in any way, just because he's been around for a while doing this kind of work.

I can't help but wonder though if I would cause any damage, like a crease, if I tried to straighten it. It doesn't have to move much though.


BTW: 68gmsee, I bought this cab and doors for $200 5 miles from my house.

[68gmsee]

Originally Posted by sdailey

....BTW: 68gmsee, I bought this cab and doors for $200 5 miles from my house.

Unbelivable! I've been looking and waiting for about a year. All the ones I've seen are either rusted out or cut up. May have to bite the bullet and buy a whole truck and sell what I don't use.

Re. reason for bowed cab: We're just throwing out possibilities. I removed the rear windshield on my 69 last year by cutting around the rubber seal. A previous glass installer had used silicone sealer some 15 years ago so it was somewhat stuck but I did removed it without doing any damage to the cab.

As I mentioned before, the biggest concern would be the new glass. I know the seal is somewhat forgiving but you may also get some wind noise with all the windows closed if there was a slight gap.

[sdailey]

I'll probably go ahead and try to straighten it. It just puzzled me when I first saw it.

Thanks for the comments everyone.