Seam above rear window...

[Psycho_SWB]

Does anybody know why these trucks have a seam above the rear window at the back of the cab?

Has anybody filled them up before getting their trucks painted? Any flex cracks?

[Keith Seymore]

That's where the separate roof panel joins the cab back panel.

There would be a similar joint at the top of the A pillar where the panels come together except it was brazed over and filed down prior to paint.

You can see pictures of truck cabs being welded and insightful commentary over on Jeff's site: http://www.73-87.com/7387info/Assembly%20Line.htm

K

[Jonboy]

I would imagine what you filled it with would determine any flex cracking. I filled mine with 3M 8115, and welded the corners.

[moonshiner]

I filled mine in with fiberstrand and sanded it down

[esbstuff]

This has been discussed before, might look for that thread.

From experiance these seams ARE NOT welded good at the factory. I have taken 2 off (one 79 and one 87) and neither one was welded in more than a couple places... Best bet to fill would be weld and grind smooth. Or just wire brush the old seam sealer out and reapply.

I should note that the front (under windshield) piller (brazed) and sides (around the door) were welded together good. It was just the seam from door to door on the rear. I would bet that there was only 5 good spot welds on either cab. But even those only took a good wack from a chisel to remove.

[esbstuff]

I should note (and Keith can concur) the roof and back was welded together and then the inner panel (metal headliner) was put in. Keith can chime in on the order as I can't find my assembly manual right this minute... This prevents the spot welded seam from showing...it also would make roof skin replacement a pita if it was actually welded in the first place.

We installed a 79 roof skin on an 87 cab. Believe it or not, it fit quite well at least to period standards. We did no extra work to it and you can't tell it has been replaced. We ended up using the newer Panel Bond stuff on the hidden seam and touched up the seam with seam sealer as the factory did.

[Keith Seymore]

Originally Posted by esbstuff

I should note (and Keith can concur) the roof and back was welded together and then the inner panel (metal headliner) was put in. Keith can chime in on the order as I can't find my assembly manual right this minute... This prevents the spot welded seam from showing...it also would make roof skin replacement a pita if it was actually welded in the first place.

I don't recall that level of detail but your assessment makes sense.

The Flint Line 1 (pickup) cab shop was highly automated; so basically the individual panels were fed to the line and a completed cab popped out the other end. What happened in between was a little hard to follow (without getting squished).

The Line 2 cab shop (Blazer/Suburban) was much more of a manual process, with separate fixtures/gates and hand spot weld application. It was a little easier to see what was going on over there.

K

[Psycho_SWB]

Thanks for everybody's input. I guess I'll have my filled before it gets painted.

[esbstuff]

For those of you that need something to be visualized here you go...

This is from a 1984 GM parts book, the exploded diagram of the cab assembly.

#1 is the outer roof skin
#2 is the inner roof skin (headliner)
#3 is the rear panel

I still can't find my other book, but if i remember right the cab jig was removed and #3 was the last piece to be installed before the cab was complete.

I had to study this real hard because we couldn't find any body guy locally that could remember installing a roof skin on a square. If the outer skin was damaged and needed replaced, the truck would usually total so it wasn't an issue. (or replacing the outer skin totaled the truck lol)