Cab Roof Replacement
 

I'm helping a friend out with rust repair on his cab. Started out with the usual problem areas. Rockers, lower kick panels, bottom of the kick panel vents from leaves and rodent nests, small floor patches, etc. The cab had a spot light through the middle of the roof. The cab had been sitting outside for several years and it leaked. So the middle of the inner roof panel was rusted. Then we found pinholes above both doors. There was also damage to the drip rails and outer edge of the roof where the cab was lifted using a strap that rolled up the drip rail and dented the outer roof.

Neither of us have attempted a roof replacement before but he decided to spend another $500 on new roof panels and we gave it a shot. Removing the old panels wasn't that hard, just a lot of spot weld drilling.

When we got the outer skin removed, mouse nests fell out of both sides above the doors. Most of the damage to this cab was caused by sitting outside. Nice and moisture. This was a nice rust free cab before that.

Re: Cab Roof Replacement
 

I'm using 3M panel adhesive to secure the new parts. The cab is mounted on a dolly. The frame around the doors and windshield are pretty stout so we didn't feel the need to add more support. We ground down all of the spot weld areas and cleaned up the surface rust, especially on the areas where the adhesive will go. We pre-fit the inner roof panel first and it looked like a really good fit.

This is where we made a mistake but didn't realize it until later.

Having no experience doing this and finding nothing online or on the forum we figured that the inner panel had to go in first because it's the only way to get it in over the top of the A pillars and the rear inner cab panel. Then put the outer skin on. Attaching the inner roof panel was easy enough. We used a few self tapping screws in the rear pinch weld area and clamped the front and sides to the inner structure. Everything looked great.

But then getting the rear pinch weld together for the outer skin is difficult. I managed to get it together pretty well but it could have been better if we changed up our plan.

What we should have done is also remove the rear inner panel around the rear window. I believe that's how it was done at the factory. If you take that out, then you can put the outer roof skin on first and be able to clamp or weld that rear seam. Then you weld or glue the inner roof panel to the inner rear window panel together. Get that done then install those into the cab as a single piece.

But we didn't do that so getting the rear seam aligned and tight was a little more difficult. Learn from our mistake!

Re: Cab Roof Replacement
 

Thanks for sharing:metal:

I really like your signature:lol::chevy:

Re: Cab Roof Replacement
 

Once the inner roof panel was set up we put the sound deadener in. We used fatmat. Then the outer skin could go on. The fit wasn't bad but needed a little more tweaking. This would have been easier if we had done it in the order described in the previous post. Oh well, live and learn, make the best of it.

I had to do it in 2 steps. First glued the rear seam. Then after that set up I glued and clamped the front and sides.

Re: Cab Roof Replacement
 

Last step was doing the drip rails. Probably the easiest part of the job. BTW, removing the old drip rails was probably the worst part of the job. They had spot welds about every inch! Lots of drilling.

The new ones fit up nice. Clean everything up, mix up the adhesive and clamp in place!

Using adhesive has a lot of benefits. It completely seals the joints and keeps moisture out so it won't rust after. It's very strong and if you use the right one you have plenty of time to move and adjust the pieces. It's how the manufacturers are building them now and how most body shops do things. If a seam splits you can still drill a small hole and plug weld. And in some areas I use adhesive and plug welds together.

Re: Cab Roof Replacement
 

This thread was just to share our experience doing an uncommon job that really wasn't that difficult to do. The new panels weren't cheap, I think $500 for the roof skins and another $50 or so for the drip rails. The adhesive is about $45-50 a pack and I used more than one pack for the roof replacement. You need a special tool to use the adhesive that cost about another $50-60. I bought mine several years ago when I did the restoration on my 71. Mine is for the SEM version of adhesive but also works with the 3M stuff. But the 3M tool won't work on the SEM adhesive. They have different diameter tubes.

As I said, we didn't have prior experience doing this and maybe we made mistakes. If any pros want to comment, criticize or just share pro tips that would help everyone. If you need to do this and you have any experience with rust repair, you can handle it.

Oh, you will need a TON of vise grips. The kind for this type of work. You can see what I used in the pics. And we used every single one we could get our hands on. I filled a 5 gallon pail with vise grips.

Re: Cab Roof Replacement
 

Very nice work!

Re: Cab Roof Replacement
 

Good tips- thanks for sharing! Looks really good

Re: Cab Roof Replacement
 

Where did you find good drip rails? All of the comments say they such and most venders don't carry them.

Re: Cab Roof Replacement
 

Thanks for sharing the info HG.

Re: Cab Roof Replacement
 

Bowtie truck stop is local to me. Call Kevin gramentz at 507-723-2843. His prices are comparable to anyone's and he always tries to get the best version of the parts. Doesn't want to sell light weight, low quality, poor fitting parts. And he is pretty well stocked.

Re: Cab Roof Replacement
 

Man that's a bunch of work. Looks good. We were thinking about cutting the top of a donor cab, and if the A pillars were also rusty that's probably what we would have done. But he didn't really have a good roof on any of his parts trucks.

Re: Cab Roof Replacement
 

Nice work.
I have a roof already cut off and ready to go if you need to do another one...

Re: Cab Roof Replacement
 

Outstanding work! And I thought I had a rusty cab...

You are indeed a gifted craftsman. I'll certainly be following this build. Thanks for sharing!

Re: Cab Roof Replacement
 

INCREDIBLE.

Subscribed and bookmarked if I ever get the courage to take this on for my GMC.

Thank you!

Re: Cab Roof Replacement
 

Nice work on the roof. Been there and done that it is a boat load of work and takes some time and patience to do it right.
Really like the approach and craftsmanship. Again nice work!

Re: Cab Roof Replacement
 

Thanks for the drip rail info.

Re: Cab Roof Replacement
 

Sure, NOW brothers puts out a video on doing a roof. Oh well, their tutorial isn't quite the same situation we had and they welded rather than using adhesive. I think they HAD to weld the rear seam because they didn't do the full inner roof panel so there isn't access to the inside with that in place, so the rear cab seam gets welded closed. We discussed it and decided to stick with the original look rather than weld it and smooth it out.

There was also a patch panel someone made a while back, not sure if it's still available, but it basically removed the rear seam and replaced it with a radiused piece for a smoother look.

https://www.youtube.com/watch?v=S_0ImjRL6jI

Re: Cab Roof Replacement
 

Very nice work! I have a cab I have to do a complete roof on as well. The inners down the b pillar are rotted too unfortunately so I will be cutting the pillars and doing it that way.

Re: Cab Roof Replacement
 

Dang. I wish I had friends like you!! Well done:c2:

Re: Cab Roof Replacement
 

I get most of my parts from bowtie truck stop. Kevin and Lisa are great people and have always done right by me. Whenever I go up there on a parts run, I plan on an extra 45 minutes of talking to them.

What are you planning on using for drip rail sealer? I used some stuff from 3M and have found it peeling out. I think it's because I was lazy and didn't remove the factory ecoat from the new roof panel and the sealer didn't stick to it. I need to clean out all of the sealer and grind away the ecoat.

Re: Cab Roof Replacement
 

I,d just have looked for a nicer cab personally

Re: Cab Roof Replacement
 

That's easier said than done in our area. Usually the entire floor is roached or the roof and floor are roached. When you do find a good usable cab, you'll be spending $500 for a bare rusty cab. It's nuts.

Re: Cab Roof Replacement
 

Mine is a 67 small window...even harder to find in good condition...

Re: Cab Roof Replacement
 

A member here in southern Iowa had one at a reasonable price. Needed rockers/inner rockers, light floor repairs and cab corners. Russ/counter had it.

Re: Cab Roof Replacement
 

It goes both ways. He helps me out with engine work, we trade parts as needed, etc.
I don't remember what I used on my 71. It's been like 8 years, but I think it was the 3M one. Should only need to scuff the e-coat to get things to stick on it.
There was already a bunch of money spent on acquiring the cab (it was pretty much rust free when purchased) but the damage came later from sitting outside and rodents. So do you throw it out or hope to get something for it selling as is or fix it? Lots of better cabs around but they're not bargains. He spent around $600-650 in patch panels. Can't find a decent cab for twice that much.