replacing portion of windshield farme - advice?

[chevy69]

So I've decided to replace my windshield frame (see pics below) on the '69. I went to 20th st. auto and picked up a perfectly rust free windshield frame off an '82 for $150. I had them cut it as low as possible (below the VIN) and they did a nice job getting it out. They also cut it back 12"-14" into the t-top, giving me plenty of options on where I splice it in. I oversaw the whole operation and it came off a real straight car. They wouldn't cut it out till I ok'd the one I wanted.

As you can see from the pics below (sorry for quality of some - focus issues but you'll get the idea) my corners are really bad, especially the passenger side. The area where the t-top attaches into the top frame and the whole underneath of the top frame is badly pitted as well. There is no rust below the VIN area or into the section of the birdcage that goes down into the door frame (that would suck).

I would like to get some advice, before I cut anything, of the best way to go about this operation. I have a Millermatic 175 gas shrouded mig welder and am confident in my welding abilities. My biggest concern is not changing any of the geometry so that the T-Tops, windows, etc.. all line up when I'm done. I have even considered "piecing" it in to protect the current dimensions. I have a plasma cutter so I can cut smaller sections fairly easy. I've done some measuring and have some ideas how to set up some supports and jigs in order to keep things stable, but wanted to get some advice from the pros out there :

[anmracing2]

Looks like some of the work we had to do on the 442. It's lots of fun but time consuming.

http://www.anmracing.com/1968olds.htm

Good luck with it...... It will take some work to keep it straight from the looks of what you need to do. Get lots of vise grips and if you need a hand give us a call and we do help out on a Saturday afternoon or some Sunday..... This will need some helping hands....

Andrew

[Desertdawg]

Go read through Monty's post on the corvetteforum, he did a great job of documenting his process...

http://forums.corvetteforum.com/showthread.php?t=1304846

I think the best info is in the 3rd post...

quote

Prior to cutting out and replacing the windshield frame itself, I welded several pieces of steel tubing and rod to the body brace I installed previously. I welded two pieces of steel tubing to the windshield top frame to support it in place while I removed the sides of the frame. I also welded two pieces of steel rod to the body brace angled up to the top corners of the windshield frame in order to provide a reference for the windshield frame rake and width. Additionally, I took several measurements of the original windshield frame to ensure that the new frame is dimensionally accurate and located properly in relation to the rest of the car.

Be sure to take the time to photograph your work, and you can always PM Monty for help if you run into trouble...

[chevy69]

Thanks guys - I think I'm really gonna take my time with this and do the braces as mentioned. There is a nice reference point on the T top as well where I can splice the T top in - centering it with the T top mounts. I can screw the top mounts in on both sides before tacking it in place. The A pillars will definately be tougher. I'll holler if I need help - Thanks!

[Guest Simpson36]

A sawsall or cutoff wheel is a lot better option than plasma. If you have the option (and it seems you do) make your cuts where there are a lot of bends and folds in the sheet metal, not in long flat areas.

I've done 50's and 60's chevy cars with rusted out sheet metal at the bottom of the windshield. The way your are doing it with a large complete section is definately the way to go. If you measure carefully and make the cuts in the exact same spot on the old and the new (without heat) the job should be a piece of cake and you shouldn't need all that bracing. Nice straight sawzall cuts are easy to match up and tack together.

Sheet metal sections often have stresses that make them spring when you cut out portions of the structure. Trust your accurate cuts. Move the body to match up to the new section, clamp it up, and then check your reference measurements that you took in the beginning. Don't trim up the new section to fit the sprung body after the old section is removed.

[chevy69]

Thanks Simpson36,

I ended up doing this job on sunday. Some test cuts helped me realize your point about using a sawzall, which is what I chose

I supported the car with multiple jackstands and got things as level as possible before measuring or cutting. I carefully marked both frames in the same locations (all the way around), and decided to split the T-Top at the center where the front T-Top mounts screw in. It provided a perfect reference there.

The cuts went well and I tacked everything together using the T-Top mounts and multiple vice grips and clamps to hold everything in place. The welding went well, and I slowly spot welded it in place to keep heat issues out of the equation, ultimately filling in everything completely. I used a grinder to grind the excess off the welds.

I probably need to use a small amount of filler just to smooth out the grind marks, etc.. but I am happy with the way it looks. I'll post some pics soon. Any recommendation on what filler to use?

[Guest Simpson36]

Any Bodo should do fine, but I prefer the lightweight kind. It has microscopic bubbles instead of just talc as a filler.

Since you're working with steel, treat any bare areas with wax and grease remover followed by a acid/phosphate treatment like 'metal prep' before you prime or fill.

If you're going to fill over bare metal, use a coarse grit to prep, and use the wax/grease remover on the whole surface before you start grinding because you can pick up silicone and wax from the old surfaces and grind it right into the metal making it very difficult to get a really uncontaminated surface.

Arizona is very forgiving environment, but take it from an old Yankee, if you don't treat the bare metal, you're painting oxidation and perhaps silicone and not metal. It's common in the northeast to see body repairs start cracking and falling off the car after a few years.

Sorry I didn't see your post in time to give you a hand . . I really like that kind of stuff!

So . . . . where are those pics?