So I bought some beautiful glass tops for a great deal. While installing/aligning the driver side t-top there is no way the three alignment points are going to get the rear bayonet pin to mate with the plate in the rear of the driver side door jamb. Since the passenger side fits perfectly I measured the distance from the center of the front pin hole on the windscreen frame to the rear of the roof top. The result is a full 0.5" difference in the distance between the driver side front to back and the passenger side front to back. See below. Anyone else see this before? I noticed the original t-top driver side latch has been modified by cutting out the oval adjustment hole completely out and shoving the latch all the back to the rear as much as the bolts will still catch metal. I transferred the old latch to my glass top and it just will not work because the bayonet pin will not travel far enough to enter the rear door jamb plate.

I plan to cut the latch pin base then weld a piece of 1/2 metal to extend the pin plate 1/2 forward (thereby moving the pin forward) so that the rear of the t-top will travel 1/2 toward the rear door jam and then the pin may fit.

Any input will help me. Is the latch metal weldable with a flux welder?

 

Start by loosening all the pin brackets and set the top into the opening and fit the t top by sliding for and aft for the best fit. You may want both tops on the car and both loose to achieve the best results. I would recommend looking at photos with glass tops installed on other vettes and you should notice that the fits varies from car to car. I brought some for my 76 including the conversion kit for the single latch and got them to fit where they looked ok. Not overall happy I reinstalled the dual latch originals.
Make sure that rubber seals are installed and you should not have to use much force to get them to latch. You might have to buy some shims or remove shims where the tongue bracket slides into the t bar.
I really liked the look on my vette but just to damn picky so I sold them to my neighbor for 25th anniversary and they fit his car quite well.

 

Thanks. I understand the alignment process fully. My issue has to do with the fact that, as in the photo I posted, the t-top openings for the driver side is soooo much bigger than the passenger side that the tops cannot be aligned without modifying the latches since the latches only allow for a small amount of adjustment, not 1/2 of adjustment.

 

Is that black sealer I see between the top receiver plate and outer windshield molding? If so could the receiver plate have been moved reward a little (maybe in an attempt to get the top to fit), and the sealer used to fill the gap left from repositioning the plate? What kind of shape is the a-pillar in, is it rusted or showing signs that it's been repaired? What about the windshield header, is it rusted or has it been repaired? How does the driver's side door glass fit to the a-pillar and existing top, and is there any wind noise or water leaks around it? What kind of shape are the number 2 and 3 body mounts in and the birdcage in the area of the mounts, is everything solid, tight and rust free?

For the windshield frame to be that far out of alignment I'd be looking everything over to see if there are signs of (poorly done) repairs or rust in the a-pillars, cowl and/or windshield frame's header. Before modifying the tops (especially glass tops that will crack quite easily), I would pull the header molding, a-pillar moldings, kick panels, body mount inspection plates, etc., and make sure everything is solid and where it's supposed to be.

Those dimension appear to be out of spec. There has to be a reason for it, and the first thing I'd want to know is what the reason is.

 

I also have a 1980 and just measured the same dimensions on my car. From the face of the roof to the center of the front pin hole: Driver side is 23-1/4" and passenger is 23-5/8" Comparing to your dimensions, I agree with gbvette62, something is wrong. Might be "twisted" since the average between the short side and long side of your car is almost exactly what my car measures.

Question: Did you have a pair of tops prior to the new glass tops? Did they fit better? Might be worth comparing dimensions off those. Might also try your new tops on a friend's car before you alter them.

FYI: My t-tops do not fit great. Have to press and wiggle the two "tongue tabs" to engage enough for the front lever pin to land right, and the rear pin to catch correctly. Growing up my mom had several new C3s and I don't remember ay of those tops being as difficult to engage. Makes me suspect my tops are not original and they need to be adjusted. Haven't seen anything about how to adjust them though. Almost never put them on so not my priority.

 

Unfortunately there is not much that can be done for a several of reasons. The first reason is that these cars are not are not a precise vehicle and have variable tolerances for the build process where those tolerance's can bee as much as 13mm or and .5" unlike a lot of modern cars the can have a zero tolerance difference.
The second reason is that the glass t tops are bonded to the t top frame and not always the same fit side to side or from one pair of t tops to another. Variable tolerances are possible with non original GM t tops. Oem glass tops were not perfect either.
The third reason could be from the vehicle in a accident and the body mounts on the shorter side have collapsed allowing the gap to change. Technically more of a stretch for some like this since this type of problem would show up some where else like door to 1/4 panel and rocker gaps.

Even though my smc t tops fit the vehicle I spent a considerable amount of time measuring and adding/removing body mount washers to no end up with same results trying to fit the mirrored glass tops (oe GM) once I decided I wanted the correct fit more than the mirrored tops I changed everything back.

I hope this helped explain why I said you may have adjust them in the openings the best you can.