I know the 1982 trans ams had a different "hook" type latch mechanism for the t-tops and that later they changed to the "pin" style with pin shaped cylinders that moved outward into a slot with a nylon bushing. What year did this change take place?
I am assuming it was done to reduce rattles and create a tighter fit with less flex? Correct?

I used to know. LOL I can't remember now if it was 84 or 85. They changed again later to larger pins, and there are Lexan T-tops, and weatherstrip changes, and C&C aftermarket ttops.

Least annoying T-tops I've owned were the stock Lexan tops on my 91 V6 Firebird. They didn't leak, rattle, or anything like that. An occasional dribble at the corners where they met the window glass, when sprayed with high pressure water was about it. Sometimes the rubber on plastic would squeek.

Yes,I remember the Lexan t-tops. That was done to save weight,right? They would haze over and scratch like crazy. I'd rather have glass.
I know by 88 they have the thicker pins. Seems like the cars improved a lot by 88.

Funny thing is all of them seem to leak a little in heavy rain where the front plastic piece joins the a pillar.

Would 90 firebird tops be an upgrade for an 88 iroc?

Most likely... About that time GM was looking everywhere for weight that could be cut. Also made them easier to handle when removing them from the car. In theory anyway, the Lexan was coated, and required upkeep like other parts of the car. Of course most people don't clean and polish their lexan ttops just like most don't wax the clearcoat on the OE wheels.

The tops on my 91 V6 Firebird had some visible internal checking, but they were smooth and shiny on the outside. The fact they could be handled with one hand easily made them nice too. But now the set I got off a parts car a few years later, they were more like 100grit sandpaper, and so cloudy and decayed you couldn't see through them.

Had a set on my '90 GTA that were horribly scratched up, but functioned fine. I sanded them down, prepped, and painted them black to match the car. Was a nice custom touch and the interior stayed a lot cooler too lol!

I've never seen the hook style on any car after 82. I've had a few 84s and they all had pins. A friend of mine had an 83 years ago that also had pins. I've always assumed only 82s had the hook style.

One thing I never noticed until recently is the design of the glass changed as well. Only reason I noticed was because I was changing the seals and repainting the outer strips on both cars. On my 82, the tops only have one wide opaque black band on the outer edge of the glass toward the door windows. The other 3 sides of the tops are mirrored glass right to the edge. On my 89, it has a black band around all 4 sides, one wide on the outer edge, a smaller one front and back and then even a bit smaller one facing the ttop center bar. Also, the tops on my 82 used to have small plastic trim around the edge which I removed because it was cracked badly and very brittle. With new weatherstripping, the tops actually sit flush with the roof now and look cleaner. The plastic trim that was on there sit up higher than the roof and looked out of place, I always thought.

One other thing, I'm also working on a buddy's 91 Trans Am and while the ttops are identical to the ones on my 89, the pins on the 91 are bigger than the 89.

Interesting info! So the pins got larger after 89. I wasn't sure if 82 was the only year with hooks,thanks for clearing it up Kentucky KITT

1982 and 1983 had the hook style t-tops. They switched to the pin style in 1984.

The "large" pin style just have a springloaded plastic piece around the small pin in the center. Not sure why they did it that way, maybe to try to reduce rattles?

My GTA has the lexan T-tops. Besides all the scratches on the outside of them they are great. They dont leak for me when washed, or in some rain. Anybody know how I can get some of the scratches off the top? Maybe a light polish?

Try a polishing compound first. If that fails, you can start with say 600 grit wet sanding, progressing up from there. Meguiars makes some nice fine grit (1000, 1500, 2000) wet sanding paper.

Try a plastic polish, or cleaner then polish. If they're not too bad the plastic will shine up. If they are pitted, forget it.

Now that you mention it I do remember my 83 Firebird Se having the hook style t-tops. Was the reason the design changed to reduce rattles and leaks? The pin style seem to be much more ridgid.

Ill try polishing them. I'm not too worried about them being pitted because i wanna get new ones in the future (hopefully) just getting them shiny and smoother then they are will be good enough for me.

82-83 - Hook style
84 only maybe - pin style but with no lock?
85-92 - pins with locks
89-91? (Leximar ACRYLIC Top option) for weight reduction.
91 1/2 - 92 changed to better weather seals.

As for larger pins, the only differences I have found is the Acrylic tops had a spring loaded sheath to better center the top. Not seen it on the glass tops, but I may have never noticed them.

THere are some differences in the paint on the tops as well. Some (mostly the later tops) had paint all the way around the outside, others had just a stripe on the outside.

N/A

I have a 92 with factory glass tops with the spring loaded plastic pin covers. It is a 07/92 built V6.

My late 84 build Van Nuys Z has the LOF glass locking factory tops.
(with pins)
The window sticker price is $850.

Ok... I knew it was on the Acylic tops never seen it on the Glass tops however, it would make sense. Good to know, thanks.

I do not remember it being on my 91 T-top Formula.

John

Cool to know, thanks Thus the ???

John

The 91 RS I ordered new back in late 1990 had the Lexan T tops and I hated them. They scratched very easily and they were much darker than the glass ones. It didn't take long for me to scratch mine while trying to stow them in the bag.

I have the large pin Lexan Tops in my 92 and have been trying to find a set of glass for a while now. Were the large pins only offered for a couple of years 91-92? If I find a set of glass with large pins can I assume they will fit?

I believe they will all fit (except the hook type from 82-83)

If you get an early set, I believe you can transplant your pieces to the new tops if you want the larger pins.

Thank you okfoz! That makes finding a glass set much easier.