are the shape and fit of all 91 t tops the same weather plastic or glass? I tryed to give a guy a set of glass off a 90 bird for his 91 rs plastic and they didnt work.they had different shapes in the frame.when did they change? im getting a 91 rs with plastic and drivers side is cracked.where can I get replacments

 

From what I can tell, the cam location for the T-top adjustment is different, You should be able to adjust the cams on the front and rear of the body to use the standard Glass. Depending on when the car was made in 1991, the seals might be different. Mid year they changed the weatherstripping, it really does not work to use one type of top with the other type of seal.

The pins on the plastic tops are also apparently larger, But there is a large portion that is spring loaded when installed. I think this somehow aligns the top front to back for some reason, it is unclear. I wonder if it is as the car flexes that it keeps the pins in the car. If they were to get off center from front to rear they might want to try to pop out. If you kept the top more in the center then it would keep that from happening.

As for replacement Plastic panels... I have considered making them, (I make aircraft windshields and windows, it is not a stretch at all) BUT BUT BUT, the color is really unique, it looks like a standard color, but the tint is twice as dark as what I can get without getting a custom run of material which would cost $10,000+ So I kind of dropped it.

John

 

I thought back in the day GM was replacing peoples Lexan tops with glass under warranty for certain complaints. How could this be if cam location were different? Did the dealers have to make this adjustment you are speaking of? I've never heard of that before...

Are we sure the Firebird and Camaro tops are interchangeable? He did say his Firebird tops to a friends RS.

...and plus 1 on the weather stripping changing at some point in the model year.

Just spit balling here lol

 

1) The material is Acrylic, not Lexan
2) It is a simple cam adjustment in the front and back of the window that retains & adjusts the top. T15 Torx bit IIRC. You might have to remove the front and rear window trim. It would take all of 20 min of messing around for each top once you did one...

If you look at the plastic tops they have a distinct bubble to stiffen them, I think the Plastic tops were more prone to leaking, as they are more flexible, they also have extra metal strips on the front and rear to make them more rigid.

Going from one to the other does not seem to be a big deal... IIRC when I pulled my set from the junkyard I grabbed the female cams on the car, I found out they were the same part as the ones I had on my car.

John

 

Right you are! I always have that brand name of Lexar that's printed on them stuck in my head so I think Lexan lol.

Didn't know they were that easy to adjust, good to know!

 

Honestly, people thing that they want Lexan... Really they do not. If well taken care of Acrylic will outlast Lexan by about 10 years. Lexan will fog and craze immediately if you clean it with Windex or an ammonia based cleaner.

Acrylic is a little more forgiving in this area.

1) when it burns Acrylic does not give off toxic fumes
2) Acrylic is breakable - seems counter intuitive, but if your only way out was through the tops, then you want to have a chance to break it.
3) Acrylic Lasts longer

 

Probably the biggest headache is they are made from plastic, so when you tighten them down, or they were originally tightened down they take a set from the original screw... I think if memory serves you can interchange them, so if you needed another screw spot you can switch them to get them away from an embedded screw head mark.

 

so if im understanding this right,any gm made top should work.Cam may need ajusting or seals may need to be replaced to insure no leak

 

Yes... and No...

82-83 or 84 had a hook style T-top, From 1984 or 1985 & up had the pin style, these are not interchangeable, unless you convert a car over one way or the other.

All Pin style Tops should interchange with other pin style tops... Plastic, or Glass. And yes you would more than likely have to adjust the tops if going from one to the other...