R-Model Lexan Rear Window

[R-MODEL1965]

I am about to install an r-model lexan rear window in my fastback. I have the original type that has the aluminum horseshoe frame. I was wondering if there is anything that goes between the aluminum frame and lexan window? After looking at numerous pictures it appears that there is something black that is between the frame and widow. Is it rubber to raise the window up flush to the body panel?

Thanks for your help.

[gt350bp]

That would be the Lexan compatible adhesive to glue the window to the frame.

Don
gt350bp

[tesgt350]

That would be the Lexan compatible adhesive to glue the window to the frame.

Don
gt350bp

I thought they just used the Factory Rubber Seal and just cut the Top portion off of it.

[Jbarela]

Please if you could do a step by step tutorial with pics..I am sure it's a no brainer but it's always good to see how other people do their installs.

[gt350bp]

The horseshoe frame is attached into the window area with sheet metal screws through clear holes in the aluminum frame. Window will need to be trimmed, as they are typically oversize to allow a better fit. Once the window is trimmed to suit, adequate adhesive that is compatible with Lexan is used to glue the window to the frame. Aluminum retainer clips are then pop riveted to the body.

I believe the adhesive is a urethane, as some silicones will craze Lexan. Have not been able to locate information on what I used 20 years ago, but no degradation or crazing of the Lexan is visible. I'm sure others will have better input on the appropriate adhesives.

[TJinSA]

I thought they just used the Factory Rubber Seal and just cut the Top portion off of it.

As I have looked through dozens of early R-Model photos, there was no apparent trim or channel, but there was a black line between body color and transparency.  I believe you are right, but for what time frame...1/2 way through the first season or so. I'm interested in the other opinions and experiences...

[gt350bp]

The later style rear windows that use the factory trim uses a rear window gasket and trim clips. This is an easier method to attach the rear window but is not accurate for era.

Don
gt350bp

[CSX 4133]

Just a FYI the sealant underneath my Lexan window appears to nothing more than black Butyl tape, possible double stick variety. As gt350bp stated the retangular aluminum clips are what fixes the lexan to the frame.

[gt350bp]

Pretty sure it isn't butyl, as butyl degrades under UV light. I have seen some replica cars that have used VHB tape, but I do not believe it was used in the day. I do think a high quality urethane adhesive that is compatible with Lexan is the best method. Windshields since 1969 are structurally glued with urethane caulking and the urethane is also the weather seal.

Don
gt350bp

[Jbarela]

This whole time I thought the two aluminum frames were just painted black I was not aware that the window was actually secured also by some sort of  "black adhesive tape?" as well as the aluminum tabs. any rmodel owners or restorers want to chime in on what was period correct and what is the norm now in regards to that

[Bob Gaines]

This whole time I thought the two aluminum frames were just painted black I was not aware that the window was actually secured also by some sort of  "black adhesive tape?" as well as the aluminum tabs. any rmodel owners or restorers want to chime in on what was period correct and what is the norm now in regards to that

It was a natural for the rubber gasket to be used in the r models given it held the glass widow that was removed. Not to say the other doesn't work but I think the black that is seen in vintage photos is the rubber gasket . It is cut short at the edge where the plastic dips down. I don't think the butyl tape was widely used in 1965 . Just my opinion until more concrete evidence suggest otherwise.

[Jbarela]

Bob I would have to say that is the most likely fact, as it is very symmetrical looking and evenly spaced..I would think a lot of effort would go into trying to make it look perfectly spaced around the edges for a race car effort and time that did not make the car any faster. Just my thought

[gt350bp]

I don't see how the gasket can work with the aluminum horseshoe channel, as the channel takes the space of the gasket? If you do not use some type of adhesive, the window will rattle and leak more than what you can expect when done with the adhesive. The four clips themselves will not secure the window alone in my opinion at speed.

Don
gt350bp

[Jbarela]

I was thinking the rubber was used in place of the aluminum spacers..did not know those were correctly reproduced pieces to use. I am learning about r models right now for my build.

[gt350bp]

Check Jim at Shelby Parts and Restoration for his rear window kit. The kit includes the aluminum horseshoe spacers. Not sure that these are the correct parts for a very early R-Model, but Jim is know for his exact reproductions. When I built my car, I was fortunate enough to have numbers 105 and 534 that I used for trying to get the details correct. Back in the late 80's to early 90's, 5R534 was the most original car to use as a guide.

Hope that someone that has better R-Model knowledge can confirm this!

Don
gt350bp