Rear window lexan

Dan Carter

Bronze Supporter
Has anyone observed any yellowing with the rear window? I assume it is lexan, which has several additives, and UV protective to reduce any yellowing.

What experiences do we have so far?

Hi Dan!

I've done nearly 9,000 miles on my SLC here in Sydney, we have very harsh sunlight/UV here in Aust and my rear window and side windows are all fine.

cheers Stu


Lifetime Premier Supporter
Dan, it's not Lexan -- Lexan is a brand of polycarbonate and Superlite doesn't use it. I know at some point Superlite switched to a superior hard-coated polycarbonate which is more scratch resistant. I'm not sure when they made that switch or if it would have any effect on yellowing.

Dan Carter

Bronze Supporter
Great info

I'm trying to get smart on how to care for this product.

Being a super hard coated poly, can we assume the cutting and care is the same as any poly?

I have to trim my rear window, how did you cut yours?


Dan Carter

Bronze Supporter
Thanks Pete

I note the terms plexiglass and polycarbonate get used interchangeably in that 2014 discussion.

I gather that the same cutting technique apples to either product.

Is this the case?
It is my understanding that the scratch resistant coating material cannot be formed. If it is, maybe the curve of the rear window is slight enough to allow for it?

Mark Clapp

Bronze Supporter
Hi Guys, I cut even curved polycarbonate with 36-teeth-per-inch fine metal cutting blades in my saber saw. I use Bosch brand, which are available in packs of 4-5 from Lowes. The edges come out almost polished with no roughness or "heat boogers" (technical term). When you're done you just run your fingers along the edges and all is clean. The keys are: (1) the very fine tooth blade and (2) cover the foot of the saw with some tape and just glide the saw over the plastic without pressing down so as not to scratch or mar the plastic. Also, keep the protective film on to keep from scratching the plastic.

Mark Clapp


New Member
Also never use flathead screws/bolts. They cause hoop stress and will eventually crack the polycarbonate. Use a bolt that puts the material in compression like a pan head bolt. Drill oversized holes and use washers to distribute and cushion localized stress and compensate for expansion and contraction of the polycarbonate as the temperature changes.

Last but not least never ever ever ever use thread locker on the bolts. They are not compatible with polycarbonate and will eventually craze and crack the material.

When making cuts always try to leave a radius (even a 0.020" radius is a big help) on all inside corners. polycarbonate is very notch sensitive and always use good support along the edges.


Active Member
it amazes me so many people countersink their windows ... that's gotta lead to cracky-cracky down the road.

for my windshield i just used 4 #6 screws w/ washers and powercoated them a wrinkle black color so they don't look like cheap-ass machine screws :D
Hmm. I countersunk all my windows 8/32 in the rear clam, doors and windshield. I've not seen a single crack in any of them in 14k miles. I think the trick is Fran recommended using black nylon screws. A huge amount of give. My last track event we ran counterclockwise on Eagles Canyon. The front was getting airbourne on bad pavement in turn 8 for four sessions x 8-10 laps. Still no cracks... no yellowing either since 2009.

Dan Carter

Bronze Supporter
Has anyone ever tried using standard windshield butyl glue to set the Windows? It's flexible, water tight, and if you ever remove the "lexan" it should come off with a standard windshield removal tool.




Gold Supporter
Just a thought - If you're planning to do any open track events, many of the organizations require the windows to be rolled down so you can waive people by. On an SLC that means either removing the windows or having a hole in the window to stick your arm through. Windows held on with screws are easy to remove for the track.