Lexan Window thickness... REPORT!

Hey everyone. I'm looking at the rules on the lexan/polycarb window replacement.

(NRS GRR 3.24) "In classes where it is permissible to replace glass side and rear windows with Lexan, it should be of equal or greater thickness than the original glass."

It seems to me that it would be much more user friendly to say "In classes where it is permissible to replace glass side and rear windows with Lexan, it should be 3/16" thick or greater."

It just doesn't make sense that one car would need 3/16 and the next 1/8. Plus, how would you ever verify what the originals were if teching?

So, has anyone even seen less than 3/16 used? Or a window that was less than 3/16 thick?

Quickly!

Anders

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Grassroots rally. It's what I think about.

Here is an aftermarket replacement window in Europe that measures 4mm which is like .03 thinner than 3/16"

http://www.templerallysport.com/index.php?_a=viewProd&productId=1773

Though it looks like all of Flex a lite kits are 3/16"

http://www.flex-a-lite.com/auto/html/flexite-flat.html

We used 3/16" on the XR following the old rules. It seems to be a bit over kill for the smaller rear side windows but good for the rear hatch. 1/8" would probably need a brace on the hatch.

Good find Andrew. Something like:

thickness equal to or greater than 3/16" or 4mm

would do it. I'm just thinking that the whole process would be much simpler if the thicknesses were spec'd.

Moar!

Anders

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Grassroots rally. It's what I think about.

Anders,

I would like to thank you for being proactive with the rules. It is very important that every sanctioning body keeps on top of their technical rule set. Posting your ideas on this forum is really good.

For me personally I prefer a certain amount of wiggle room in the regulations. I will now contradict myself and say that I support well defined technical specifications. The second most common type of questions that I am asked have to do with poorly defined specifications. (The most frequent questions come from not having read the book at all.)

Keep up the good work.

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

What about if rules were drafted for things that are meaningfull.
What the fawk difference does it make if a stoooopid side window or hatch window is 1/8 or 3/16"?
Zero, zip, nada, neinte, rien, sweet fuck all, nuthin',

Rally has other fish to fry than over bullshit like 1/16 difference of poly in a side window.
OR!

Mandate the size for P and PGT. or SP or anything hinting of Ploe-duction.

Most auto glass these days is 1/8" for sides and rear. Real Lexan is damn strong and 1/8" is plenty thick. The only change I'd make is to say "minimum .120" lexan". I'd also rule out polycarbonate(home depot style), the shit is dangerous with the way it can shatter.

It's also a good idea to mount them is such a way that they can be kicked out in the event of a roll where the car is maybe in a ditch with front and rear exit blocked. I use the small 1/8" alloy rivets so they can be kicked out pretty easy. I've seen guys with 3/16" and SS screws with nylocks every 2", might as well weld a steel panel over the opening.

All that being said...I have to agree with John, although I appreciate you taking the time to clarify the rules, this rule is totally meaningless and does nothing.

Thanks for the props guys.

Yes, we all know that Great Lexan Debate of 2010 will go down in rally history as the biggest waste of time ever. Relax and have some fun John. Some kids like to do this, and let's make it easy. It doesn't hurt, it's optional, and it's not that pricey. Making an easier spec means a fun Saturday afternoon with a jigsaw and not a month of research with calipers and worrying about what the tech inspector says when they show up. As far as NASA Rally Sport is concerned, building the car should be as easy and fun as possible.

Trust me, I work on big important rally stuff all the time. That doesn't mean I'm not going to have some fun and work on some easy trivial stuff.

So in that spirit, go measure me some XR4Ti windows John, and Happy New Year everyone!!!!

Anders

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Grassroots rally. It's what I think about.

Lexan is polycarbonate... Are the home depot ones plexiglass?

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john vanlandingham
What about if rules were drafted for things that are meaningfull.
What the fawk difference does it make if a stoooopid side window or hatch window is 1/8 or 3/16"?
Zero, zip, nada, neinte, rien, sweet fuck all, nuthin',

I don't get the rule either. I could understand a minimum thickness for the driver & passenger windows to make sure they are strong enough to keep your arms and head mostly inside during roll. Isn't this why we require nets and/or arm restraints if the windows are rolled down or are missing?

BUT, any windows behind the B-pillar -- Who cares? They are just there to keep the dust out. In fact, I would think it is legal to run without any of the windows behind the B-pillar if you wanted to (although I think it would be silly to do).

So, what is the reason for the minimum thickness rule in the first place?

Merkur windows:
Drivers/Passenger glass .125"
Pop Out window behind Driver/Passenger .165"
Rear hatch .125"

So what do I do if I remove the "C" pillar and replace the 2 windows with a one piece widow like the Sierra? do I match the
thin or thick window?

In reality it is near impossible to measure the 'glass' thickness anyway, especially if it is in a rubber seal. How do we tell Lexan from plexi at a glance? Would you boot a guy for having to install plexi overnight to continue? (I wouldn't). As Josh mentioned we let people run with the back windows down or missing with no squabble, so just make the rule require 1/8 for all the windows. State Lexan for the front side windows. If we have to break a Lexan door window 1/8 inch might be better than 3/16.

My god! Reasonable responses, I'm gonna faint!

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Gravel Spray
It's also a good idea to mount them is such a way that they can be kicked out in the event of a roll where the car is maybe in a ditch with front and rear exit blocked. I use the small 1/8" alloy rivets so they can be kicked out pretty easy. I've seen guys with 3/16" and SS screws with nylocks every 2", might as well weld a steel panel over the opening.

I think this is the only thing that's been said in this thread that should make it into a rulebook in some form or another.

I'm in the "who cares how thick it is?" camp.

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Dazed_Driver
Lexan is polycarbonate... Are the home depot ones plexiglass?

Correct, but take note. Not all "Polycarbonate" is "Lexan", I've tried what is marketed as poly >> something similar to "lexan" and it breaks just like the plexy. Real lexan is damn near bullet proof, freeze it hit it with a hammer or whatever and it wont shatter like the rest.

"lexan" is a trade marked and specific material made by GE, I beleive it is actually spec'ed as the only material allowed for windows by NHRA etc. So if your going to do plastic windows make sure it has the GE/"lexan" logo all over the protective vinyl cover.