Stopping cracks in an RT windshield

[paegelow]

What's up guys I have another question.  My '85 K100RT windshield has this crack situation going on at the upper right mounting point.  It hasn't gotten any worse in the 3.5 years I've been riding this bike, but I always worry about it anyway.

Is there anything I can do to help keep it from getting any worse?  Like drilling a little hole at the end of each crack?

Anyone know what type of plastic these windshields are made of anyway?

[WayneDW]

Don't see a picture other than a big minus symbol.  But I have heard that drilling a hole will stop a crack from spreading.  Have not had personal experience in it though.   I think it's an acrylic with some kind of a coating which makes it not want to be polished.  (I tried with no success).

[paegelow]

Oh whoops let me try to fix the picture real quick here...

[paegelow]

Alright I think I fixed the picture!  Anyway yeah I've heard of stop drilling cracks but I don't think I've ever seen it on a windshield like this.

Has anyone tried it with any success?  Mostly I just want to validate my idea before I try it and end up making it even worse!

[Motorhobo]

Six years and probably at least 30k miles ago I drilled a stop hole at the end of a crack in my 18" Parabellum Scout windshield and put some plastic cement crap on it which probably did nothing at all. The hole, though, stopped the crack. So it definitely worked for me. I think the hole is about 1/8 inch but you could probably go smaller than that, not sure exactly what size is recommended.

 The shield is acrylic, which is pretty standard -- Lexan is more durable and shatter-resistant but it discolors and scratches very easily and is very difficult  to mold into a curved windshield. Acrylic, i.e. plexiglas, can be shaped more easily under heat and is more scratch and ding resistant.

More info than you probably asked for but there you go.

[paegelow]

Awesome thanks for the info!  That's just what I was looking for.  I was curious about the material in case it was something that would respond real badly to drilling.  I think if it's acrylic I can probably make it work.  I'll report back after I try it.

[TimTyler]

It looks to me like the crack was caused by missing hardware.

Do you have "hollow washer" #6 (part number 46631453997) ?

[paegelow]

It's there but it's mostly broken off as you can see in the picture!  I just ordered a few of those washers along with a bunch of other random parts.  The other side's uppermost mounting hole actually is missing ALL of its hardware so I'm replacing that too, but it has no signs of cracking!

[paegelow]

Quick update; it was actually pretty easy to drill the holes at the end of each crack.

I have read that when drilling plastic one way to prevent the bit from grabbing and creating more cracks is to use a somewhat dull bit.  Then the tip will kind of just melt its way through.

I used a fairly worn out #40 bit, high drill speed, and almost no pressure, and it worked just fine!  Much less sketchy than I thought it was going to be.

Then I filled each hole with a little blob of 5-minute epoxy.  I doubt it'll do anything structurally but at least it will prevent airflow from whistling through the holes or whatever.

My fairing is all taken apart now while I do some other projects, but once that's done I'll reinstall the windshield and see how it holds up!!!   :riding: