Headlight lens cracks

[Greb]

Has anyone considered heat being the cause of crazing? I ask because I noticed on my '06 just the start of crazing, right in the middle of the lens, where the beam from the bulb is pretty concentrated. (Sorry, no pics, bike is gone.)

My bike often has dirt and bugs on its front, these would tend to hold heat on the lens, as would any other opaque substance.

A cleaning fluid left on might appear transparent to light, but could well stop infra-red.

This could explain the sudden onset, also crazing on either surface - I would expect both inside and outside to get similarly hot, crazing would probably start on whichever surface was more stressed from its original moulding.

Just a thought.

Something like this happened with mine by not removing the simple green solution. It baked in and cracked the lens. There has to be one of those 10 pound brain types that can explain what happened. The best I can do with chemistry is making a Jack and Coke.

 

[Greb]

Did some research on Polycorbonate and found this quote on New Hampshire Material Labratory website.

NH Labs

HydrolysisRemember the water molecule that is given off when the PC molecule is being made? Give back the water and the PC molecule may come apart. This process is referred to as "Hydrolysis" and it is bad news. So we can't use PC in high humidity at elevated temperatures -- no steam for polycarbonate!

I suspect it was an uneven expansion from the partially wet lens (stress corrossion) or hydrolysis that caused my crazing and cracking.

I've ridden in tons of rain and never suffered a crack, maybe since the headlight is already up to temp and hydrolysis doesn't have the time to act on the Polycarbonate. It may have been something with the simple green that caused hydrolysis to occur.

I hope this info helps others protect their PC lenses.