Yamaha right hand mirrors - why?

[G-wizz]

Now I'm no engineer, but every screw or bolt I've ever seen has had the same thread. Clockwise to tighten, anti-clockwise to loosen. Apart from the right-hand mirror on my Yamaha, which is threaded the other way round. As far as I can make out every other right-hand mirror on every other bike has a normal thread, and every other bolt on the Yam has a normal thread.

Why? What on earth is the point? Was this some drunken engineer's prank?

The worst bit is that aftermarket mirrors come with an adaptor, which has a 'right' thread on one end and a 'wrong' thread on the other. So as you tighten the adaptor into the handlebar, the mirror loosens, and as you tighten the mirror, the handlebar mount loosens.

It does my head in...

[TonyOut]

G-wizz said:

Now I'm no engineer, but every screw or bolt I've ever seen has had the same thread. Clockwise to tighten, anti-clockwise to loosen. Apart from the right-hand mirror on my Yamaha, which is threaded the other way round. As far as I can make out every other right-hand mirror on every other bike has a normal thread, and every other bolt on the Yam has a normal thread. Why? What on earth is the point? Was this some drunken engineer's prank? The worst bit is that aftermarket mirrors come with an adaptor, which has a 'right' thread on one end and a 'wrong' thread on the other. So as you tighten the adaptor into the handlebar, the mirror loosens, and as you tighten the mirror, the handlebar mount loosens. It does my head in...

Yamaha have been doing this for years IIRC. I would assume it's so that if you catch the mirror it just loosens and swings out of the way, rather than wrenching your bars and pulling you off.