KBW21 transmission

[stevec195]

I have a KBW21 Hurth transmission mated to a 4JH2-HTE. I need to re pitch my max prop next time out if the water as I’m way over pitched. Problem is that I can’t determine which input option I have. The KBW21’s were fitted with either 2.16 or 2.6 to one arrangement, which obviously makes a big difference in computing pitch. I’ve been all around the transmission with a light and mirror and there is just nothing stamped anywhere. I suspect the previous mechanic guessed wrong at this same topic, which is why it’s over pitched. The engine data plate has a field for “prop shaft rpm” but no nomenclature was ever stamped.

[skipperpete]

Well since it’s a mechanical gearbox all you need to do to verify the reduction ratio is to engage ahead with the selector, put a mark on the propshaft coupling and manually rotate the engine 2.6 turns with a breaker bar on the front pulley hex. If the mark ends up in the same position it’s a 2.6:1 reduction. Contact PYI regarding the correct Maxprop pitch, they’re really good at getting it right as long as they have the correct information.