I hate castle nuts...

[willy13]

Over the weekend I went to install the prop on my Yamaha 115. Yamaha specifies a torque of 40 ft lbs. I torque it to 40 ft lbs, and as usual with castle nuts, the hole is blocked and I can't get the cotter pin in. So I read the manual further and it tells you to torque the nut to the next notch in the nut if this happens. I hit 65+ ft lbs and its still not there. Not to sure if Yamaha want me to go much higher.... I backed off the nut and re-torqued to determine the minimum. It looks like 20 ft lbs would allow me to install the cotter pin. The other choice is a different thickness of washer. But I am having a hard time find one locally. So its either 20 ft lbs or 75+ ft lbs...

Anyone else run into this?

[rancherlee]

I tend to tighten it past on big motors and go looser on kickers. 75# is nothing on 115 HP shaft, the threads should take 150# easy. The down side is if you need to swap props in the middle of the lake and you need to loosen the over tight nut!

[willy13]

Rancher, you make a good point as far as max torque on the threads.

It looks like its an 18mm shaft. My local fastener supplier skips from 16mm to 20mm.

[rbiederwolf]

just changed prop on my Yamaha 150hp. Didn't even consider the torque. All I know is the nut was seated just below the cotter pin. Thus I put it back where it was and installed the cotter pin. The cotter pin was such a bitch to remove that I am not worried at all about what the torque is on the nut.

On my previous Mercury engine, I changed the prop dozen of times and never checked the torque. Just seated it well and then a little more. Mercs do not even use cotter pins. Never a probem

[willy13]

I ended up putting anti-seize thread lubricant on the threads and was able to get the cotter pin in at 65 ft lb. Without the thread lubricant the torque was heading up close to 100 ft lb.