i have a 13hp lt only put about 6 hrs of deep water on it, and the 3/4 inch shaft snaped off were the threads started. is this common or just a bad shaft? shaft was done by a machine shop and made from 3/4 cold rolled, now having a shaft made from 4140 hardened steel.

Ive got a 7/8 cold roll shaft on my mb 35 put 30 hours on it in the mud mostly with no problems yet were all the bearings changed with the shaft? Maybe a bearing seized

viewtopic.php?f=6&t=27445&p=316454&hilit=oops%21#p316454

It happens.

all the bearings were free, but went ahead and replaced everything that moves from the back of the motor to the lock nut on the bottom of the shaft. had a lil virbration before, but has nun now dont know if it is the new prop or what,

If it broke right behind the prop shaft housing the threads were machined too deep, your 3/4'' shaft may have been 1/2-7/16'' in the thread valley. Where did it break?