Re: my bravo outdrive gear experiment
 

Thanks,I am putting a stellings ext box on my boat over the next week or 2,started sunday night on it. Before i pulled the drive off,I pulled the prop shaft as I am also going to put the heat treated gears in when it goes back together. I haven't dissassembled the lower completely yet but as soon as I do I will take pics of the stock xr gears I put in last fall,I can see they haven't broke thru the hardness yet but are galling. They have about 10-15 hours on them,with a little time at wot,Smitty

Re: my bravo outdrive gear experiment
 

Some aftermarket driveshafts act like torsion bars to twist and absorb shock. I have a few Imco shafts like this that are necked down. BBB

Re: my bravo outdrive gear experiment
 

I received a good suggestion that worked well for me. Stainless Marine makes a tee fitting that goes in the fuel tank fill hose, with a 3/8" barb connector for this purpose. They sell both a 1 1/2" and 2" o.d. part. The fill hose on my Velocity is 1 1/2" and this made a very simple way to return the regulator bypass fuel back to the tank.


By the way, I've got an Aeromotive 11104 Eliminator fuel pump for sale with only 10 hours on it. It was too much capacity for my application and I had to drop down to an 11101 to get the pressure under control.

Re: my bravo outdrive gear experiment
 

Unfortunately my motor can't be moved a full inch up to get perfect alignment with gimbal with +1 setting on stellings box other wise I'd eliminate the stellings carrier bearing and use one,Smitty

Re: my bravo outdrive gear experiment
 

Heres what I did :drink:

Re: my bravo outdrive gear experiment
 

The reason the gears are failing is as mentioned above. The base material is soft. The outer case hard material is only in most cases .050 of an inch thick. The base material gives way or moves from presure causing the hard surface to micro fracture which will then in time fail. The cryo process will only remove stresses caused from machining. Your best bet is to coat the gears. You must use a cold coat process but there are a few out there that will give you a 93+ rockwell. There are some new materials on the market that may flame or quench harden that may be better suited, but the cost would be substantial.

Re: my bravo outdrive gear experiment
 

micro fracture and micro welding the same thing?

I was told that how they fail the surface of the gear starts failing /welding from the EP and the surface starts breaking /eating away making the gear fail. Dean at the Bravo shop on his B-Max's is coating his gears in the same manner and he said his rockwell is in the 90's. The Bravo Shop is coming out with a helical cut lower gear set that will give 3 teeth of contact over the one tooth of contact of the stock Bravo gears .That sounds like a good idea ,but its going to be awhile before its ready.

Michigan troll thanks for the explanation

Rob :D

Re: my bravo outdrive gear experiment
 

I'm presently testing the new gears, but I only have a few hours thus far. Dean said these gears are coated to a hardness of 90 Rockwell. In the past my lowers gears rarely last past 30hrs. Dean wants the drive back for inspection after 20hrs. These gears had 5 hours use before they were coated. I'll keep you posted.

Re: my bravo outdrive gear experiment
 

You still at 1000hp? Have ya truned it back up yet on the new gears?

Rob :D

Re: my bravo outdrive gear experiment
 

I don't have it turned all the way up. But I'm pushing between 100 and 200HP more than Smitty. Hence, my gears die quicker than his. If I can make 50hrs it will be a success, and I'll recommend them to everyone with big HP. Unfortunately it will take a couple months to know for sure. :D

Dave