Ball Gear Cracked

[rlbrooks99]

Anybody know why a ball gear would crack across the hub like this? This is the intermediate gear on an 83 stringer. The gear was installed by a shop before I got the boat and has maybe 1 hour time on it. The threads on the shaft are pretty rusty - my suspicion is that the nut was tightened to the right torque but due to the rust, it did not tightened the gear properly leaving some play in it. What else could cause something like this? I would like to get it back in right so it doesn't happen again!

Thanks

 

[Howard Sterndrive]

Re: Ball Gear Cracked

wish I could see it in person... maybe cracked during manufacture (hardening)
play in splines .... maybe... a flaw in the material might cause it to break through where it is thin - I suspect it's broken through to the sharp edge of one spline....

shouldn't be any rust when assembled- that's oil side of things
that crack would let water in the intermediate- then rust things

how did you even notice it?

 

[rlbrooks99]

Re: Ball Gear Cracked

I found it because of water in the intermediate - and lube flowing out.

It's hard to see but appears to be broken down the center of a spline. You said "play in the the splines"? The shaft splines themselves appear to be OK but it's pretty rusty on the splines and threads of the shaft - from the seals aft. It didn't have the cap on the gear. I don't know if there was rust there before or after the cap got "lost". I just want to try to be sure it doesn't do it again.

 

[Howard Sterndrive]

Re: Ball Gear Cracked

appears to be broken down the center of a spline.

probably a bad part then.

the crack was probably not visible until the engine torque opened it up

then the cap popped off

is it OEM or aftermarket?

 

[rlbrooks99]

Re: Ball Gear Cracked

This one is a Sierra. I'm "glad" to hear it's just a defective part. I was imagining deeper problems with the drive!

 

[Howard Sterndrive]

Re: Ball Gear Cracked

it's a guess from here, but most probable

a metallurgist would break it open and look at it with a loupe - looking for forging laps or hydrogen flakes and all sorts of other issues to really determine what went on

 

[zbnutcase]

Re: Ball Gear Cracked

Don't be so hasty to blame the part! Was it Loctited to the shaft? You must apply a liberal amount of Loctite Red to the splines (as per factory service manual) which is basically an epoxy, to take up any play in the splines and 'glue' them together. If there was NO Loctite, you can't blame the part! Installer error causes more 'defective' parts than anything else!

 

[rlbrooks99]

Re: Ball Gear Cracked

If there was NO Loctite, you can't blame the part! Installer error causes more 'defective' parts than anything else!

Or locktite on a rusty part? If they had not cleaned it well could that be the problem?

And if I can't get the splines cleaned back to solid metal I guess I need a new shaft?