My mechanic found a broken tooth on one of my lower gears. There were no symptoms- it was opened to change the prop shaft seal which was worn, although the case was still holding 15lbs of pressure. Here's my question- the mechanic is recommending tearing down the upper and replacing all the bearings in case metal has contaminated them. Another mechanic I talked to who is very experienced w/ TRS's says breaking a lower tooth is common but he's almost never seen it cause a problem w/ the upper bearings. Do I spend the extra grand tearing down the uppers or just rebuild the lower??

I guess the problem here is that it isnt like you blew the lower gear, shut it down, and disassembled the drive. Sounds like the gear has been going bad for some time and you were running it. I'd be fairly certain that the metal has caused some bearing damage or upper gear damage. If it were me i'd open the whole drive up and see what you got.

I haven't seen it myself, but I'm told by the mech. the cap's been pulled and the upper gears look fine. He's recommending new bearings only, upper and lower as a precaution. I want to fix it right, but I hate to spend $ needlessly -there's always a hundred other boating things I can spend money on. I guess what I'm struggling with is if a gear tooth sheared off cleanly in the lower, which I'm told by a very experienced TRS mec. is very common (Jim at Dubbarts in Port Clinton OH) , what are the odds that any serious metal migrated all the way up the case? Thanks for the input, and by the way- I have a 357 SR-1.

If the broken gear piece was located, then I'd just rebuild the lower. If not, I'd probably bite the bullet and have it all gone through to be on the safe side.

The TRS has a very efficient oil pump (the pump is the coupler, lower to upper) I've blown many TRS drives over the years and when they break, the metal goes everywhere and fast. I've never seen one break without denting the bearing races badly from the debris.

I'd check the case thoroughly as when they spit out a tooth, the case usually gets stretched and the gear contact pattern will be poor. You are very lucky it did not go through the case.

Kurt