split pinion gear

[bildit4u]

Who else has experienced this, the pinion gear in my lower unit split, and a piece of the gear punched through the side of the gear case, the pinion gear nut, and its still tight on the end of the driveshaft, spin inside the split pinion gear. This is a Merc 4 3/4" gearcase with a Bobs low water pickup, I was running the propshaft 1/4" below the pad on a Baker Mod VP tunnel hull, I had a 15x29 4 blade ET prop thats had a little more cup added to it. The question is why did the pinion split. My thoughts are a big prop surface piercing for one, and the other maybe a weak pinion gear, these gears were RED RHINO gears and they had only about 4 hrs use on them, the mesh pattern on the gears looks perfect. If its weak gears where can I get a set of gears that will handle this type of use or maye some would call it abuse :thumbsup:. The motor is a modded 2.5 Merc carb. and I was only turning around 6000 rpm at about 80 mph when I felt the gears let go, the interesting thing about this incident is at about the same instant that the gear broke and the boats G force droped of I was cutting the motor off so I could do a plug reading, timing was perfect , the motor never even got a chance to over rev. The gear ratio is 1.87, any thoughts on the cause of the failure would be appreciated. Thanks again.

[Specialized P4-12]

dude u need some hardened gears if ur going to realy beating it up.. sporty or late cle.. the stockers arnt hardend although i have never seen that happen to a merc stock gear and we beat them up pretty good.. sounds like u got some bogus gears...

[T-REX]

Chit happens!!!!

Not a good answer, but az close to the reel answer az U kan git....If it'z mechanikle, it iz gunna break if it's used enuff....1:87 geers are tuffer than most, but big diameter props, surface operation, and possiblly a flaw'd geer set, can all contribute to a failure.....If this has happen before, or more tha a couple times, U better start look'in for anuther case.....U need a CLE for that tug bote prop!!!

[LARRY D]

If the pinion gear nut was over torqued or the loading and off loading of the gearcase with a big prop in rough water. But could be a bad gear also. later Larry D

[6Killer]

....these gears were RED RHINO gears.......

What is a RED RHINO gear? If it isnt a gear from the OEM, chances are it is made from lower cost steel (8620 VS the 9310 Merc makes them from). You get what you pay for. Stick with Merc stuff. Now you know why.

[T-REX]

. Stick with Merc stuff.

Dat kumm'in rite out tha hed ov a sukka dat bleed's OMC geer oil instead ov blood!!:D :D ...LOl.......Don't OMC use Red Rino geer'z???....;)