SOLVED- Final Drive: How much noise is too much noise?

[Oklahoma_Valk]

Either something's wrong, or Im paranoid. Or both.

97 standard. 77k miles. Rebuilt the final drive last fall (7k ago) with new ring gear and wheel flange. U joint was OK at that time. Shaft and pinion cup looked great. Greased the pinion cup, moly'd the splines, changed the final drive oil. Tightened axle, tightened pumpkin.

I'm not sure why, but it seems I've got a whine. When the bike is in high gear, under LIGHT/EASY load, there is a definite whine coming from the pumpkin area. It's not the transmission whine. Im positive. It's most definitely coming from the rear.

The more the bike is under load/acceleration....the less I hear the whine. It dissapears under load. It does not sound like the clutch. It's coming from the pumpkin.

So my question....how much pumpkin whine is too much whine?

The nature of a shaft drive will always produce SOME noise, I understand.

[pancho]

"whine"  the word you used is what is heard from a helical cut gearset...... usually you do not hear any from properly setup helical cut gears run in oil. If you are hearing that whine, stop, check and see if you still have your hypoid rated oil in the case,, make sure it did not leak out.

You said you replaced the ring gear, I wonder if you replaced the pinion at the same time?? When either or both of these are replaced, there is a procedure that must be followed with selectively sized thrust washers on the ring gear, and selectively sized shims on the pinion to get proper clearance and riding position... it is not plug and play. If you are noticing this "whine" it must be louder than it was...... I would certainly stop and look into it.

[Oklahoma_Valk]

Thanks pancho. Makes me wonder.

I didnt replace the pinion gear, and didnt shim anything either. Im going to change the oil out and run it today, then if Im still having problems, I'll probably pull the drive off and diagnose.

[pancho]

Didn't mean to come off as a know it all,, only speaking from experience with similiar drives for other vehicles and what little I have picked up from the downloadable manual I was pointed towards by Thulsa Doom.. section 12-8 for the setup procedure..... When you hear the whine, it is time to stop and look,, I know that as a fact from experience.

[Ricky-D]

The biggest problem with whine from the rear end is that means there is heat being generated to an extreme.

The heat will cause the gear teeth to degrade among other things.

The rear drive cannot last long under those conditions.

***

[Grumpy]

If you only changed the ring gear and not the pinion, the rear should have been re setup to specs. The manual covers the procedure as to gear clearance, back lash etc. Putting a new gear with an old one  will throw all the clearances off. My self, I would tear it down and setup it to specs. if it is whining, the gears will not last long.

[Oklahoma_Valk]

Thanks for input guys. I'm going to tear it down.

Luckily, I have a spare drive on the shelf that's all original. Hopefully the rear wheel isn't chewed from the thrustwasher problem. I had no idea about the thrust washer shimming shannanigans until I read panchos thread.

Ride safe all

Okie

[Oklahoma_Valk]

Thanks to Grumpy, Jabba, and Pancho

The problem has been found.

When I replaced my ring gear and wheel flange last fall, I used the OEM thrust washer. The washer is 2.06mm in thickness. The 2.06mm is roughly the "middle" washer of the assortment sold by honda. My drive had absolutely no "thrash" or "slack" between the ring gear and pinion gear. To me, this means the thrust washer is too thick, and I should buy a few of the thinner ones (at $7 each, ouch) and try them until I find the one which allows the correct amount of slack between the ring and pinion.

Additionaly, the vent cap was clogged, causing oil to leak from the filler cap, and run the drive dry. The dryness caused the drive to whine at certain RPMs in certain gears.

All splines (wheel flange, ring gear, pinion cup) were in great condition, and lubed well. Orings were all in tact. Luckily, I think I caught the problem in time to avoid any damages to the ring and pinion gears.

Ordering new thrust washer assortments today. This drive will become my new spare.

Photos below.

Okie

[pancho]

Glad to hear it,, looks like you got to it in time,,,, number one cause of bevel gear whine.... no oil....  are   those vent caps pressed in??

[Oklahoma_Valk]

Vent cap was tac welded on. One little dot right at the top. The JB Weld will come in handy when time comes to re-install.