final drive running hot

[jilldwr]

I just changed out the wheel bearings on my 99 RSV (with 50k miles), then took it for a good 3 hour ride today. When I got home I checked around for heat from the bearings when I noticed how hot my final drive gets! I could touch it for say 30 seconds but any longer would start to burn my finger. I replaced the final drive oil with 80W90 gear oil in the spring.

 

How hot are these units supposed to get?? It was a 3 hour ride, so it perhaps should have been rather warm?

 

I noticed when doing the bearing job that theres a bearing visible on the wheel side of the pumpkin. Is this something I should replace? Or are the splines themselves causing too much friction? Are the splines replaceable or is this a matched set and do I buy a complete new pumpkin?

 

Is the stealer going to laugh when he sees me coming?

[dingy]

I just changed out the wheel bearings on my 99 RSV (with 50k miles), then took it for a good 3 hour ride today. When I got home I checked around for heat from the bearings when I noticed how hot my final drive gets! I could touch it for say 30 seconds but any longer would start to burn my finger. I replaced the final drive oil with 80W90 gear oil in the spring.

 

How hot are these units supposed to get?? It was a 3 hour ride, so it perhaps should have been rather warm?

 

I noticed when doing the bearing job that theres a bearing visible on the wheel side of the pumpkin. Is this something I should replace? Or are the splines themselves causing too much friction? Are the splines replaceable or is this a matched set and do I buy a complete new pumpkin?

 

Is the stealer going to laugh when he sees me coming?

 

It's gotta generate some heat. A beveled gear set isn't the most efficient form of power transmission. With loss of power, the lost energy is converted to heat. 30 seconds is a real long time to touch something before it gets unbearable. Around 115 F. the body reacts very negatively to heat rather fast.

 

The needle bearings on the outside of the final drive are not real easy to replace unless you are good with mechanics. As with any bearing, yes they can wear out, but not really often mentioned here.

 

No the dealer won't laugh, he will probably thank you !!

 

Gary

[jilldwr]

So I guess I can chalk this up as "normal operation".

Good to know, thanks Gary.

D.W.

[Guest tx2sturgis]

DW, those things get very hot, and that is why the gear oils and grease used in and around the drive units are rated at several hundred degrees before failure.

 

I once measured the outside housing after a one hour ride in moderately warm weather and saw a reading of about 185F with a small IR gun.

 

I believe the gear oil inside has to be reaching a high enough temperature to 'boil off' accumulated water vapor, so that means the gears are expected to heat the oil at or above about 212F.

 

So yes, its normal for the drive hub to feel quite warm to the touch after riding for a while.

 

 

 

 

 

[frankd]

Some of the heat comes from the gears turning in the 80-90W and in the process causing the oil to move or flow. This is known as pumping loss. Synthetic lubricant does reduce the heat. It won't run cold though.....But I did notice a difference when I put synthetic in mine.

 

Frank D.

[lonewolf96]

All gear cases create heat. Next time you're at a light behind a pickup on a rainy day check out the differential on teh rear axle. If they've been driving it very long the differential will create enough heat to make the water evaporate and the differential will be dry even in a downpour.

[GeorgeS]

Did you liberally !!! Greese all the gear surfaces on the wheel, and drive unit ??

Did you pull out the drive shaft, and greese the splines on the drive shaft ??

 

I'm assumeing you did.

 

Also this is interesting, as I had never really checked my rear drive for being hot after a ride, I'm going on the road in about 30 min. and will check it when I get back. Interesting

[skydoc_17]

I would expect a Final Drive to get well above 100 degrees under normal operating temps.

What I have seen is, the nose of the Final Drive being short, so when you tighten the four nuts that thread onto the studs at the nose of the Final Drive, The rear wheel axle is NOT perpendicular to the drive shaft axis. Yamaha actually makes a shim for this. I also make one. To check for this issue, raise the bike so the rear wheel is off the ground slightly, and level. unscrew the four acorn bolts on the nose of the Final Drive, give the rear wheel a shake, and see if the nose of the Final Drive pulls away from the Drive Shaft Housing. If it does, a shim on the nose of the Final Drive will return the Final Drive to perpendicularity, and reduce the heat caused by the binding Final Drive and Rear Wheel.

You can also see this issue in tire wear if your swing arm bushings are up to snuff. You will see scuffing on the outer edges of the rear tire due to the axle misalignment.

Earl

[jilldwr]

I had removed the drive shaft in the spring and greased the splines with Honda moly 60 grease. I then reassembled the final drive to the swingarm following the service bulletin instructions here: http://www.venturerider.org/forum/showthread.php?t=1705 I then used the Moly 60 on the wheel splines when installing the rear tire.

 

Earl, is the shimming procedure necessary even if you install the rear axle prior to tightening the acorn nuts on the final drive, as described in the service bulletin? Afterwards, I could slide the axle thru with no binding.