How hot should the final drive get?

[JeremyL]

I'm on my phone typing so can't do a lot of details but I just did a 70 mile one way ride to a family members for the weekend and when I was checking out the bike I noticed the final drive was very warm. Not like engine hot but hot enough so I could keep my hand on it only a couple of seconds before I had to pull away.this was after all 80-85mph interstate riding and the temp was 75 degrees and humid. what kind of alarmed me was that there was little drippings from the final drive on the edge of the rkm that spread out to the edge of the tire from centrifugal force. It wasn't soaked but I noticed it. I changed my final drive fluid a few months ago and I don't think its coming from the overflow or the drain bolt. Think its being flung out from the edge of the drive where the plastic cover is. But I might have greased those splines inside when I put a new rear tire on this spring.

Maybe its nothing to worry about or maybe its 2 miles from locking up on me at 90mph so I thought I better ask you guys. It makes sense the final will get warm but I dunnk about 'hot'.

[CaptonZap]

Pull the fill plug, and look down in there with the bike on the center stand. If you can see oil, you're good to go. The rear end will read from ambient to 150, depending on a lot of things. If it gets hotter than that, you will probabaly be able to hear it before it locks up.
The last group ride I went on, the temps over 8 bikes were around 135 deg F.
Wipe the rear wheel clean, and keep your eye on the oil slinging. If it was the grease, it will slow down and quit after a while. Next time you have the wheel off, you will be able to tell what it was. Just check the oil every now and then.
CZ

[WMarshy]

Not sure of exact temps but it will get hot, too hot to touch. Check you oil level with the proper dip stick.

[bikerphil]

The stock 11 FD gets pretty hot, the 850 mod drive not as much. Synthetic oil will run cooler, but more prone to slip past 30 year old seals. Keep an eye on the level, don't even need the dipstick, just look in, should be just below the threads.

[skids]

They put those cooling fins on there for a reason. They can get hot to the touch. I suppose that is related to efficiency losses disipated as heat (direct drive vs chain drive.)

[JeremyL]

Thank you guys!

I now am not too worried about riding back today. The FD isn't bone dry. I had a zip tie but no dipstick so I stuck it in and wanted to make sure it wasn't dry at least and when I pulled the tie out the bottom few inches had fluid on it.

When I noticed the grease streaks on the FD side of the rear wheel the other day I didnt get to ride for a couple of days and nothing is just dripping it's only coming out when riding. So I'm hoping it's just the grease I put on the inside the whatever you call it when I put rims on.

I figured it'd be warm because it's a moving part but I wasn't sure about hot and the leaks made me scared. A wheel locking up at 90mph on the interstate is a one of my worst biking fears.

[skids]

Make a dipstick. If you overfilled it, it will expell th extra oil (85W140 synthetic gear oil is what I use)

[JeremyL]

I ordered a factory one from some Yamaha dealer and i got a refund out of nowhere and no dipstick. The last time (and first time) I changed the rear diff oil was last fall. I put in some Lucas gear oil. Don't remember which but it was recommended on this site. 90wsomething maybe not sure. Then I'm about 80% sure I put some grease on the inside of the hub behind the plastic cover where the gears mesh with the wheel sprocket thing. I'm used to chain drive sorry. Anyways there's a gap between the plastic piece and the hub and I wonder if its flinging through there.

I'm pretty sure it doesn't leak sitting still, only after rides. And whats odd is that the little grease streaks is just like a light film.. you almost can't see it on the polished part of the rim but when you wipe your finger on it there's grease. Thought about wiping it down again really dry and clean and then putting a strip of masking tape over the gap between the plastic rear drive/wheel cover and the final drive casting itself. I don't know if it's for heat dissipation or just a part that doesn't fit well together. The gap is like 1/8" if not less. Enough for grease to come from. But will it hurt anything to tape it up and ride all day and see if the rim is coated again? Is it a vent?

[Tat2demon]

This is from CatanocBugs website. Printable dipsticks.

[motoman]

I ordered a factory one from some Yamaha dealer and i got a refund out of nowhere and no dipstick. The last time (and first time) I changed the rear diff oil was last fall. I put in some Lucas gear oil. Don't remember which but it was recommended on this site. 90wsomething maybe not sure. Then I'm about 80% sure I put some grease on the inside of the hub behind the plastic cover where the gears mesh with the wheel sprocket thing. I'm used to chain drive sorry. Anyways there's a gap between the plastic piece and the hub and I wonder if its flinging through there.

I'm pretty sure it doesn't leak sitting still, only after rides. And whats odd is that the little grease streaks is just like a light film.. you almost can't see it on the polished part of the rim but when you wipe your finger on it there's grease. Thought about wiping it down again really dry and clean and then putting a strip of masking tape over the gap between the plastic rear drive/wheel cover and the final drive casting itself. I don't know if it's for heat dissipation or just a part that doesn't fit well together. The gap is like 1/8" if not less. Enough for grease to come from. But will it hurt anything to tape it up and ride all day and see if the rim is coated again? Is it a vent?

IIRC, there's an O-ring in the hub housing that keeps grease on the splines from coming out.

[DGXSER]

What king of grease did you put on the splines?

[WMarshy]

That plastic cover is ther for aesthetics to my knowledge, it helps keep water and road grime out of the hub too. I've had a similar issue of grease coming out if it from hub splines. Just wipe your tire clean is about all you can do unless you want to take the rear tire off and wipe the excess grease off...

I supose the seal could be going bad but unlikely IMO.

[JeremyL]

This is from CatanocBugs website. Printable dipsticks.

I need to do that again. When I changed my rear diff fluid last Winter I used one of those but I didn't have card stock so it just wrinkled up and was hard to use. But it worked. Thanks for reminding me of the site.

IIRC, there's an O-ring in the hub housing that keeps grease on the splines from coming out.

I'm just going from months old memory but I just slightly remember seeing the splines and can't really remember an oring but that doesn't mean one wasn't there.

What king of grease did you put on the splines?

I don't remember exactly but it was just a little tub of generic axle/bearing grease I think. Nothing fancy like synthetic but it was a light tan color, like as light as fresh motor oil or lighter.

That plastic cover is ther for aesthetics to my knowledge, it helps keep water and road grime out of the hub too. I've had a similar issue of grease coming out if it from hub splines. Just wipe your tire clean is about all you can do unless you want to take the rear tire off and wipe the excess grease off...

I supose the seal could be going bad but unlikely IMO.

I'm not happy about wiping it but I was only really concerned because I was afraid something was leaking like the rear drive itself. And when I felt that the rear drive was hot after my ride I started worrying that the fluid on the rim was from the drive itself and now it was bone dry or really low and was overheating and would lock up and I would die after wrecking my bike on the Interstate and being ran over by a big rig... but I worry a lot

[Tat2demon]

I need to do that again. When I changed my rear diff fluid last Winter I used one of those but I didn't have card stock so it just wrinkled up and was hard to use

I folded it the long way so its like a V. Stiffened it up pretty good.