Why is there final drive oil on my tire?

[Guest]

I changed the final drive oil in my bike to 85w-90, and now the oil is leaking out of my final drive unit and onto my tire... Makes for some unsettling turns.

What could cause this? It's coming out of the seam where the final drive unit attaches to the rear wheel. I greased the splines with wheel bearing grease like I was supposed to, and it's not wheel bearing grease getting onto my tire. I posted about this some time back, but I wasn't around and wasn't riding my bike.

On the up side, my bike started easily after sitting for 4 months. Love me that chevron fuel (no stabilizer to gum up the carbs this time) and AGM battery

[Steve]

Are you SURE it's not wheel bearing grease from the splines?

Because wheel bearing grease is not the proper stuff to use on the splines.

The only proper grease to use is Honda Moly 60 or its equivalent.

.

[WilliamGLX81]

Yeah, unless the hi-temp wheel bearing grease is melting and dripping down the tire, and never returning to normal viscosity. It also smells like the final drive oil I put in. I should have re-checked my post about this before I left. Looks like there may be a seal for the splines. It's not leaking around the crush washers.

[tomcat24551]

William, very likely you have overfilled the final drive. The oil level is correct when you have filled the unit up to the BOTTOM of the filler plug hole. If you filled it till the hypoid lube ran out of the hole, you've overfilled it.

When it's overfilled, the oil level blocks the breather hole inside the unit, the pressure in the unit builds up, and then the oil gets forced back out of the top breather hole on the exterior of the unit (between the final drive and the wheel). Then it runs down and out onto the tire or the pavement. If you check carefully, you will probably see where the oil has run down from the hole towards the bottom of the unit.

Another possibility (probably not likely!) is that the breather passage is blocked internally. If you drain the oil again, blow compressed air into the exterior breather hole to make sure the breather passage is clear. If it's clear, the air will come out of the filler hole or the drain hole, or both.

What I've said above applies to the GS850 and probably the GS1000/1100G. Page 4-12 in the GS650G shop manual shows a breather passage that is similar in design to the 850 and it appears that a too-high oil level could block the return oil hole.

Hope this helps.

[Nessism]

William, very likely you have overfilled the final drive. The oil level is correct when you have filled the unit up to the BOTTOM of the filler plug hole. If you filled it till the hypoid lube ran out of the hole, you've overfilled it.

When it's overfilled, the oil level blocks the breather hole inside the unit, the pressure in the unit builds up, and then the oil gets forced back out of the top breather hole on the exterior of the unit (between the final drive and the wheel). Then it runs down and out onto the tire or the pavement. If you check carefully, you will probably see where the oil has run down from the hole towards the bottom of the unit.

Another possibility (probably not likely!) is that the breather passage is blocked internally. If you drain the oil again, blow compressed air into the exterior breather hole to make sure the breather passage is clear. If it's clear, the air will come out of the filler hole or the drain hole, or both.

What I've said above applies to the GS850 and probably the GS1000/1100G. Not sure about the shaft drive GS650.

Hope this helps.

Good advice here. Over filled final drive would be my guess.

Wheel bearing grease is no good for the splines. You need some high moly grease special for the application - Honda makes the best stuff that is commonly available.

[jbs80106]

William, very likely you have overfilled the final drive. The oil level is correct when you have filled the unit up to the BOTTOM of the filler plug hole. If you filled it till the hypoid lube ran out of the hole, you've overfilled it.

Hope this helps.

Thats what I was thinking too. Easy enough to check the level through the plug hole. Cleaning the oil off the tire, making sure it's not on the brake rotor and pad. If suspect on the brake pad, you can take it off, pour on some alcohol and try to burn it off....

[WilliamGLX81]

Thanks for the replies guys. I was just thinking today how much I'd like to go for a ride, and the oil issue.

I'll get ahold of the high moly grease. Dare I ask why it has to be high moly?

The leak's on the side opposite my single rear brake, so I think the brake pad's going to be clear.

If it's overfilled when fluid runs out the fill hole, then it's definitely overfilled. Should I just drain a little fluid, clean everything up, and see if it's still leaking? I don't think the passage is internally blocked. It didn't leak after I r/r'ed the rear tire, only after I (over)filled the hypoid gear.

[BassCliff]

Hi,

Check out this page: http://motorcycleinfo.calsci.com/Shaft.html#Splines . Look under the "Spline Lubricants" section.

The spline gears need a grease that will withstand high heat and pressure. The high moly content grease is just the ticket.

I agree that you should fill the final drive to the proper level and keep an eye on it.



Thank you for your indulgence,

BassCliff

[raistian77]

I cheated I used Lucas high temp high pressure grease, we use it at work in the hydroseeders, works great.

[WilliamGLX81]

Thanks guys. I checked out the Moly lube the other day.
I see the reason for it. And why a high-temp grease won't work well at all, even if it has 3% moly.

So... I don't understand what you mean about the lube being to the bottom of the fill hole, but not leaking out. Isn't the difference only a few tablespoons? If so, I may have lost that much already. It's been raining for the last 3 days, so I've been twiddling my thumbs indoors and want to get it fixed asap.

[WilliamGLX81]

WHOA!

I should have put in only 200mL. I put in quite a lot more than that.

I'll drain, refill, and that should take care of it.

200mL is about 6.75 oz's, which is about 3/4 of a cup, and is about 1/5th of a standard size bottle of gear oil.

Happy rides

[Steve]

WHOA!

I should have put in only 200mL. I put in quite a lot more than that.

How did you manage that?

Since oil will start coming out the fill hole, it seems that it would be hard to put in much more than that
unless you laid the bike on its side so the hole would then be on the top of the final drive unit.

.

[Nessism]

As tomcat said, the oil should only be filled to the bottom of the threads, not until it comes out the top of the threads. Measuring is a good idea but just be sure you have the correct amount.

[WilliamGLX81]

I squirted as much oil as I could into the fill hole, and as far back as I could, to the point that it was leaking out the fill hole, and quickly popped in the drain plug.
Sounds like the people who overfill their car's oil thinking more is better >.<

I don't understand how it can come to the "top" of the threads. That seems a little impossible.

From what I remember, 200mL doesn't seem like it would be anywhere near the bottom of the fill hole threads.

I'll post back when I've picked up my oil and figured this out tomorrow.

[tkent02]

Dunno how it works, but my 850 leaked all over the tire when I got it, it was to the top of the threads. Drained and refilled to the bottom of the threads, hasn't leaked a drop since.