Rear wheel drive gear oil change

[Taarne]

Hey there.

 

I drive a '99 R1100S with 32 000 kms on it. Lately, I've noticed that there's a small vibration coming from the rear end of the bike, so I decided I'd change the rear oil, since I don't know when it's last been done.

 

I got some Shell Spirax axle oil, 80W-90, API GL-5 and a whole bunch of other markings. This is the right kind, I assume? Well, out comes the drain plug, and the oil is pretty much pitch black. I let it drip for about 15 minutes, then put the plug back in and fill it with about 2,5dl of the new oil, so that the oil level is just up to the lowest point of the filler hole threads.

 

In neutral, the rear wheel spins freely. However, in first, with the clutch pulled in, the wheel doesn't spin quite as well, and makes a small, but audible noise. When I turn the direction the wheel is spinning, there's actually a rather big "klonk". I let it idle on the center stand in first, and when I gave it a little bit of gas, the bike jerks quite a bit. Needless to say, I didn't try that again.

 

I didn't take the bike out for a test drive, in fear of braking something very expensive. Please tell me I'm just paranoid? Any insights into the matter would be greatly appreciated

 

-Taarne

[MattP]

Sounds like you did the final drive fluid change correctly, and used the correct weight oil and spec.

 

Your description of the wheel spinning freely in neutral but dragging slightly in 1st with the clutch pulled in sounds spot-on to me. In the latter situation, you are spinning the transmission as well, so it makes sense that the resistance you feel would be greater. So far, so good from what I can tell.

 

Can you expound on your "the bike jerks" comment? It's hard to tell if you are experiencing a transmission problem, engine problem, clutch problem, or maybe no problem at all. Do you have any reason (other than the vibration you mentioned) to think it's the final drive? Is the "klunk" you mentioned coming from the final drive box? Also, year and miles on your ride?

[MattP]

oops, nevermind on year/miles, you mentioned it.

[Joe Frickin' Friday]

I got some Shell Spirax axle oil, 80W-90, API GL-5 and a whole bunch of other markings. This is the right kind, I assume?

 

Manual specs SAE 90 GL5, so what you've got is fine.

 

Well, out comes the drain plug, and the oil is pretty much pitch black.

 

Dark is not a big problem. Were there any chunks on the magnetic drain plug? Fine sludge is OK, and it'll even look like slivers due to the magnetic field, but you should be able to pinch some between thumb and forefinger, roll it around, and not feel any grit or lumps.

 

You say you don't know when this was last done. Did you buy the bike recently?

 

In neutral, the rear wheel spins freely. However, in first, with the clutch pulled in, the wheel doesn't spin quite as well, and makes a small, but audible noise.

 

In neutral, when you spin the rear wheel you're spinning the driveshaft, gearbox output shaft, and a gear on the gearbox intermediate shaft.

 

In gear with the clutch pulled, you're turning all of that, plus the gearbox intermediate shaft, plus the gearbox input shaft, plus the clutch friction plate, which drags slightly against the pressure plates (even with the clutch pulled). IOW, you're trying to move a lot more stuff, so it's natural for the wheel to turn less freely when in gear with the clutch pulled, and you might even expect to hear a smidge of gear noise with that greater load. That's all fine.

 

When I turn the direction the wheel is spinning, there's actually a rather big "klonk". I let it idle on the center stand in first, and when I gave it a little bit of gas, the bike jerks quite a bit. Needless to say, I didn't try that again.

 

Confused. Can you clarify?

[smiller]

The only thing that would worry me concerning your comments was the black oil and the vibration. Unless the oil was some odd variety of gear oil that was black to begin with then it shouldn't be that color. Also, vibration is bad, but tire vibration can often be confused with final drive problems.

 

I would carefully rotate the rear wheel with the rear caliper temporarily removed and feel for any roughness, and check for any crown bearing play (i.e. between the brake rotor and drive housing.) If it passes these tests I would check it and the oil again every 1k miles until I was satisfied that everything was OK. If it doesn't pass these tests then might be time to go into the final drive.

[Taarne]

Ok, went out to test it a little more, let me try to clarify.

 

When I turn the wheel one way, and then to the other direction, there is an audible clunck that sounds like it's coming from somewhere close to the rear wheel. The sound is quite similar to that you get when you turn the wheel in gear and then release the clutch. As long as I turn the wheel in the same direction by hand, there is no further alarming sounds.

 

I turned on the engine, and tried letting it idle in first.. It does seem to make similar sounds rather frequently, maybe once in 1-2 seconds, along with a vibration. Scares the hell out of me.

 

The oil was black, but it didn't look like there were metal bits in it, and the stuff on the drain plug was just a black sludge, no bits and pieces.

 

And yes, I purchased the bike last year, and have put about 4k kilometers on it.

 

-Taarne

[Ken H.]

This is normal. There is a significant amount of total drive line lash and without a load, i.e. rear wheel off the ground, as the engine pluses change, even minutely, it will show up as lashing back and forth in the drive train. TADT.

 

Ride, enjoy.