Sludge in old final drive oil

[ChrisMA]

Now that my 80 GS1000G is finally on the road, I've changed my secondary and final drive oil, following Basscliff's excellent instructions. I have no idea how long it's been since this was last done. The bike has just under 16k on the odometer.

The old secondary drive gear oil was black but looked otherwise clean (no noticeable debris). The final drive oil was also black, but there was some sludge built up on the drain plug. Assuming the plug is magnetic, then maybe that sludge was metallic. But maybe it's just oxidized oil buildup.

How concerned should I be about the condition of the final drive?

[bwringer]

I wouldn't worry about it - some very fine metallic "sludge" sticking to the drain plug is perfectly normal. Hypoid gears slide across each other a bit as they engage.

Plus, yours might never been changed.

Now, chunks of metal are a problem...

[ChrisMA]

Thanks, Brian - that's reassuring. I did look carefully for chunks / shavings, and found none.

[Brendan W]

I'm with Brian on this one.
It's likely it hasn't been changed at all, ever.
My forks, secondary and final had very picturesque sludge.
Do another change soon-ish and it will confirm whether you have an ongoing problem or just neglect that needed flushing.

[fastbysuzuki]

Regarding the final drive it may be the po has over greased the splines with moli grease and it has pushed through the oil seal into the oil and discoloured it (ask me how I know) I have not seen secondary oil black though, not sure how that has happened as said before change both oils and run it a while and drain again if there is a problem it will show.

[ChrisMA]

Thanks guys - I definitely will re-replace the fluid pretty soon. It certainly can't hurt, and will probably flush more sludge out.

As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning...

[Nessism]

Thanks guys - I definitely will re-replace the fluid pretty soon. It certainly can't hurt, and will probably flush more sludge out.

As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning...

There are tons of threads about how the shaft drive spline in the wheel strips out and how it's critical to grease the spline anytime the wheel is removed. Try searching on "moly grease" or "moly 60" and you will find tons of info.

[fastbysuzuki]

As for grease... I didn't see any specification for grease in either the secondary or final drive maintenance, but then, I'm still learning ...

the moly grease I mentioned as a possible point of oil contamination
comes from someone over greasing the splines on the final drive to rear wheel
when the wheel is put back in it can force excess grease under the oil seal and into the oil discolouring it

[ChrisMA]

There are tons of threads about how the shaft drive spline in the wheel strips out and how it's critical to grease the spline anytime the wheel is removed. Try searching on "moly grease" or "moly 60" and you will find tons of info.

Thanks, Ed - I haven't had the rear wheel off yet, but that's another thing to look at. I've started looking at the moly 60 threads.

So much to learn

[bwringer]

The molybdenum paste is actually abrasive to plastic and rubber seals, so the trick for greasing the splines is to get enough to protect the parts without goobering on so much that it gets crammed into the seal.

And yes, the paste on this coupling is mandatory, and I'd say fewer than 1 out of 10 motorcycle shops have any idea you should use a specific lubricant and not just ordinary grease. And I call it "paste" because it is NOT a grease; it's made specifically to prevent metal to metal fretting wear in splined couplings; it's not suitable for parts that move.

For reasons unfathomable, Honda shops no longer sell the 60% moly paste that was perfect for this. I'm not sure what they use on Gold Wings and such nowadays. The moly grease found in parts stores has a very low percentage of molybdenum, 6% or 7%; better than leaving the coupling dry, but mostly useless for this application.

I believe this stuff is the closest actually currently available equivalent (hopefully this link works):

https://www.amazon.com/Loctite-234227-LOC51048-Anti-Seize-Compound/dp/B001HWBSJW/ref=sr_1_1?s=industrial&ie=UTF8&qid=1537190041&sr=1-1&keywords=Loctite+234227

8 oz should last you about 50 years...

[ChrisMA]

The molybdenum paste is actually abrasive to plastic and rubber seals, so the trick for greasing the splines is to get enough to protect the parts without goobering on so much that it gets crammed into the seal. .... 8 oz should last you about 50 years...

Thank you, Brian - added to my shopping list. I'll take the wheel off at the end of the season and do a careful re-greasing. My bike is nearly 40 now, so the paste should last just up until it's centennial birthday. I'll be sure to add it to my will.

[Wingsconsin]

..... I'm not sure what they use on Gold Wings and such nowadays.

8 oz should last you about 50 years...

The 1800's are single sided swing arms and have no need for this lubrication -
As for ME - I bought 2 tubes of the old Honda 60 when I heard they were going out of availability -
So MY personal stock is deep in goo right now -
Seeing as I only use it on my GS now-a-days I think 2 tubes will last my lifetime
As for the Goldwing owners who did not stock up...