Refilling the Airhead Swing Arm

[montmil]

I have not yet found a reliable -at least for me- technique to check the gear oil level in the swing arm. To be sure, I just drain and refill with the stated 150cc. Per Mr. Clymer, same volume for all Airheads except for the short wheelbase /5 which takes 100cc.

Draining the warmed gear oil is not too bad as long as you can keep that stinking lube off the rear tire. Refilling usually means cleaning up excess gear lube that gets past whatever method I'm trying. The refill hole location is just a pain, until...

Harbor Freight has a set of five funnels for less than a buck when they're on sale, which is almost always. Each has a small tab with a hole in it. I've discovered what the tab is useful for. The smallest funnel fits the fill hole and can be secured to the shock spring with a small zip tie. It's still a tight area to work in but by using small, graduated medicine cups and keeping track of the volume added...

No drips. No runs. No errors.

[Barry]

Funny you should mention transmission oils as I just did all my last week.  I do the same for the drive shaft pouring in 120cc as for mine any more migrates to the final drive.

You know how satisfying changing engine oil is  - black oil out and nice new amber oil in feels very worthwhile.  And the old oil looks to be fit only for the refuse depot.

When I did the transmission oils it felt like a waste of time and the oil looked far too good to be chucked away.   I've been changing at 2 year intervals but with only 2000 mile per year that's seems far too soon.

Final drive oil came out looking brand new with no fuzz at all on the magnet.

Gearbox oil only slightly darker and a very small amount of smooth fuzz on the  magnet.

Drive shaft oil similarly clean and new.

When you consider modern cars have transmissions and final drives filled for life our airhead service intervals look a bit ridiculous. Not that I believe in fill for life as I intend to do a 50,000 mile change on my car.  But there's still a big difference between 50K and 4K so I've decided I'm going to change the intervals.

I'll check levels every year but not do a change unless I see water contamination though I never have over the years.

Final drive  oil is staying in for 12000 miles or 6 years which ever comes first

Gearbox oil is staying in for 6000 miles or 3 years

Driveshaft oil I will do annually just because as Monte points out you can't check the level.  

It's not about the cost of the oil which is insignificant, it just seems wasteful to be  chucking away perfectly good oil.

[Tony Smith]

I simply drain the blasted thing, which gives me an eclectic means of determining if I am gettign too much leak-through into the final drive, and then refill with a measured 150ml from a horse syringe with a bit of plastic heat bonded where the needle would have gone - been using the same one for near 30 years.


If I may digress onto another topic. If you are getting excessive leak through from shaft to final drive, do not necessarily blame the seals. In fact it is unlikely to be the seals fault, they are in a closed environment, drenched in oil and will likely last forever - but they cannot do the job alone.

Next time you have the final drive off make sure that the drive cup is absolutely full of grease before inserting the final drive - the more grease the merrier in fact, much as you can get in there.

Chances are your leak will stop.

[thrang]

I use to a couple of 200cc Vet's syringes with a off cuts of 5mm bore beer line over the needle holder leading the filler hole. This lets me fill the transmission components accurately and with out spilling any oil. I also use the same system for the forks.

[Bob_Roller]

The BMW shop manual makes a statement, that upon reassembly of the final drive, place a thread sealer on the threads if the input shaft, before installing the nut .
Oil can migrate through the threads, I wouldn't think that much heavy gear oil would make it's way past the threads, but what do I know !!!

Tony, what type of grease do you use, like a wheel bearing grease ??

[Tony Smith]

Tony, what type of grease do you use, like a wheel bearing grease ??

waterproof trailer bearing grease. It is designed (allegedly) to go in boat trailer bearings and to survive multiple dunkings in salt water. I like it because it is "soft" and easily worked in, and it really does seem to hang in there (at least I have not had to replace trailer bearings as often as I used to) The brand-name will be useless to you "ChemAlloy" they are nothing more than a branding house who sell a lot of boutique products obtained from other sources and re-badged as their own.

[georgesgiralt]

Hello !
We ask for transmission oil to make a thin and very sturdy film of oil under extreme pressure at the gear teeth.
What is different in a thread with a nut on it ? Contact surfaces "sealed" one to another with high pressure sealing them. Therefore, it is normal for this oil to snug in !
Worse than oil for gears is watchmaker oil. It follows the bottle vertical walls, find it's way through the cap thread and leak outside the bottle ruining the label. This process takes time but it is known !
Oil can be funny at times.