Gear Oil

[Air4Life]

What you all think about using 85W-140 gear oil in the transmission and rearward?

[Bob_Roller]

Is it a synthetic gear oil ?

[Air4Life]

No.

[Bob_Roller]

That may be a bit too heavy of an oil for your area .

[Air4Life]

That's what I thought.  I had the heavy stuff in it for this past summer and just recently switched to 75w.  

I just came back from a 320 mile ride at 65 mph most all the way.  I have always had a bit of weeping from the neutral switch, but I no longer can consider it weeping, its jumped into the 1/4" puddle category.  

I'm pretty certain its gear oil...  I thought that's what it smelt like.  Do you think the lighter weight would have it pour through the switch quicker?  I hope its not my main.

[Bob_Roller]

It's quite common for gear oil to leak through the 'innards' of the switch .

It's lousy design for a switch .

Motobins has an aftermarket replacement switch, I think Monte is the only member here that has one installed, so don't know if it's an improvement or not, but it is less costly if you order some other parts, to offset the shipping charges from  London (UK) .

[Bengt_Phorqs]

Moto Bins does have the neutral switch.  However you should know that there is an "Inny" and an "Outy".  BMW made the switch over in the Fall of 1975 about the time my R90 was made.  Unfortunately Moto Bins won't tell you that and shipped me the wrong one and won't take it back.  Send me a PM if you determine you need a switch.  I'll sell you my new and unused one at a fair price.  -Mike

[Air4Life]

How long can I leave the switch in there with this kind of leak?  I would think there would be a limit to the rate of leakage on these things, or could they possibly blow out completely, dumping all the contents in minutes?  I'd rather just check the oil level that much more if its not going to become a serious issue.

[Bob_Roller]

They usually don't fail and cause a massive leak, at least, i have not of this happening .

Usually you'll get fed up with the oily mess and change it .

[Air4Life]

Thanks Bob.  I guess I won't be parking it in anyone's driveway, anytime soon.

Thanks Mike.  If I understand you correctly, I'd have to determine which type it is by first pulling the old one out?

[montmil]

The OEM neutral switch has a crimped aluminum "flange" around the perimeter of a plastic switch body. The design eventually allows gear oil to weep past the crimp, puddle onto the engine "tray" and eventually find its way to ground.

My leaky switch on the "81 kept the lower-rear of the bike filthy. Replacing the switch, due to its location, is a royal PITA. The good thing is the bike now stays clean... er.

It's not going to blow out and dump the gear box oil but it does tend to make you park in the road when you visit your friends homes.  

[Barry]

Do you think the lighter weight would have it pour through the switch quicker?  

Probably would because it's a lot thinner and by a bigger margin than you might think.


At say an oil temperature of 50 Deg C

85W140 is approx.  190 cSt.  

75W90 is approx.  60 cSt


At 60 Deg C the difference is much the same. 85W140 is still 3 times thicker.


I think that except for hot climates 85W140 is grossly too thick for winter use. At 20 Deg C it's getting on for 2000 cSt and at 0 Deg C it's off the chart, something like 10,000 cSt. Must be like treacle. Try spinning the back wheel by hand in neutral when it's 0 deg C and the amount of oil drag will tell you all you need to know.
 

[Air4Life]

-- Thanks Monte, from what I can remember, that's the kind it is.  

-- Thanks Barry, your numbers are convincing, and had me running to Wikipedia for some history on cST.

http://en.wikipedia.org/wiki/Viscosity

http://en.wikipedia.org/wiki/George_Gabriel_Stokes


-- I think I'll just deal with it for now and wait till ready to do more chores related to that area.

From the quick read I did of the procedure, I suppose its safe to assume their is not enough clearance to simply spin the old one out?  Or is it getting the replacement started without cross threading that's the issue?  If its the latter I'd be willing to do away with the switch till next spring and SIMPLY put a threaded plug up there.

[montmil]

From the quick read I did of the procedure, I suppose its safe to assume their is not enough clearance to simply spin the old one out?  Or is it getting the replacement started without cross threading that's the issue?  If its the latter I'd be willing to do away with the switch till next spring and SIMPLY put a threaded plug up there.

My '81 had a leaky neutral switch that was annoying, to say the least.

Having grown up on several bikes that had the shift lever on the right-side, with up for low gear, finding neutral was just part of riding a motorcycle. Educate one's boot.

I cured the leak on the '81 with a new crush washer and a short bolt. Removing and replacing the aft motor mount bolt and its big, aluminum spacer is the chore.

Cross threading? As Grandpa Jones says on Hee Haw. "Don't do that."

[Bengt_Phorqs]

The response I received on the MOA Airheads forum is...
Most likely your bike is in the middle of the switchover. According to Tom Cutter, the "innie" switch 23 14 1 352 153 was used up to 9/75. The "outie" switch 61 31 1 243 097 was used from them on. The "innie" pushes in to make contact; the "outie" pushes out to make contact. The switches are designed to work with the camplates inside the gearbox.
So the R65's are "outies", which is what Moto Bins sold me.  Should work for you so let me know if you're interested.  -Mike