gear lube

[beep]

What is the best weight to use, for gears 90 ???

[bradthreee]

The dealer suggested I use 10W-40 Honda Motorcycle oil for the gears.

I've often heard others on the forum suggest 10W-30.

[Wheelman-111]

Greetings:

Maybe Honda-san had his reasons for using regular multi-weight motor oil? It's a low-stress application. You could probably use Mazola, but motor oil's cheap, available. You only need 3 Fluid Ounces - 90cc. Don't overfill.

[Kenny_McCormic]

Why not overfill?

[Bear45-70]

Because you need the air space in there so when it gets hot and everything expanses you can compress the air. Oil just does not compress, at all.

Oh and using 90 weight is over kill for protection and will slow the scooter down due to a super increase in drag from the heavy oil.

[Kenny_McCormic]

I know oil expands and doesn't compress but it has an open vent tube, so it should just puke if truly overfilled?

[eclypse]

Should of seen the trans on my 01 SA50 SR Elite i bought from a guy.. I didnt take the drain screw off for a couple of weeks and boy was i shocked to see all that oil coming out. I believe the guy had the thing maxed with oil! Took forever to drain it out.

I was worried that something would be wrong as my old man was telling me that there was probably tore up gears or something in there as the reason to over fill it to hid the evidence.. but it sounded fine.

[Wheelman-111]

Greetings:

Reasons not to overfill, in no particular order:

1. The roller bearings are splash-lubed. If you overfill, the bearing becomes "draggy". Furthermore,

2. the plain bearings on either end of the countershaft are lubricated by that little trough carved into the aluminum metal socket.


(You could see this if I could remove the countershaft gears and look behind...)

As the shaft spins, it "draws" oil into the bearing surfaces and creates a continuous flow of fresh oil through & around itself. If you overfill, you lose that circulating phenomenon. The same oil goes round and round, getting hot. I suspect the 3-oz. level keeps the oil just at the lower rim of the bearing socket, keeps fresh juice constantly flowing.

3. Probably not a big issue with this vented case, but smaller airspaces compress up higher and can blow by seals.

[Kenny_McCormic]

Makes sense enough.

[elited]

I put an extra 1/2 - 3/4 of an oz extra in mine a while ago when i changed the gear oil, no change in performance and everything is good.

[Lunytune]

Reasons not to overfill, in no particular order:

1. The roller bearings are splash-lubed. If you overfill, the bearing becomes "draggy". ..................
As the shaft spins, it "draws" oil into the bearing surfaces and creates a continuous flow of fresh oil through & around itself. If you overfill, you lose that circulating phenomenon. The same oil goes round and round, getting hot.
3. Probably not a big issue with this vented case, but smaller airspaces compress up higher and can blow by seals.

Sometimes at the parts store, you will see a display of the latest "gimmick" additive, like STP, with gears in a clear plastic container. The oil and gimmick in the bottom. Turn the gears and watch the oil travel up the gears. It's a perfect example of the way oil travels "up" as gears turn...

Ever notice that in auto/truck transmissions (manual) and rearends, the fill hole is about 1/2 way, not at the top to cover "all" the gears? It's hard to overfill a rearend or transmission without making a mess. Same should apply to a scooter. Don't make a mess, and do it with scooter level. Also, car rearends and transmissions have a vent. The scooter vent is not real classy, just a piece of plastic tubing, but it does vent to avoid pressure buildup.