Motorcycle Shaft Drive Gear Maintenance

Shaft Drive Gear Maintenance

There are two types of maintenance you must do on a shaft drive bike. At your rear wheel there are pinion gears where the spinning drive shaft motion is turned 90 degrees into the rear wheel motion. These gears are bathed in oil which much be changed after break in, and about every 10,000 miles thereafter. Honda says this gets done the first time at 12,000 miles. Don't believe it. Do it at about 1,000, and when you see what comes out you'll decide to do it again in about 250 miles to flush the rest of the garbage out.

Also, a shaft drive bike will have splines on each end of the drive shaft, and on a large ring which transmits the power to the rear wheel. These splines must be lubricated. This is a rather tricky subject, as the lubrication requirements of splines are very different from gears or bearings.

Gear Oil

• AMSOil AGL sae 75w-90 synthetic gear oil, about $8 / quart.
• Mobil-1 75w-90 synthetic gear oil, about $8 / quart at Autozone.
• Valvoline 75w-90 synthetic gear oil, about $8 / quart at Autozone.

Change Gear Oil

Put the bike on the center stand. Place a large flat metal pan under the real wheel, like a cookie sheet. This process is a bit messy. Remove the 17mm bolt on the bottom of the rear wheel hub. Next, remove the inspection plug, 17mm large bolt at the rear of the hub. If your drain plug is magnetic, make sure to clean it completely. Replace the drain plug. To fill, get 70 or 80 weight gear oil, and put it into the inspection hole until it comes back out. About 160cc, about 1/6 quart. You may as well buy good synthetic oil, a quart is good for 5 changes.

Spline Lubricants

Grease your drive splines each time you change your rear tire. The drive splines get surprisingly hot. Additionally, there's a lot of pressure on the splines and a lot of back and forth sliding motion. Any liquid type of grease will quickly be squeezed out of the splines, and leave you with no protection.

Honda specifies a spline grease which is 60% molybdenum disulfide ("moly"). Moly is a dry lubricant which bonds to the metal surfaces, offering lubrication properties even when the parts have squeezed everything liquid out. A lot of greases now say "Moly" on the container, but you must be careful about this. Ford and Caterpillar specify moly greases for particular applications, but the requirement is for 3% moly, not even close to the 60% requirement of Honda.

If you let a dealer or shop change your rear tire, be certain they are using Moly-60 paste or Krytox.

Moly greases with 60% + molybdenum disulfide:

• Honda Moly 60 paste
• LocTite Moly paste, 65% molybdenum disulfide.
• TS-70 Moly Paste

An alternative to moly is the new poly-flourinated lubricants made by DuPont called Krytox Teflon Bearing Grease. Nascar mechanics have found that Krytox grease can reduce the temperature of spline joints on drive shafts by 150°. Krytox is compatible with moly - in fact DuPont sells a high pressure Krytox which mixes the two.

Krytox greases:

• DuPont XHT-AC extra high temperature anti-corrosive Krytox.
• DuPont XHT-BDX extra high temperature extra bonding Krytox.
• LocTite Krytox HyperLube, pn 29711.

Spline Lubrication Process

With your rear wheel off the bike, the drive splines will be exposed. They're the brass colored bumps in the middle of the drive ring, above right. Clean off any factory stuff with a rag. You will likely need some solvent like Kerosene or Gasoline to get them clean. Now put Moly-60 paste or Krytox on the exposed splines. The idea here is to more or less paint the splines - you're not looking for a large volume of grease, like you would use on a wheel bearing. You want an amount of grease about the size of a pea. It's helpful to use a clean popsicle stick to spread the grease. Try not to get too much on your hands, neither the Krytox nor the Moly greases clean off very easily.

At the first tire change, you should also remove the rear drive system from the swing arm and clean and lubricate the splines on the drive shaft. After the first time, this should be done about every 50,000 miles or so.