Classic Motorcycle Build

Sportster Bendix Gear (Remove and Install)

Text and Pictures by Mark Trotta

On an Ironhead Sportster, the bendix drive gear is located in the starter housing between the starter motor and clutch ring gear. Replacement requires removal of the starter motor from the right side of the bike, and the primary cover on the left side.

Sportster bendix gear

What Is A Bendix Gear?

A bendix gear (also called a starter drive) is a mechanism that allows the pinion gear of a starter motor to engage or disengage the ring gear. It's named after American inventor and industrialist, Vincent Bendix.

Think of a bendix gear as a hand-tool ratchet. It can rotate freely in one direction and lock itself in other. This allows it to rotate one way to start the engine when engaged, and then free itself once the engine starts.

Sportster bendix drive replacement

This style of starter drive has several drawbacks. The starter can still spin without engaging the flywheel, or it can jam during engagement. And if the engine kicks back while you try to start, it forces the gear to turn backward, damaging it.

There are springs and ball bearings inside the bendix gear, and with age and usage the springs break' This will allow the gear to turn both ways, making it inoperable. When this happens, it will "whine" when trying to start the motor.


Ironhead Bendix Drive Removal

On the right side of the bike, remove the chain sprocket cover. Remove the cable from the starter motor terminal. The starter motor is removed with two long bolts.

remove Sportster starter

And then switch over to the left side of the bike. The pinion drive assembly is on the inside top of the left engine case.

remove and install Sportster bendix gear

Depress the retainer cup, and remove pin from hole in plunger shaft. Remove the spring. Remove attaching bolts.

The fork that holds the pinion gear assembly in place is called the starter pinion lever. Rotate this until the fingers clear the pinion gear shifting collar, then remove.


Remove Bendix Gear From Shaft

After you have the pinion gear assembly off the bike, place it between copper jaws in a vise. Tighten only until its snug.

CAUTION: The pinion shaft is left-hand thread. Unscrew the nut from the shaft.

Remove and replace bendix gear assembly on Ironhead Sportster

The pinion gear assembly in order of disassembly is left-hand nut, bearing race, pinion and shifter collar.

Remove the lock ring to separate gear and shifter collar.


On several-year Sportsters, including my old 1976 XLH, the primary chain and clutch assembly have to be removed to replace the bendix gear drive. There are many extra steps necessary for this, and specialty tools are required. A service manual is helpful.

Ironhead Sportster with primary cover removed

If your primary chain needs to be removed, see Sportster Primary Chain Removal.


Bendix Gear Replacement

The bendix drive I purchased and installed on my 1976 Sportster is a V-Twin #32-0639. It replaces HD #31443-65A and fits 1967 through 1980 Harley Sportsters. It also fits 1965 through 1988 Harley Big-Twins.

replacement Sportster bendix gear 31443-65A

Shop: Bendix Starter Drive Gear

Sportster bendix gear 31443-65A

The replacement part was a little different looking than the factory original, but it fits and works fine.


Bendix Gear Re-assembly

TIP: Put a dot of Red Loctite on the shaft nut when reassembling the shaft assembly.

Spin the assembled shaft in the bearings to check for free movement. Stake the starter shaft housing washer.

Harley Sportster starter shaft housing diagram

The rest of re-assembly is the reverse order of disassembly.

TIP: Before you put the starter back in, this would be a good time to replace the rubber oil lines.


Related Articles:

Sportster Primary Chain Removal
Ironhead Clutch (1971-1984)
Ironhead Special Tools
Ironhead Engine Build
Sportster Hitachi starter

Read: Electric Start Ironheads