The Stovebolt Site Forums The Shop Area The Electrical Bay Starter-Motor Drive Question

I have a 1958 Chevrolet 235 engine, that is in a 1946 Chevrolet 1-½ ton Utility. 6 Volt Starter, 12 volt system. 216 flywheel, 216 starter motor.
My question is, when I go to start the engine with the foot stomp, the starter engages correctly, smooth and turns over for at least 2-4 revolutions. On particular occasions, primarily cold starts, if I adjust the choke, or just let the engine rest, or even on first attempt, the starter-Motor Drive engages the flywheel, but during the crank it releases as if it thinks the engine has started, but it has not. In doing so, the starter-motor continues to rotate until I release my foot from the pedal. It sounds like, ruump, ruump, ruump pak-ching zoom. I think it may be the starter-motor drive mechanism. Dose this sound correct? I checked the flywheel, and it has no missing teeth. I pulled the starter apart, but am unable to see any problems with the drive gears, or clutch mechanism.
Am I on the right track?
Thank you,

Dale

Sounds like the starter drive (clutch) is weak and kicking out. Napa should have a replacement.

Thank you gtow69,

I think we are on the right path. I recall somewhere it being called a “Bendix” drive unit too. I will check with NAPA and see if they are available.
Dale

Dale if you have a weak cylinder ie burnt valve etc the starter will speed up on that cylinder disengage and then reengage
kinda crank - zing - clunk (bendix reengages) - crank. I would run compression check first.


Dan Bentler

Put a new drive on the end of the armature & you will solve it. Put a little grease on the bushings & the arm. shaft. This part is often called a Bendix but it actually is called a starter drive or over running clutch. The original Bendix type was used many years ago. It had a big spring on it that broke sometimes &was called a Bendix spring

Your starter drive/clutch is slipping and needs to be replaced. Inside the drive is a cam and roller setup that locks when it turns in one direction, and releases in the the other direction. If the rollers or cam get worn or the springs break, the clutch won't engage properly and the starter acts as you describe.

That drive type is an over-running clutch that prevents the starter armature from over-speeding when the engine starts, because the drive gear remains engaged with the flywheel until you release the starter pedal, or solenoid switch if you have a solenoid starter.

A Bendix drive is a different drive that uses acceleration of the starter armature to drive the gear along a spiral spline on the armature shaft and into the flywheel. Sometimes the gear engaged with pretty hard clash. Bendix drives use a spring to disengage the starter drive gear when you release the starter switch, but the Bendix drive also disengages the drive gear by 'unwinding' the drive gear, so to speak, along the spiral spline on the armature shaft when the engine starts. The Bendix drive would also disengage if one cylinder fired, but the engine didn't start and run, so starting a balky engine could be a frustrating experience- you had to let the starter motor stop almost completely before the Bendix drive would engage again. They were also called an 'inertia drive' because they used the armature acceleration to drive the starter gear into the flywheel.

Bendix drive starters haven't been used for several decades, but were common on vehicles prior to about the mid-1950s, although I don't think Chevrolet ever used them. Delco-Remy did make some Bendix-drive starters, I believe, but I don't know if any GM vehicle used them. Bendix-drive starters were mostly made by Electric Autolite and Ford, maybe some others.

As a bit shop-talk history, replacing the 'Bendix' was the common reference when replacing any starter drive, regardless of the starter being a Bendix-drive or an over-running clutch type-- in case anyone is interested in that tidbit.


Harvester

Wow,

I am impressed to the knowledge of all out there. I did try a prior search on this subject, and came up empty, but when I posted not only have we nailed down my problem, but I now know the difference between a Starter Motor Drive unit and a Bendix-Drive Starter.

As for the compression test Dan, no re-engagement from the starter motor. Once it releases from the flywheel the starter-motor just keeps spinning. I understand the principle you explained and it makes good sense. Although, once I get the engine back together, as part of the tune-up process, I will do a compression check, before and after adjusting the valves. This truck has been sitting, abused and pushed around by lazy and inconsiderate yard folk, kids with rocks and bb-guns and the weather since the 70’s.

Thank all of you for assistance.


Dale