Sticky Bendix

[CamMan]

I've had a starter Bendix which would stick and frequently not engage the ring gear. When I took it apart I found a divit at the end of the channel or threads. I have dressed it with a small dremel tool, but I think it will reoccur due to a more fundamental problem. This Bendix has a new reproduction gear. I compared it to another Bendix with an original gear. The two photos show the comparison. The first one has the original gear and the 2nd is the one has the repro gear. When retracting, the original is stopped by the face hitting the edge of he spring. The repro is stopped by the Bendix running to the end of the channel or threads. This is not a good stop and creates a divit at the end of the channel. The last photo shows the end of the channel after I dressed it to remove the divit. Has anyone else run into this and what did you do about it? I think there is a problem with this repro gear.

[DanTreace]

Have experienced similar with earlier reproduction Bendix as the square tooth form on the shaft wasn't real nice, and this early one would stick on return from the flywheel.

Don't think the spring abutment is what returns the Bendix gear, but just the way the tooth form works. You should be able to fast twist the gear up the threaded shaft, and it should bounce just a tad to show its loose from the last thread. If the gear sticks and has to be hand twisted back, then the issue is thread sticking a the end.

For the fix of an early repro, I used some grinding paste along with a tiny bit of Dremel to make the last course of the square thread be even. The opening of the last thread root should taper up just slightly.

Noted on your photo that last tooth root ends in a dead end, that probably could be an issue with sticking.


Early repro Bendix on right with little bit of closed end and square teeth hanging up the gear travel, compared to Ford Bendix on left

100_1353.JPG (123.39 KiB) Viewed 1939 times

Freed up the last part of the square teeth for easy sliding return of the gear.

447183.jpg (99.04 KiB) Viewed 1939 times

Just received this new repro Bendix, on the brown paper, and right out of the wrapping it is pretty nice, and the gear won't stick at the end when twisted back quickly with hand force slinging it to the end of the threaded shaft. Working freely.

[CamMan]

Dan, I think my problem is different. Maybe my explanation wasn't clear. Unfortunately, I had already dressed out the divit before I took the bottom photo. Just pretend there is a divit there where it is now shiny. The divit made the Bendix a bit sticky in the retracted position. It must spin easily because only centrifugal force from the turning starter makes it engage. The Bendix retracts because the flywheel begins spinning faster than the starter, so it gets flung back until it stops. The original Bendix stops when the face hits the spring (no clearance in top photo). The new gear stops when it runs out of thread and this creates a divit at the end of the thread. I guess if no one else has had this problem, I must be the only one to receive a bad gear.

[CamMan]

I should probably have added. I believe the gear is a relatively new repro (maybe 5-10 years ago), but the shaft is from older production (no telling when).

[DanTreace]

Larry

Agree, must be issue of the screw shaft too, as the threads shouldn’t end in an abrupt stop, rather that last groove should be smooth opening.

The little drift pin should then be in the reduced section of the shaft. That keeps the gear from vibrating back towards the flywheel since the spring loaded pin is now expanded in the rear most section of the shaft.