The Cessna 120-140 Association Forum

Periodically the ring gear will be in an orientation such that the stater pinion will not travel it's full 7/16"

The teeth on the ring gear and starter pinion are meeting without meshing. Ends up being a 'safe' condition as there is no way this amount of travel will allow contact and energizing the starter.

Fix is simple, just move the prop a half inch and make sure the starter pinion can travel 7/16" prior to contacting the switch in the final 1/8" inch.

I don't remember this being a regular issue in other people's 120/140 that I've flown. Anyone else get this condition too?

It's part of the design. If you continue to pull the handle, a spring inside the starter drive compresses, putting more pressure on the pinion gear. When the switch closes and the pinion starts to turn the spring forces the gears into engagement as soon as the teeth line up.

Don't have this condition on my C120 with pull starter. I pull in two steps - pull out until resistance is felt, then "pull through" to start it spinning. I.e., not a continuous pull from panel to running.

For those still running with pull starters - Aerotech indicated that at the moment there are no overhaul parts for the CAM1971890-R clutch. They can't overhaul them anymore and they said they thought Niagara was in the same spot. Anyone can confirm?

edidin wrote: ↑Sun Dec 31, 2023 1:48 pm...
For those still running with pull starters - Aerotech indicated that at the moment there are no overhaul parts for the CAM1971890-R clutch. They can't overhaul them anymore and they said they thought Niagara was in the same spot. Anyone can confirm?

About 6 months ago Niagara's webpage had a notice that they were selling out the remaining stock of the clutches. Now, the webpage doesn't show the clutches at all. One reason I'm switching to a B&C starter during my current engine overhaul.
Josh

6643 wrote: ↑Sun Dec 31, 2023 1:06 pm It's part of the design. If you continue to pull the handle, a spring inside the starter drive compresses, putting more pressure on the pinion gear. When the switch closes and the pinion starts to turn the spring forces the gears into engagement as soon as the teeth line up.

Thanks John. In the past I've had that experience and always hated the sound it makes in this case when the teeth ker-chunk and start turning the crank over. I guess that's just the way she goes.

8413 wrote: ↑Sun Dec 31, 2023 3:16 pm

edidin wrote: ↑Sun Dec 31, 2023 1:48 pm...
For those still running with pull starters - Aerotech indicated that at the moment there are no overhaul parts for the CAM1971890-R clutch. They can't overhaul them anymore and they said they thought Niagara was in the same spot. Anyone can confirm?

About 6 months ago Niagara's webpage had a notice that they were selling out the remaining stock of the clutches. Now, the webpage doesn't show the clutches at all. One reason I'm switching to a B&C starter during my current engine overhaul.
Josh

Seems we are just about at the end of an era. Thank your all for your input.

on my former c120 with a pull starter, when i check my oil, i would pre-engage the starter, to line up the gears, so when i start it, its fully engage when i pull the starter cable

VIP620 wrote: ↑Tue Jan 02, 2024 8:22 pm on my former c120 with a pull starter, when i check my oil, i would pre-engage the starter, to line up the gears, so when i start it, its fully engage when i pull the starter cable

I always did the same during my preflight at the beginning of the day. On followup starts while I'm out and about I don't do this as I felt like I was trading wear and tear on the gears for wear and tear on opening the hood latches over and over. The hood is already open during the preflight to check the oil and engine, so no extra opening going on there.
Josh