P Ponk throwing belts

Stewartb said:
My B&C gear driven alternator on my Cub has a break-away shaft to prevent and engine damage from a seized alternator. I believe the Plane Power equivalent does as well.
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I would think most gear drive alt builders would at least have some sort of safety mechanism in place. I'm learning that's not always the case. I'm looking over engine re-build/maintenance costs on some of the planes that I might be interested in purchasing.
 
azblackbird said:
I would think most gear drive alt builders would at least have some sort of safety mechanism in place. I'm learning that's not always the case. I'm looking over engine re-build/maintenance costs on some of the planes that I might be interested in purchasing.
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Bad things happen when a gear drive assembly falls into the accessory section. So there is no way a gear driven alternator can seize and shear the shaft that holds them in place.

They will destroy the rubber drive blocks and allow the gear to spin on the shaft.

I've never seen one do that.
The larger Continentals 0-470 and up have a remote belt drive, where the Vee belt pulley is mounted to the oil pump drive shaft.
 
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UPDATE:

The manufacturer came to our hanger and changed out the starter housing as it had a 1/2" wobble to it. We only noticed it when we ran up the engine with the cowl off to 2700rpms. At idle it did not wobble. We honestly thought that would clear up this problem. I also had the prop dynamically balanced. It was out very little. We went with a 31" belt as the one that came from Steve was a 31.19 and it almost touched the max pull of the bracket.

NOW....... I am still having an issue with the belts but they are lasting between 4-6 hours. The last new belt was run 3.2 hours then re-tightened. The plane was flown again for 1.2 and today for 2.6 total hours over 2 legs. The belt came off about 20 minutes before landing at home. This time the belt was pretty tore up and had a few chunks out of it. Every time previously the belts looked new when they flew off. This belt was a 30" Continental and it looked pretty narrow compared to the rest of them. Maybe it rolled in the pully.

I'm at my wit's end!!!
 
What does the starter housing have to do with it? Have you tried a different alternator yet?
 
Stewartb said:
What does the starter housing have to do with it? Have you tried a different alternator yet?
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Some Continentals with belt-driven alternators have the pulley off of the starter adapter housing. The 310 that Cloud Nine used to own was that way, and I suspect the P-Ponk is as well.
 
OK ...... finally solved!
The engine was built at an authorized repair shop (Lawson Aviation) in Michigan. An unrelated event (bad jugs) caused me to return the plane to his shop to have the defective cylinder heads replaced. Upon removing the plane and setting the engine on it's nose, they noticed that the alternator pulley was off 1/8" but couldn't be seen when engine was in the plane. He replaced all 6 cylinder heads and fixed the pulley. Now all is well.
 
How was it off? like 1/8 inch radial run out? That would explain it all. Like was the pulley a 3/4 inch bore slapped on to a 5/8 inch dia shaft?

Or is it 1/8 inch axial run out (i. e. wobble)?

Somebody originally sure screwed up. How was it corrected?
 
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