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B&S 16.5 hp engine on my Murray lawn tractor. My parts manual lists 3 pinion gears based on the ring gear. I'm assuming it's not steel since a magnet doesn't stick to it but how do I know which it is for sure?

timoth said:

B&S 16.5 hp engine on my Murray lawn tractor. My parts manual lists 3 pinion gears based on the ring gear. I'm assuming it's not steel since a magnet doesn't stick to it but how do I know which it is for sure?

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Well you know its not steel because of the magnet. You should be able to tell the difference between plastic or aluminum by just scratching it. Aluminum will be a silver color. plastic can be any color and as a rule not silver.

The pinoin on the starter for the steel ring gear is made of steel. the pinoin for the plastic and aluminum ring gear is plastic. At one time the aluminum and plastic used the same pinoin, then Briggs went with one plastic pinoin gear for the plastic ring gear, and another plastic pinion for the aluminum ring gear. As of late they are back to using the same pinoin for both the plastic and aluminum ring gears. So I suspect if you look up the supercessions for both the plastic pinoins in your manual they will now cross to the same part number.

At one time both the plastic and aluminum used the 280104S starter pinion. that later became 693058 for plastic and 693059 for aluminum. The 693058 and 693059 both supercede to 695708

From the parts list I found on their website, I see three different gears. The ring gear is the same color as the flywheel and I assumed at first that it was steel also but since it fails the magnet test I was hoping something in the model, type or code would tell me which it is. There's nothing aluminum colored so I guessing it's plastic. From what you're saying, it probably doesn't matter as long as I don't use the steel gear. Thanx for the heads-up.

timoth said:

From the parts list I found on their website, I see three different gears. The ring gear is the same color as the flywheel and I assumed at first that it was steel also but since it fails the magnet test I was hoping something in the model, type or code would tell me which it is. There's nothing aluminum colored so I guessing it's plastic. From what you're saying, it probably doesn't matter as long as I don't use the steel gear. Thanx for the heads-up.

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Yours has a plastic gear ..I called my parts supplier because I needed one also ...When u call yours in take your model number they can cross reference it ..Well most of them can