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moll780

Well Known Member
I've had to replace the tach drive a couple of times and the last time it broke I wired my D10A into the p-leads for a MUCH better experience.
My question is; I've left the tach drive in place and I've seen an aluminum anodized cap for 40$ but does anyone have any ideas of cheaply purchasable or modifyable parts to cap the drive off safe and reliably?
 
There is an internal seal within accessory case for the tach drive. The cap is only a dust cover to keep dirt out.
 
moll780 said:
I've had to replace the tach drive a couple of times and the last time it broke I wired my D10A into the p-leads for a MUCH better experience.
My question is; I've left the tach drive in place and I've seen an aluminum anodized cap for 40$ but does anyone have any ideas of cheaply purchasable or modifyable parts to cap the drive off safe and reliably?
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Van's has one that's much cheaper. I seem to remember about $8. It's been on mine for ~100 hours with no tendency to fall off, even without safety wire.
 
Be careful

I'm relying on some really old brain cells, but I have a Mooney electric tach on my O-320-D3G and simply cut an old tach cable apart to use the nut and machined an aluminum disc to fit inside the nut and function as the dust seal.

BUT... About 1,500 hours into my first Mattituck overhaul the tach drive cross-pin failed and parts went into the accessory case. Mahlon told me he'd seen this before when there was no load on the tach drive as they tend to "dance" when unloaded. When Mattituck did their Red-Gold magic on the engine we left the tach drive out knowing 1) parts that aren't present can't fail and 2) this engine couldn't easily be converted back to a mechanical tach. These tach drive failures, although rare, do occur and make for an unhappy day.

Mahlon told me they recommend some sort of load be on the tach drive pin; a right angle drive or anything to provide a small load to dampen the tach drive pin's oscillating.

I wish I remembered this better but it's been over 25 years ago.
 
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i ordered one from AS at the booth in OSH. got a bunch of stuff too for free shipping.


deek said:
No issue per se with a cap - see post #4 about using a cap without some load on the drive pin on the end of the cam.
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