Throttle repair question

[pdb]

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My throttle is slipping so I unscrewed the friction lock and discovered that the nylon wedge washer is cracked. When I tighten the lock, the nylon washer simply distorts and slips.

When I tried to figure out who could supply a replacement I was totally skunked. I can’t determine either a part number or a supplier. Does anyone have a clue about where to source a replacement?

Thanks,

[daedaluscan]

I think I would be making that.

[Bruce Fenstermacher]

I'm with Charlie on that. A nice little project for a lathe.

[Bruce Fenstermacher]

I'm with Charlie on that. A nice little project for a lathe.

[GAHorn]

I have taken plumbing “packing” (usually made these days of teflon but in “olden” times was made of jute)...and wound a few wraps around the shaft and it worked for many years on my 206. https://www.homedepot.com/p/DANCO-3-32- ... /203193512

If you take the “replace” route:

https://www.aircraftspruce.com/catalog/ ... kkey=12964

[n2582d]

George,
To replace the entire cable when the only problem is a friction packing is like buying new shoes when a shoelace breaks. But in looking at your recommended throttle I see that while the price looks good it is not a PMA'ed product. While it's tempting -- compare the price of your suggested cable to an FAA-approved one from McFarlane,-- I'd advise against going cheap. Earlier this month I was talking to a guy at our EAA chapter meeting. He related a story to me about having to deadstick his experimental onto a short grass strip built on the side of a hill nearby. His throttle cable had failed leaving him with only idle power. It's a long walk to civilization out in Pete's neck of the woods. A middle ground -- at least price-wise-- would be to buy Aircraft Spruce's FAA-Approved A-800 throttle cable. Their Part# 05-03866-1 (MFR Model# A-800-12-1), while not approved for the C-170B, is approved for the early model C-172. Both the 1953 C-170B and the early C-172 share the same throttle cable p/n 0411091-9.

Pete,
I wonder if McFarlane's EC12SK or EC312SK friction packings would work in place of the teflon. They have this page entitled "Extend the Life of Your McFarlane Throttle Cable" on their website. I think the original throttle cable was manufactured by Shakespeare. The friction lock material was rubber. Here's a clip from Service Letter 64-3:

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[n2715d]

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We had some throttle creep and found the nylon wedge ring has perfect linear split. We were not certain it was not manufactured that way to permit replacement. (It still works pretty well and we suspect we created the problem by silicone spraying the throttle in the past.)
I suspect one could 3D print a replacement in two halves and it would work if made from the right plastic.

[GAHorn]

That split-ring is for assembly during manufacture.

Yes, if you applied silicone that likely removed the friction the split-ring is intended to provide. Alcohol or electronic cleaner might restore it.