Control Yoke Bushing

[GAHorn]

All you have to do is either put washers...or short bushings you can mfr yourself...beneath the "socket"/cover to relieve pressure on the ball.

[kf958]

Pete,
The IPC drawing which has the p/n for the socket you listed isn't very clear. Does your yoke socket look like either of the ones pictured below? The teflon ball is designed to fit between two retaining sockets on the C-170, one on either side of the stationary panel. These sockets are mounted with three screws. If your socket is like the C-175 style pictured with four bolts maybe you could mount a second one on the back side of the panel to capture the teflon ball. Might have to trim the length to give you full elevator travel. It goes without saying that your A&P would have to supervise and OK such a modification. Wag-Aero lists the teflon ball as a PMAed part--which means (in my book anyway) that it can replace the identical existing part without an STC. No mention of STC SA666NW in their catalog.

Early 172 yoke mount.jpg

C-175 yoke mount.jpg

I have a 175 in your drawing. i need the housing/collar and the bushing from wag-aero. Can you point me in the right direction to get collar and support bar? Thanks, Keith

[Hatz617]

Looks like Wag Aero has discontinued selling the teflon bushings. Any other alternatives other than OEM from Cessna?

Bob

[n2582d]

Bob,
It looks like new ones from Cessna (p/n 0411224) are just under $100 each. Use that as a reference point before following any of my advice here.

I'd consider going to a machinist and having some new ones made or reaming your existing ones and pressing bushings in them. There are a lot of options for bushing or ball material. Other engineering types could pitch in here and give more educated opinions on what material would be best. A place to start would be page 3407 in the Grainger catalog. Phenolic tubing or PTFE (Teflon) might also work. Whatever you come up with could you make two for me too?

[n2582d]

I did a little more research on this. You're not going to find anything with lower friction than Teflon. The phenolic control yoke bushings in the C-170 are spheres with a 1.5" O.D. Precision Plastic Ball Company has 1.5" diameter PTFE (Teflon) balls for sale at $40 each--the lowest price I could find when just buying two. One would have to drill the 3/4" hole through the center and call it an owner-produced part. If there is enough interest maybe we could try for a larger group buy for a better price.

Teflon-and-PTFE-Balls.jpg (86.42 KiB) Viewed 16648 times

Alternatively, US Plastic has 1.5" dia. Teflon rod available for $28/foot. Anybody have access to a lathe like this?

[ron74887]

guys, we use Teflon and bakerlite balls by the hundreds in the oil field to pressure up tubing and set packers. (I know not many knows what that means) however I can check with a packer co and see what I can get 1 1/2 "Teflon or bakerlite balls for and all anyone would have to do is drill a 3/4 hole. If interested and I can remember Monday I will call and see what kind of price I can get them for. I made mine years ago. Ron

[morrison]

I'm in!

[ron74887]

OK guys, I remembered well some of it. I need to call a place tomorrow and get a firm price on Teflon balls. Bakerlite which is a phenolic ball is 9-10 bucks ( somebody had those here and knew the cost). Did not have the Teflon but gave me the name of the place where they get them. so I will keep working on it. offshore tomorrow may be Wed. Ron

[ron74887]

Just checks I used the Bakerlite balls years ago-- still tight but not that many hours probably 500 or so. Ron

[jlwild]

Ron, At one of the past Cessna 170 conventions, I purchased a set of control tube balls during the auction. They were donated by "Wag-Aero" with a part number of M-322-000. Included with the parts was STC # SA666NW issued to George O. Johnson, 28102 150th Avenue East, Graham, WA 98338. I assume Wag-Aero was/is marketing Mr. Johnson's parts. Installation instructions say the ball fits all Cessna 120, 140. 170, early 172's, 175's, 180's, 182's and 310"s. Hope this lead helps

[ron74887]

Jim, I was not planning on trying to STC this I was planning on getting the Teflon/Bakerlite balls and let anyone who wanted make an owner produced part. The Bakerlite cost around $10 and I have 4 places to get the 'Teflon which I will get price tomorrow. One co is the largest producer of them used for oil well fracs. I will publish the cost for either and if someone wants them it is up to them to drill the hole???? Should beat the tar out of $100 each. I have 2 sets of old ones so I must have given somebody a set?????? I have slept since then...Ron

[ron74887]

Hey guys, got 1 price back on Teflon balls at $29.00 ea if I order 50. Still waiting on another company to quote bakerlite balls were $41.00 ea. I will keep everyone informed as I get it. Ron

[falco]

McMaster-Carr has 1 1/2 inch teflon balls for just under $40 each, and delrin for $19 each.

Delrin is pretty slippery stuff too, is harder, and machines a heck of a lot better than Teflon.

[ron74887]

Falco, would they make you a better deal on a bunch of delrin. That may be the way to go as long as they are fairly easy to drill. At $19.00 be very well worth it to try they have to be better than the original. They will not wear out in our lifetime! Ron

[falco]

CORRECTION

the 1.5 inch delrin balls are $17 and change for a pack of FIVE balls. So you can screw up the first one and still have enough for 2 airplanes, or you can keep a pair handy so your grandkids can replace them when they wear out in 2063.

(the price on the teflon balls was by the each)

mcmaster.com
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