Page 2 of 3
Re: Control Yoke Bushing
Posted: Wed Apr 06, 2011 3:04 am
by 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.
Re: Control Yoke Bushing
Posted: Sat Aug 18, 2012 6:16 pm
by kf958
n2582d wrote: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
Re: Control Yoke Bushing
Posted: Fri Jul 19, 2013 1:02 am
by Hatz617
Looks like Wag Aero has discontinued selling the teflon bushings. Any other alternatives other than OEM from Cessna?
Bob
Re: Control Yoke Bushing
Posted: Tue Jul 23, 2013 6:02 pm
by 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?
Re: Control Yoke Bushing
Posted: Sat Aug 17, 2013 4:03 am
by 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
Alternatively, US Plastic has 1.5" dia. Teflon rod available for $28/foot. Anybody have access to a lathe like
this?
Re: Control Yoke Bushing
Posted: Sat Aug 17, 2013 6:05 pm
by 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
Re: Control Yoke Bushing
Posted: Sat Aug 17, 2013 6:33 pm
by morrison
I'm in!
Re: Control Yoke Bushing
Posted: Mon Aug 19, 2013 10:56 pm
by 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
Re: Control Yoke Bushing
Posted: Tue Aug 20, 2013 12:41 am
by ron74887
Just checks I used the Bakerlite balls years ago-- still tight but not that many hours probably 500 or so. Ron
Re: Control Yoke Bushing
Posted: Tue Aug 20, 2013 1:15 am
by 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
Re: Control Yoke Bushing
Posted: Wed Aug 21, 2013 1:44 am
by 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
Re: Control Yoke Bushing
Posted: Mon Aug 26, 2013 2:27 am
by 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
Re: Control Yoke Bushing
Posted: Mon Aug 26, 2013 3:22 pm
by 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.
Re: Control Yoke Bushing
Posted: Mon Aug 26, 2013 3:31 pm
by 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
Re: Control Yoke Bushing
Posted: Mon Aug 26, 2013 3:44 pm
by 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
P/N 9614K39