yoke freeplay

[n2582d]

The chances of getting a used one that is drilled correctly for your shafts are pretty slim. As some have mentioned, the yokes may be cocked off. Another problem is the sprocket end play will be too much, or the yoke will bind up to varying degrees. The attach bolts may not even go all the way in due to hole misalignment. If the holes need more than very slight chasing with a drill bit, start with a new u-joint.

It appears that the new ones are pre-drilled so I think your chances for correct end play are as good with a used one as a new one. Here's a picture of one from McFarlane:

MC0411257 -mas3.jpg (33.51 KiB) Viewed 20611 times

MS20270-B10 is the light duty universal joint and MS20271-B10 is the heavy duty universal joint. These univeral joints are made by Apex (Cooper Tools), Belden and probably others. Here's a link to their catalogs: See pages 18 and 19 of this Apex (Cooper Tools Catalog, Belden MS20270 light-duty universal joints, and Belden MS20271 heavy-duty universal joints. The heavy-duty one can take five times the axial tension and compression loads. Notice in both catalogs that the heavy duty one shows a boot on it and on the light duty one the boot is absent (although one can buy boots from both companies). I wonder if McFarlane is selling the light-duty MS20270 u-joint as MC0411257 (for $236) as they show it without a boot? The light duty u-joint is significantly cheaper than the heavy-duty one. At the bottom of this page it is only $19.80.

I recommend leaving them exposed as Cessna intended. (Not to mention they will be easier to inspect and lubricate per the Service Manual recommendations.)

According to Belden, "Boots play an important role in protecting the joint and keeping it fully lubricated. Lubricant retaining boots will prolong the useful life of an assembly by a factor of as much as five." Granted there is a difference between sealed boots and a slice of hose. But newer Cessnas use a 1.12" section of hose over the universal joints.

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#21 is p/n S1495-10 which has been superseded to R221609, a bulk item. $4.59/ft. My U-joints had badly deteriorated boots on them. I thought they were original but I guess not.

The IDENTICAL U Joints can be bought at either Grainger or McMaster-Carr for less than half of the price at Spruce.

McMaster's p/n 6443K46 might fit. At $28.34 the price is right. This one for $45.45 from Grainger would probably also fit. But I think it's a bit of a stretch to say that these are IDENTICAL u-joints. Ya think with a brand name like "LoveJoy" it might be made in China? If you install these make sure and use the hose over them--the hose will help keep the roll pins from falling to the floor during flare. A primary pitch and roll control part is probably not the place to pinch pennies. I'll be installing two new MS20271-B10 universal joints on my project.

[Brad Brady]

I use Mcmaster Carr and Granger (along with craftsman...their U-joints are unbelievable) for many parts in the Experimental aircraft I Build. But I work on the assumption that they are experimental. I would never use them in a certified aircraft. (just my opinion) The proper parts and part numbers are the only things to be used in our aircraft........Brad

[ronjenx]

The IDENTICAL U Joints can be bought at either Grainger or McMaster-Carr for less than half of the price at Spruce.

McMaster's p/n 6443K46 might fit. At $28.34 the price is right. This one for $45.45 from Grainger would probably also fit. But I think it's a bit of a stretch to say that these are IDENTICAL u-joints. Ya think with a brand name like "LoveJoy" it might be made in China? If you install these make sure and use the hose over them--the hose will help keep the roll pins from falling to the floor during flare. A primary pitch and roll control part is probably not the place to pinch pennies. I'll be installing two new MS20271-B10 universal joints on my project.

The u-joint quoted in the Grainger link will not work. At least one end of the u-joint has to be hollow so it can slip over the sprocket shaft.
I could not link to the McMaster u-joint, so no comment on that one, other than it is not approved for our use.

[n2582d]

That's a good point. I'm away from my plane now. I was just looking at the O.D. on these universal joints and had forgotten that the universal slips over the sprocket shaft. Not that I would recommend or use the Grainger unit but it does say, "Bored Units Must Be Rebored To Maximum Diameter Shown" which is 1/2".

[lowNslow]

I use Mcmaster Carr and Granger (along with craftsman...their U-joints are unbelievable) for many parts in the Experimental aircraft I Build. But I work on the assumption that they are experimental. I would never use them in a certified aircraft. (just my opinion) The proper parts and part numbers are the only things to be used in our aircraft........Brad

This is one of those gray areas where you have to decide if you consider this a "part" or "hardware". I don't think you are wrong in your statement as the Ujoints do have a "part" number but these are also available as "hardware" made under a Mil-Spec which I would consider a suitable replacement. I know those who work on airplanes professionally have to take a more conservative approach for various reasons.

[cessna170bdriver]

Well, the cost of this annual just went up a bit. With the instrument panel still out, it was very easy to see that the universal joint on the left yoke is worn; I'd estimate that it takes about a half inch of turning movement on the outside of the yoke before the sprocket starts to move. The right one maybe only about an eighth of an inch. The fore/aft play is negligible on both sides. In this case, I'm leaning toward the idea that the joint is a "part", not "hardware", and I'll be going with a new McFarlane unit. At nearly $250, I'm only going to do the right side. At only about $6 extra, I'm going with the installation "kit" that includes new bolts, nuts, and a protective sleeve (that appears to be just a short piece of hose).

I'm also giving in to a slight case of the "while-i'm-at-its" and will be replacing both control yoke bushings, (I don't call them "balls" so as to not have any environmentalists that may be snooping on this site think we are endangering the Teflon population, as discussed here recently).

Wow, between this and the seat rails I'm up to one full Aviation Monetary Unit, and I haven't even paid for the inspection yet. Hopefully the expense of this hobby causes us have more respect for it...

[Bruce Fenstermacher]

Miles I had no problem calling the part a standard part and bought a cheaper but still very expensive (compared to McMaster Carr) MS unit from Spruce. Fit perfectly.

[cessna170bdriver]

Miles I had no problem calling the part a standard part and bought a cheaper but still very expensive (compared to McMaster Carr) MS unit from Spruce. Fit perfectly.

Just checked Spruce, and they are within a few $$ of McFarlane. Spruce illustrates a McFarlane part, so I'm guessing that's where they get them.

[n2582d]

Miles,
These u-joints meet a mil-spec, are a lot cheaper, and have dust boots.

1490.JPG (25.32 KiB) Viewed 10075 times

[Bruce Fenstermacher]

http://www.aircraftspruce.com/catalog/a ... joints.php

MS20271-B10 is the exact size you need. I payed 77.55 a year ago. They are now $85.75. Gary's link wants $99

Still way to expensive but a hell of a site cheaper than McFarlane.

[cmsusllc]

Bruce, how did you drill the holes correctly??
Scott.....53B

[Bruce Fenstermacher]

Bruce, how did you drill the holes correctly??
Scott.....53B

VERY CAREFULLY. I removed the yoke and the sprocket from the aircraft and did it in my basement shop. The side for the yoke is pretty easy. Just slip the new one inside to the right depth and clocking and drill using the old holes as a guide. The sprocket side is harder because the shaft of the sprocket fits inside the u-joint and you can't see the old holes.

Here is how I remember doing it. I did the sprocket side first because I figured if I got the it off clock a bit I could correct on the yoke side. First I measured the old u-joint holes about 10 times and carefully place a mark on the new u-joint taking care that the clocking of the sprocket and the yoke would be the same. I then held my breath a drilled a slightly undersized hole through one side of the u-joint. I slide the sprocket inside and triple checked the line up of the new hole with the old and also the clocking. I undersized the hole so that if I was a bit off I might be able to correct a tad one way or another with the finished side. Once I was satisfied I had the one side drilled in the right place it was a simple matter of continuing through the sprocket shaft and out the other side of the u-jount.

Then I did the yoke side by sliding the u-joint inside the shaft setting the clocking and using the old shaft holes as a drill guide. You do not want to drill all the ays through on this end however. Drill one side and pin it. then turn it over and drill the other side to match. Once both sides are drilled from each side a drill can be run through to clean it up.

When I was done I reassembled everything back int he aircraft and I got it straight enough that I didn't have to readjust the chain to clock the yokes together.

BTW doesn't matter if you by MS u-joints or the MCFarlane MS u-joint with the Cessna part number. They are undrilled and will have to be matched to the sprocket and yoke.

Oh and if you think the holes are centered in the shafts and drilled straight from Cessna, your WRONG.

[edbooth]

I wish you guys would knock this crap off !! I guess I will have to go out and check mine now. I don't want to move that wheel anymore than I have to on the way to SD. I have had this airplane so long (41 years) that the little things happen and you don't really notice them until someone brings up the subject. Guess if I have too much play on the left side, I'll let Mary handle it from the right side.

[Bruce Fenstermacher]

Actually Ed, when I'm by myself or flying with my wife (who won't touch the controls), I often fly using the right yoke (while I'm sitting in the left seat). Lets me stretch my arms and adjust my seating position.

I've not landed (yet) using the right yoke from the left seat as keeping my right hand on that yoke and the throttle would be a real trick. But if I ever have a flame out I might consider it for the emergency landing. Of course I AM a helicopter pilot AND would be flying a GREEN plane.

[cessna170bdriver]

I went to install the new universal joint in the pilot-side yoke, and noticed that there was a gauge-hole in one end of the new joint, similar to what you see in a rod end socket or turnbuckle. (Left end of the joint in the picture below.) I'm assuming this end of the joint goes over the control tee shaft in the airplane, but I'd like someone who knows more about it than me to please verify. There is no similar gauge hole in the old joint.

...BTW doesn't matter if you by MS u-joints or the MCFarlane MS u-joint with the Cessna part number. They are undrilled and will have to be matched to the sprocket and yoke.

Evidently, things have changed.