Control Yoke Guide Block

[NC26528]

My question concerns the phenolic yoke guide block mounted in the instrument panel. In addition to mine being slightly worn in the center hole, it was floating in the "c" chanel mount to the tune of at least .250 side to side and top and bottom. Made for a very sloppy yoke.

In the interim, I have machined a new yoke block which now fits nice and snug in all axis and works perfectly, but I'd sure like to see a drawing or picture of how the factory wanted it done.

Can anyone describe how this block is supposed to be secured? Mine is secured side to side with the "c" chanel, and top and bottom by two through bolts, but because the block in my car is so "undersized" it has a ton of slop. Is there supposed to be rubber filling the gap, or do I have the wrong block?

[mikeg]

Re: Control Yoke Guide Block

The guides sit in the steel channel mounted in a "U" shaped rubber extrusion on the right, left, top and bottom. Then there is a long #4 screw at the bottom and top that support the horizontal portions of the rubber channel. The guide does not move if installed properly. I bought new channel from a locale rubber supplier a few years ago for my '40 project. Hope this helps.
Mike
NC29804
NC27451

[Ray36048]

Re: Control Yoke Guide Block

My question concerns the phenolic yoke guide block mounted in the instrument panel. In addition to mine being slightly worn in the center hole, it was floating in the "c" chanel mount to the tune of at least .250 side to side and top and bottom. Made for a very sloppy yoke.

In the interim, I have machined a new yoke block which now fits nice and snug in all axis and works perfectly, but I'd sure like to see a drawing or picture of how the factory wanted it done.

Can anyone describe how this block is supposed to be secured? Mine is secured side to side with the "c" chanel, and top and bottom by two through bolts, but because the block in my car is so "undersized" it has a ton of slop. Is there supposed to be rubber filling the gap, or do I have the wrong block?

Yes, mine was installed as per Mikeg. But, I have a question about the one you machined. Is the hole perpendicular with the block or at an angle? I was working to make news one some time ago, I believe I found by old ones were at a 12* angle. But, these were also badly worn.

I found the rubber channel at McMaster-Carr.

[NC26528]

Re: Control Yoke Guide Block

Mike and Ray, yes, very helpful info. My guide blocks were just rattling around in there with no rubber of any kind. And yes, I did compensate for the slight (non perpendicular) angle with the new part.

[astjp2]

Re: Control Yoke Guide Block

I put 1/8" ID rubber hose over the screws to keep the phenolic tight, the rubber U channel I got from Metro Molded products or brown aircraft supply, I cant remember which one now. Tim

[Robert Lees]

Re: Control Yoke Guide Block

I used Oilon when I remade mine. It's green, but this picture shows the general layout:

[NC26528]

Re: Control Yoke Guide Block

If I had the appropriate size of Teflon I would have used that. Now that I have the manufacturing concept figured out I may upgrade to a more appropriate modern material.

[astjp2]

Re: Control Yoke Guide Block

The best thing I did was getting the shafts replated, they were so worn that you could see the chrome/nickel/copper/bare steel layers...Phenolic is more than sufficient. Tim

[NC26528]

Re: Control Yoke Guide Block

I was wondering about having the yokes nickel plated. Mine are just paint at the moment. Not very good to slide on, thats for sure.

[3Dreaming]

Re: Control Yoke Guide Block

If you have the round wheels they should be plated. The shaft is left in plating and the wheel itself was covered with some kind of thick plastic coating. When I did mine I had the re-plated and painted the wheels to match the airplane.

[Mark Julicher]

Re: Control Yoke Guide Block

The hole is rounded or chamfered. Rob's picture shows this and it is very important.

[TimHicks]

Re: Control Yoke Guide Block

I made new ones out of Teflon that I got from McMaster-Carr. I chamfered the hole by hand.
What I don't like about the Teflon is that it is white. As such, it peeks out of the hole in the instrument panel.

[TimHicks]

Re: Control Yoke Guide Block

And I didn't re-plate my shafts.

[PA1195]

Re: Control Yoke Guide Block

Black UHMW Polyethylene is available in several thicknesses and is easy to machine and fit (mine's white). We use it to cover the bottoms of skis (typically 3/16") or sled runners to prevent ice accretion, sticking, and wear. Lots of Internet sources. https://en.wikipedia.org/wiki/Ultra-...t_polyethylene

Gary