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Fix "slop" in control stick?

flymo

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There is a bit of “slop” or free play in my purchased RV-7’s stick that I’d like to eliminate. When I hold one stick and move the other, I can see a little movement in the AN4-27 bolt head (that goes thru the aluminum tube bushing), that connects the WD-610 control column to the WD-611 control stick right.
Any recommendations before I dive in and re-invent the wheel? Thanks in advance.
 
Pull the seat pans up to get a good look at it, and it's a pretty simple mechanism.
 
Seems like the most likely cause would be that the brass bushing in that weldment is worn out.

If that's the case, parts to fix it will be about $5.

Do yourself a favor though and if you take that assy apart, diagram or photograph the washer stackup at each location. The washers are used as shims.
 
There is a bit of “slop” or free play in my purchased RV-7’s stick that I’d like to eliminate. When I hold one stick and move the other, I can see a little movement in the AN4-27 bolt head (that goes thru the aluminum tube bushing), that connects the WD-610 control column to the WD-611 control stick right.
Any recommendations before I dive in and re-invent the wheel? Thanks in advance.

The AN4-27 should not move. It is designed to be a tight clamp on the 610 "clevis" and the brass bushing. The bushing should not rotate on the bolt. The stick should be just barely shorter than the bushing. Enough to provide free motion when the bolt and clevis are tight on the bushing.

It's a "cut to fit, paint to match" operation. :)
 
For my RV-12 I made new bronze bushings and knurled the OD to increase diameter for a more snug fit into the stick pivot. Cut off most of the knurl to get close rotational fit. A side benefit is that knurl holds grease...
 
Thanks all. I didn't see a brass bushing in the plans, I'll disassemble and see what's what.
 
Thanks all. I didn't see a brass bushing in the plans, I'll disassemble and see what's what.

The brass bushing is standard 3/8" stock. Mine was too small to fit the drill reamed stick. I bought a second stick and bushing and they were sloppy too. I bought some 1/2" dia brass and machined it to fit the stick. I suggest a slight spool shape where the last 1/2" or so is the only part that contacts the stick tube, as the tube was not straight either. Be aware that tightening the bolt though the brass bushing can compress the length and expand the diameter.

It is just not a precision part, but to Vans credit, it may not be any issue when flying either.
 
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zone B9 on print 38. It's either mentioned in the plans or someplace on the print that it's supposed to be a tiny bit longer than the sleeve that it rides in on the WD-611. Then when you tighten the bolt down, it clamps the bushing so that you end up with the bushing rotating in the tube, but the bolt stationary with respect to the bushing if that makes sense.
 
bushing

The RV-6 plans also do not show any brass bushing in that assembly, maybe it is in the construction manual, or maybe you just know to do it.
 

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Note 2 on the RV7 drawing

In my experience the most slop came from the length of the bushing being too long. The stick then slides fore and aft in the bushing by a couple of 0.001 which feels like much more at the top. When they say “slip fit” you should really strive to get it all super close.
I love the bearing improvement in the -14.
 
The brass bushing is standard 3/8" stock. Mine was too small to fit the drill reamed stick. I bought a second stick and bushing and they were sloppy too. I bought some 1/2" dia brass and machined it to fit the stick. I suggest a slight spool shape where the last 1/2" or so is the only part that contacts the stick tube, as the tube was not straight either. Be aware that tightening the bolt though the brass bushing can compress the length and expand the diameter.

It is just not a precision part, but to Vans credit, it may not be any issue when flying either.

+1
I had to do the same to get rid of the slop. Key issue was out of round issues in the stick and too small of a bushing.

Larry
 
+1
I had to do the same to get rid of the slop. Key issue was out of round issues in the stick and too small of a bushing.

Larry

Mine too, out of round, too large and not straight. Each end different too. Just not enough room for many design options.
 
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