Use a cotter pin here?

The plans show a elastic stop nut on this big bolt, but the bolt itself is serving as the pivot. Can't really crank it down either because it would lock up the bellcrank.

Shouldn't this be a cotter pin situation?

I believe that there is a bushing around that bolt that is slightly longer than the hole in the weldment. When you tighten the bolt, it bears on the bushing, not the weldment. Thus, the weldment is relatively free to move around the bushing. Check the install instructions, as I'm not absolutely certain of this.

Greg

There is a bushing

Hi Greg,

You're right that there is a bushing. Mine are extremely tight in the steel bellcrank so all of the rotation occurs between the bushing and bolt. Do your bellcranks rotate on the bushing instead? Hmmn.

David

Ream and polish

You're going to need to ream the bellcrank or polish the bushing, or both. I spent a lot of time working on mine. With some effort you can make the bellcrank run silky smooth on the bushing.

I also had some trouble with the bellcrank dragging when the brackets to spar bolts were tightened. Some additional work fixed that problem as well.

Do whatever it takes

Do whatever it takes to tighten the bolt properly so that the bushing is clamped between the brackets and cannot turn on the bolt.
The bellcrank must turn on the bushing, not the bushing on the bolt. The bushing has to be made a little longer than the bellcrank, as posted above, so the tightening of the bolt will not hamper the rotation of the bellcrank. Van's suggests a little light grease on the outside of the bushing for the bellcrank to spin on. Double check those directions and plans, it's in there.

Thanks guys for pointing me in the right direction. I've got one bushing fitted and I'll work on the second tomorrow.

David

Get the bushing working right, AND use a cotter pin

As has already been said, make it so that the bushing fits properly -- bushing is held rigid when the bolt is properly torqued, and the bell crank rotates freely and smoothly around the bushing.

After having done all that, it's still not a bad idea to use a drilled bolt + castle nut + cotter pin.

This is a nice safety measure, just in case at some point in the future the bushing stops working properly due to gunk, or corrosion, or any other reason that would cause excessive friction between the bell crank and the bushing, which in the extreme case could cause the bushing to rotate.

This is improbable, and some will argue that a cotter pin arrangement is overkill for this situation. Maybe. But, so what? It's an extra safety measure on a safety-critical component, and it doesn't really cost you anything.

roee said:

After having done all that, it's still not a bad idea to use a drilled bolt + castle nut + cotter pin.

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Just make sure you torque within spec then adjust washers to make the castle nut line up. Otherwise you are doing more harm than good by allowing the bushing to rotate!

I have oriented my bolt so that if the nut were to fall off the bolt would remain in place. The nylon lock nut is more than sufficient for the task.

jdeas said:

Just make sure you torque within spec then adjust washers to make the castle nut line up. Otherwise you are doing more harm than good by allowing the bushing to rotate!

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Yep. Like I said:

roee said:

... make it so that the bushing fits properly -- bushing is held rigid when the bolt is properly torqued, and the bell crank rotates freely and smoothly around the bushing. ...
...
having done all that...

Click to expand...