Larry
I cant really see what color the clevis's to the left are. I think they are silverish? Kavan made some like this years ago and they seemed to hold up although I think I have one laying around that the pin is missing from it.
The modern China cheepies are silverish.
I agree with Bob on the Sullivan Gold 4-40. Even with out the pin's safety retainer clip it seems ridged enough to not open up under load. I use the safety clip!
The barrel/ threaded section of clevis is rolled with an interlocking seam so just to be safe I Shrink/press a piece of aluminum or brass tube over that area.
After finding the thread worn severely from not using a lock nut I make sure that they are locked down tight now.
Sometimes have found the lock nut backed off so nylock nuts will be retro fitted in the near future.
The weak link in the Sullivan seems to be the Brass coupler. They can be bent when in difficult areas and then will fail soon after straightening them and this only from a very slight bend!
Hope to make up some steel couplers soon. need to find the right size tubing.
For the slop fit of the pin to the horn I cut a short piece of aluminum tube to fit over the pin and then drill horn to tube od for zero slop fit.
With slop it shows up in the overheads when reversing directions. After flying a zero slop linkage airplanes the airplanes with slop miss the turn point consistently! Zero slop is nice............
Have Been checking out the push rods that Down Under uses with the DuBro ball link and with the addition of a pin I think this is what my next build will have.
Mike, I had similar problems using tubing to retain clevis, the safety clip on the Sullivan is nice solution.
Nylon clevis to nylon horn ok, nylon clevis to steel horn---not ok ??
Frank, never seen that happen! Hope you find the piston!
For R/C having the servo mix switch on when you don't use mixing will produce wild aerobatics from take off to landing(crash).
Solution: adjust switch with cutting pliers
. No switch--no problem! other than building new aerobatic plane.
David