MOD Changing the CubCrafters "click" mixture control to a Vernier control

[Neal]

I saw some discussion regarding the Vernier mixture control and how simple it supposedly is to change out the "clickity" ratchet whatever is used in my Carbon Cub FX-3. I ordered one and it will be shelved until I'm decowled which hopefully won't be until later summer early fall for next condition inspection. I'm opening this MOD discussion for anyone to discuss how to change this out. With anything that could cause an engine failure I'm likely NOT do this myself so I will likely prep for the change and have the local maintenance shop and A&P/IA do this for me. But I'm open to learning what needs to be done.

I ordered the 96 inch option per what I saw I think on the CubCrafters forum:

A-790 Vernier Control - Red | Aircraft Spruce ®

Interesting the cost is $163. Back in 2021 CubCrafters wanted $1100 for this over the standard mixture option.

Why do I want to change this? 1) Failures in the existing ratchet setup, 2) I hate when I'm right near lean of peak and need one more click out and I pull it gently as if I'm going to kill the engine if it pulls too far. I hate that feeling! Yeah, I know...but this is why. I just want a higher quality setup and one I don't need to be concerned with failing.

Discuss as desired. This MOD is on HOLD for me, part arrives today however.

Do any interior panels (left forward) need to be removed to do this? Or can everything be accessed from under the panel and forward of the firewall? I assume also a 3/4 inch hole will need to be created in the panel in the old location, not knowing what that size already is.

 

[Cactus Charlie]

I have made several flights since the detent spring failed on my mixture control. No problem with mixture creep and I think I prefer it over the detented operation.

I have no plan to fit the vernier control but the hardest part seems to be getting a wrench on the nut behind the panel. It was really awkward inspecting the broken spring and I ended up using a borescope.

Picture taken during factory build (Thanks Zach)

 

[Neal]

For those using the Vernier, does it contact the fuel line (bundle/wrap) coming down the left windscreen? I seem to recall it being a conflict. I'm not sure if maybe CC later angled them or if it's not that bad. Let me know your opinion.

 

[ve6yeq]

I recently replaced my smooth mixture control with the vernier mixture control (the A-790 at 96" which I cut off lots off).

Removing the old one was quite simple, although the A&P that I was working with did not like the factory's use of a castle nut on the old mixture cable, where the correct thing is a metal self-locking nut, and the fact that the cable was not bent backwards correctly.

I then carefully used a step drill to enlarge the hole in the panel and then threaded in the new cable. The vernier cable is both larger and stiffer, so I had to adjust the routing and some of the Adel clamps. This was the step that caused me the most pain and took the longest, as getting the Adel clamps back together required some technique that I did not have (I finally figured out using an awl and safety wire). I then measured 4 times and cut once with a Dremel cutoff wheel. Then it was reassembling the vernier cable correctly with the ball (do NOT drop the ball), and bending the wire at the correct place - remember fine adjust of the length is done by spinning the black Adel clamp. I finally had idle cutoff in the correct place and it has been really great. I finished up the adding back the anti-chaffing cover under the panel and some orange stuff to make it obvious if anything moves in the future.