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Trim and Jack Screw

I have had that issue when installing the Dakota Cub jack screw assembly on 2 flying Super Cubs. Turned out both were tweaked in the tail. Have used them on the last 4-5 rebuilds with no issues. Rebuilt a friends frame and it bound but seemed like it was rectified when the tail wires were rigged. I want the jack screw assembly to last till the next recover and have found the billet, through hardened DC yoke with Acme threads far superior the the cast yoke original style. Steve Conatster in Fairbanks was going through one a season until he switched, last I talked to him he had 4-5 season on his.
This is correct doing three to six min takeoffs and landings a day from May 10th till Sept 23 I would wear out a univair yoke in one season installed a Dakota and this year I think will be 7 seasons still good shape I Had to shorten the bungie assist cable 1” it attaches in a Different spot than original piper
 
Threaded jackscrews take lube beyond oil or even none. Alaska Airlines discovered that to some sadness 20 yrs ago. It's a source of fretting and moly (MoS2) based lubes can help defer that wear.

Gary
 
Denny,
no pulleys are broken.

mike,

ill reroute cable through pulley. Also do I just pull the elevator spring or is there something else I need to do? Does this count as the issues for lack of trim?

That pulley is for the bottom bungee cable that is not needed on your airplane. DO NOT run the elevator cable through that pulley.
 
This is correct doing three to six min takeoffs and landings a day from May 10th till Sept 23 I would wear out a univair yoke in one season installed a Dakota and this year I think will be 7 seasons still good shape I Had to shorten the bungie assist cable 1” it attaches in a Different spot than original piper

Dakota Cub rectified the trim cable mount so you can now use your stock trim cable.
 
Ok. Thanks for the clarification. I do have one spring it may be the top. This doesn't sound like the out of trim issues explained tho.
 
If you want to go to the double groove pulley system, there is more to it than just the pulley on the jackscrew. Not sure on the Cub, but on the PA-16, it involves welding on brackets, adding idler pulleys, changing the tensioning system, changing the front pulley, and a longer cable.


Sent from my iPhone using Tapatalk
 
I’d li98F2E58E-C110-4731-8805-6BEABA4EA33E.jpgC9AF14D0-CA1A-447E-A928-A3C1C39513BF.jpegC9AF14D0-CA1A-447E-A928-A3C1C39513BF.jpegke to hijack this a bit….
dakota parts going in next annual.

what I’m dealing with now is that when I’m at full nose up trim, the cheeks on the sleeve that attaches stab to yoke are what stop the trim’s travel, and they are fretting the crossmember where they rub. Is there supposed to be some sort of actual trim stop?
 

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Type Certificate Data Sheets. This will show how a basic cub is set up. If you change anything from stock like engine location/angle, or wing incidence relate that to stabilizer and elevator stock angles and adjust as needed. The adjustable stabilizer allows for a LOT of abuse when weight is a factor but only to a point. If you stick with stock cub angles and dangles it should be close. Building in as much tail up and down force as possible is never a bad ideal.
DENNY

 
Trim, Well there is always ........... the set the basic plane up right for the CG, if you do as I have mine I use very little trim even changing the load and all within the envelope of the CG!
If I go bare and take out all the extras I am Nose Heavy, add the few parts/weight/either weight in the tail, tools in the extended baggage, etc. as needed and then very little trim needed from take off, cruise, landing.
Yes I have flaps.

DOug
 
I know this is an old thread - sorry.

I want to replace the trim jackscrew and yoke on my Tango Cub. It has a 2 grove trim system. 1) Any pointers or tips on replacing it on a covered fuselage? I believe the trim indicator and bungee are connected to it and the trim cable has spring tension on it. Kind of looks like a set up where you could disconnect the wrong thing at the right time and shoot parts across the hangar plus there seems to be too many things to hold on to at the same time that all have tension on them - LOL.
2) There is no cover piece over or visible access above the jackscrew to pull it out through the top. How do I find that access opening, reach in through the fuselage and push an awl up through the fabric?
3) This thread would lead me to believe that the Dakota setup is/was the best. When I go to their site, it just says "Sold Out". No mention of when or if they'll ever get more. Is there news about Dakota that I missed?
Thank in advance.
 


I would seriously suggest you read this before going with Dakota Cubs trim



Actually, after putting up my post, I went back and read that link. Bummer. So that leads me to the question, which setup should I use, Univair?


...Steve Conatster in Fairbanks was going through one a season until he switched…


Holy Cow!!! One per season?!?! I’d be willing to bet that there are J3’s out there with original jackscrews still in them. I wouldn’t be surprised if the one in my Tango Cub is original. I think some people aren’t aware of the issue of the wear or they figure all Cub horizontals are always loose but one a year, wow.
 
I know this is an old thread -
3) This thread would lead me to believe that the Dakota setup is/was the best.

I would seriously suggest you read this before going with Dakota Cubs trim
https://www.supercub.org/forum/showt...a-Trim-Concern
That was a trip down memory lane. Built 4 Super Cubs since and used the Dakota Cub jack screw and yoke with the revised bungee cable attachment and it works as the original as far as the bungee part of the system goes. The finer Acme thread with the hardened yoke wears way better than the old cast aluminum and standard part. However, the tighter tolerances do cause problems if the alignment of the jackscrew tower is not correct and smooth. In old covered Cubs where I was not so sure of the alignment I used the Univair jackscrew. I have used the Dakota Cub jackscrew in all my Super Cub rebuilds and have had no issues.
 
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