I had the little crappy single spring on my airplane since I got it. It bent during an off airport landing the other day and I've been told it's not if but when it was going to snap off. I picked up the this double TW spring from Airdale (The new Avid Flyer) for $120. I had to drill an extra hole in the channel for the second bolt and I had to open up a small hole in the fabric to put the bolt in. You have to grind the head of the bolt down some to fit between the longerons. Also I had to re-rig my chains because it's longer than the stock spring. The geometry of my TW is much better now. I didn't get a chance to taxi it because we had winds gusting to 26 this afternoon. Not good weather for taxi testing.

BEFORE







AFTER



And this is what happens when you open a place on an airplane that has been sealed since it was built. I found all this crap in the very bottom of the tail where the tubing comes together. Basically everything that had been dropped anywhere inside the plane made it's way here. Some of it probably came from when the horizontal stab was off several times in the past because that makes a straight shot down into the tail. That's a gascolater screen, a hinge pin, a castle nut, and other random crap. There was also a Penny stuck in there that I couldn't get out. Guess it'll be my good luck penny.

Nice shop floor. Im Jelous.

I've been looking for my camera lense cap for a couple months, I think I know where it is now....
The fewer holes in a tailspring the better, also the more leafs. I use a T-Craft muti leaf tailspring, similar gross weight to my Rans S-7S, they had it all figured out 60 years ago! I only use one front bolt, and "capture" the rear of the spring to the fuselage with a clamping type bracket, one less hole to mess with and to propagate cracks. This is why we call them experimentals

I just got the new Maule tail spring from Wup to try on my Tundra. Mine is flattening some and the castor angle is suffering, soon so will the ground handling. Hopefully a side benefit will be to help the view over the nose by raising the tail and give a little more clearance between the tail wheel and the bottom of the rudder. 175 bucks.

Did a little testing today

I see you're running a Matco tailwheel- what's your opinion on it- any problems?

Love it so far.. That is the 7" tailwheel instead of 6". It's holding up so far and works far better than my solid 6" Maule TW.

Years ago , I had an old IA friend who is deceased now who said Maule couldn't build a decent tail-
wheel , let alone an airplane !!!!

I know people who've had good luck with both solid rubber and pneumatic Maule t/w's, but they all have airplanes with light tails. Heavier-tailed airplanes seem to do better with a Scott (now ABW) 3200.

This is what Wup sent me so I would get the right castor angle on the tail wheel when I installed the new AKB/ Maule 1 3/4 inch triple leaf spring on my Tundra. The castor pivot pin when fully loaded should not tip forward more than a 90 degree angle with the ground and when lightly loaded the pivot pin should be at an angle that puts the top of it more rearward than the bottom. This will severely change ground control handling from an empty plane to a full one and can make shimmy an issue. My tailwheel is the 3424 AKB, formerly Scott. (Method even works on grocery carts.)

I will need to shim 1/4 inch between the fuselage and the top spring above the rear clamp to get mine right. I sent Wup the photo and the pin is vertical now with no load in the plane. Maybe this info is of help to check yours.

I had negative caster angle before. It was even worse after I bent old spring. I never had any shimmy issues before but my ground handling is significantly better now with the new set up.

Dirtstrip,

That is the diagram that was draw by Gilbert Pierce of Pierce Aero in Texas. It's been a good aid in solving the problem for a lot of folks.

Evidently Gilbert Pierce had it right to be the best explanation AK Bushwheel can send out. Makes you wonder how come it took so long to figure this out, I mean most companies were already done building tailwheel airplanes by the time this guy solved their shimmy problem.

So, dirtstrip, you asshole, why don't you just put on those big tundra tires and raise the front higher, which would tip the top of the castor pin rearward where it is supposed to be. Or are you scared of your wife so bad you won't spend the money.

Replying to your own post is like talking to yourself. Even if you pay attention to every word, you never learn anything.

That trailing-camber-causes-shimmy thing is old news to some of us. To cure it, some folks re-arch their tailsprings, others make tapered wedge-shaped spacers to go in between the t/w head & the tailspring.
You'd have to really hike the front end of the airplane up to make much of a difference at the tailwheel. Do the math sometime to figure how much up i the front equals how many degrees change.

I have the Matco on mine and like many Highlander drivers, I'm a little concerned it won't hang in there. Several of the Highlanders have gone to this: http://www.irondesign-airparts.com/Tailwheels.htm

I'm starting to work on Mrs. HighlanderninerKC

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Prining sure looks good- $650-ish for a 8" or 10" t/w assembly, or $850-ish for a fat-tired version- a little more than a maule, but less than a Scott/ABW. Of course maule doesn't offer a tundra version..
My impression is that these are built from (or originally designed around) the Bob Barrows / bearhawk tailwheel plans? The way the t\w fork and head is arranged, it looks like the tail of the airplane would be lower (more angle of attack) with this t/w than with a Scott or Maule. This could be a good thing on some airplanes.