Longer Leaf Springs

[swift1b]

After pondering over the many favorable reviews on the forum, I am installing a new Alaskan Bush Tail Wheel on my BC12D. In the past I noticed that there did not appear to be much distance from the rudder horn to the tail wheel arms causing too much slack in
the rudder-to-tail wheel springs.

Are there longer leaf springs that are available to allow the tail wheel to be moved farther back? I installed a new set of leaf springs from Aircraft Spruce several years ago which appeard to be the same length as the old set.

swift1b

[PA1195]

Re: Longer Leaf Springs

After pondering over the many favorable reviews on the forum, I am installing a new Alaskan Bush Tail Wheel on my BC12D. In the past I noticed that there did not appear to be much distance from the rudder horn to the tail wheel arms causing too much slack in
the rudder-to-tail wheel springs.

Are there longer leaf springs that are available to allow the tail wheel to be moved farther back? I installed a new set of leaf springs from Aircraft Spruce several years ago which appeard to be the same length as the old set.

swift1b

Hello. I'm confused about what you're trying to accomplish, or rather what the problem is when the tailwheel is installed with the standard Taylorcraft spring? Maybe you could elaborate more about the "too much slack" in the spring assembly?

Most folks use the springs (or similar size and design) that Airframes sells (not cheap weak substitutes), 3-4 links of chain per side to create a straight run from the rudder arm to the wheel arm, a quick clip to attach the chain to the tailwheel arm, and an eyebolt (eye down) on the rudder arm.

When turning one spring will momentarily get some slack until the tailwheel arm catches up and parallels the rudder arm. That's normal.

Use the grease recommended: Exxon-Mobile SCH-100 grease. I also use Aeroshell 22 after removing the former.

Edit: Consider these before changing leaf springs. Any length increase moves the tailwheel arm rearward and can affect the plane's CG. There's already lots of weight back there as is. Depending on the shape/downward angle of the spring it can adversely affect the steering geometry by adding downward pull on the rudder arm, and upward pull on the tailwheel arm. That's why some Scott tailwheels (as on Cessna's) have raised ends on the tailwheel arm to reduce that angular effect. Any heavier duty spring may adversely affect forces re-transmitted into the rear of the fuselage.

Gary

[astjp2]

Re: Longer Leaf Springs

I have the 3200 which is the same thing, you only need a tension spring and the retainer between the horn and the tailwheel.

[cvavon]

Re: Longer Leaf Springs

Here is a photo of a AK Bush 3200 on my tcraft.the springs are from AK Bush as are the quick links the spring are what they sell for supper cubs they also sell the eye bolts also there is 1 link of chain. The eye bolts keep the springs from wearing the rudder arms and the tail wheel.

[PA1195]

Re: Longer Leaf Springs

Here is a photo of a AK Bush 3200 on my tcraft.the springs are from AK Bush as are the quick links the spring are what they sell for supper cubs they also sell the eye bolts also there is 1 link of chain. The eye bolts keep the springs from wearing the rudder arms and the tail wheel.

Thanks for the pics. I like that double eye bolt setup better. A couple of chain links and it's done. Going to upgrade mine soon and add eyebolts to the wheel arm. It levels the tension spring better which probably reduces vertical loads on the rudder and tailwheel arm.

Hope the OP replies so we can learn more about the problems he foresees with the stock leaf spring.

Gary

[cvavon]

Re: Longer Leaf Springs

That is a stock leaf spring it is half univair and half original the coil springs are supper cub.also if you look close at the clamp there is a 1/4 in steel spacer on top of the spring and the rubber to adjust the camber on the tail wheel.with this set up i think you could land at 100 mph and control the plane with out any problems.

[swift1b]

Re: Longer Leaf Springs

I have too much downward angle of the connecting springs on the current tail wheel which causes the tail wheel to be squirrely to say the least.l I was thinking that longer leaf springs would move the tail wheel back to lessen this steep angle. However, with adding eyebolts to the bottom side of the rudder horn and with the Alaskan Bush Tail wheel having upturned ears on the rudder arms the geometrics will improve.
swift 1b

[swift1b]

Re: Longer Leaf Springs

I have too much downward angle of the connecting springs on the current tail wheel which causes the tail wheel to be squirrely to say the least.l I was thinking that longer leaf springs would move the tail wheel back to lessen this steep angle. However, with adding eyebolts to the bottom side of the rudder horn and with the Alaskan Bush Tail wheel having upturned ears on the rudder arms the geometrics will improve.
swift 1b

[PA1195]

Re: Longer Leaf Springs

I have too much downward angle of the connecting springs on the current tail wheel which causes the tail wheel to be squirrely to say the least.l I was thinking that longer leaf springs would move the tail wheel back to lessen this steep angle. However, with adding eyebolts to the bottom side of the rudder horn and with the Alaskan Bush Tail wheel having upturned ears on the rudder arms the geometrics will improve.
swift 1b

Is the current tailwheel that shimmies a used one or the new Airframes' unit you noted in the first post? If new and properly adjusted for rotating tension it shouldn't shimmy with the Taylorcraft spring in my experience. http://www.airframesalaska.com/v/vsp...stallation.pdf

If a used tailwheel is giving you problems, you may want to have it disassembled and inspected for internal wear...both the fork assembly and tire. Over time wear can create increased internal stacking clearances that allow shimmy to occur. The tailwheel depends upon a certain degree of friction and resistance to rotation to properly work. There's a spring catch that resists lateral rotation beyond a certain point that eventually wears. When it does the wheel can freely swivel-shimmy when it shouldn't. Same for a variety of thrust washers and coli springs that wear and let things get too loose.

Gary

[astjp2]

Re: Longer Leaf Springs

Your pivot bolt needs to be vertical or it will shimmy, you may need to shim the bracket to get it there, its kicked forward at the bottom according to your pics. After you inspect and repair any worn items. Tim

[M Towsley]

Re: Longer Leaf Springs

What pictures? Chuck's?

[astjp2]

Re: Longer Leaf Springs

Yeah, Chucks. I had the same problem with mine until I changed it by adding a shim. Tim

[M Towsley]

Re: Longer Leaf Springs

Oh, ok. Chuck wasn't complaining about shimmy so that is what threw me off. Apparently he could have shimmy, then.

Swift1b, whomever that is, was the original poster with a question.

[cvavon]

Re: Longer Leaf Springs

The photo is miss leading as the wheel is set up perfect and DOES NOT SHIMMY when i assembled the leaf spring i re arched it to put the turning plates level and also that was what the 1/4 in shim was for to fine tune the wheel just did the same thing to my stinson and it also tracks straight and true.

[PA1195]

Re: Longer Leaf Springs

Airframes' installation info (attached) agrees it should be level "at gross weight"...may tip up at front otherwise. Most of us always land perfectly....the rest of us bounce a few times and that angle changes with each contact cycle. Whatever. If the fork assembly is loose or the tire imbalanced or wobbling it'll cause a problem.

Scott in their early models used only three coil springs set over fixed pins attached to a fiber thrust plate to maintain internal dampening friction between adjacent plates. Later or with heavier applications they added two more springs to increase their effectiveness, providing the plate stacking tolerances aren't exceeded by wear. If one or more of the retaining pins shear (common in off airport use or frequent shimmy) over time the friction can be compromised. See parts #6 and 7 in this link: http://www.airframesalaska.com/v/vsp...stallation.pdf

Gary