Tail wheel springs and tail wheel settings

[skypics 89]

Well, I finally broke my tail wheel spring that had been on the MK4 for many moons. This includes landings on back country strips.

It was a double leaf type. I could see from the area of the brakage that it must have been cracked for a while and finally gave out. So make sure you check closely for any cracks. I am 1 mile from AC Spruce so I ran up and bought the "experimental" on which is less than half the price of the certified ones.

This one os single leaf and 4 inches longer that the one being replaced. So it lifted the tail and gives a bit more over the cowl visability. It isd also very springy. Trouble is the hole for the tail wheel bolt was 3/8 and I needed 7/16. It took a lot of work and drill bits to get tha hole enlarged.

The extra length meant lengthening the tail wheel steerering spring hookup. This is where I ran onto an issue.

If I made the steering hookup tight enough to give positive steering the MATCO tail wheel would not kick into the castering position. If I loosend the steering I could get the castering to work, but the steering required too much pedal to get the nose to turn.

Then I read something on this forum that said MATCO sells 25 degree "wings" that kick into caster mode much better than the 45 degree ones the builder had put on my tailwheel. This made sense since the Avid rudder only turns a littl over 30 degrees.

This helped, but my steering springs were too stiff so I found a spring set that was a bit softer and now all is well.

This was A frustraiting effort and I wish to thank whoever posted the comment on the 25 degree wings.

John M

[BryceKat 125]

 What are the wings that you’re talking about? Do they go on that tail wheel or do they go on the rudder? Thanks Bryce 

[skypics 89]

The "wings" are where the steering chains from the rudder to the tail wheel attach. As the tail wheel is turned to a specific angle by the rudder, one of the wings will disengage the tail wheel steering allowing the tail wheel to caster.

I also found that Spruce offers a tail wheel steering spring set that is supposed to eliminate shimmy.

This consists of two different springs...one larger than the other. This is supposed to prevent resonance set up when the wheel shimmys.

John M

[nlappos 413]

Those "wings" are the tabs on the tail wheel release mechanism that trigger the release of the centering lock. The normal Matco wings release at 41 degrees of rudder, which is too much for an Avid, so the tabs don't unlock the tail wheel; consistently.  The 23 degree tabs or wings release the TW when you put a boot full of rudder in. Attached is the Matco print that describes it all. The 23 deg tabs are about $15 if I recall. The tabs can be modified with a grinder to any angle, I think.

 

TW control Matco.pdf

[BryceKat 125]

Thanks Nick!

[skypics 89]

Nick:

 

I believed you post earlier led me to buy the 25-degree wings.

Thanks,

 

John M