I just received a "standard bracket assembly" from ABW, and since installing it, some issues have come to light. This is a new-to-me plane (Stinson 108-1), and the angle of the pivot on the tailwheel has always seemed a bit steep to me, visually, and it takes some effort to get it to trail properly after it has been castoring.

The main problem popped up after installing the bracket assembly (maybe it’s been there all along and I wasn’t aware of it), but the tailwheel unlocks pretty easily to the right, but is either very difficult or impossible to get to unlock to the left. There is a lot of tension on the right steering chain and spring that I think is working against the castoring function. The notch in the steering arm assembly for the compression spring is pretty rounded on the right, but the one on the left is still quite square.

Also, the plane tends to want to turn to the left while taxiing, requiring full right rudder to keep it somewhat straight. I think this could be due to the tailwheel spring not being mounted perfectly straight.

Any thoughts?

It is too steep, the bolt going down through the caster should be closer to vertical, but still slightly slanted in the direction you have. I'll have to see if I have pics at home later.

Too steep is right. It makes for too weak of a self-trailing quality by the weight being nearly balanced vertically so it wanders or over steers easy. In the last pic the tailwheel appears to be leaning to the right, which could cause it to break over faster one direction more than the other and it also appears that the leaf spring is not in alignment with the center of the aircraft as you said.

Wup and crew have a really helpful video on their website on proper angles for the spring/tailwheel assembly. That head should be close to horizontal, not tilted down like that.

http://www.akbushwheel.com/index.php?op ... &Itemid=83

Gump

Not the question you asked, but it appears you have the wrong steering springs. The Scott 3200 uses tension springs instead of the compression style springs in your photos. You can get the correct springs from Univair or Spruce. Might help with steering after you get the bracket angle right.
http://univairparts.com/shopping/produc ... s_id=28855

1:1 scale, call ABW
Wup, you're needed.
Sounds like the wrong pawl in the mechanism.

Thanks for all the replies. What would be the best solution to changing the angle of the caster? Should I try to flatten the leaf spring (caveman aircraft maintenance ), or just get a new one? I assume Univair or Earl Allen is going to be the best source for that?

You don't want tension against your springs for one thing that's why you're tailwheel is locking and not wanting to break over

Are your springs different lengths?
Some of these springs are supplied that way to upset the natural frequency of the system. Maybe try swapping sides for the springs, if ones is shorter?

OK Sorry to not have gotten on this sooner...
1) Did you change the spring from our first conversation?
2) The angle will cause the hard steer and the non level will send you to one side or the other..
The spring angle with P factor will contribute , Also it don't matter which springs you use as long as they are set up correctrly (see video posted above..)

Also, the plane tends to want to turn to the left while taxiing

You don't want tension against your springs for one thing that's why you're tailwheel is locking and not wanting to break over

Correct...

All the good folks above have given you the right info, I will only add that unless it is an illusion that tail spring is bent, way too much arch and twisted off to one side. I would recommend replacement because the stress to actually straighten the thing will likely damage it and if it breaks at a bad time it might get spendy.

Thanks again for all the input. Hotshot- that is the spring that came with the plane when I bought it. There is definately some assymetry in the system- the chains are the same length from side to side (with a little bit of slack), but the castoring function only works properly to the right. I think it would work OK to the left with another link in the right side chain, but that would limit my ground steering to the right to almost none due to the geometry of the system. I'm going to source another leaf spring and mount bushing and go from there.

All part of the process of buying a used vehicle

I wonder how much straighter a spring you could use in that thing? It looks to me as if the spacer/bushing/????that mounts between the aft bolt and the spring itself is waaaaaaayyyyyy too thick. If that were somewhat smaller, it would significantly improve the spring geometry with the spring you have. Is that part stock you Stinson guys?

MTV

The compression type steering springs should have the thicker one on the right to help against P factor.

I do not think that part is stock, mine has nothing like that.