Tail wheel troubles

After changing the tail spring over the summer because of a break in one of the leafs, the new tail spring hadn't been performing like I wanted.  After just a few landings I started getting a significant shimmy back again.  It appeared that the bend in the spring was not holding well and was flattening out.  This would change the relative angle of the rotating plane of the wheel and was the cause of the shimmy.

I needed to change the tire and repack the wheel bearings anyway, so while I was at it I decided to take the whole assembly over to Tim's and try and bend the spring to a more acute angle.  Using an iPhone app I was able to measure the rotating plane angle.  I first calibrated the phone to the floor and set it as 0 degrees.

The target was to have the plane at 3-5 degrees positive and I was measuring around -2 degrees.

I took the whole tailwheel and spring off and loaded into a backpack on the Vespa and took it over to Tim's.

I removed the tire and tube and cleaned up the bearings before repacking with grease and reassembly.

It's amazing how much the tire expanded when inflating it.

The tire was inflated to 25psi.

Good for another couple of years.

Here was the angle of the new spring I had just put on over the summer.  But from past experience Tim had put a little more bend to it, because with my relative tail wheel main tire configuration I was still getting a sight shimmy.

Here was the angle the spring matched when I put it on over the summer and it was apparent how much it had flattened.  That changed the critical angle of the rotating plane of the tail wheel.

Here is where we ended up after rebending the spring again.

This gave me approximately a positive 4 degree angle which should resolve the shimmy.  Time will tell and we will see if the spring angle will hold.  It definitely has me doing more wheel landing to keep the pressure off the spring.  But the spring itself seems too soft and doesn't resist distortion enough.

One other issue I fixed was not being able to fully fit a wrench on the bolts that hold the aft part of the tail spring to the frame of the airplane.  I took a short 1/2 inch open ended wrench and narrowed the sides on a grinder.

Now the wrench fits all the way over the bolt head and can be carried in the field tool kit in case I ever have to replace a broken spring again like last summer.