The International Cessna^® 170 Association

Having just bought my 170 I thought I'd give it a good examination using the knowledge gained from reading the forum. Where better to start than the tailwheel? On inspection, I found that the tailwheel only locked in one direction, but swiveled freely in the other, and the chains were unequal lengths, 15 links on one side and 16 on the other. On disassembly, this is what I found, presented for your entertainment.

Here's why it only swiveled in one direction. One wing of the spring is broken:
All the pins were broken off the upper bronze thrust plate:
And look, 5 compression springs!
I didn't know how the lock release function worked. Just in case I'm not the only one, here's an explanation. The arm is locked to the fork by the wings of the spring fitting into notches in the arm. The pawl is held fixed to the top bracket by the half-round piece fitting into a recess in the bracket. It slides in a slot in the steering arm as the tailwheel swivels.
Here's how the release happens. When the pawl slides far enough, it hits the spring and pushes the wing inward (out of the notch), allowing the wheel to swing free of the arm. I took the arm off to show just the essential pawl-spring contact.
So now I know I need the following parts, which won't be too expensive.
thrust plate, Scott p/n 3234
spring, p/n 3222
pin, p/n 3257

Can someone tell me how I get the pin out of the fork?
Do I install the spacers the way they were, both on one side of the spring, or do I install one on each side as shown in the IPC?


Dave

Dave, its been a while but I seem to remember if you remove the center bushing you can drive the pin out. Giving the instructions heavy weight I'd see how the new spring fits and determine were and what shims are needed.

Dave, the shims are used to adjust the spring release-tension on the arm assembly. If you space the spring outward by using a shim inside the spring, it'll increase the release-effort required.
I'd recommend you place the shims just like the IPC to begin with, and note that the two shims are different part numbers because they are different lengths. The short one goes on the inside of the spring.

I brought the fork to my mechanic and we removed the bushing and pin. Took about one minute.

I am replacing the pawl spring (Scott pn 3222) in 97C. I ordered it from ACS, and when I went to install it with the old spacers (3258 and 3258-1), the stack wouldn’t fit in the groove in the fork. The new spring measures 0.040” thick and the original measures 0.035” thick. Anyone else have this issue? Since ACS is just a distributor and not likely to be helpful with technical issues, I sent an email to Alaskan Bushwheels asking what the thicknesses of their spring and spacers are.

BTW, the two spacers that came out of the tailwheel are the same length. The difference in the thickness. One is 0.015” and the other is 0.025”.