tail wheel spring

[Pacer42Z]

I used the template to have my leave spring re-arched. It was good when I flew solo or maybe just one passenger. When rear seats were loaded or luggage I still got the ocational shimmy. I took a second spring I had and had it done with about another 1/4 inch bend in it and it works fine.

Juergen
Pacer N3342Z

[Rollie]

Juergen, Thanks for the info. I'll try that.

[pistoncan]

I was just suring the web trying to find a spring shop that could rearch my tailspring (nothing around here) and I ran across a couple articles which I would like to hear comments on.

One (actually several) was from Eaton Springs in Detroit which is opposed to cold arching springs as they say the spring has a "memory" and although cold forming will work short term, It doen't take much of a knock and it will return to its old memory posistion. They contend the only way to truely correct it is to heat it above 1650 degrees and then oil quench it followed by a 950 degree tempering.

Years ago, I was rebuilding a horse drawn carriage (that had been in a fire) and I took the springs to an amish spring shop in Shipsawana IN and they did the hot method. (which worked beautifully) I wonder if we could find a shop that would do this (give them an approved pattern? and let everyone know, and possibly stop to this repeated manitance?


Here is one of the pages

http://www.eatonsprings.com/rearching.htm

I look forward to your comments.

[MN_flyer1]

If your looking for a cold method you may want to look for a large truck brake or suspension shop. Maybe like a Peterbuilt service shop. Most of these shops cold bend their spring leafs.

[Gilbert Pierce]

My tailwheel spring was cold bent here in Memphis in 2001. It still has the arch they put in it then. It was done by a shop that makes trailer and heavy duty truck springs so I assumed they knew what they were doing. They did check to insure they had 1-1/4 spring material before they started in case they broke one. They also had a furnace for tempering if necessary. They used a hydraulic press with a round solid Cummins piston pin on the end of the ram then had base plate with with two more pins welded to it spaced about six or eight inches apart. They rolled each individual spring leaf across that base plate while bumping it with the ram. I would say they gently bumped it into the arch I wanted.

[akt]

I re-arched mine to the template and it was fine until we loaded up to go to OSH, then it shimmied something fierce. As soon as we got back I put on a 1-3/4" spring I got from Alaskan Bushwheel. Works great, very happy with it. Their eye bolt is pretty cool, too.

[Southern Aero]

Steve, thanks for the info. The article on shimmy was enlightening. I've been asking pretty much every tailwheel pilot I meet what causes shimmy and how I can avoid it and nobody would even make a guess. Now it makes sense and I can do something to avoid it.

I'll get my spring off and to a spring shop tomorrow. I've got the template printed out to scale and should be all set now.

Re arching the spring will help & work for a while. Add a leaf maybe or stiffer spring to stop bending. BUT regardless of spring, I have found it very important to have the springs arched to a point that leaves the tailwheel pivot axis parallel to the fin post/rudder spar in most all airplanes (in the unloaded position). You cant count on the springs mounting up the same on every airplane. Especially if there has ever been a repair in the tail spring mounting area. Perpendicular to the surface may work fine...... until you load it up. Take a look at a shopping cart or a large wheel "creeper".... wheel shimmies when mount bent back, like a weak spring on a tailwheel airplane. Another item to look for is ....... viewed from behind, does the spring lean to one side or the other? This will show up in the tire wear eventually. I re arch springs quite often and have found this method to be quite effective.

Wayne

[Steve Pierce]

Like this?

[Southern Aero]

Like this?

Hi Steve,

Long time ........ Dayum!! That's pretty much right on. Its real hard to get folks to understand all they need to do most times is re-arch their springs, like pullin teeth. Sometimes the area where the tailwheel meets the spring needs to be addressed also. (worn because of all the shimming thats been going on!) Most think it needs to angle more the other direction or they go out buying all new parts and end up with the same problem............... while cussin one brand of tailwheel or another..........

Hey, Steve how about sending me a number I can call you. I need to ask you about something not related to this. I talk a little better than I type.

Thanx

Wayne

wd248@aol.com

[SuperPacer]

Much as Gilbert describes, I have re-arched my PA25 1 3/4" spring set using an 8" piece of c-channel for a rest and rounded press pin on the hydrolic press. The data provided by Steve & Gilbert on Positive Castor Angle really does the job to get rid of the shimmy. It is amaising how fast the tail wheel tire tread is worn down when shimming! I beleive the ABW spring set will be the "ticket" if I ever need to repalce the Pawnee spring set.

Enjoy the day,
john