National Aeronca Association Bulletin Board

Our '46 7AC has a Scott tailwheel that always shimmied on rough surfaces. At the last annual, it appeared that the mounting bolt was too long since there was play between the spring and the tailpost. A shorter one was installed, and now the shimmy is worse, particularly with someone in the back seat. I have read about the spring pads, but can't find a drawing for the assembly. Should all tailwheels have the pads? Where does the pad go? Is there one pad or two?

Sparky,

There are two pads that you need. On Page 28 of the Aeronca Champ Service Manual, you will find a diagram of the leaf springs. The two pads are noted as I-557-1 and I-557-2. The sizes are different. If John Probst reads this, he has more specifics. If I can find it, I'll try to give you the blueprint number. One pad goes on top and one on the bottom, between the spring leaves, as shown in the diagram.

There is an article posted on Aeronca.com related to the tailwheel pads. Unfortunately the site is currently temporarily down for updating to the Aeronca museum. Contact me offline and I'll email you the info you need.

Sparky,
Take a look at the tail wheel pivot. It should be near vertical to the eye when assembled with the correct components. It not, you may need to replace or arch the spring. Plus it will steer easier.
Paul

For a long time mine had an aluminium block, and no rubber pads. Now the pads.
Anything can wear and loosen up, but if the spring sags, particularly under load, you will get shimmy.
Re arch, or replace.

Univair carries the pads. As is always the case with their website, you must be a genious or clairvoyant to find something.
I searched under tailwheel pads, tailwheel springs, Scott, aeronca etc. and found nothing. I finally tried "pad" and sure enough, they popped up. 2 different part numbers. I guess upper and lower? $7 apiece.

Brian Walker
NC1197E '46 7AC/DC

I got the pads from John Propst and took them to the plane, only to discover that we have a "non-standard" mount, and only 1 rubber pad. Univair has the proper fitting, U1-555, but they show 2 different U-bolts. Part# U1-10589 and U1-10325. Does anyone know which one I am supposed to use?

Home Made
I don't much like the looks of the lower bracket. Following the factory drawings would not be difficult, and use the pads.

Don't make it too complicated....Radiator hose material cut to shape works too.

I cut mine out of an old mudflap.
Mike

Sparky,
The stock fitting has a U shaped channel and connects with a couple of bolts. In the later planes they used a single U bolts. Some of the U bolts fit the Champ spring width and some the later Citabria spring width. I don't have a parts manual handy but Univair adds a U to the factory part number to indicate PMA manufacture as opposed to NOS.
It may just be the photo, but the second leaf looks broken. The three springs should follow the same contour with the second spring attaching at the tailwheel. The main spring will attach to the fuselage and the tailwheel, with the little top spring kind of floating there supported by the fitting.
Your fitting looks like a Taylorcraft set-up.
Paul

Drawing 4-620 shows the assembly of the various components for attaching the tailwheel assembly to the aircraft. The "U" shaped bracket, called the fitting assembly, is shown on drawing 1-555. This part is available from Wag and others. As shown on drawing 4-620 it is attached with two AN4-16A bolts and two AN365-428 nuts. Pad 1-557-1 goes above the leaf spring assembly and pad 1-557-2 goes below the leaf spring assembly.

Here are a set of photos showing before and after installing the official Aeronca rubber tail spring pads. I hope this helps.
Regards,
Sam

Good photos. It looks like there is one washer between the front of the spring and the fuselage. Is that correct?

I am happy to report that we put in the new pads, and the shimmy is gone. Thanks for all the help!