Re: [f-AA] Aeronca Mechanical Brakes

[Thomas Holmes]

Thanks Bob.  Very helpful.  I hadn't thought of the eBay source.  I'll add that to my "parts finder"!  

I was busy moving the front seat so that I could get better leverage when it occurred to me that fixing the brakes would make a lot more sense, and it's time to clean and lube the wheels anyway.

Thanks again.  I'll have them apart this week and get a better idea on how to proceed.

Tampa Tom

On Sun, Oct 25, 2015 at 9:13 AM, Bob Jacoby <jaco...@bellsouth.net> wrote:

Hi Tom,

I'm responding to your post on the FAA.  I'm on the distribution list, but have never figured out how to post back to the list – I may not have the right permissions.

Regardless I've got a 1946 Champ 7AC with mechanical brakes.  If they are "barely holding", they're probably just fine! Not a very satisfactory answer to your question, but that's about how mine work. I can do right ups no problem, but they do want to creep unless I've got the heel pedals firmly pressed.

However, if you want to make sure you're getting everything possible out of the mechanical brakes you can do the following things:

1) Scuff the inside of the brake drum perpendicular to the direction of the brake shoe travel with 150 grit sandpaper and clean very thoroughly with brake cleaner.  If you happen to have the wheels apart  (for inspection) you can even glass bead the contact surface of the brake drum and again clean thoroughly with brake cleaner afterwards.

2) Rough up the shoes with 80 grit sandpaper - degrease with brake cleaner before you rough up the shoes, and clean again with brake cleaner after roughing up the shoes. Some people believe if the shoes are contaminated with oil or grease (common if the wheel bearings are over greased) that the shoes are shot. I've always had pretty good luck cleaning them with brake cleaner.

3) Alternately, re-line your shoes, or replace them – the seller on eBay (search "Van Sickle brake") sells reproduction parts that are completely fine for this application. I suspect they're the same shoes that you can purchase from a certified seller.

4) Make sure the cable cover is not slipping in the mount underneath floor.  You can probably check this by pulling the inspection covers near the landing gear and look up at the cable case mount while someone step on the break inside the plane.

5) Make sure your brake cables are not too tight because then the shoes will constantly drag and glaze themselves. A little friction is fine too much just constantly polishes and glazes the braking surfaces.

6) Check to make sure that the cable isn't binding and the little pulley behind the brake mounting plate turns freely.

7) If you've  got the brakes apart, make sure the hole in the mounting plate where the lever arm and cam (search "VanSickle mechanical brake cam" on eBay) come through is not overly worn. If so replace them with new parts from the same eBay seller.  The backing plat is listed as, "Van Sickle mechanical brake torque plate"

8) Finally, make sure that the brakes and all the fasteners are correct and installed in the correct orientation. Mine were not. Use the engineering drawings either in the service manual or available on the aeroncamuseum.com.  I also replaced both sets of springs (on the inside and the outside of the brake assembly).

I purchased my champ in April and have gone through the brakes very thoroughly including the installation of new brake cables. I think they're more than adequate for this weight of aircraft.

Hope this all helps

Bob Jacoby

Jacksonville, FL