Shimmy Damper by Larry Matlock (11/2017)
I am going to tell you a story about an unusual job, overhauling the shimmy
dampener on the V35B. It is OK to call it a damper, a dampner, or a dampener, as
it dampens the gyrations of your nose gear.
The first clue there might be trouble was attempting to measure the 5606 in
the unit, and the cotter pin was closed, not opened with an awl so the measuring
wire goes in. Removing the innards, done many times before, no shooting springs
and tiny washer... in fact no springs, no washer, no plungers, and no fluid of
I had the parts on hand, purchased from Performance Aero, and had to buy
about 200 AN 960-3 washers, just to get one + a spare. ( if you need some..)
Inserting the brass bore brush, I found it would only go halfway through, the
clevis side had a stuck floating piston and spring. Rusted solid! After a soak
of Hoppe's #9, a tip from Bob Butt, I was finally able to knock out this rusty
debris with a long drift punch. I was left with about 2.5" of rusted bore way
back in the clevis end.
I plugged the hole with a shaped chopstick, and with an eyedropper, filled
the bore halfway with Phosphoric acid, this one called "Rust Mort" by Loctite.
After a 15 minute soak, I was able to get the brass brush the full distance, but
a look inside showed the damage from the rusting spring. I shaped a bamboo
chopstick on my drill press, using two files, to just fit the bore, fitted this
rod in my electric drill, soaked the bamboo with MMO, and dusted it with diamond
dust polishing compound.
About 5 minutes later, I had a shiny polished bore, that the floating pistons
were happy with. Reassembled with new O rings, the dampener worked like new,
very hard to push and pull, as the 5606 moved from one side to the other. A tip
is to pull the 6/32 all thread out the clevis side as far as possible against
the spring, and use a nut to hold it while filling.
Filling the back end, where the cotter pin goes was done with an eyedropper,
then a special tool I devised consisted of a 1/4" OD tube, similar to a old car
radio antenna, with a slot 1/2" deep to clear the cotter pin, and a stiff wire
to line up the spring and keep the tiny AN-960-3 washer from shooting away. The
center bore was filled, safetyd, and re installed.
Adding a squirt of LPS3 in each end of the dampener, to lube and corrosion
proof the springs is the final thing to do prior to installation. Also, a little
of the same on the open plunger shaft will be welcomed by the O-rings. Mike T.
says he greases those springs prior to the installation. Another good idea!
The moral of this story is to never wash your airplane with soap and water
and a hose... and heaven forbid a pressure washer. Be a great Beechcraft owner
and hand wash your bird with an old cotton towel and dry with a chamois. When
spraying water all over the place, the water will go inside your shimmy dampener
clevis end, and it can't get out, until you have the rusted unit from hell I
just described above. Wash N Wax all, or a brush with avgas to clean the nose
Keep the water away from your shimmy damper!