Seals, Shimmy Dampener, Yak 52 Nose Gear
Two O rings and one felt shaft wiper.
Best installed with Shimmy Dampener removed from the Nose Gear.
To do so, disconnect the Spherical bearing from the castellated nut and retaining ears of the Nose strut. Remove the two cotter pins that retain the upper and lower pivot pins - and withdraw the pivot pins.
Moving the the bench, look first for M4 slotted cone point set screws at the edge of the Shimmy dampener body and remove the two next to the large hex (where the shaft is meant to protrude), and at the other end with the blind B nut.
With the set screws removed, unscrew both hex fittings, remove all components and drain any oil inside.
This cavity is a reservoir for the adjacent dampener mechanism. The correct volume is indicated by at least one line engraved on the shaft protruding out past the 27mm hex fitting. The correct pressure is set by the compression spring.
Remove the old and install the two new O rings (whose different sizes make replacement self-evident).
In the bore of the light aluminum 27mm hex fitting, use a sharp point to fish out the old felt wiper, (which may, over the years, have been replaced by an O ring ). Install the new one in the internal groove.
This is a shaft wiper, to keep out dirt, but the real work is done by the two Viton O rings that retain the pressure in the fluid cavity.
Install the long shuttle from the 24mm threaded end, then the compression spring, finally passing the engraved tip through the hex fitting's bore and engaging the M24 threads of the larger hex fitting until fully engaged into the body.
Hold the Shimmy Dampener body in a bench vise with this cavity vertical, M27 fitting end downward.
To correctly set cavity volume, depress the shuttle's larger end against the compression spring (apply force from the end with the M18 internal thread). Depress the shuttle until at least one engraved mark extends down past, outside the body, past the large hex nut. Use a clamp or vise grips on the shaft to keep it in this position.
Fill the cavity full with 5606, then screw in the M18 fitting, expecting some overflow as you install it.
Once both hex fittings are tight, release the vise grips, safety wire both fittings and re-install the set screws that lock their threads. Reinstallation of the shimmy dampener onto the nose gear is the reverse of removal detailed above. Use new Cotter pins upon assembly.
Failing seals will not keep the shaft sticking out and will cause the tip to disappear within a day or two of this setting procedure.