Cherokee Strut Lower Strut Seal Replacement Report

On Wed, 20 Jul 2005 01:22:26 GMT, Mike Spera
wrote:

Getting the snap rings out on the mains are a REAL wrestling match. The
snap rings are not of the type with the eyelets, rather they are the
kind with the ends bent (almost) 90 degrees. Once you have a grip on the
ends and squeeze, it is a real bear to work them out. They are pretty
"robust". There is a spacer ring above the snap ring that is split. If
you find the end and work it a bit the spacer will "spring" closed
slightly and remove easily.

The nose gear snap ring is of the eyelet type, but the original (circa
1974) rubber scraper is right in the way of compressing the ring and
removing it. For the nose, once the snap ring is removed, the gear
fork/tube drops out with an inner assembly that holds all the seals.
Conversely, on the mains, you work upside down getting out the various
scrapers and seals.

Installing the main seals, scrapers, spacers, and snap rings back in are
a lot easier than taking them all out. The nose gear has the main "quad"
seal stuffed in the groove along with a leather "backup" seal. Install
the leather one first with the smooth side facing the quad seal, and
then the quad seal. Any other order won't work. The service manual does
not mention any of this. The nose scraper rubber needs to be cut to
size. CUT IT 3/8 inch TOO LONG. I did and it JUST FIT. Another little
tidbit the service manual fails to mention. By the way, the new design
of the scraper ring makes it so that it does NOT interfere with getting
at the snap ring. Made it a lot easier to get the nose snap ring back in.

Hi Mike,

I had to replace the seal on the pilot side main on my Cherokee a
couple months ago. It was leaking down every couple weeks and sagging
a couple inches on that side.

I was working with an A&P, but apparently he hadn't done a Cherokee
before. We disconnected the torque links and removed the schrader
valve. He started to remove the snap ring and had a bitch of a time.
It doesn't have rings on the ends, just a barely 90degree bend on the
ends of the ring. We fought and fought for almost an hour to get it
out. We could get one end out, but the bends on the ends were so long
that once we got one end out, the other was NOT coming out. Just not
enough room between the stationary strut body and moving strut shaft.

Finally, I got ****ed and we pulled hard -- twisting the ring into a
unusable shape, but got it out. OK, we replaced the seal and headed
to the Piper dealer to get a replacement. TWENTY dollars for this
damn little snap ring. I know aircraft parts are expensive -- but
that's ridiculous.

Went back and tried to put it in. NO WAY. When you put the shaft in,
you squeezed the ring ends together. They would come completely
together and still not go inside the shaft body. We tried moving one
side above the other to get the two ends past each other a bit -- but
still couldn't get it up into the groove.

OK, pulled the shaft out and tried it without the shaft in the way.
It took some doing, but we got it into the groove. And guess what --
I took a guess and tried to stuff the shaft in with the snap ring
ALREADY IN PLACE. And what do you know -- it went in!!!

Turns out the ring does NOT hold the shaft into the body. We pulled
the shaft again to double check -- and sure enough, there is no
"larger" area at the top of the shaft that the ring would hold. The
ring apparently just holds the seals in place. The torque links keep
the shaft into the body.

DAMN -- twenty dollars down the tube. If we'd just tried pulling the
shaft with the ring still in, I wouldn't have been forced to buy a
replacement. Next time, save yourself the fight. Disconnect the
torque links and pull the shaft first. THEN get the ring out to
replace the seals.


Chuck (learning the hard way)
PA28-180