Honda FT500 Shock Refresh How To...

[J6G1Z]

My old Honda FT500 Ascot's shocks were getting pretty flacid so I bought some inexpensive Progressive Series 14 shocks
from Dennis Kirk to replace them. One thing that was immediately apparent was that although the Progressive shocks were
about 1/2 inch longer than the OE Showa shocks, they had less travel -only about 2.5" versus 3.25" . The Progressives are a
simple hydraulic shock whereas the Showas are gas-charged. The Progressive shocks provided damping on both
compression and rebound whereas the Showas had very little resistance to compression but significant resistance to
extension (although not nearly as much as the new Progressives). I reused the Ascot springs which were significantly more
compressed on the Progressive shocks. With the Progressive pre-load adjuster in the lowest position, the springs were
compressed about the same as in the highest pre-load position on the OE Showa shocks.


My assessment is that while the Progressive shocks provide a more controlled ride on smooth pavement they transmit much
more impact on rough surfaces than did my admittedly worn OE shocks. They are certainly a viable replacement if your OE
shocks are shot and I would rate them as better for aggressive riding than stock but I question their benefit for simple ride
quality particularly if your OE shocks are still functioning reasonably well. But, they were cheap and readily available which
with a bike as old as the Ascot is important. I suspect this is one of those examples of you get what you pay for. More money
would have gotten better performance AND a better ride. However over time, I've grown weary of the very stiff ride over rough
surfaces and since I have "rebuilt" motorcycle shocks in the past I thought I might give it a shot with the old Ascot shocks. I
really had nothing to lose since they were pretty much junk in their worn state.

I've removed and replaced the fluid in sealed shocks before but one factor that complicates the rebuild process this time is that
the Showa shocks are gas-charged. I knew I would not be able to replace the nitrogen charge in them before I started but as it
turns out that's really not a problem. The process is:

1. Drill a strategicly placed hole in the shock body
2. Force out the old fluid
3. Measure the quantity and determine it's relative viscosity so you can decide what weight fluid to replace it with
4. Weld, or in this case, epoxy a threaded fitting onto the shock body over the previously mentioned hole
5. Force the replacement (usually heavier) fluid back in
6. Seal the hole.
To get started, you'll need to remove the spring from the shock. Those bright Showa engineers made the treads on the shock
rod just long enough so that you can do this without a spring compressor -sweet! Just hold the 14mm nut on the shock shaft
and turn the mounting eyelet counterclockwise to unscrew the mounting eyelet/spring retainer from the shaft. Remove
adjusting cam and you're ready to roll.

There is some pressure in the shock but very little volume so I didn't expect relieving the pressure would be a big deal. It
wasn't. I started out with a very small drill and when it punched through there was a little pssst! but that's all. I then pumped as
much fluid as possible from the shock into a measuring flask -got 80ml from one and 83ml from the other so I'll put as close as
possible to 80ml back in. I then drilled my hole out to 13/64" and cleaned the area thoroughly with sandpaper then a solvent to
remove all the oil residue.

[J6G1Z]

When I have done this before, I welded the nut onto the shock body. This time I thought I'd take the easy way out and just used J-B Weld instead. That J-B Weld (a metal filled epoxy) is amazing stuff. I used it in many hot oil environments and after curing it's just like metal -soft metal but metal just the same. So the J-B Weld epoxy, some #10 machine screws and nuts and barely visible in the picture, some 3/16" aluminum washers (the kind that are normally used with "pop"-rivets) AND some replacement shock fluid is all you will need.


As you can see I've already drilled my holes in "strategic" locations on the shock body -more on why the location is important
later. FWIW, I positioned the shock so that I could drill up allowing the shavings to fall out rather than into the shock body.

[J6G1Z]

To attach the #10 nuts, position your shock bodies so that the holes are up and they are stable. Then, mix up your J-B Weld
and using some type of applicator (I used a small screwdriver) apply the epoxy around the hole. You'll want enough to fill in
around the nut when you place it. Here's how mine looked just before I set the nuts in place. The epoxy is somewhat fluid at
this point and after placing the nuts on the shock body, I dripped a little more epoxy around them to build up a little "shoulder"
against the nuts.


Heres how the nuts looked when positioned correctly on the shock. Let the epoxy harden overnight and since there might be a
little in the threads, it's not a bad idea to run a tap through the nut when everything is hardened up. You'll want to let the epoxy
harden without the screws in them. Sorry, I just didn't take a picture at that point. This photo was made after the J-B Weld
hardened with everything buttoned up.

The purpose of the 3/16" aluminum washers is to serve as "crush" washers. I also coated them with HondaBond 4 to improve
the seal. So, while sealed now, the screws can be removed later if I want to to do this again.

[J6G1Z]

Okay so we took 80ml of used oil of some unknown viscosity out,
right? What are we going to put back in? To determine the viscosity
of the old oil, I used a crude relative viscosity measuring device
consisting simply of a clean piece of plate glass. To compare the
viscosities of several fluids, lay the plate glass flat, place a single
drop of each fluid on the glass, then incline the glass plate and then
measure how far each fluid runs in a 15 seconds or so. If you have
heavier and lighter fluids of known viscosities you can actually
interpolate the viscosity of your unknown fluid but I was really only
looking for relative, not actual, values. I had the following suitable
shock fluids on hand -the old Showa shock fluid of unknown
viscosity, some automatic transmission fluid (about 7 wt I think),
some 15W fork oil and some ancient 40wt fork oil. The ATF was far
thinner than the Showa fluid and ran over twice as far. However the
used Showa fluid fell right in between the 15wt fork oil and the 40wt
fork oil. Since I wanted a thicker fluid to compensate for wear in the
shock, I decided to use the 40wt fork oil as the replacement.
About now you're asking, just how the heck did you get the 80ml of
40wt fork oil back into that little hole in the shock. Good question,
Grasshopper! I used an old-school "squirter"-type oil can. BTW, I
actually put 90ml of the 40wt fork oil in the oil can to allow for loss
(i.e. oil that would remain in the can/pump). That was just a guess but
it seemed to work pretty well. I held the shock body in a vise and
while extending the shaft slowly with one hand, I squirted oil into the
little hole with the other. Extending the shaft pulled a slight vacuum in
the shock and sucked the oil right in. Took several times but I got all
of it in with very little spillage.


Remember earlier when I referred to the strategic position of the hole. Here's why. The pre-load adjusting cam must clear the
nut and screw. The hole has to be positioned properly so it will. All that remains is a little black paint and since the shocks
mount upside down my fill holes/screws are hidden by the side covers.

[J6G1Z]

Okay then. The $64K question (actually that was a boat load of money when that TV show was on the air... but that's another
discussion) is how does it work. To begin with it takes a LOT of force to extend the shock by hand. Substantially more than the
Progressive shock. As before there is very little compression damping -no reason to expect that would have changed -and
now without the pressurized nitrogen inside, the shock does not extend itself without a pull. But no worries, the springs
will take care of that when installed on the bike

After the "rebuild" I rode the bike about 100 miles today. I'm quite satisfied. The old Ascot is much more comfortably than with
the very stiff Progressive shocks and the ride is, I think, adequately controlled. It's not a sportbike -never will be but I'm happy
with it. After my ride there was no evidence of oil leaks from my fill hole/screws. So I rate this as a success. Only time will tell if
the "fix" holds up. I'll keep the Progressives on the shelf for a while just in case. But so far, I really like this repair.

Good luck with your project!

Jim Randall

2/22/2011