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Got a good old vintage bike and can't afford
some trick new aftermarket shocks? Or
maybe you've just bought a tired (well-used)
trail bike and see that the shocks are
non-rebuildable and feel like there's
not much damping in them.
There
is a way around all of this, and the best
part is that it'll take just a little bit
of work and no money at all.
First,
some background. Most of the dirt bikes
of the vintage era (mid-60s thru the mid
70s) came with non-rebuildable shocks. Just
about all of the bikes from England were
equipped with Girlings, as were many of
the other European brands. The Japanese
bikes of that era were pretty, and not much
else. Honda and the other Big Four seemingly
concentrated on chroming the springs and
ignoring the performance.
So,
at that time, the Girlings were state of
the art, and with the limited short travel,
did the job and did it well. A large number
of spring rates were also available and
the damping was correct for the application.
Their
biggest drawback was that they just don't
last long and cannot be rebuilt. A serious
MX competitor could expect a set of Girlings
to last approximately two to three months
at the most. The top desert racers got about
four races and then replaced them. The average
rider, with a little luck, got about six
months of service before they were shot.
Girling did make some rebuildable shocks,
but they were not available in this country.
"PRIMING"
THE SHOCKS
There are two ways to extend the life of
Girlings, neither of which will cost you
any money. The most important method is
something called "priming" the
shocks. When bikes are stored for any length
of time, the longer they are stored, the
more air leaks into the internals. Even
the smallest amount of air can damage the
sensitive internal damping mechanism.
When
you buy a new shock, or get a bike that's
been stored for a long period of time, take
off the spring and gently pump the shock
up and down for about 20 minutes. The air
bubbles will then pass out of the oil passages.
After priming, the shock can be reassembled
and used.
If
the shock is to be stored any length of
time off the bike before using, do not lay
it on its side; instead, hang it up by an
eyehole in the normal position. In this
way, less air will enter the internals.
Priming will at least double their life
span.
THE
FIX-IT METHOD
The second method is to replace the oil
after the shock has worn out. When the shock
is done for, oil will have leaked out and
all internals will have loosened and worn
slightly. Make provisions to put fresh and
heavier oil into the shock, thereby giving
it a second life. And a third, and so on,
if needed.
After
removing the shocks from the machine, take
the springs off and set them to one side.
If they are sacked, they must be replaced.
A good way to check this is to compare them
visually with new springs. If they're shorter,
they will need to be replaced.
Clean
the shock thoroughly before attempting to
work on it. Make a mark three-eighths of
an inch from the base, making sure that
the mark is facing outward from the normal
position on the machine. It will be necessary
to use a punch lightly to start the drill.
Using a 3/16 inch drill bit, carefully drill
a hole in the shock base through the nut.
The
trick here is to keep any stray metal chips
from falling into the shock. It works best
if the shock is laid on its side during
the drilling. Clean as you go, drilling
slowly. Don't penetrate any deeper than
needed; the internals can be damaged by
poking a drill bit indiscriminately. After
the hole has been drilled, clean the area
and check for burrs.
The
shock can then be drained of the old oil.
There should be about 1½ ounces
drained out of a typical 12.9 inch Girling.
If less comes out, it just means that
some oil has leaked out over the years.
Hunt
through your tool box and find a ¼
- inch, 28-thread nut and bolt. Clean this
thoroughly, then weld or braze the nut
near the base of the shock. Make sure that
the shock is fully extended when welding
A word of caution: get the oil out of the
shock first before welding the nut on,
as we have heard tales of old timers literally
blowing a shock apart from burning oil.
Got that?
FILL
'ER UP!
Your new oil should be mixed carefully.
The best ratio is ¾-ounce automatic
transmission fluid mixed with ¾-ounce
20-weight motor oil. You can also add a
tiny bit of alcohol to soften seals and
O-rings. A 3-in-1 oil can with the bottom
cut off makes a great funnel for refilling.
It will be necessary to stroke the shock
up and down to get all of the oil in.
Install
the bolt in the nut and tighten down firmly.
The fine threads should guarantee against
leaks. If leaks are encountered, use a red
fiber washer. After the bolt is in place,
prime the shock again and install.
The
shock will eventually wear again. It is
then a simple matter to remove the bolt,
draining and putting in a slightly heavier
oil. The heavier oil will make up for the
worn O-rings and seals. Some riders have
run as heavy as a straight 30-weight oil,
and the shocks are still functioning well.
Once you get to the point where 30- weight
won't do the job, then the Girlings are
truly ready for the trash can.
This
technique not only works well for Girling,
but other non-rebuildable shocks as well.
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