DIRT BIKE HOW-TO
Race Tech chucks every inner fork tube up in a special fixture
on a floor-stand drill press. Using 220 wet/dry sandpaper wet,
the surface is given a quick crosshatch surface treatment. This
allows the surface to hold a little oil and eradicates any small
nicks or pits that might have cut the seal lip and caused a leak.
This is the order in which
the parts of the seal and
bushing pack come off of
the fork leg. Of these parts,
only the snap ring and support washer will be reused.
You can see where the
bushings have worn
through the sacrificial copper to the underlying steel.
That is a sign that the
bushing is worn. If you see
any vertical wear marks in
the gray, slippery sliding
surface on either bushing,
you must check the fork
tubes for damage.
Race Tech makes a special plastic bag to slide over the top of
the fork tube, but the main advantage is that it is tough
enough to reuse. You can also cut a corner off a plastic bag
for the same purpose. The plastic bag keeps the sharp
machine edges where the bushing rides from cutting the
edges of the wiper or the seal. The wiper goes on first, the
snap ring second and the seal (with a little light seal grease
wiped inside) third.
The bag comes off, and then the washer and outer bushing,
and finally the split inner bushing goes on. Some techs use a
light film of grease under the split bushing. Notice how smooth,
gray and perfect the sliding surface of the new bushing is.
Slip the inner tube and split bushing into the outer fork tube.
Use a 48mm seal driver (TFSD 48) to seat the outer bushing,
washer and seal. Some techs drive them in separately, while
others drive in all three at once. There are some fork tools
that are optional, but a seal driver is a must. Put the snap
ring in and make sure that it is seated. Push the wiper in by
hand. In this case, where we just have the inner and outer
tubes together without the cartridge inside, you can use the
inner tube to seat the wiper.
Fill the inner chamber approximately two-thirds full. The level
will drop as you work the air out of the system. The level is
not critical, but there needs to be enough so that the fluid
overflows when the bladder is inserted.
Peck keeps one hand over
the top of the chamber
while cycling the cartridge
rod up and down. You will
be close when you no
longer hear air bubbles—
just the constant sound of
suspension fluid passing
through the system. Make
sure that the fluid is at
least a third of the way up
the inside of the chamber.
Now it is time to attach
the nitrogen needle to a
small tire pump. The
small pump has plenty
of volume for the task.
At this point, enough air
is added to round the
bladder so it doesn’t
compress too easily with
pressure from the fluid.
Remember that when it
was pulled out, it had