Fork Seal Replacement 

Description Fork Seal Replacement
Author Matthew Date Thu Jun 16, 2005 9:41 pm Type Type 1
Category Fix It / Mods
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Fork Seal Replacement



You would be hard pressed to find anything more neglected on a motorcycle than
its fork oil. Some bikes carry the same few ounces of fork oil for their
entire lifetimes. For all the hard work the fork does in keeping your ride
smooth, you should reward it with fresh oil every two years or 15,000 miles.
Perhaps, even though you've been a good caretaker of your cruiser, you noticed
a teardrop of oil on the top of the slider during your pre-ride check. You'll
need to replace the seal and minimize your riding until you do. If you're not
careful, the oil could drip onto the caliper, rendering the brake useless.

Set aside around two hours to replace the fork seals. Gather all the parts and
tools you'll need in advance. Even if you only need to replace one seal,
replace them in pairs to keep them on equal footing. The parts are usually
under $20. Be sure to calculate how much oil you'll need. This V-Star 1100
required exactly 1.1 ounces more than a single bottle of fork oil held, so
don't assume one bottle per fork leg will be enough. For tools, you'll need
the usual assortment of mechanics' sockets, ratchets and wrenches. You'll also
need a way to support your bike with the front wheel off. If you don't own a
lift, a floor jack and piece of wood works just fine. Other items you'll find
useful are: an oil recycling container, a Ratio Rite (to measure out the
proper amount of fork oil), a Race Tech Fork Oil Level Tool or a tape measure
that will fit inside the stanchions, seal drivers or a piece of PVC pipe of
the right diameter, rags, paper towels, a garage door frame (or other
convenient, solid wall), and a heavy four- wheeled vehicle.

Before you jack the bike's front wheel off the ground, loosen the axle and
brake caliper bolts. If you're just jacking the front wheel off the ground,
make sure the bike is in gear and the rear wheel is chocked, If you're using a
lift, make sure the bike is securely strapped to it.

Remove the wheel and unbolt the caliper bolts. Having an assistant hold the
calipers away from the shiny, delicate fender paint will make life easier.
Remove the fender and place it somewhere it won't get kicked or have something
knocked on it by the dog. (Don't ask me why I stress this.) Do not leave the
calipers hanging from their hydraulic lines; hang them from a convenient part
of the bike.

Cruisers with fat fork covers can be a bother. So, to make sure everything
stays in line while you're working, only remove one fork leg at a time. Start
by loosening the top pinch bolt. When that is loose, remove any plastic fork
caps that may be in the top triple clamp. If the fork has screw-in caps,
loosen it a quarter turn to break any stiction the threads may have. Hold on
to the fork as you loosen the lower pinch bolt(s). Often the leg will drop
free once the pinch bolt(s) has released. If the leg doesn't drop free, gently
pull downward while twisting the fork.

Now comes the fun/messy part. Those of you whose fork caps have threads,
unscrew the cap with a socket wrench. Be forewarned, when the threads
disengage, the cap will pop out, possibly with a good deal of force. Even when
you're prepared for this, the cap can still get away from you. So, keep your
face out of the line of fire and try to point the cap at something that will
safely catch it! Forks with circlip secured caps often require three hands to
free up. One person presses down on the cap while the other removes the
circlip. Then the circlip remover should wrap a rag around the top of the fork
as the presser slowly releases the cap.

Remove the spring and any preload spacer and/or washers from the stanchion and
set them aside on some clean rags. Laying them in the proper order and
orientation will ease reassembly. Using a small flat-head screw driver, pry
the dust seal away from the top of the slider. Slip it off the top of the
stanchion. Now remove the retaining ring from inside the slider just above the
fork seal.

You now stand at a fork in the road. (Sorry about the pun.) To the left is the
traditional means of replacing the fork seal: drain the fork, remove the
damping rod bolt from the bottom of the slider, remove the damping rod,
and-returning to your prehistoric roots-muscle the stanchion out of the
slider. The advantage of this method is that you can actually inspect the fork
bushing for signs of wear. The disadvantage is that lots of extra steps and
sweat are involved.

So, instead, we'll take the road less traveled. All you'll need is some cheap
motor oil, a catch pan, a jack, a piece of wood, and a car or truck. Fully
extend the stanchion out of the slider and completely fill the fork with oil.
If possible, make sure there is no air in the system. Reinstall the fork cap.
You now have a closed system with nowhere for the oil to go. Lay the fork on
top of the catch pan with one end against your garage door frame. Now park
your car with its front wheel parallel to the door frame. Place a board across
the car wheel and wedge your car's jack horizon- tally between the fork and
the board. Slowly extend the jack. With nowhere to go, the fork seal will push
out. As soon as the seal slides out far enough that you can pry it
the rest of the way with a screwdriver, stop compressing the fork, or things
could get messy.

Remove the fork cap and drain the oil into a recycling container. Pump the
fork several times and drain again. Repeat until all of the oil has been
removed. Before you slide the old seal off the stanchion, note its
orientation. While most fork seals look similar, their orientation can vary
from model to model. Closely inspect the stanchion for any dings. Minor ones
can be cleaned up with a gentle rub of fine grit wet/dry sand paper. Use a
little WD-40 as lubricant and wrap rag around the top of the slider to keep
any dirt out of the fork. Wash the stanchion with contact cleaner and a rag.
If you find a major ding, take the fork to your local bike shop to have a pro
look at it.

Moisten the inner surface of the new seal with fresh fork oil. Carefully slip
it over the top of the stanchion and slide it down to the slider. If you have
a fancy seal driver set, simply drive the seal into the slider. If you're
cheap like me, take the old seal, cut out the inner surface, and place it
upside down over the new seal. If you're lucky, you were able to find a piece
of PVC pipe that matches the outer diameter of the fork seal perfectly. If
not, take a hacksaw and cut out six sections evenly spaced around the PVC.
Clean up all the grit and place it over the stanchion. Wrap a beefy wire-tie
around the pipe and tighten it until the PVC fingers fit the diameter of the
fork seal. Now, tap. the top of the PVC until the fork seal is completely

After installing the dust seal, measure the proper amount of fork oil. Slowly
pour oil into the fork. About halfway through, pump the stanchion a few times
to transfer oil to the slider internals. When you've poured in all the oil,
pump it at least 10 times before measuring the oil height. Before I acquired
a Race Tech Fork Oil Level Tool, I used to dangle a piece of coat hanger with
tape on the end to measure oil height. You can also use a tape measure. The
Race Tech tool allows you to draw out the excess oil. If the tool doesn't get
any oil, add oil until it until it is slightly above the end of the tube and
suck out the excess. Fork oil height should be measured without the spring
installed and with the stanchion fully compressed.

Clean the spring before reinstalling it, and make sure you position a
progressively wound spring in the same way it came out. Screw-on fork caps are
much easier to install alone. You'll need your assistant again for circlip
fork caps. Slide the stanchion back into the triple clamp. Be sure to bring
the stanchion to the same level on the top triple clamp as the other one.
Tighten the pinch bolts to spec. Now, you're ready for the second fork leg!.


From: Michael W Hall

Well I've got the forks back together with the Progressive Lowering Kit
and the RaceTech Gold Valve Emulators inside them, tomorrow I'll put the
fork oil in after work at the Station and Sat AM I'll reinstall them. A
couple of items I learned doing this job. Hopefully these tips will help
someone else in the future.

1. Only one of my damper rod bolts came out with the impact gun
with the 17mm fork cap still on. The other one I had a threaded rod with
an 11/16th nut welded to each end to put into the head of the damper rod
down inside the upper fork tube to hold it while I used the impact gun on
the 8mm damper rod bolt. This rod only needs to be 24" long.

2. I also used an 11/16th by 2" bolt with a nut welded on it to
try to break the 17mm allen fork cap loose but the bolt snapped right
away, luckily I had gone to Sears and bought a 17mm allen wrench the day
before or $8.99.

3. Also before you take off the front tire make sure you loosen
both 17mm fork cap bolts. I only did one first so I had to put the tire
back on to loosen the second one.

4. My 86-1100 has the air assist sleeves on the top of the forks
with a connecting tube between them and a valve on one side to fill the
forks with 5-10 lbs of air to firm them up. The book says to loosen one
of the fittings on the sleeve (for the air tube that runs between them)
but when I did this and tried to pull one fork out at a time the tube
bent and the threads on the fitting got a little messed up and I couldn't
find a 10mm 1.0 thread tap and die to clean them up so I went down the
street to my local Suzuki shop and he used a thread chase (like a file)
to clean up the male fitting and then I went to my local body shop and he
used a paste to clean up the female fitting in the sleeve. Since the tube
between the two sleeves is fairly rigid and the sleeves are mounted on
the forks with no play the only way I can see to get the sleeves off is
to pull both forks down and out of the sleeves (there are stopper rings
below them on the forks which you have to pull out also) and right out
the bottom pinch nuts. I'll do the reverse I hope to reinstall the forks.

5. Also when putting the upper bushing that goes underneath
washer and fork seals in the top of the lower tube I used an 1-1/4 in PVC
coupler to pound in the bushing with the washer on top of it. It worked
perfect. Then I used the same PVC coupler on top of the fork seal and put
a length of 1-1/2 in PVC slid over the upper tube to pound on the coupler
to drive the fork seal in. This also worked great. Hopefully when I put
them on I won't have any leaks.

6. Since I used both the Progressive and RaceTech systems I
couldn't used the PVC spacers as they were that came with the Progressive
lowering Kit so I had to cut 1/2" off of them to make up for the Emulator
in the fork.

Oh, I also got a Craftsman M/C lift/jack for Christmas but the
lift doesn't match up to the Virago motor so I have to devise something
to make it work. Next will be my Progressive 412 11" shocks for the back.
That should be much easier. Once you do this it really isn't too
difficult, but I'm always afraid I'll break something so I go real slow
and ask alot of ?'s. Thanks to everyone that helped my with this. Mike

User comments 
Matthew Posted: Thu Jun 16, 2005 9:41 pm    Post subject [ KB ]

[ Article updated...Matthew ]

Category: Fix It / Mods
Type: Type 1

Article Name: Fork Seal Replacement
Author: Matthew
Description: Fork Seal Replacement

>>Read Full Article
pachakutek Posted: Wed Aug 22, 2007 7:35 pm    Post subject

Original article published in Motorcycle Cruiser Magazine:

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