Fat Is Where Its At !!
Making Room for Wider Tires
Have you ever
considered installing a fat rear tire but thought the fit might be a bit
to tight ? Well here is a tip that will free up a little extra space you
may need to accommodate that oversize tire. In a recent V-Boost issue we
listed many of the available tires that will fit the Vmax and some that
may be a marginal fit. The Metzler ME880 170/80-15 is just such a tire. A
call to Metzler confirmed that the stock 3.5 inch wheel width is within
specification for this tire application. However, without a little more
clearance this tire will rub on the shaft side of the swing arm. There are
a few brands of 170 size rear tires that will fit but for those of you who
choose the marginal ones or just desire a bit of extra swing arm-to-tire
clearance this may be the ticket for you.
basically moves the washer located on the rear axle between the brake arm
and the swing arm to the other side of the wheel between the differential
drive unit and the wheel drive hub. This provides extra clearance for the
tire on the swing arm side of the tire equal to the width of the washer,
about 1/8 inch. A bit of additional clearance may be obtained by making
sure the differential unit is mounted to the swing arm as far to the right
hand side of the bike as possible.
motorcycle on the center stand, or something appropriate if the stock
center stand has been removed (sometimes necessary for fitment of an
aftermarket exhaust system).
license plate to facilitate removal and installation of tire/wheel
Remove the two
bolts holding the rear brake caliper to the brake arm and swing the
caliper out of the way. It will rest on the outward side of swing
arm/shock or if you remove the right side shock it will simply sit on the
Remove the rear
axle cotter pin, (pre-'96), axle nut, and washer on left side of bike.
Loosen the axle pinch bolt on the right side of bike. You should now be
able to pull the rear axle out from the right side of the bike while
lifting the tire/wheel (to get the tire/wheel weight off the axle; it
really isn't going anywhere at this point as the drive hub is still firmly
seated in the differential unit). The washer mentioned previously on the
right side of the wheel should drop to the ground when the axle is
The wheel will
be continue to held off the ground as it is still seated in the
differential drive unit. Pull the brake arm toward the rear and up past
the top of the tire to get it out of the way. You may need to loosen the
bolt holding the brake arm to the brake torque rod to swing it out of the
way or it may simply be removed if you want some extra elbow room.
You should now
be able to pull the tire/wheel assembly to the right and away from the
differential assembly while supporting its weight; it should drop to the
ground. Roll the tire/wheel assembly out to the rear of the bike. If you
have a very large tire already fitted to your wheel, you will probably
need to let all the air out of the tire so it will slide between the
differential and the right side of the swing arm.
This is the
prefect opportunity to clean up the inside of the differential and wheel
assemblies, the brake arm, the rear caliper, and the axle. Maybe even your
reassembly (and after cleaning), apply bearing grease to the splines
inside the differential drive unit and lightly coat the rear axle, (moly
grease is recommended).
With the rear
wheel off and out of the way you also have an opportunity to make sure the
differential unit is mounted to the swing arm as far to the right as
possible to take advantage of any extra clearance this may provide. Loosen
the four nuts that hold the differential on to the swing arm. Just a bit
loose; allowing the unit to be moved slightly with a few mallet taps. Tap
the differential to the right side of the bike with a plastic or rubber
mallet, and tighten the four nuts. It may or may not move at all,
depending on factory assembly and tolerances.
We are now
ready for reassembly. Take the washer that was previously between the
brake arm and the swing arm on the right side, (don't confuse it with the
thicker washer that came off the left side from underneath the axle nut).
Place this washer into the differential unit spline area near the center
where the axle hole is. Insert a screw driver or other suitable instrument
from the outside of the differential unit and into the axle hole to keep
the washer in place until we can slide the axle back in through the wheel,
tire/wheel assembly back in between the swingarms and lift it up and onto
the differential unit engaging the splines on the wheel and drive unit to
hold it in place. Push the wheel to the left to make sure it if firmly
seated in the differential while guiding the screwdriver through the
center of the wheel hub. Once the wheel hub is fully seated it will press
up against the washer we placed in between the hub and the drive unit and
keep it from sliding our of position.
At this point
you may want to look into the axle hole from the outside of the drive unit
to see if the washer in centered. If not, you should be able to move it
slightly to center it before installing the axle, (leave the screwdriver
in place until you are ready to push the axle through just in case).
Swing the brake
arm down and forward; make sure it is aligned between the wheel and the
Slide the axle
back through the right swing arm, brake arm, wheel, washer (in between the
wheel/differential unit), and differential. If you still had a screwdriver
inserted to hold the washer in place, it should have been pushed out at
this point and the axle should be protruding from the outside of the
left side axle washer and nut and torque to the proper specification;
reinstall a new cotter pin if so equipped.
brake caliper making sure the brake pads have been spread to facilitate
sliding it over the brake rotor. Install the caliper retaining bolts and
torque to the proper specification.
Torque the axle
pinch bolt on the right swing arm to the proper specification.
license plate (we wouldn't want you to get pulled over!).
Be sure to your
tire is inflated to the proper pressure and check for tire-to-swing arm
clearance on the left side. You should have enough clearance to fit many,
(perhaps all), of the 170 series tires available. Remember, the tire will
expand when it gets hot under a load.
has been tested for years under heavy load conditions, (high speed,
wheelies, etc), on many different Vmaxes with the long lived Metzler ME88
and the more recent replacement ME880 170 series tires with no apparent
adverse affects to the drive engagement splines or any of the drive gear.
Some rear ends do have minimal clearance due to manufacturing tolerances
and the tire may still be too close after it heats up. This seems to be a
rare occurrence but if it is encountered it would be wise to make sure the
entire swingarm is not severely out of alignment.
A special thanks
to Brad Thomas of Mesa, Arizona for sharing this tip. His many years of
experience in the application of this modification on so many different
Vmaxes allows it to be recommended without reservation.
place prior to modification
880 -170/80 -15
where the washer went ! NOTICE Screwdriver holding washer in PLACE