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Wide Tire Conversion And A Performance
Close Ratio!
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WideGear is a plus 30mm (1.18") extension
kit for late model (1991 and up) Big Twin five-speeds
with trapdoor access. It also fits earlier five
speeds that have been updated with a splined
clutch kit. (At present, we don't offer a Sportster
kit.) We offer transmission spacers for FLs,
STs, and Dynas.
Incorporating Johnson Engineering's breakthrough
TwistGear-based close ratio fifth-gear replacement
set, tire clearance is provided by extending
the transmission and engine sprocket Incorporating
Johnson Engineering's breakthrough TwistGear-based
close ratio fifth-gear replacement set, tireclearance
is provided by extending the transmission and
engine sprocket shafts as opposed to the potentially
unstable workaround of offsetting the wheel,
entire drivetrain, the transmission only, or
various combinations of the above. The billet
transmission spacer shown in photo is for FL/FXR
applications. Dynas require a two-piece spacer,
while STs use our exclusive cast one-piece spacer,
seen at bottom of page.)
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What About My Twin Cam?
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| Thinking about a wide Twin Cam?
Then forget about the transmission offset kits.
The only way to fit wide skin behind a TC is by
extending the primary, or offsetting the entire
drivetrain (don't forget to put your foot down),
or offsetting the wheel. For the first time you
can take advantage of TwistGear performance and
Twin Cam power in a wide tire profile...perfect!
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Fit Up To 230mm — And Wider!
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| The
extended main and input shafts safely move
primary 30mm outwards. |
WideGear’s 30mm extension
(trapdoor assembly shown at left) means real rear
tire fitment of at least 230mm (Canadian manufacturer
Custom Valley uses WideGear in their own demo
bike, offers 240mm ST and Dyna conversions) can
be achieved without offsetting the wheel, engine,
or transmission.
The result is a huge increase
of 100mm of additional tire width when installed
using a chain final drive. When a 1.5" belt
is retained, 60mm (i.e., a 190mm tire when 130mm
is stock) is the maximum width increase without
additional modifications for more clearance. Use
of a narrower, 1.125" belt for more clearance
is another option, but due to the higher stresses
generated by larger engines hooking to bigger
tires through a close ratio box, there is a greater
risk of belt damage or failure as a result. Practically
speaking, chain conversion is the simplest method
of gaining additional clearance, and has the added
benefit of many more (and simpler to install)
ratio options, although a good many riders are
hesitant to give up the comfort and convenience
of their belt. |
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Offset? Not If You Can Help It
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| Viewed
from the front, WideGear's massive 30mm
engine spacer is at right, with our 30mm
extended main gear seen on end (left). Right
behind the maingear is the transmission,
kept in line with the drivetrain with our
billet spacer for FLs and FXRs. Spacers
are also available for STs and Dynas. |
Some of the inherent drawbacks of the other wide
tire conversion methods currently used include
intentionally offsetting the rear wheel to gain
clearance, which can introduce a nonlinear tracking
situation, as well as headaches trying to fit
fender and struts. If wheel offset is used in
addition to any factory offset, the results can
be alarming. Another factor to consider when dealing
with wheel offset in particular is the tire design.
Different manufacturers products can have a dramatic
impact on riding stability.
Shifting the engine and/or transmission, the
main method of providing the necessary clearance
for a wider tire, has the undesireable side effect
of intentionally repositioning the center of gravity
to the left (outboard) to an even greater degree
than offsetting the primary alone. When combined
with an offset wheel, the resulting ride can be
erratic. If you've ever watched a wide tire conversion
rider fighting the handlebars, listing to the
left while riding, or wondering what direction
the bike will take going into a curve, you've
seen the effect extreme offset has on handling.
WideGear (right) avoids these shortcomings by
using spacers between the tranny and engine, and
by extending the main gear (shown above, foreground)
and mainshaft 30mm (1.18") outward. (Notice
the helical angle of the extended main gear, as
well as the extended engine sprocket nut and coupler
in the photo.) And although the weight of the
primary is moved outboard, the additional penalty
created when the tranny and starter are also moved
is avoided, as is the extreme weight relocation
caused when the engine is also offset. |
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30mm For Plenty of Clearance
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| That said, if show's the name and
sitting's the game, WideGear provides an excellent
starting point for stuffing that fat skin between
the rails. WideGear gets you going by allowing for
an additional 2.36" of tire width, and if more
is needed, than tranny offset with appropiate spacing
at the engine is always an option. For all around
performance, though, offset should be avoided, particularly
when the aggresive gearing of our close ratio tranny
is factored into the equation.
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| Side
by side comparison shows TwistGear profile,
left, and WideGear's massive plus 30mm,
right. The extra 1.18" of extension
accomodates a wide variety of tire widths,
without the need to offset the transmission
or engine. |
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| Before the introduction of the TwistGear family
of helical close ratio transmission modifications,
more aggresive acceleration usually meant a lower
(higher numerically) overall ratio, which could
only be accomplished by dropping the tranny pulley's
or raising the wheel pulley's tooth count, which
affected the entire ratio, including fifth, and
severly limited top end performance. |
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Fully Integrated Design |
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Unique
cast transmission spacer (ST only) is one
third the weight of billet, and heat treated
to resist additional stress placed on components
by extending the primary. |
WideGear is the only close ratio engineered approach
that retains proper design geometry and weight
distribution, while maintaining the overall integrity
of the drivetrain as it relates to the driven
wheel.
The complete kit contains all necessary parts,
including extended clutch pushrod, engine and
transmission spacers, starter coupler, extended
compensator sprocket, and nut. Also included are
our exclusive triple lip oil seal, chamfered transmission
spacer, and 4-point trapdoor bearings.
WideGear also features a needle bearing (extra
cost) that fits the engine sprocket nut for outboard
engine shaft end support. (A suitable outer primary
with a built-in support shaft or nub is needed
to utilize this feature.) |
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What About Performance? |
| WideGear is the only performance
oriented conversion kit available today. Manufactured
in the USA, our gear components are the highest
quality available, and are superior to offshore,
imported kits. If you're interested in checking
out just how good WideGear can be or need info on
just what pulley combo's right for your kind of
riding, then check out our gearing charts for answers
to these commonly asked questions. You'll know ahead
of time whether or not you need more gear or engine
speed reduction, depending on your riding style. |
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SportGear™ and TwistGear® are
trademarks of Johnson Engineering,
Inc. Buell™, Dyna™, and Sportster™
are trademarks of the
Harley-Davidson Motor Company. No affiliation
with the
Harley-Davidson Motor Company is implied or
inferred.
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