June 3, 2003
That Early 5-Speed Into A Smooth, Modern Performer!
Harley made the move from four to five-speeds in 1984-85, it began
a process that wouldn't be finalized until 1991, with the transition
splined output shaft to replace the keyed taper shaft that was prone
your 1985-1991 five-speed to a modern day TwistGear/WideGear setup
is easier than you think.
TwistGear and WideGear to Older 5-speeds
TwistGear and our new WideGear 30mm extension are easily retrofitted
to 1985-1990 BT 5-speeds, resulting in major increases in reliability,
performance, and comfort. Harley-Davidson's
5-speed, introduced in 1984-85, retained the traditional key and tapered
shaft design joining the clutch hub to the
The key tended to shear, usually in direct relation to available
horsepower and torque, the spacer seal was easily damaged during
installation, the main shaft bushing was prone to leaking, and servicing
required case removal.
1991 the splined mainshaft design was introduced, which not
strengthened the drivetrain components significantly, but made servicing
the clutch and transmission much easier as well — a definite
improvement all the way around. Ball bearings replaced the needle
the main gear, while the old style main shaft bushing was converted
to needle bearings and sealed with an interior oil seal.
convert the old style 5-speed, you'll need a splined main shaft
and clutch hub, along with your preferred clutch.
also need a transmission output sprocket to go with theTwistGear
WideGear kit you're installing. You may also want to invest in a
late model trapdoor that can take advantage of the larger bearings
used since '98. To the best of our knowledge, the following OEM
part numbers can be
are available from the aftermarket.
(not required with WideGear)
compensator sprocket, 24T
compensator sprocket, 25T
clutch shell and sprocket, 37T
clutch shell and sprocket, 36T
Include Major Upgrade In Seals And Spacer
improved spacer and oil seal are also major improvements that result
from upgrading. The old spacer design (see our new,
improved version for four-speeds that combines
spacer and seal) was wide, with a small, fragile cross-section and
during oil seal installation. Further degrading longevity are the
transmission sprocket splines, which generate high spline stress.
1994 sprocket upgrade is wider, allowing a large diameter narrow
in turn allows a bigger lead-in chamfer. The end result is reduced
spline stress and easier seal installation. Our
spacer, included in the TwistGear kit or available separately, has
a lead-in chamfer twice that of the 1991 OEM spacer, speeding
and reducing the potential of installation damage.
oil seal design is different as well. All our helical system upgrade
- TwistGear, WideGear, and SportGear - kits include our exclusive
triple lip oil seal, which
separately, as can our alloy spacer. If
you're considering an overhaul, now's the perfect time to upgrade both
the reliability and performance of that vintage tranny. It's easier
than you think, and better than you could imagine.
About Four Speeds?
for four-speed frames, there are several manufacturers of "five
into four" cases that fit square swingarm frames and accept
trapdoor cassettes. Although we haven't tested them, we see
no reason why they wouldn't work. Disclaimers usually include having
back to a tapered mainshaft, but in order to use TwistGear, you'd
do the opposite and fit a splined late model mainshaft, which would
also affect the rest of the drivetrain, including the clutch hub.
also the issue of shifter linkage and cable routing, but
all in all it looks like a relatively easy workaround that can
bring modern technology to those old Shovels, Pans, and Knucks.
We're currently developing sources for
riders who don't want to give up their classic rides in order to
benefit from modern five-speed transmission technology.
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.