TwistGear Seals and Spacers




Johnson Engineering
100 Blake Road
Denver, IA 50622
(319)984-9299 fax

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April 3, 2003

NEW! One Piece Four-Speed Spacer and Seal
IMPROVED! Five-Speed Triple Lip Transmission Oil Seal

seal spacerTired of frustrating leaks and expensive repairs because of damaged or worn out seals? Then you'll welcome our engineered solution to a nagging five-speed problem - sloppy, messy leaks caused by average oil seals. Our exclusive system is designed around our revolutionary triple lip oil seal and includes a tough alloy spacer and powerful installation tool that when used together deliver miles of extended service from your stock or modified powertrain. And further proving our commitment to engineered v-twin performance is our first four-speed product, a combination spacer, seal, and installation tool. Check out the details below, then call to order. (Tech sheet in our PDF library.)

Four-Speed Spacer/Seal Combo

New for 2003 is our exclusive four-speed spacer/O-ring seal combo that, in conjunction with our innovative and simple installation tool, effectively cures one of the two major sources of four-speed oil leaks around the main gear shaft. The precision ground, coated alloy spacer features an integral O-ring that installs in an inner groove halfway down the spacer, for superior sealing characteristics. The red plastic tool is laid into the groove between sprocket nut threads and sprocket splines before installation and eases the O-ring over the spline corners and edges. We recommend easing any sharp edges with a stone. (To insure problem free operation, pay attention to the main gear inner bushing. Make sure that the mainshaft isn't worn or damaged, and that the bushing isn't distorted or worn. Even a small amount of play WILL leak.)

Five-Speed Seal Gets Major Upgrade

5 speed sealOur improved five-speed seal now features an industry exclusive hybrid rubber/metal shell that actually locks the seal in the bore, preventing the seal from popping out. The metal portion, once properly seated using our new installation tool, locks the seal firmly in place by grabbing the sides of the bore. Meanwhile, the rubber coated upper portion provides superior sealing protection against any oil that may try to work it's way around the metal sides of the seal. Finally, we respec'd the seal spring for improved lip sealing characteristics. Combined with our super tough chamfered spacer, it's a system that can't be beat for ease of installation, extended service intervals, and miles of trouble free riding.


Superior Seals and Spacers from TwistGear

four speed parts

Four Speed Spacer

Brand new four-speed spacer and seal combo features nitrided spacer with machined O-ring groove. Secret to installing without tearing is the use and toss tool, top right.

four speed seal

Four-speed tool is inserted into groove between sprocket nut thread and splines. Ramped tool allows O-ring to slide over spline corners without cutting. Can also be used with later model main gears with existing O-ring for double protection.

Four-speed spacer is shown ready to be installed. O-ring is secure in machined inner groove about halfway down the spacer and is protected from nicking while sliding over the sprocket splines by the unique use and toss installation tool just to the left of the spacer.

five speed parts

Better Five Speed Seal

Improved five-speed seal features metal - rubber outer surface for excellent sealing and retention in the bore. Our new tool, left, contacts only the outer rim and presses the seal squarely into place.

install one

Installation's A Snap!

Improved five-speed seal is first assembled with TwistGear heavy duty chamfered spacer, ready for installation over WideGear 30mm extended mainshaft. Procedure is easy in-frame repair.

install two Seal is centered in case bore, hand pressed to start into place. Pen point indicates hybrid rubber metal composite, adapted from latest automotive technology and highly resistant to deterioration from new oil compounds and additives.
install closeup Close up view of seal edge demonstrates width of lower metal locking surface, while rubber upper surface, several thousandths wider than metal, provides superior leak protection.
install three With seal ready and in position, tool is ready to be placed over main gear.
install four Tool is snugged up firmly against seal, making sure both are square to bore before pressing seal home and that transmission is locked up.
install five Sprocket locking nut is threaded on. Removal sprocket can usually be hand tightened until seal bottoms out and is felt to be fully seated.
install six Installed seal is now firmly in place, without the need for staking. Leaks are almost always the result of installation misalignment - impossible with our exclusive TwistGear tool. Works with OE and aftermarket seals, but why would you want to when ours is this good?


Temperature Rated to Over 300 Degrees!

seal lipConventional seals have only one or two lips, providing meager resistance to the high temperatures generated when sand, dirt, oil, and water become trapped between the lip and the spacer - your typically hostile interstate conditions. Failure occurs quickly thereafter, and with it certain mechanical damage to the spacer. Johnson Engineering's triple lip seal overcomes OE and aftermarket limitations by adding a third outer lip, seen at right, that's angled outward to form a virtually impenetrable barrier against everyday road grime and grit.

five speed tool
Our new oil seal installation tool, shown in regular length and also available in 30mm extended version for WideGear application, actually uses the main gear as a press, insuring smooth, secure, square seal installation both out of and in the frame.

The main function of our outer two lips is to seal off the inner lip from dirt and debris. The inner lip actually provides most of the oil sealing, and is very susceptible to mechanical or temperature damage. Both the outer lip and our alloy spacer (below) are chamfered for super easy installation. Our new for '03 installation tool (left) insures that the seal seats squarely in the bore. The polyacrylate seal material is temperature rated to 340F, making it well suited to the unforgiving location of the main gear sprocket environment: hot, grueling temperatures, baked in road grime, water, gas, oil, and an occasional high temp pressure washing. You'll enjoy a lot more time on the road — and a lot less time in the shop waiting on expensive seal R&R.

In order to maintain proper sealing characteristics, it's important that the transmission fluid be maintained at proper levels. One of the most common reasons for leaks is simply overfilling, so watch your levels. More is definitely not better.

Our major upgrades to main gear design also pay close attention to the main gear oil seal; SportGear features a special retainer that prevents the seal from walking or cocking in the bore, an especially irritating source of leaks for Buells and Sportys.

Exclusive Chamfered Spacer That's Space Age Tough!

spacerOur unique alloy spacer's precision ground then heat treated to .010" case depth, resulting in a service item that’s extremely hard and durable. Unlike typical stainless steel spacers that need constant replacing, ours is highly resistant to grooving, wear, and the grime and acid of urban roadways. (Reusing an OE spacer usually results in new leaks soon after service, because the new seal lip and old spacer grooves don’t match.) Considerably tougher than stainless, hard chrome, or nickel plate, our spacer's outer edge is specially chamfered for easy installation. It also delivers superior lubricity and corrosion resistance while reducing surface roughness and friction coefficient, which allows the spacer to easily rotate in the seal and further reduces lip temperatures and component wear for greatly extended service schedules. Also available in a plus 30mm wider version for extended primaries, our long version can be machined down with no loss of superior properties for use with wide tire chain conversions.

Triple lip oil seals and chamfered spacers are included with every TwistGear, SportGear, and WideGear helical gear system. They are also available individually or as kits. Ask your dealer or order direct.

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.