Flywheels

Complete pre-assembled flywheels with pinion shaft, sprocket shaft and connecting rods. Balanced and trued, ready to install. Pistons are not included, but any stock replacement pistons may be used. S&S flywheel assemblies are of the best quality money can buy and concerning stability and smooth running they easily meet new OEM parts and by far exceed all used flywheels.

Worn flywheels are a major obstacle during the rebuild of an engine, mostly with big expenses required to put them back into service. In such a case it is often more economic and safer to go for a new set. The Truett & Osborn flywheels offered here are manufactured from 80-55-06 ductile iron blanks, which are then heat treated. The 80,000 pound tensile strength blanks undergo an exacting 20-step manufacturing process, utilizing both CNC and conventional precision milling and machining. This insures accurate surfaces, legendary reliability, and excellent „truability“, an absolute necessity when setting up high performance motors to blueprint specifications.
They are made just like the stock counterparts, i.e. the left wheel is thicker than the right one (exc. JD and 45”), with the same weight and resulting torque.
All versions are unbalanced and require adaption to the respective lower end components. All T&O flywheels feature pre-installed and replaceable connecting rod thrust washers, providing increased service-life and restorability.

Of all measures to increase horsepower and torque of your factory engine, stroker flywheels are among the most effective. Boost your stock displacement 61” or 74” Knucklehead, Panhead or Shovelhead up to 84 cui (=1380cc) (@ 3-7/16” bore) and experience arm stretching performance and a significantly increased fun factor.
Especially with original engine cases these 4.5” stroker flywheels are the way to go. If any, they require only minor modifications for installation and unlike with machining for Big Bore cylinders cases become not weakened. Consequently, engine life expectancy is near stock.
All versions are of Torque Monster type with thick left flywheel as original and require special stroker pistons, which are also available.
Manufactured from 80-55-06 ductile iron blanks, which are then heat treated. The 80,000 pound tensile strength blanks undergo an exacting 20-step manufacturing process, utilizing both CNC and conventional precision milling and machining. This insures accurate surfaces, legendary reliability, and excellent „truability“, an absolute necessity when setting up high performance motors to blueprint specifications. With pre-installed and replaceable connecting rod thrust washers, providing increased service-life and restorability.
Recommended for qualified mechanics only, because the flywheels need to be balanced and clearances in engine cases need to be checked.

There is NO Substitute for more cubic inches! Boost your little Flatty up to 54 cui or 900cc respectively and experience the change from a lame duck to an agile pony. These 4.5” stroker flywheels require special stroker pistons which are also available. Recommended for qualified mechanics only because the flywheels need to be balanced and the engine cases and cylinders must be relieved for the rods to clear.
The selection includes:
flywheels for stock 45” crank pin and connecting rods, flywheels for racing purposes which work with stronger 1957-84 Sportster crankpins and connecting rods,

As late as 1999 HD used flywheel constructions with conical crank pins with their respective nuts. For tightening these nuts with correct torque please refer to the factory manual.

Complete sets with different sizes. Used to establish the correct side play of your flywheel assembly in the crankcases.

Stock replacement flywheel shaft nuts. For tightening these nuts with the correct torque please refer to factory manuals.

As late as 1999 HD used flywheel constructions with conical shafts. The keys lock the shafts in their position.

Spacers between left side Timken bearing and engine sprocket for Big Twins 1955-1968. Use to align the engine sprocket with the clutch basket, especially on models with belt drive kits.

Replacement sprocket shaft spacer between the left side Timken bearing and the engine sprocket.

Spacers shims which are inserted between the left side Timken bearing spacer and the engine sprocket to align it with the clutch basket (important on models with belt drive kits).

Big Twin Evo models from 1990–up, which are factory equipped with the one-piece flywheel and pinion shaft, require this pinion shaft conversion kit in conjuntion with S&S Sidewinder or Stroker Kits, because S&S flywheels are using the earlier system with the pinion shaft bolted to the flywheel. The kit contains the pinion gear, oil pump drive gear, pinion shaft spacer and pinion shaft nut.