Harley-Davidson Evolution Big Twin - Crankcases

Harley-Davidson Twin Cam Rocker assembly














S&S crankcases for Harley-Davidson Evolution Big Twin

Harley-Davidson Evolution Big Twin Crankcases

S&S crankcases for Harley-Davidson Evolution Big Twin

These cases have proven immensely reliable, and do not suffer from any of the problems inherent in the stock Evo cases. They come supplied with all required hardware and all bearings are pre installed and the pinion race is already sized. The pinion bearing must be chosen to give the correct running clearance with whatever crankshaft is installed, and it may be necessary to use a different spacer between the Timken bearings to achieve correct end float. Other than that, it's as easy as it gets.

Main features are:

These are available pre machined for big bore cylinders (or we can machine them at extra cost), natural or black powdercoat finish, and to suit 84-91 and 92-99 oil pump bolt patterns. These are also used on S&S's own engines and we can rebuild them here if required.

Harley-Davidson Evolution Big Twin sprocket shaft bearings


Harley-Davidson Evolution Big Twin Timken bearings

Timken crankshaft bearings

These strong and durable Timken bearing sets fit stock Harley and all aftermarket crankcases, including S&S, Delkron, and STD. Removal and installation requires service tools and a press. End float must be carefully set, and is controlled by selecting the correct shim that is sandwiched between the two inner races. There are 15 different shim thicknesses available.

Harley-Davidson Evolution Big Twin pinion bearing outer race


Harley-Davidson pinion bearing race

Evolution pinion outer race

The Evolution version of this outer race has an annular groove and additional oiling holes to provide better oiling to the longer rollers used. Removal and installation requires special press tools, which are not commercially available (we designed and manufactured our own). After installation, this race must be aline lapped to the bearing in the other case half. A lapping tool and precision measuring equipment is also a requirement. We can carry out all of this essential work S&S crankcases use their own race which is slightly longer and has the oiling groove in a different position. The S&S race can be used in OEM cases, but must be modified in order to allow an oil supply to the bearing rollers.

Harley-Davidson Evolution Big Twin pinion bearings


Harley-Davidson Evolution Big Twin pinion bearing rollers

Harley-Davidson Evolution Big Twin pinion bearing rollers

These caged bearing assemblies are available in four (colour coded) sizes.

.2500 Green
.2501 White
.2502 Blue
.2503 Red

The correct size is determined by measuring the crankshaft pinion shaft and the pinion bearing outer race in the crankcase, and allowing for the appropriate clearance. Measuring equipment, accurate to .0001" (one ten thousandth of an inch) is essential. The correct, heavy duty, retaining ring must be used with this bearing. The earlier, double spiral type, as used with the Shovelhead bearing, will not work, and will cause severe engine damage.

Harley-Davidson Evolution Big Twin Breather Valve

Harley-Davidson Evolution Big Twin Breather Valve

This S&S breather valve is a replacement for the troublesome OEM plastic breather valve in these engines.

We also have this available in a .030" oversize to be used with our crankcase repair procedure. Please note that the OEM plastic shims used with the original valve must not be used with the upgraded steel valve.

Therefore we also supply the valve with a set of steel shims. The correct shim must be selected during assembly to control end float.

Harley-Davidson Evolution Big Twin Breather Reed Valve

Harley-Davidson Evolution Big Twin Breather Reed Valve

This S&S breather reed valve can be used as a replacement for the rotary valve in the 93-99 head breather Evolution Big Twin engine.

It has a number of advantages in that it does not have to be timed, end float is dealt with by a spring, and it reduces the potential for excessive oil carryover.

Also, since it doesn't rotate, debris from other component failure will not damage the crankcase bore. We also have this available in a .030" oversize to suit remachined damaged crankcases.

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