4-speed Transmission 45”/750cc

Fully assembled, ready-to-install, 4-speed (!) transmissions for 1941-up 45 cui./750 cc Sidevalve Harleys.

It is a fact that while the engines seem to last forever, those worn, clunky 45” transmissions can be a continuous source for trouble. Full restorations - and that’s exactly what is often required - are expensive and tasks for the real experienced only, so it is definitely worthwhile to consider a complete replacement. Especially when this replacement is not just a well functioning duplicate of the same old thing but a large improvement, too.

A real drawback with original 3-speed transmissions is the large gear ratio difference between 1st and 2nd, i.e. from 2.47 to 1.57:1 with a consequent big rpm drop. If you ever rode 2-up in the mountains you will know how annoying this can be. The 4-speed version with its extra gear is a vast improvement here because it allows you to stay in the power band much better for an overall riding performance unknown before. Additionally, all gears are machined from modern materials for higher strength and feature an updated tooth-design for smoother and quieter running. Solo machines, sidecar rigs and Servi-Cars - all likewise benfit from these features.

The 4-speed transmission comes completely assembled with all gears, shafts and covers installed for a quick, straightforward installation. It accepts your original primary drive with clutch and the chain sprocket with cover. It looks exactly the same as its 3-speed counterpart so nobody can tell the difference from its outer appearance. The only extra part required is a 4-speed shifter gate.

Stock 3-speed gear ratios:

1st - 2.47:1

2nd - 1.57:1

3rd- 1:1

4-speed gear ratios:

1st - 2.67:1

2nd - 2.03:1

3rd - 1.42:1

4th - 1:1