We use cookies for analytics, advertising and to improve our site. To find out more see our privacy policy.

4-speed transmission by Samwel Supplies

Item №
74-003

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 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

  • fits 45”/750cc Flathead solo models 1941-1946
  • cast aluminum / steel
  • Europe
  • NOTE: These transmissions are designed for →1946 shifter gates (1st gear forward).
  • gross weight: 10.3 kg
Price incl. VAT*
2,330.00 €
* The price includes 372.02 € German VAT (19% or reduced rate of 7% for Books).
In stock. Ready for immediate delivery from our Würzburg, Germany warehouse.
each
Save to wish list

See also:

4-Speed Conversion Kit 45”/750cc

4-Speed Conversion Kit 45”/750cc

A 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. With the installation of this 4-speed conversion kit one can achieve a big improvement here because its extra gear 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 benefit from these features.
The conversion kit includes all gears and the shifter drum to transform an old 45” gear box into a 4-speed transmission. All other stock 3-speed parts, like shafts, shifter forks, etc. can be retained or must be purchsed separately if not present. The original primary drive with clutch and the chain sprocket with cover fit without problems. After installation the 4-speed tranny will look 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. The stock side cover has to be machined for clearance. As an option a pre-machined version is also available.
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
more …