We use cookies for analytics, advertising and to improve our site. To find out more see our privacy policy.
>
Shop
>
Transmission
>
Transmission 45cui/750cc
>
Transmission Complete

Transmission Complete

4-speed Transmission 45”/750cc
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
more …

Repair it (again) or install a brand new gearbox in the flattie? Maybe even 4 gears?

Anyone who doesn't insist on having a 100% original restoration of the bike will be happy to answer this question with "a brand new one". And if you are a sporty rider, you will appreciate an extra gear.

The big advantage of 4-speed gearboxes is that especially the large step in the transmission ratio between 1st and 2nd gear is eliminated including the resulting sharp drop in speed. Closer gear ratios result in smaller rpm drops and better acceleration.

Why gearboxes from Samwel?

Samwel always attracts attention with innovative products in an old guise - i.e. old housings: a 12.7 mm belt drive und stock primary covers, electronic regulators under the Delco cover, electronic ignitions for distributors up to 1962 and now the integration of four gears in a 3-speed housing. Mechanically not that complicated, because the original countershaft combination gear also has four gears. However, kudos for all the innovations in the details - the design of the teeth and shifting claws.

Have any questions?

Our service team will be glad to help out: Mondays - Thursdays 08:00-17:00 CET, Fridays 08:00-16:00 CET, Phone: +49 / 931 250 61 16, eMail: service@wwag.com