4-speed 'close ratio' transmission for 750cc Flatheads

Identical appearance to the original 3-speed transmission. Ratios 1, 2 and 3 are shorter and 4th gear has the same ratio as the OEM one. We all know that the power range of 45" side-valve engines is not very wide and the torque is not exceptional. The original 3-speed transmission can, especially when accelerating uphill with a sidecar or riding at a certain speed, give the feeling that a gear is missing to smooth out the shift. The step from 1st to 2nd gear is quite wide and can cause a significant drop in RPM that pulls the engine out of its ideal RPM/torque range. This transmission includes shorter ratio ('close-ratio') gears for 1st, 2nd and 3rd gear, but 4th gear keeps the same 1:1 ratio as the original 3-speed transmission. The only part that gives away the 4-speed conversion is the 4-speed shift fork, which must be ordered separately. The transmission comes fully assembled and ready to install. Just add oil after installation, invite your mother-in-law along and climb the hills with confidence.
The original 3-speed transmission ratios are: 1st = 2.47:1, 2nd = 1.57:1, 3rd = 1:1.
The ratios of this shorter-ratio ('close-ratio') 4-speed transmission are: 1st = 2.67:1, 2nd = 2.03:1, 3rd = 1.42:1, 4th = 1:1.
Note: The 4-speed shift fork must be ordered separately and is available in 909605 (chrome) and 909073 (black).


Specifications


Brand
Samwel


Application
41-51 WL (NU)


Material
Steel


Packaging weight
10.3 kg


HS Code
87141090


Original name
4-speed 'close-ratio' transmission for 750cc Flatheads