Part Description
4-speed 'close-ratio' transmission for 750cc Flatheads
Identical appearance to the stock 3-speed transmission. 1, 2, 3 are smaller and 4th gear is identical to OEM ratio. We all know that the power band of 45" side valve engines is not all that wide and torque not that great. The original 3-speed transmission can, especially when accelerating up-hill with a sidecar, or cruising at a certain speed, give you the feeling that you'd like an extra gear to smooth things out. Especially shifting from 1st. to 2nd. is quite large and can result in a large RPM drop that takes you outside the ideal RPM/torque range. This transmission comes with a bit smaller 1st., 2nd. and 3rd. 'close-ratio' gears but the 4th gear has the identical 1:1 gear ratio as the original 3-speed transmission. The only thing that will give the transformation to 4-speed away is the 4-speed shifter gate, which must be ordered separately. Transmission is fully assembled and ready to run. Just add oil after installation, invite your mother in law and take to the hills with confidence! Stock 3-speed ratios are: 1st = 2.47:1, 2nd. = 1.57:1, 3rd. = 1:1. This 'close-ratio' 4-speed transmission ratios are: 1st. = 2.67:1, 2nd. = 2.03:1, 3rd. = 1.42:1, 4th. = 1:1. Note: A 4-speed shifter gate must be ordered separately and is available as 909605 (chrome) and 909073 (black).
