Transmission Parts

Complete selection of Andrews transmission components. Why Andrews transmission parts? Andrews gears and shafts are made from stronger-than-stock materials. They have heat-treated and polished surfaces where necessary for smoother and faster shift operations, which results in much longer durability of all transmission components. It's hard to believe there is such a big difference between Andrews gears and others until you ride a bike with these products installed.

Used for the restoration of worn-out stock 4-speed transmissions or building new custom transmissions for Knuckleheads, Big Flatheads, Panheads and Shovelhead models 1936-1976. With an Andrews gear set transmissions last longer, shift faster, and just plain run better. In addition, you will receive optimized gear ratios since each kit includes specific close ratio gear combinatons for an improved riding experience. Bikes with Andrews gears feel so good that it’s hard to believe until you feel the difference for yourself. Each kit includes all gears, two shift clutches and two shift forks. Shafts and small parts kits must be ordered separately.

For all 4-speed Big Twin transmissions from 1936–86. Each kit contains Jims proven transmission parts and all necessary gaskets by James. Everything together in one package make for a big time saver.

Ok, it served us well for decades, the trusty main drive gear bushing, but it is certainly possible to improve this feature as we can see in the later 5-speed transmissions. So you simply modernize the set-up by installing needle bearings? Not quite. A mechanical engineer from good old Germany really did his homework here and came out with some extra fine products. We are looking at high end precision parts manufactured after the latest German automotive industry standards and when it comes to material selection, surface hardening, structure and function of components they are second to nothing. Weak points in the original design were consequently eliminated:
Mainshaft updated with rolling bearing surface, Redesigned main drive gear with bore for needle bearing, Double "full circle" needle bearing support in lieu of bushing,
The results are the precise alignment and guide of main drive gear to mainshaft, plus significantly improved service life and oil tightness. Only Carlo’s mainshafts serve as replacement parts. These, in turn, can be used as stock replacements.

Reproduction of the original transmission adjuster as used on Big Twins 1936–64.

Dual adjuster for 4-speed transmissions 1936-64 (tin primary) and 4-speed transmissions thru 1984 with open primary drives.

Replaces the stock vent screw on all Big Twin transmissions 1936–79, which is often plugged by dirt. A plugged vent screw causes pressure build-up and consecutive oil-leaking. To make things worse an open OEM  vent screw allows water to enter the transmission case when riding in the rain or washing the bike. Our new style vent screw with tube easily solves both problems.

When using stock clutches you require this special adjuster screw.

When using aftermarket clutches like Barnett Scorpion and Rivera Pro-Clutch with 7/16”-20 adjusters you require this special adjuster screw and locknut.