Zipper’s is the source for the Bisagno Bros. billet 5 speed Big Twin transmission door! This heavy-duty door originally designed by Frank and John Bisagno is now being produced by Zipper’s. Its main features are the double-row ball bearings used to support the main and countershafts. Stock single-row bearings allow the shafts to flex considerably, causing accelerated wear on the gears and frictional power losses. This door holds the shafts straight and true for much needed additional support. Shifting is improved and more precise. Supplied in machined billet or black powder coated finish with spacers and shaft nuts for assembly.  Made in USA!

Weight 1 lbs

Country of Origin

Engine Type

Transmission Type

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