Knucklehead Harley Build Part 9: Primary Cover, Clutch, Driveline and Chain

Kevin is moving right along with this Knucklehead rebuild, which by the end of this video will be 90 percent completed. He begins by assembling the rear brake system. This assembly does not use any brake fluid or hydraulic driven parts. The brake system is fully mechanical, consisting mainly of shafts, arms, and linkages. One long shaft transfers motion to the left side of the motorcycle where another linkage joins the shaft to the rear brake drum assembly.

A spring is attached to the rear brake arm. The springs function is for brake pedal return and it actuates the rear brake switch.

*Note: On early Harley Davidson models, it is typical for the rear brake arm to have this (12, 1, or 2 o’clock) standing position. Yes, using it is as awkward as it looks*

After installing the right side footboard, Kevin checks for free movement of the rear brake assembly and moves over to the left side of the motorcycle. He then installs the inner primary cover. The cover mounts to the engine crankcase in the front and mounts to the frame and oil tank in the rear. It is very important that the correct hardware is used. Especially when threading bolts into the crankcase. A damaged engine case can turn into a difficult or costly repair.

Next, the primary drive is installed. Both the engine output shaft and the transmission mainshaft are tapered. The front pulley and the Knucklehead clutch hub are located with a keyway and secured with a large nut. The nut that threads onto the transmission mainshaft is left-hand thread. The nut that threads onto the engine shaft is normal thread. Kevin carefully tightens both large nuts with a half inch impact.

With the transmission loosened, the primary drive belt is installed with letters and numbers facing outward. The primary belt is adjusted and the transmission is finally tightened to the transmission plate.

Kevin assembles and installs the Shovelhead style foot shift assembly. This assembly consists of a bracket, shift arm, footboard, linkage and kickstand assembly. The Knucklehead clutch plates are installed and the clutch is adjusted.

The secondary drive chain is installed and chain tension is set with chain and wheel tracking considered and set accordingly. The rear drum brake is now adjusted. Kevin wraps up this video by installing the outer primary cover.

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