Article By: Will Ramsey – Faith Forgotten Choppers
Originally Published In The May 2013 Issue Of Cycle Source Magazine
It’s really hard to beat the old style 4-speed transmission on a chopper. It has a classic style, a simple construction, and is generally bulletproof. However, if you choose to run a foot clutch (good choice) and have a tendency to ride hard, you may find yourself hammering down the road wondering why you suddenly can’t engage the clutch. This is likely the unfortunate result of a small retainer clip popping loose inside your transmission due to aggressive foot clutch abuse. Years ago at Sturgis, I was discussing this issue with James Simonelli from Baker Drivetrain. He gave me an excellent suggestion that I have used successfully ever since. By simply drilling and tapping the release finger, a set screw can be used in place of the retainer clip. This easy modification allows the 4-speed clutch release system to withstand a great deal of aggression and fun.
Start off by removing the kicker cover on the right side of the transmission.
Remove the retaining clip from the bottom of the release shaft. This is the little guy that likes to come loose during serious foot clutch abuse.
Although this can all be done with a hand drill, a mill or drill press will make quick work of the drilling and tapping procedure. Since the release finger has a steep angle on this side, a ¼” endmill is used to create a small flat for the drill bit.
Following a center drill, the wall of the release finger is drilled with a No. 7 drill bit.
The drill hole is then tapped with a ¼-20 tap.
A small file can be used to remove the burr on the inside of the release finger.
The set screw will need to be secured with a thread locker. Therefore, it is critical that any remaining cutting/tapping oil is removed from the threads.
After placing the release finger back on the shaft, a transfer punch is used to locate the point at which the set screw will contact the shaft.
The shaft is then dimpled with a center drill to create a pocket for the set screw to index. This is a great way to ensure that the release finger cannot slide along the shaft.
A quality thread locker should be used to ensure that the set screw does not back out of the release finger.
Once the set screw is torqued, there is no need to reuse the retainer clip on the bottom of the shaft. Now, just reassemble the kicker cover and you are ready to stomp your way through the gears!