You may or may not know that because of an inner tubing accident January of 1982, I am paralyzed from the waist down. So I am not that good with a foot clutch. :) I spent over 2 1/2 years restoring this Amphicar (95% alone) and only after I finished it did I start on making the hand controls. About 25 people got to drive my car before I did. Backwards, yes, but effective incentive to make it work.
I did much the same thing with the hand controls I built and patented (5.299.652) for my Harley. However they were very different because the Harley already had a hand clutch and I needed to operate the foot shifter by hand. The Amphicar already has a hand shift and I needed to operate the foot clutch by hand. With both, one feature was a non-negotiable. This being that all factory controls must operate and appear as stock but without interfering with the hand controls or visa-versa. No permanent modifications with the exception of a single hole to pass the clutch cable through, were made. The following short pictorial (mouse over each picture for more info) illustrates how I accomplished the task at hand, umm so to speak! :)
Hand Operated Vacuum Assisted Hydraulic Clutch:
I used parts from 3 different brands of existing hand controls to operate the throttle and brake, along with parts from a Harley (of course!), International pickup and Chevy Geo to make up the hand clutch.
The brakes (3) operate by pushing the handle forward toward the floor. (The handle is directly attached to the brake pedal via an adjustable rod).
The throttle (1) is operated by rotating the handle down toward the seat. This rotating motion is translated into a downward force via a cam that actuates the pedal (4).
The clutch is operated by squeezing the clutch handle (2), pulling the cable (8) attached to the power booster (5) which in turn pushes the plunger in the master cylinder (6).
The Master forces hydraulic fluid (10) at about 900+ P.S.I. into the clutch slave cylinder (11). The slave's plunger pushes forward the end of the existing clutch cable (13) thereby moving the clutch arm (12) forward. Exactly the same way your foot would operate it manually.
All controls operate as intended by the factory, or equally well by hand. I was forced to drill only a single hole to pass the clutch cable to the trunk during the installation of this system.
The poor little 1147 cc engine just didn't have the volume needed to operate the power booster so there is also a 12v vacuum pump mounted beneath the rear seat (not pictured) to energize the power booster.
Next thing to do is to powder coat it all black to better blend in with the existing style of the car and create permanent mounting brackets for the master and vacuum pump (not shown).
The view under the dashboard showing the controls mounted beneath.
The view of inside the trunk showing the master/booster and temporary mountings.
The view of the clutch arm showing slave cylinder mounting.