[Bob Moseley (RIP)]

Hi Tony
I concur re. the author of the Manuals being misled. I have visited various manuals and have also sacrificed a speedometer head to expose its makeup. Below is the explanation of a typical speedometer taken from Wikipedia and I should have read this and then thought about the makeup of it. Of course the speedometer head cannot contain any gears other than the worm drives for the odometer. The speed indicated by the needle is dictated by the gear ratio between the driving gear and the driven gear at the transmission end of the speedometer cable. Apart from the indication by the number 5 on the rear of the 2pdr speedometer, doesn't show the Carrier number as stated in the Manual, possibly this is stamped where the speedometer cable enters the transmission or transfer case, not sure where in a 2pdr Carrier.

"The most common form of speedometer relies on the interaction of a small permanent magnet affixed to the rotating cable with a small aluminum cup affixed to the shaft of the pointer. As the magnet rotates near the cup, the changing magnetic field produces eddy currents in the cup, which themselves produce another magnetic field. The effect is that the magnet 'drags' the cup--and thus the speedometer pointer--in the direction of its rotation with no mechanical connection between them.

The pointer shaft is held toward zero by a fine spring. The torque on the cup increases with the speed of rotation of the magnet (which, recall, is driven by the car's transmission.) Thus an increase in the speed of the car will twist the cup and speedometer pointer against the spring. When the torque due to the eddy currents in the cup equals that provided by the spring on the pointer shaft, the pointer will remain motionless and pointing to the appropriate number on the speedometer's dial.

The return spring is calibrated such that a given revolution speed of the cable corresponds to a specific speed indication on the speedometer. This calibration must take into account several factors, including ratios of the tailshaft gears that drive the flexible cable, the final drive ratio in the differential, and the diameter of the driven tires. The speedometer mechanism often also drives an odometer".