Speed Control

[S Brian]

I received a new control sheave and quadrant assembly this week for my 1980 Mark V. Last night I exchanged the quadrant on the speed control, but it will not turn freely. For 1/2 a turn the dial turns easily and then is hard to complete the revolution. While holding the speed control in my hand, I went from low speed to high speed and back again and there are marks on the quadrant teeth showing wear. The old quadrant had considerable wear on the lower speed half of the teeth and for several months the dial had the same easy and hard to turn areas. I cannot imagine that the worm control shaft cold be bent and when rotating the speed control by hand and without engaging it with the quadrant, it looks to be running true. Do you guys have any suggestions as to what the problem might be.

[billmayo]

I have found a few worm gear shafts slightly bent that I had to replace. I can be very hard to tell so I mark the end of the worm gear when it was first hard to turn and see if the hard to turn is occuring at the same mark. I have used a flat metal file to remove (flatten) the top of the quadrant teeth sometime in the area of where it is hard to turn. Make sure the bracket legs are not bent by insuring the worm gear tracks in the center of the quadrant teeth.

Looking between the worm gear teeth and the quadrant teeth as you turn the worm gear should give you some idea of where the binding is occuring. I have a few V-shaped jeweler files (Harbor Freight) that I use to file the sides of the quadrant teeth as they are a cast aluminum part, not machined.

I recommend replacing the quadrant roll pin with a allen head #10 32 X 2 1/2" bolt, 2 star washers and a nylock nut. Contact me offline for pictures and instructions.