Speedo pinion gear keeps wearing out.

[Tom Selleck]

I own a 1972 240Z, and the speedometer did not work when I first bought it. I ordered a new pinion gear because the nylon cog was worn out on the first one. Well, after only about 350 miles, this one is worn out too and my speedometer does not work. It just abruptly stopped working one morning. Does anyone know what could be causing it to wear out the cogs so fast, and where to buy one? The one I ordered was from Courtesy Nissan, and it took about 2 months to get it, and was pretty expensive to only work for a few hundred miles. Any help is appreciated.

[Ed]

I would venture to guess that either the allignment of the cog was off somehow. Or there is something binding, maybe the cable is kinked? Dunno.

[72' 240]

Tom,

One thing that you probably have already noted is that all these plastic gears are not the same color. For instance, you may have removed a red one and received a yellow one from the dealer. These differ in the degree of "cut" angle and or tooth size. That is to ensure that the speed reading that is picked-up at the tranny is accurate as there were several trannys produced in 4 and 5 speed. I am not exactly sure which color is compatible with yours, but this may be contributing to the failure. Also older cables either from salvage yards or even still lying around these dealerships (God bless them all) may have gotten waxy or stiff, and the gear simply spins the teeth off.

Hope that's helpful-

72' 240