lever knobs

[cheatmtn]

My Allis Chalmers 5050 4WD is missing just about every lever knob on it, does anyone know what the thread pattern, size is or an inexpensive replacement?
CJ

 

[SimS]

cheatmtn;

Test the thread size using a nut that fits. After you determine what thread size you then need to visit McMaster and search for the knob(s) that you need. Works for me.
SimS

 

[RoyJackson]

If you have a caliper or micrometer, measure over the outside diameter of the thread (this is called the Major Diameter).

Assuming the tractor is using American thread sizes, you can determine the thread.
Two examples: if you measure .312, it is a 5/16ths thread and probably a coarse thread so it would be 18 threads per inch. If you measure .375, it's a 3/8ths thread and probably 16 threads per inch. In a hardware store, you'd look for .3125-18 and .375-16 threaded fasteners. You might see these called out as fractional (5/16-18 or 3/8-16).

If you know the thread is metric, you'll have to convert unless your mic (or caliper) reads in metric as well as english. If you measure .394, multiply that by 25.4 which comes to 10.0076. Round that to the one decimel place and you'd know the thread is 10 mm. I'm not sure of the thread pitches, but they are measure by threads per millimeter so a 10 x.5 thread would be 10 millimeters in diameter and ½ threads per millimeter. That would be a pretty coarse thread.

 

[ZJ_HR]

If I remember good, your AC 5050 is FIAT tractor. On mine FIAT tractor all knobs have M8 threads, except one on gearshift lever, where is M12x1.5 I think