Re: M or Super M

Posted by john d on July 29, 1999 at 08:25:21 from (206.141.74.34):

In Reply to: M or Super M posted by jAcK on July 29, 1999 at 06:25:01:

The serial #, as mentioned in another post, is the most reliable way to go. Visual clues are not always consistent, as there appear to have been lots of minor variations in M-SM tractors around the time of the model change.

There was an after-market kit produced by M&W, Heisler, and maybe others that mounted on the left brake assembly and provided a "live" PTO by disengaging that side of the differential. Worked fine, but you can't shift gears with the PTO running.

Differences like disc brakes on the SM vs. band brakes on an M are a telling clue, but very late M tractors had disk brakes. Live hydraulics came in on some SM models, but lots of Ms were later fitted with this system. Seat type is not always a good clue, as there was a lot of variation in these also. SM models evidently came in three general versions: (1)pretty much identical to an M except for engine, faster ratios in gears 3&4, and disk brakes, (2)with holes cast into the rear transmission housing to accommodate a "fast-hitch" system, and (3)the SMTA model with live hydraulics, the torque amplifier lever on the left side, and live PTO on the right.

There are subtle little clues that sometimes indicate the difference between the models, but unless it's an M with band-type brakes (sheet metal covers) or you can read the serial #, there may be some doubt. Part of the problem is that parts were generally interchangeable and farmers kept upgrading lots of Ms with SM (or later) parts when repairs were needed. Likewise, more than a few SM models received used parts (even engines) from M tractors. Depending on what's been done to the engine during overhaul, an old M may produce power equivalent to or better than many SM tractors.

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