M steering problem

I am a "new-bie" working on my first tractor, a 1951 M . The steering worm gear is worn and allows the front wheels to wobble in road gear. All of the new worm gears I find to buy are full circle. Mine is only 1/2 circle. Can I replace mine with a full circle gear? Also, is there a trick to getting the worm gear off? I took out the key,removed the castle nut, but the gear won't budge! Is there something else holding it on?

The half moon gear can be swapped for a full circle gear.

However getting the old gear off the pivot shaft can be an SOB as you have discovered. It’s on a tapered spline and is usually stuck on pretty well. Sometimes a suitable puller can break it free. However I’ve always had to resort to “brute force” to get ‘em off:

1 - Jack the tractor so the front wheels are off the ground (jack from beneath the clutch housing, then crib for safety).

2 - Remove the front wheels/lower bolster assembly at the flange (4 bolts beneath the fixed bolster) and set the front wheels aside.

3 - Invert the castle nut and thread it down so it’s flush with the top of the pivot shaft (to protect the shaft threads during the next step…)

4 - Now use your biggest hammer (I use an 8# sledge) and give the top of the shaft a few good licks. With luck the gear will pop free.

5 - Now remove the castle nut and slip the gear off. (Crib beneath the pivot shaft first so it won’t fall out – the shaft is heavier than it looks!)

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Tip: Check the pivot shaft bushings for looseness and replace ‘em if necessary while you’ve got the front end apart. Any radial play at all - particularly at the upper bushing – will result in sloppy steering even with new worm and gear installed!

Thanks, I"ll give that a try. I tried tapping on it, but I guess I"ll have to get midevil!!

Yes, a round gear should work fine.

IT WORKED!!!! Just like you said it would. Thank you so much. I would have never gotten that gear off without your help. The bearing at the bottom was shot. It came out in pieces and rusted balls rolled all over the shop. I suspect that may have been contributing to the wobble. Now, I need more help. After tearing it all apart I noticed that one of the bolts that holds on the front wheels has an extra tall head. I assume that is some sort of stop to keep the wheels from spinning all the way around? Problem is I did not notice which postion it was in, front or back right or left. When I get all the parts and put this all back together, where do you think I should put the tall headed bolt?