Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I've got a 28"/8.5hp/2-stage Yardman (MTD) snow thrower and it looks like the 20-tooth worm gear that transfers power from the worm/impeller drive shaft to the augers is shot (worm drive shaft from the impeller turns but the augers don't). Also wondering why the shear pins, didn't shear but they're fine and the augers are loose on their drive shaft. Didn't check the torque...that may be the problem.

Has anyone out there replaced this gear? If so, I really appreciate benefiting from your experience by hearing the steps you took. At first I thought I could simply pull the auger assembly by punching out the two roll pins that hold the impeller to the shaft but after getting them out it looks like the worm/impeller drive shaft runs through the auger/impeller housing, a ball bearing and  the two auger pulleys. It's a very crowded area around the auger pulleys and this looks like it will turn into a major tear down. I'm pretty handy but beginning to wonder if I should bag it and head to the shop. If they had just put removable side panels on the auger housing, you could easily pull the gear box apart.

All advice appreciated with thanks!

Bill Curry
Snowbound in Walpole, NH!

    start be removing blower housing from tractor .  flip onto front so the auger pulley faces up.  remove nut slide pulley off, there will be a key in there also. remove fastners from side of unit that hold the auger shaft to the blower housing.  flip unit back down and reach in and pull assembly out.,    now   remove one  auger assembly at a time and try not to mix them.  next remove bolts holding gearbox together,  you can take both halves off or just the one.  remove bad gear.    absolutley clean both gear case halves of old grease and shavings.   reassemble in reverse order.   use 2 new shaft seals....  dont skimp  the box will leak.   use some loc-tite  515 or similar gaket material on the 2 halves.   when all said and done put some lube in gear box.  we use bentonite in the shop.  it thicker than 90w less  chance of leakage.  it also has clay in it.  this kind of lube actually sticks to the gears.  where 90w sits in the bottom of case and just splashes onto the gears.   good luck

Thanks mech12...great, helpful description!

I'm in the process of replacing my auger gear as well after the shear pins didn't shear. I think in my case the reason was that my augers are rusted onto the shaft. Now if anyone has any ideas on how to unstick the augers I would very much appreciate it since I need to remove one side (or do I need to pull both sides) to get to the auger gear.

Several ideas:

1. Lots of grease;
2. Any one of the several rust breaker/cleaner compounds;
3. Heat the auger axle with a torch and start banging.

I've never had to replace the worm drive so I can't say if you HAVE to take out the augers but it looks like it. I believe you have to get some special gear oil for it though.

Part of the end of season maintenance is to remove the shear bolts, grease the auger driveshaft and then spin the augers to distribute the grease. That why there are grease nipples on the auger axle. don't forget to put the shear bolts back in.

  torch and a 3lb maul

Thanks much for the suggestions.  If all else fails, I might cut them off by slicing length-wise.  I know someone who is very proficient with an arc welder who can weld the auger back up for me if I need to resort to the slice method.  My Crafsman didn't have grease fitings.  I think I'm going to drill/tap the augers to add some to avoid this problem in the future.  At least we are near the end of the winter so I have time to "play" with this.  JAB