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Is the spiral gear for a 450 available from MTD?

Is it repairable?
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The original style isn't available but the new one they have will interchange as the front boxes didn't change with the newer units, the 450, 451, 551 and even many of the newer blowers use the same gearbox. The internal parts are available but you may find a complete replacement unit to be cheaper than the parts. What is the problem with the one you have? Case cracked or internal parts?

Internal, it froze up. This is on my previous 450 which I'd like to get operating.

How is the front spiral box removed from the thrower?

That isn't a good sign. Removal isn't bad but it's not fun. Remove the two end bearings for the spiral auger support shaft, then the top strut bolt that supports the gearbox and you pull the entire rotating assembly out as a unit, including the impeller. Once out you can remove the shear bolts prom the spirals and slide them off the shaft. At the impeller there should be a 5/16 spiral pin but many have been replaced with a bolt. Remove that and the impeller will come off the main shaft. Now comes the fun part. The spiral shaft needs to be cleaned off all rust and crud on at least one side from the gearbox to the end (I do both and then once done give them a coat of oil for now). Then you can remove the bolts and split the gearbox, the box holds everything inside it in place so do this over a bench with something under it to catch the grease and pieces as it comes apart. With one side off you can remove the gear from the sleeve and the upper drive gear, watch out for the end bushing and the thrust bearing and washers. Clean it all up and determine what parts you need. Two common failures are the large bronze gear and the housing itself. The gear because it is designed to wear and the housing because that thrust bearing can stop working and then the washer starts eating the case. I have repaired a few like that by killing the worn areas in the case halves and installing a thicker steel ring that will clamp in place in the housing to support the bearing.
Here you can see the sleeve inside the main gear the spiral shaft fits through. A nice clean bare steel shaft will slide into that fine, the common rusted crappy one in a used blower doesn't !!

Steve thanks for the detailed instructions!

Summer 2021 project!

No problem, I've been inside a few of them. Oh, if you don't want to buy the benalene 920 grease or cannot find it for a reasonable price, Because you will have it cleaned out you can use a more common grease, I've been using the Super S CPGRS.1232.097 Cotton Picker Spindle Grease 00 in mine, seems to be just fine. And it's $6 a quart vs $30.00 for 8 ounces.

Steve thanks again

https://www.tractorsupply.com/tsc/produ ... -grease-00

That's the stuff I and many others use in the gear boxes. It seems to be much less effected by the changes in temperature than the OE stuff.

In anticipation of a return to winter, finally working on the 450. For future reference here is what you need to remove to get the auger assembly out.
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Note that auger on the left, looks like it ate a few things!
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The end of the auger shaft bearing, does it require lubrication?
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