trouts2

>>I especially noticed that Craftsman and Troy-Bilt are identical.

Product ID: 137558741
Manufacturer: MTD
Mfg Part No: 88690
Brand: Craftsman
UPC: 043033547616
SKU: 07188690000P

MTD makes Troy-bilt

Paul,

   You’re right the part numbers cross and all the good stuff in the old cast iron gearbox gone.  I knew the new cast iron gearbox was different shape but did not know about the internals changes.  The new worm assemblies are 52419600 cast iron and 52100900 aluminum.  They look the same in the drawings so not sure what differences call for a part number change.

trouts

If the governor arm is moving at all then the insides are probably ok. Inside is just a simple mechanism to push against the internal governor arm. If it's moving outside of the machine then it's probably ok.

Have you tried to re-set the external governor arm? The procedure was posted here a few days ago so should be easy to find.

I think your carb may have the top plate with the linkages under it. If so then there is a small screw under the plate to set the high end.

Are you sure you have the governor links in the proper holes? Spring tension can be a factor also.

Are you sure the low idle screw is not pushed out too far?

   The drawings are from the model year 2002.  2004 gearboxes are the same.

Pvrp,

   The Pro designation seems to be the name of the models with a cast iron gearbox so I’m not sure how you saw a Pro with an aluminum looking gearbox.  They are very different.

 

Ariens has changes their gearboxes.

 

All the latest models listed on the Ariens site have the following:

 

520EC, 520E, 624E, 724E all Compact models:

Durable Aluminum Gear Case with alloy steel auger gears with specially blended lubricant for long lasting, smooth performance. (Note: me – no Heavy-duty XS Gear Case so it seems like it’s the old aluminum gearcase with new type steel alloy gears).

 

The rest of the new models, LE, LET, DLE, DLE Classic have:

“Heavy-duty aluminium XS® Gear Case with alloy steel

auger gears.”

 

All models labeled Pro have the cast iron gearbox.

 

The local dealer has seen the new “steel alloy” gears and did not think highly of them.  He called them powdered metal.   

   There is usually some confusion when referencing Ariens made gearboxes.  The terms aluminum and steel are used to differentiate between the two types.  The housings are different but it is what is inside that makes the difference.  If you do not know what is inside you are left wondering why an aluminum case is better than a steel case (case iron). 

   The terms used of steel and aluminum are used to distinguish between the better quality gearbox (steel) versus the lesser quality gearbox (aluminum).  The quality connotation includes the material used in the gearbox but the real meaning mostly refers to the internal components.   Below is a link to exploded views of an aluminum and cast iron gearbox. 

It’s easy to make a very strong gearbox of aluminum as Toro has done.  That is nice but it is what is in the Toro gearbox that makes it a good gearbox.  By the way the Toro aluminum gearbox is much thicker than most other companies gearboxes (MTD, AYP, and all others that I know of).

http://www.kedawei.com/Doc1.doc