I find it much easier to work on and repair a snow thrower on warm September evenings and weekends than on cold February mornings when I'm trying to get the car out. This year will be the 13th year of service for this MTD 8hp snow thrower. MTD products fill the lower cost market niche in equipment but my experience with their products has always been extremely positive. There are more expensive machines that are built to supposedly last longer -- and maybe they would. Would they last twice as long? They cost twice as much so that's the real question to ask.
I've also found MTD products to be very well engineered. One of the ways they save money when they build them is to use very simple drive mechanisms. These are ingeniously built, however, and end up being much easier to keep working. The mower uses a "Constant Velocity" transmission based on pulleys and belts that change ratio based on speed in a smooth curve. This is extremely efficient, and some day we'll all have these in our cars. For now, they're not strong enough to handle most cars (the Subaru Justy used one, but that was more a go-cart than a car).
This snow thrower also uses a drive mechanism that is pure genius. The motor turns a belt that makes a large, flat plate spin around like a record. Above the plate is a rubber ringed wheel which contacts the spinning plate on its flat surface a right angle.
When the plate turns, it turns the wheel much in the same way a pair of gears set at right angles would mesh. Unlike gears, however, the rubber wheel can make contact anywhere on the spinning plate -- not just at the edge. All the gearshift does is move the rubber coated disk further out to the edge of the plate where it will spin faster, or closer in toward the center where it spins slower. Reverse is accomplished by moving the plate even further -- across the mid point so that it contacts the plate spinning the other way. The rubber ringed disk is around an axle with a gear at its end. The wheel can move side to side, but always along this axle. When the wheel spins it turns the axle, which drives the gear that makes the wheels go. Its brilliantly simple and the only two wear parts in the system are the belt that turns the spinning plate, and the rubber ring around the drive disk. Both are easily replaced and readily available.
You can see blown up diagrams of the whole mechanism here: http://www.m-and-d.com/pdfs/MTD/E640F_E660F_E6C0F_E660G.pdf
This unit is, as I said, about to see its 13th service year. In some Maine winters, that can mean being used thirty or forty times, often handling six to eight inches of heavy snow. The scoop was bent and rusted. The scraper bar on the bottom had worn half away and had exposed the bolts which hold it to the scoop. Those bolts were half to fully worn away themselves. The bushings on the auger blades were worn, the blades rusty and long since scraped clear of paint.
As you can see from the pictures below, I tore the unit down and cleaned the old paint off. I used a wire brush to clean as much rust off as possible, and stripped the paint to bare metal. Parts for MTD products are very easily found. I downloaded a parts diagram showing a blow-up assembly plan with labeled part numbers and used that to order a new scraper blade, new bushings for the auger blades, a new bearing for the auger shaft, new belts, and new springs for the controls and idler pulleys. Every bolt, nut, and washer I removed was replaced with a new one from the local hardware store.
The scoop was heated with a propane torch where it was bent and a five pound hammer used to bang it back into shape. The crease at the leading edge was done by placing that edge of the scoop against a piece of angle iron and hammering against that as an edge. Anywhere rust could be found was prepped with rust-reformer (available at NAPA and other such places) then the unit was brushed and sanded again before paint. I used seven cans of Rustoleum "Farm Implement and Tool" paint in the color "International Red" over the course of several days. The few bolts that weren't replaced due to being part of the chassis itself were cleaned using the appropriate sized thread cutting die then treated to prevent rust.
For the screw gear at the front of the auger, MTD recommends 1.5oz of Alvania bearing grease. Though I couldn't find that particular grease (and didn't want to order it) NAPA was able to call their "Valvoline Help Desk" and quickly cross reference it to a high grade synthetic bearing grease they carry. The grease is fantastic stuff. Its red, which is a bit odd, but seems to be almost totally impervious to washout. In fact, I had a really hard time getting the stuff off my hands. Even the degreasing, abrasive, mechanics soap I used wouldn't touch it. I also used this grease to coat some of the hidden parts that tend to rub as levers are pulled and so forth, and any places where newly painted parts were joined by bolts to prevent the paint from bonding there.
When I finished, the unit started right up -- I hadn't touched the reliable Tecumseh 8hp motor other than to replace the spark plug. When I went to test it, I couldn't tell if the auger was even moving. I had to tie off the lever that operates the auger and walk around the front to make sure it was working. The movement of the auger was wonderfully smooth and silent.
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