Hot geat box on 450/451

Frank1541 · #1 02-01-2011, 11:52 AM

I have on older 450 snow thrower on my 1541. I changed the gears with a set from a 451 so I could use a larger pulley on the PTO. Today is the first time I needed it. It sounded different then I was used to. I checked the main gear box after an hour of throwing and it was pretty hot to the touch. I could hold my fingers on it for a while, but just barely. I never checked it before, so I have no idea if they run hot. Can anyone with the 450 series blowers tell me if their gear box gets hot when in use? Is this normal? We have another 12 inches coming Wednesday, so I want to be ready.

Thanks in advance

young enthusiest · #2 02-01-2011, 12:28 PM

Not good!!!! Should be just a little warm, not hot. Pull it apart and turn it by hand and see if you can find something binding. I hope you find the problem!

Matt G. · #3 02-01-2011, 12:41 PM

Sounds different + heat = not normal. Take it apart and see what's going on. I don't want to sound like a smart@$$, but did you relube the gearbox after changing the gears?

R Bedell · #4 02-01-2011, 12:44 PM

Well, spending the time to look this up, looks like you have a "cocktail" of Assemblies and parts.
I am surprised this thing ever spun...

cub123 · #5 02-01-2011, 12:54 PM

The first thing that comes to mind is the bearings,if they were at all rough they will get hot and fail.It could also be what Matt said,i have done that kind of thing before

or it could be the new gears are not meshing right and are getting hot.Any way you look at it you are going to have to pull it apart to see whats going on in there.

cubs-n-bxrs · #6 02-01-2011, 01:26 PM

Just wondering you said the GB was taken apart and altered with a set of gears from a 451 which is no big deal. I have done the same alteration myself and is an easy task. All parts are interchangeable as long as the gears are done as a set. The problem I had was the lack of a gasket between the case half's so I tried substituting RTV in place of a gasket. Gasket is there to seal and also provide some end play for the gears otherwise the gears bind in between bronze bushings and the bearings. Well you know the story, I took it back apart and made a gasket and re-assemble. Mine gets just about warm enough to melt the snow off of it.

Frank1541 · #7 02-01-2011, 01:38 PM

Thanks to everyone. I took it apart and found no metal shavings or any sign of metal on metal contact. I did notice that 99% of the grease was thrown off the larger gear and stuck on the side of the unit. I probably added a half cup of grease the first time around. So I put it back together and added a lot more grease. This way I figure that the large gear will be contact with grease all the time.

Is this a great forum or what??

Rockit4 · #8 02-15-2011, 05:10 PM

I have three 451 gear boxes I have over hauled. In the exploded above it shows item 4, 736-0259, flat washer. None of mine have that washer. I assume that somewhere down the line they modified the gear width to do away with that washer. If you added the washer when the gears were changed it could be pinching and causing the heat. Can you check the shaft for end play? I assume there should be little or none, but not real tight.

Frank1541 · #9 02-17-2011, 11:24 AM

Rockit4,

That is interesting. I assumed it had the washer due to the parts diagram, so I got one and installed it. It feels tight but not binding with the washer in. Without the washer, it had well over a 1/32 in of play. Which is better?

Matt G. · #10 02-17-2011, 12:25 PM

How thick is the washer? 1/32" of end play is just over 0.030". That's probably a bit excessive, especially considering the aluminum housing will expand more than the steel shaft and cause that end play to increase when the gearbox is warm. If the washer is thicker than the amount of endplay, that could be part of the problem.