MMM gearbox hot to touch

[Southernfarm]

I probably have 20 hours on my 60" MMM. When I bought new and uncrated it, I had to put gearbox oil in it. I believe the stuff was standard 75w-90. Filled it until it came out the top filler bolt. Anyway, been cutting grass for about 2-3 hours today and went down to clear off the dry grass off the deck and noticed the gearbox was rather hot to touch. Should it be that way?

In the coming days I will be removing the deck and going over it, greasing it, cleaning it. Should I drain out the gearbox oil and replace? Should I put the same 75w-90 in it or put Kubota UDT in there?

 

[Daren Todd]

Gear boxes can get pretty hot after running that long. But also, our perception is skewed when judging what's hot, and what the temp actually is by touch If your concerned you can always check it periodically with an infrared thermometer.

 

[85Hokie]

Gear boxes can get pretty hot after running that long. But also, our perception is skewed when judging what's hot, and what the temp actually is by touch If your concerned you can always check it periodically with an infrared thermometer.

What he said ^^^^^^^^^^^^^^^^ twice as good as what I could have said!

 

[Southernfarm]

Never knew they could get hot at all. Wifey was helping clear off the dried grass on the deck when she noticed it, and was concerned about a fire hazard. I don't think it was hot enough to ignite dry grass but still hot none the less.

 

[RCW]

Southern Farm- I don't recall exactly, but seems my gearbox has a bolt part way up the side that indicates full. Fill from top until it gets there.
Pretty sure it's not full to the top. No room for expansion. Just double check that. They do get warm!


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[Daren Todd]

I know a couple folks that have had there mowers go up in flames Warned a landscaper a couple years ago, that his brand new zero turn started smoking everytime he started driving. He gave me the ol brush off. Passed a burned out trailer with a zero turn on it later in the day with the fire department just rolling up the hoses.

After seeing that, I make sure and blow out the mower deck before parking it

 

[rjcorazza]

I know a couple folks that have had there mowers go up in flames Warned a landscaper a couple years ago, that his brand new zero turn started smoking everytime he started driving. He gave me the ol brush off. Passed a burned out trailer with a zero turn on it later in the day with the fire department just rolling up the hoses.

After seeing that, I make sure and blow out the mower deck before parking it

I do the same with my mowers. 1300 hours on the original spindles and belt. My gearbox has developed a small leak though.

 

[henrysbe]

Every time I mow tall grass, I have a problem of grass getting above the stump jumper, wrapping around the transmission shaft and getting into the seal. This can cause oil leakage so I would check oil level if you haven't yet. Does anyone have a solution for keeping tall grass from wrapping around the shaft? Every time this happens I have to remove the stump jumper, the 4 bolts holding the transmission in and then replace the seal. Is there a brush hog not prone to this?

 

[hodge]

Southern Farm- I don't recall exactly, but seems my gearbox has a bolt part way up the side that indicates full. Fill from top until it gets there.
Pretty sure it's not full to the top. No room for expansion. Just double check that. They do get warm!


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^This^- your gearbox should be filled part way up, not full. It should have a breather, but extra oil isn't helpful.
Gearboxes generate heat- that's why they make baffled differential covers (to dissipate heat), and NASCAR cars have gear oil pumps to circulate and cool the oil in the rear axles. Don't be alarmed about that. But, it would be good to keep the grass clippings clear- to allow the gearbox to cool properly, and keep the small chance of a fire, a non-issue.

 

[Daren Todd]

Every time I mow tall grass, I have a problem of grass getting above the stump jumper, wrapping around the transmission shaft and getting into the seal. This can cause oil leakage so I would check oil level if you haven't yet. Does anyone have a solution for keeping tall grass from wrapping around the shaft? Every time this happens I have to remove the stump jumper, the 4 bolts holding the transmission in and then replace the seal. Is there a brush hog not prone to this?

I would try smaller bites. Either mow more often, or multiple passes, one with the cutter high, then a second pass to knock it the desired height.

I've been in grass taller then my tractor with my rotary cutter. I go super slow and take two passes to knock it down to the level I want.


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[Southernfarm]

Southern Farm- I don't recall exactly, but seems my gearbox has a bolt part way up the side that indicates full. Fill from top until it gets there.
Pretty sure it's not full to the top. No room for expansion. Just double check that. They do get warm!


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Yes I was aware of the drain bolt, then the fill level bolt above it, and the fill bolt at the top and to fill until it comes out the second bolt.

As the deck is on its first season from new, when I take it out of service for the winter, I plan on changing the gearbox oil. Should I use the 75W-90 gear oil or should I use HST / UDT oil like I did with the front axle?

 

[RCW]

Use gear oil in there.

 

[hodge]

Yes I was aware of the drain bolt, then the fill level bolt above it, and the fill bolt at the top and to fill until it comes out the second bolt.

As the deck is on its first season from new, when I take it out of service for the winter, I plan on changing the gearbox oil. Should I use the 75W-90 gear oil or should I use HST / UDT oil like I did with the front axle?

What does your owners manual say? Don't want to void any warranties.