zg327 / rck60p mower / deck Very Hot Gear Box on mower deck

[lancertech]

I am having an issue with my gear box on a RCK60P mower deck. The original gear box was run empty of
the 80/90 gear oil. I have replaced the gear box and rebuilt all three spindles. When mowing the gear box
is getting so hot I can't even touch it. I have never noticed if this is normal or not. I have verified the oil
level in the gear box, verified the air pressure bleed cap is working on the gear box, made sure the blades
are torqued to the proper torque, verified the belt is routed properly, made sure the blades are not scalping
the ground, the U-joint is working properly and it's a new belt. Does anyone have an idea of how hot
the gear box should be while cutting or anything else to check. Thanks in advance!

 

[Roadworthy]

A gearbox will normally be warm (or hot) to the touch when operating. Be sure your spindles and pulleys turn freely without binding. These can put an extra load on the gearbox. A friend who raced cars once told m the differentials in race cars can glow red during a race so I'd say they can get HOT!! Hopefully your mower isn't working THAT hard.

 

[Fordtech86]

FWIW…I have never seen a published spec in any repair manuals. What I have heard from the engineers is about 100 degrees over ambient temp is about normal (many factors though). As mentioned it will get warm when operating.

 

[lugbolt]

yeah 100 deg F above ambient is about right. So fi the outside air temp is 80, 180 deg is pretty normal. You won't be able to touch 180 degrees without getting burnt. About 130 is the limit for most people.

Something else to consider, and either I didn't see it posted or it wasn't. The lower spindle bearing. That is the ONLY thing that supports the bottom of the gearbox shaft (the long shaft) and if it's out of whack or whatever, the gearbox won't last long.

You might do a fluid change when you get the chance. I generally pop the top cap and suck it out but there's more'n one way to skin a cat.

 

[mattwithcats]

What oil did you use?

You may try Mobil 1 Delvac 50, a 90W full synthetic GL-4 gear oil…

It is expensive, however…

 

[lancertech]

yeah 100 deg F above ambient is about right. So fi the outside air temp is 80, 180 deg is pretty normal. You won't be able to touch 180 degrees without getting burnt. About 130 is the limit for most people.

Something else to consider, and either I didn't see it posted or it wasn't. The lower spindle bearing. That is the ONLY thing that supports the bottom of the gearbox shaft (the long shaft) and if it's out of whack or whatever, the gearbox won't last long.

You might do a fluid change when you get the chance. I generally pop the top cap and suck it out but there's more'n one way to skin a cat.

I have rebuilt all the spindles with new bearings, seals, grease and new 80w-90w gear oil. I never checked the temperature after mowing so this may just be what it is. Thank you for your suggestions.

 

[lancertech]

What oil did you use?

You may try Mobil 1 Delvac 50, a 90W full synthetic GL-4 gear oil…

It is expensive, however…

I used the Kubota 80w - 90W gear oil from a Kubota dealer.

 

[lugbolt]

synthetic won't help you. Use what you have.

deck gearboxes don't have a good way to dissipate the heat like a car differential does (it has air flowing across/around it while you drive), thus synthetic fluid will get just as hot as regular stuff. In my opinion, It is simply a way to spend more money than needed. To each their own.