90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck

[arto98607]

My 1997 F3060 has what I think is somewhat rare RC72R-F30 Rear Discharge Deck and was just recently told by a dealer that Kubota is no longer selling replacement gearbox!

I was just looking to buy a spare gearbox but was unable to find anything offered online by the gearbox supplier either (Superior Gearbox Company, Stockton, MO) - in all fairness I never phoned them since I decided to look for alternatives first since the last Kubota list price for replacment was $631.39 (when it supposedly was still available)!


1. Superior 211ADF 189 6 Gearbox:

2. It was easy to find a Chinese made replacement gearbox on the eBay for $135
It is rated for 40 hp at 1500 rpm - the mower PTO runs at 2500+ rpm normally.

We will put some hours on it and update on longevity later - so far only about 3 hours of use.

3. The fit was perfect:

4. Shields etc. in place:

Like was said above this is just a spare gearbox, but I also want to modify the OEM gearbox input shaft and will machine 1/4" key-way & eliminate the shear bolt altogether.

The shear bolt only arraingment is causing a loose / sloppy fit in-between the driveshaft yoke and the gearbox input shaft.


I don't like buying Chinese stuff but unfortunately was not left with many other choices I could find and would have paid the OEM list price if it had been available!


Good to have alternatives & some competition!

 

[Hay Dude]

My 1995 or 96 F3060 has what I think is somewhat rare RC72R-F30 Rear Discharge Deck and was just recently told by a dealer that Kubota is no longer selling replacement gearbox!

I was just looking to buy a spare gearbox but was unable to find anything offered online by the gearbox supplier either (Superior Gearbox Company, Stockton, MO) - in all fairness I never phoned them since I decided to look for alternatives first since the last Kubota list price for replacment was $631.39 (when it supposedly was still available)!


1. Superior 211ADF 189 6 Gearbox:

View attachment 704511





2. It was easy to find a Chinese made replacement gearbox on the eBay for $135
It is rated for 40 hp at 1500 rpm - the mower PTO runs at 2500+ rpm normally.

We will put some hours on it and update on longevity later - so far only about 3 hours of use.

View attachment 704509



3. The fit was perfect:

View attachment 704510




Like was said above this is just a spare gearbox, but I also want to modify the OEM gearbox input shaft and will machine 1/4" key-way & eliminate the shear bolt altogether.

The shear bolt is causing a loose / sloppy fit in-between the driveshaft yoke and the gearbox input shaft.


I don't like buying Chinese stuff but unfortunately was not left with many other choices I could find and would have paid the OEM list price if it had been available!


Good to have alternatives & some competition!

Hey, ya gotta do what ya gotta do, right!? I pro would have done the same thing.
Would Superior sell you one directly? At what price?
Im a little skeptical the 1500rpm limited Chinese box will hold a sustained 2500rpm, but you aren’t out a lot if it grenades, either.

related: my F3680is still being repaired. Bought it 4 weeks ago and haven’t cut a blade of grass with it since it broke in the first hour.
They are threatening to finish it today. If they do, I will be cutting with it tomorow.

 

[arto98607]

Hey, ya gotta do what ya gotta do, right!? I pro would have done the same thing.
Would Superior sell you one directly? At what price?
Im a little skeptical the 1500rpm limited Chinese box will hold a sustained 2500rpm, but you aren’t out a lot if it grenades, either.

related: my F3680is still being repaired. Bought it 4 weeks ago and haven’t cut a blade of grass with it since it broke in the first hour.
They are threatening to finish it today. If they do, I will be cutting with it tomorow.

Yes I share the longevity concern but only one way to find out!

It is just a simple bevel gearbox so maybe running it at 2500 rpm when it's rated for 1500 rpm may or may not be a big deal?

I hope you get your mower back soon and everything is in order - please give us an update later.

 

[ptsg]

I would say they are just covering their rear ends due to using some cheap bearings. I won't be surprised if the first thing to fail will be the bearings, which is actually good as you could replace them with some good quality bearings.

Anyway, it's not that the gearbox will be under constant load with 40HP pushing it the entire time, so it will probably be fine.

 

[arto98607]

I would say they are just covering their rear ends due to using some cheap bearings. I won't be surprised if the first thing to fail will be the bearings, which is actually good as you could replace them with some good quality bearings.

Anyway, it's not that the gearbox will be under constant load with 40HP pushing it the entire time, so it will probably be fine.

I agree, it's not even close to 40 hp since the engine gross is 30 hp and it's not strained at all when mowing. It would probably require 15 hp to run the deck in most normal conditions.

I am tempted to buy a second spare gearbox to open up and see the insides, but also to install a JD5801 pressure relief vent.

 

[RickB]

Two thoughts.
if the original vent was a non-pressurized style I would not consider a pressurized vent due to shaft seal durability concerns.
I would absolutely use synthetic 75W-90 gear lube in either the OEM or aftermarket gearbox.

 

[arto98607]

Two thoughts.
if the original vent was a non-pressurized style I would not consider a pressurized vent due to shaft seal durability concerns.
I would absolutely use synthetic 75W-90 gear lube in either the OEM or aftermarket gearbox.

The vent in the OEM gearbox is non-pressurizing model, just like the John Deere JD5801 is.

The aftermarket gearbox needs to be disassembled and drilled / tapped for one, but like was said earlier - it's was just meant to be a spare gearbox while I work some on the original!

I hear you about the lube oil and maybe I will switch.

The OEM gearbox internals were in very good condition after 3500 hours of service so GL5 Dino oil must have been alright.
Nothing against synthetic lubes, they have their place and I use them in my car & truck.

 

[RickB]

Your box, your dime, your choice.

 

[RickB]

75W-90.

 

[arto98607]

75W-90.

Thank you, I just found Superior Gear company manual for these, where they recommend Synthetic 75W-90 if the operating temperature is continuously above 200 F so I will give that a try even though the new gearbox is not running hot at all!