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

   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck #21  
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:

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:




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!
I noticed that your pulley is painted gray. Did you paint it or get a new one?
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck
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#22  
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   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck #23  
It's a new pulley since I wanted a spare, but it's 1/4" larger than original - no big deal.
I now run the engine at touch slower rpm just for the heck of it.


5.75" Single Groove Belt B Section 5L Pulley 1" Sheave Bushing BK60H Cast Iron | eBay
Wonder what that calculates to in blade speed at full RPM. Not sure I'm smart enough to figure out that calculation without causing smoke from my ears. LOL!
Might actually cut a little better.
Might grenade the blades and spindle bearings. YIKES
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck
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#24  
Wonder what that calculates to in blade speed at full RPM. Not sure I'm smart enough to figure out that calculation without causing smoke from my ears. LOL!
Might actually cut a little better.
Might grenade the blades and spindle bearings. YIKES

No noticeable difference at all when using the mower.
I did rough calculations before ordering and decided no need to worry about 1/4" larger drive pulley diameter.

By the way, in my RC72R-F30 mower deck the spindle bearings are the same Timken Set 14 (L44643 / L44610), as the Superior gearbox bearings but the seals are different.
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck #25  
No noticeable difference at all when using the mower.
I did rough calculations before ordering and decided no need to worry about 1/4" larger drive pulley diameter.

By the way, in my RC72R-F30 mower deck the spindle bearings are the same Timken Set 14 (L44643 / L44610), as the Superior gearbox bearings but the seals are different.
OK, All my parts are in. I didn't think my old gear box was very loose but by comparison it's quite loose! Do you know off hand what thread size that is for the JD Vent? I assume it's an NPT thread?
Also, is there any reason why the gearbox can't or shouldn't be mounted so the round plate is on top?
Mounting that way would allow for drilling and tapping that plate while off of the gearbox. No need to completely disassemble the gearbox. The bolt pattern, unless I missed something is 4.25" in all directions.
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck #26  
Was the Superior gearbox 1 to 1 also?

I put a 1/2" larger pulley on my finish mower to kick up the blade speed a little. Finish mower is a different animal with input at 540 RPM.
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck
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#27  
OK, All my parts are in. I didn't think my old gear box was very loose but by comparison it's quite loose! Do you know off hand what thread size that is for the JD Vent? I assume it's an NPT thread?
Also, is there any reason why the gearbox can't or shouldn't be mounted so the round plate is on top?
Mounting that way would allow for drilling and tapping that plate while off of the gearbox. No need to completely disassemble the gearbox. The bolt pattern, unless I missed something is 4.25" in all directions.


It's 1/8" NPT-27, so 21/64" drill bit will work.


I mounted it so the round plate is on the side for three reasons:

1. I can check the oil level by using a screwdriver as a dipstick.
2. I can evacuate all of the used oil with a vacuum oil extractor.
3. The oil evacuator tube can be easily pushed all the way to the bottom of the gearbox housing where any fine wear debris (steel) should be.

If you dismantle the gearbox you will see why none the above will work if it's mounted the other way as you suggested.
 
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   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck
  • Thread Starter
#28  
Was the Superior gearbox 1 to 1 also?

I put a 1/2" larger pulley on my finish mower to kick up the blade speed a little. Finish mower is a different animal with input at 540 RPM.

Yes the Superior has 1:1 ratio also.
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck #29  
All the kubota deck gear boxes are the same. Put a bunch in the dumpster. Didn't know anybody wanted one. Guy was packing all them mowers in a dumpster with a back hoe. Two big roll off dumpsters full. I worked at Kubota.
 
   / 90 Degree Bevel Gearbox on Kubota F3060 - 72" Rear Discharge Deck
  • Thread Starter
#30  
All the kubota deck gear boxes are the same. Put a bunch in the dumpster. Didn't know anybody wanted one. Guy was packing all them mowers in a dumpster with a back hoe. Two big roll off dumpsters full. I worked at Kubota.

No they are not all the same - since you worked "at Kubota" you should know better!

See post #1 in this thread.

Mine is in F3060 and the deck gearbox was made by Superior Gearbox Co in Stockton, MO

The only trouble with it is Kubota no longer sells parts for it, otherwise nothing wrong with it.
The reason I got another (Chinese) gearbox is because I wanted to have a future spare on hand for the above reason.
 
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