Grading Tightening Kubota Mower Blade Bolts

[hammerblossom]

Need some guidance from someone who knows what he or she is doing,

I have a BX2350 for which I just purchased a MMM, model RCK5423BX. With the deck I bought a mulching kit. When removing the standard blades I found that blocking the blade with a piece of wood while turning the blade bolt didn't work, so I had to hold the upper spindle nuts with another wrench. No big problem. The center blade bolt came loose with the block of wood trick---fortunately.

THE PROBLEM: When I installed the new blades I again used the second wrench on the upper nuts in order to be able to torque the blade bolts to specs. The wood block won't hold the center spindle, however. The whole pulley/spindle assembly rotates. Since the gearbox is on top of the center spindle, how does one go about holding that spindle? I notice there's a round rubber seal in the top of the gearbox which displays the MMM model number. Is there a spindle nut to grab onto if that seal is removed?

(It would've been REALLY nice had Kubota's instruction manual addressed this issue. Can't believe it hasn't come up before.)

Thanks for your assistance.

Bill

 

[Dyer retired]

Not sure why a block of wood isn't working. I just took my blades off and reinstalled them with no issue at all using a 2 x 4 x 12 block of scrap wood. I had to rotate the blade to a point where the wood jammed against the blade and the deck housing and then wrench some pressure to keep the block in place while I put enough force with both hands on the wrench to break the nuts free. Reverse to reinstall. This was the first time the blades have been off since 2003, so I really expected a harder time with it. I was surprised to get it all done with no blood spilled either. Maybe I'm missing what the issue is? Dyer, retired

 

[zzvyb6]

Sounds like the wood block isn't working because the shaft is turning through the blade. I suppose the easiest thing to try is to put the mid-pto in gear and hope that it loosens and does not break the gearbox. However, I would break the nut off before I would try anything that could crack a gear tooth. Chop a slot in it and use a cold chisel (ouch on the bearings) or buy a nut cracker and take it off that way. If there has been Lock-Tite applied to these nuts, heat it with a propane torch first. Too much heat could fry a seal. The heat shock ought to work. But don't be afraid to crack the nut off. Buy a spare first. Chances are the nuts are buggered up anyway from all the wrenching on them...

 

[Couple of Achers]

If the spindle is turning then the adjacent blades must also be turning. Try putting the 2x4 under one of the adjacent blades. The belt tension on those mower decks are pretty tight so hopefully the belt won't slip on the pulley. If the belts slips then try squeezing the belt tighter around one of the pulley's with a quick grip clamp.

 

[radioman]

Dunno about you guys- but using a impact wrench and peice of wood to hold blade works just fine for me. the impact action makes a quick and safe work out of it.

 

[hammerblossom]

Thanks to all who replied. Removing the nuts with an impact wrench is easy, but tightening them is another story. I've never seen an impact wrench whose actual torque was close enough to rated torque--just too many variables.

The Quick Grips work. I tightened the belt with one and clamped the belt to the pulley with another. After blocking the blade I was able to torque the center spindle nut to specs. quite easily.

Sorry, Kubota, but my problem with all this is why is there no way to tighten the center nut without all the invention, not to mention blue air and wasted time?!!!!

Bill

 

[dodge man]

Mine does the same thing, but not always. I just gave up and use an impact, which seems to hold O.K.

 

[Couple of Achers]

Thanks to all who replied. Removing the nuts with an impact wrench is easy, but tightening them is another story. I've never seen an impact wrench whose actual torque was close enough to rated torque--just too many variables.

The Quick Grips work. I tightened the belt with one and clamped the belt to the pulley with another. After blocking the blade I was able to torque the center spindle nut to specs. quite easily.

Sorry, Kubota, but my problem with all this is why is there no way to tighten the center nut without all the invention, not to mention blue air and wasted time?!!!!

Bill

Necessity is the mother of invention as they say. I did not have a impact wrench the first time I struggled with it as you did. I have since gotten one. However, the bolt that holds the blade on is bigger than any of my impact sockets
So I figured out the way to tighten and hold the spindle from turning with the clamp while blocking one of the other blades. It was a head scratch-er tho. Glad it worked for you.

 

[brizamc]

I have had the same problem torquing the blade bolts also, they are a pain. Has anyone had an easy solution other than using an impact driver and guessing the torque.

The only technical advice i can find from kobota is to use a block of wood on the blade. I have the same problem as you hammerblossom. I have also worked out various dodgy methods on holding the top bolt, tightening the belts around the pulleys with vice grips, wood jammed into the blades etc. Is there a hole somewhere for a pin that holds the spindles to stop them spinning allowing you to remove and also tighten the bolts. Kobota must have a way that is better and more secure than a block of wood?

Sorry for the long post.

Thanks

 

[dougtrr2]

I have had my BX24 almost 20 years and never had any problems removing or tightening the blades using a block of wood. I do use an anti-seize compound as insurance.

You might try cleaning the threads of both the bolt and spindle. While doing that make sure the hole isn't packed with debris causing the bolt to bottom out. I think if the bolt is binding up before you are getting pressure on the washers it could cause your problems.

Doug in SW IA

 

[m7040]

On my ZD 331 it has the same problem. I would put a large wrench on top of the two outside spindles to hold it from rotating and use a torque wrench on the blade bolts. On the center one under the gearbox I would insert a large screw driver in the Ujoint of the drive shaft to hold it. Used to use an air impact wrench but sheared a bolt in the process.
Today I use Milwaukee impact that has setting for torque and number 2 setting corresponds to the Kubota torque

 

[ROUSTABOUT]

Need some guidance from someone who knows what he or she is doing,

I have a BX2350 for which I just purchased a MMM, model RCK5423BX. With the deck I bought a mulching kit. When removing the standard blades I found that blocking the blade with a piece of wood while turning the blade bolt didn't work, so I had to hold the upper spindle nuts with another wrench. No big problem. The center blade bolt came loose with the block of wood trick---fortunately.

THE PROBLEM: When I installed the new blades I again used the second wrench on the upper nuts in order to be able to torque the blade bolts to specs. The wood block won't hold the center spindle, however. The whole pulley/spindle assembly rotates. Since the gearbox is on top of the center spindle, how does one go about holding that spindle? I notice there's a round rubber seal in the top of the gearbox which displays the MMM model number. Is there a spindle nut to grab onto if that seal is removed?

(It would've been REALLY nice had Kubota's instruction manual addressed this issue. Can't believe it hasn't come up before.)

Thanks for your assistance.

Bill

Why can't you hold the drive shaft from turning. I always used a piece of chain tied around the blade and the deck. Air wrench on the blade bolts. I worked at Kubota. Dealer has been there since 1944. Started out as a Ford dealership. I didn't ever replace the cup washers unless the owner asked for me to.

 

[WranglerX]

I have two riding mowers, and one requires blade bolt to be torqued to 110ft-lbs... I always use a 4x4 block and large "C" clamp to wood block in place to keep the blades from spinning (yes all three blades/spindles) and it has never failed me, if your wood block technique is failing you, you are doing it wrong....
Funny thing here is no one has mentioned clamping wood block in place, it would be interesting to me to see the instructions Kubota has written on how to use wood block...

 

[buckeyefarmer]

Block of wood and torque wrench. Or use impact with a proper torque stick.

 

[DK35vince]

Thanks to all who replied. Removing the nuts with an impact wrench is easy, but tightening them is another story. I've never seen an impact wrench whose actual torque was close enough to rated torque--just too many variables

I've been using an impact wrench to remove/install my mower blades for decades.
Takes minutes
Never an issue. (no wood block needed)

 

[Gem99ultra]

Why can't you hold the drive shaft from turning. I always used a piece of chain tied around the blade and the deck. Air wrench on the blade bolts. I worked at Kubota. Dealer has been there since 1944. Started out as a Ford dealership. I didn't ever replace the cup washers unless the owner asked for me to.

The cup washers give me total h*ll. Any problem with not putting them on?

 

[dadohead]

The cup washers give me total h*ll. Any problem with not putting them on?

Yes! The belleville washer transmits the clamp force from the blade bolt to the outer rim of the spindle so it can effectively drive the blade(s).

If the blade has just a round hole (not a star shaped mechanical driver) the install torque is not a big deal because the joint is self tightening. A few rattles from your impact will hold the blades well enough to stay on when the PTO is shut off and brakes engaged (5 second stop per ANSI). After mowing it just gets tighter...

 

[ROUSTABOUT]

The cup washers give me total h*ll. Any problem with not putting them on?

You need them to give clamping force on blade.

 

[zzvyb6]

On My JD deck, mulching blades are a bit thinner, so you need to add provided washers to get them tight. Otherwise, you run out of thread. Pretty close to tight, but no cigar.

 

[AndyMA]

On all my mowers I use my Milwaukee M18 impact, No blocks or chains required.

Andy