Sharpened blades on mower deck

[Petrol and Powder]

So I did some mowing today with the mid mount mower. When I was done there was still some daylight and I decided to sharpen the blades. Purchased the tractor and mower last Spring and this was the first time I did any maintenance on the deck.

HOLY COW those bolts are tight !

3/4" drive 18" breaker bar with about a 4' section of 1" pipe on the breaker bar just to get those puppies loose. The Impact wrench wouldn't even begin to break them loose.

When I was done sharpening the blades I put them back on with just the breaker bar. I put a little anti-seize grease on the threads before re-installing the bolts.

Anyone else have this problem?

Also, could only find 4 zerk fittings ; one for the idler pulley pivot, one on each U-joint for the drive shaft and one for the splined center section of the drive shaft. Is that all?

 

[Oldoak]

Those bolts were certainly put on way too tight. No way should it have taken that much force to break them lose. It would appear someone used an impact wrench to tighten them with any regards to the torque setting.

I don't have a Mahindra, but my JD X758 mower deck only calls for 50 Ft pounds of torque on the mower deck blade bolts. I just tighten them like you did, with a standard breaker bar and call it good. Never had a problem. I also use just a little Never-Seize on the bolt threads.

 

[KennyG]

Was this a new deck? I have found that factory assembly often overtightens stuff. Oil Filters, drain plugs, anything mounted to the frame, etc. Causes a lot of frustration.

 

[Petrol and Powder]

Yep, first time I had removed the blades. I understand the factory wanting those bolts to be tight but it was excessive. When I couldn't break them loose with an impact wrench or just an 18" breaker bar I grabbed a section of aluminum tubing that was handy and slipped it over the breaker bar. I snapped that tubing in about 1/2 second! I got serious after that and found a 4' section of steel pipe to use as a cheater and even that required more force than I anticipated.

Once they broke loose the bolts came right out. No rust, clean threads, no problems. Those bolts have fat cross sections and fine threads, so they're pretty strong but I don't think they need to be tightened to 500 + ft/lbs.

 

[Oldtink]

Right. The 24" blades on my 72" JD deck calls for 90 ft/Lbs, to give you an feel for it.
Maybe they had some kind of thread locker compound on the threads.

 

[JerryK]

While in a perfect world, everything would be tightened ' perfectly '. A little too tight is better than a little loose. Especially if they can loosen, fall out, and drain fluid out. Or in the case of a mower blade, fly off into the sunset. Some blade bolts tighten themselves if you hit something with the blade. And, in my years of changing diesel filters, I think they tighten themselves when they age... just out of spite...

 

[Navasot]

Why not just change the blades while your going through the trouble? Once the lift on the blade is warn down they can be sharp as possible but still not cut... or did you have a lot of rock dinks and whatnot in them?

 

[4570Man]

I've found for commercial mowing I have to change the blades about twice a year and sharpen them every couple weeks. Once the square edge of the cutting edge gets rounded over the cut quality suffers. I've never had the lift edge wear out. On my equipment I install and remove blades with my medium sized cordless impact. On newly acquired used equipment my bigger impacts or cheater bars are required.

 

[JK22]

I've read elsewhere in OTT that the WSM for Kubota decks seem to recommend 450lbs/ft for most of the MMM decks. My 1/2" Dewalt pneumatic impact will do 650ft/lbs. I haven't found a 3/8" that will go above 350. If possible, I think I'll be blocking my blades with 2x4 and leaving mine on to sharpen. Just seems nearly impossible to get the torque right otherwise.

 

[Navasot]

Yall actually check the lb specs on the mower blade? lol

Have put them on with wrenches and also with impacts and not had an issue

 

[JK22]

Yall actually check the lb specs on the mower blade? lol

I'm a little OCD with this kind of thing. I always try to go by specs when possible. Plus it justifies those torque wrench purchases. Not applicable here though, as I've never seen a torque wrench that will do 450! They might exist at NASA, but I'm sure they are extremely pricey!

 

[Gary Fowler]

I have never torqued a mower blade in my life and never had one loosen off. I use a 3/8 drive CP impact and just hammer it till the bolt quits turning (about 3 seconds after tight). The 3/8" impact with 90 PSI wont over tighten and gets the bolts loose easily.
I have to sharpen my blades about ever other mowing due to lots of crawfish mounds and rocks beating them up. I bought 2 sets when I got my Ferris 3 years ago and are still using them.

The lift tabs will wear out on blades prior to the cutting edge wearing down too much in my use due to the sand and crawfish mounds. I have actually did base metal build up with 7018 rods on the thinned spots (right where they bend upward) on the lift tabs and got another year of use out of them. It took me about an hour to weld up /balance the three blades but I have more time than money since retiring.

 

[oldballs]

I'm no expert, but find a Kubota MMM deck blade mount bolt recommendation of 450 ft lbs torque ..............way off. Hum-m-m. Maybe I'm wrong for the first time in my life.

 

[AchingBack]

I'm no expert, but find a Kubota MMM deck blade mount bolt recommendation of 450 ft lbs torque ..............way off. Hum-m-m. Maybe I'm wrong for the first time in my life.

I'm guessing these high torque specs were misapplied to mower blades instead of brush hog blades.

 

[SedonaDave]

I'm no expert, but find a Kubota MMM deck blade mount bolt recommendation of 450 ft lbs torque ..............way off. Hum-m-m. Maybe I'm wrong for the first time in my life.

Maybe inch lbs?

 

[SandburRanch]

This may not be your exact mower but it may be close enough for government work.

 

[JK22]

I'm no expert, but find a Kubota MMM deck blade mount bolt recommendation of 450 ft lbs torque ..............way off. Hum-m-m. Maybe I'm wrong for the first time in my life.

You can sleep well. Just found a manual online for RCK60 and mower blade screw torque is 72.3-86.8ft/lbs. Guess I shouldn't believe everything I read on the interwebs.

 

[Petrol and Powder]

Why not just change the blades while your going through the trouble? Once the lift on the blade is warn down they can be sharp as possible but still not cut... or did you have a lot of rock dinks and whatnot in them?

I change blades when I MUST, not when they just need to be sharpened.

And they were in good shape, no damage just not very sharp.

 

[Petrol and Powder]

And I'm not worried about how much torque I applied when re-installing the blades. They'll stay on just fine.

I was Bitc**n about how **** tight they were from the factory. I guess I shouldn't complain - they didn't fly off on their own and I was able to get them off with some persuasion.

My father had a VW Rabbit that had wheels attached with bolts (not studs and lug nuts). The factory tightened those bolts down to some extreme level. The ONLY way to get them loose the first time was to smack the end of the bolt with a 4 pound sledge hammer and then use a 6 point socket, breaker bar and a 6' + section of pipe. I don't know what you were supposed to do if you got a flat tire before you had broken those things loose for the first time.
That was a lesson learned. Every time I get a "new to me" vehicle the first thing I do is make sure the jack works and all of the lug nuts can be removed with the tire iron. After I break them loose the first time I apply a little grease and use a torque wrench to put them back on. Never had a problem after that.

 

[Pepsiboy]

I'm no expert, but find a Kubota MMM deck blade mount bolt recommendation of 450 ft lbs torque ..............way off. Hum-m-m. Maybe I'm wrong for the first time in my life.

My Kubota 54" MMM deck has a torque spec of 75 ft lbs. Plus I use anti seize on the bolt threads. I've not had to use anything but a 16" 1/2 drive breaker bar to get them off.

If I were you, I'd double check that torque spec again.

Dave