F3080 72" deck one blade loose AGAIN!!!!!

JOHNTHOMAS · May 16, 2017

One of my blades is loose again. Tightened two of them with air impact wrench before last 5 hours mowing and todya after airing up the one flat tire AGAIN I was mowing and noticed not getting a full 72" cut. Outer blade was not cutting AGAIN. I've replaced the two washers, one bowed in the center, a couple years ago on one of the blades. About to try lock tite behind washer and against blade and retighten with air wrench but going to replace blades again and keep the current ones as spares and sharpen them.
Any of you having any issues with a loose blade on your decks????

Oh yeah, I was mowing fields that should have been bush hogged (thick heavy 4' high weeds/grass/small trees and ??) with F when the blade started slipping again.

jcummins · May 16, 2017

No I haven't. But my cut quality is down a bit, I think I'm due for a sharpening. I'll pay ATtn to any loosened before taking them off.

MultiMow · May 16, 2017

Is your deck a rear discharge?

jcummins · May 16, 2017

Mine isn't. Think JohnThomas is.

JOHNTHOMAS · May 16, 2017

MultiMow said:
Is your deck a rear discharge?

Absolutely. Hate side discharge decks but sure blades clamp down the same way on all Kubota decks. There are two washers with one being domed. The bolt goes thru the washers and blade and clamps the blade tight with the washers. Least bit loose washer and blade is loose, maybe turning but not fast enough to fully cut. Never had a problem with the 60" rear discharge deck on the F2680e and Sigarm in NC now has that deck on his F3080 I sold him. Only had the problem on this current F3080 I have with the 72" deck. Maybe it's using it on some really high "stuff" that isn't all grass.

MultiMow · May 17, 2017

There's your problem. They put the wrong spindle on the counter blade.

Rear discharge decks have one blade that turns counter to the others to avoid windrowing. I'd bet money, the blade that keeps coming loose is the counter spindle.

Look up the parts manual. There should be two different part number for the blade spindles... with one having opposite threads in the spindle shaft. Get the appropriate spindle and bolt, and your problem should be solved.

JOHNTHOMAS · May 17, 2017

MultiMow said:
There's your problem. They put the wrong spindle on the counter blade.

Rear discharge decks have one blade that turns counter to the others to avoid windrowing. I'd bet money, the blade that keeps coming loose is the counter spindle.

Look up the parts manual. There should be two different part number for the blade spindles... with one having opposite threads in the spindle shaft. Get the appropriate spindle and bolt, and your problem should be solved.

Nope. Usually the outer blade (all three times in mowing in 5 years) and once it was the center and one outer blade. Thanks for the guess though but no cigar.:thumbsup:
Back to has anyone with a Kubota F 72" rear discharge deck besides me had this issue?

TailDragon · May 17, 2017

Both washers are cupped on my 3680's, cup away from blade. When I had a blade slip I too had used an impact gun. Had to get torque wrench (90 ft/lb) to further tighten. No problems since other than the dust covers cracking that protect the spindles.

JOHNTHOMAS · May 18, 2017

TailDragon said:
Both washers are cupped on my 3680's, cup away from blade. When I had a blade slip I too had used an impact gun. Had to get torque wrench (90 ft/lb) to further tighten. No problems since other than the dust covers cracking that protect the spindles.

I bought 3 new blades yesterday and plan to install today. I didn't get under machine to see if blade is slipping and the more I've pondered I've considered that my blade may just be in such bad shape it's not cutting worth a crap. I spent several hours mowing some real nasty crap in a field that had been bush hogged for years and some of the "stuff" was 4' tall with really big stalks/stems/trunks. I noticed the "missing" rows after going back to my yard to mow and it may just have been really bad cutting instead of a total miss of a blade row.
I bought a set of the two washers in a Kubota sealed pack a couple years ago, almost $20, I think, and one is cupped and the other is flat. I was going to buy a spare set till Gary told me the price. The 3 blades for rear discharge were about $76.
Your cup away from the blade means the outer cupped/high part is against the bolt head with the center not quite touching the blade/other washer in my case and being held down by the outer rim of the cupped washer? Right? I looked at Kubota parts diagram and On mine it shows one flat and one cupped. I'll look again at it and see if it indicates how the cupped part goes.
We need to get some washers this size and have someone bend the middle in a tad and start selling them.:cool2:

Sigarms · May 18, 2017

JOHNTHOMAS said:
One of my blades is loose again. Tightened two of them with air impact wrench before last 5 hours mowing and todya after airing up the one flat tire AGAIN.

You still haven't replaced those front tires yet? That was on problem I had with your old mower. Replaced them with the "no air" tires, and after greasing before each mowing session, still going strong after 100 hours.