B2X20 MMM height adjuster.

[vinzuki]

I have had my new B2920 with mmm a little over two months now and am impressed with its quality and performance that comes with the KUBOTA name. However the height control for the mmm is very dissapointing. After mowing for 2 hours the deck would not hold adjustment after lifting it up to travel . It would always fall back to the 1" setting scalping the grass. After reading and studying the manual and looking under the tractor to see how it works it seems to be under engineered. There is a shaft that goes under the tractor thats called the lift shaft. On this lift shaft is welded a metal finger about 1/4 wide that rides on a cylindrical cast iron gear with steps spiraling up it for the various heights. Now mind you this 60" deck weight is 322# and all this weight is riding on this metal finger no bigger than your pinkie finger. Remember this deck is suspended ,the wheels don't hold any weight.multiply this when you hit some bumps. Mine was assembled properly by the dealer but there was about 3/16 play side to side in that lift shaft and the finger was only touching a small portion of the step and wore it out in no time.My dealer was very helpful and called KUBOTA and said they was aware of this problem,but have no fix as of yet. He ordered me a new shaft and stepped gear but being a mechanic I chose to modify it myself.The first thing you need to do is shim the lift shaft so it has 0 side to side play in it and the finger is centered in the step in the gear. I used a die grinder to dress up the steps in the gear making my favorite 3.25" a little deeper.I also filed a new tip on the finger with a hand file. It seams to be working fine for now ,but for how long? So any one with a new B series take a looksee under your tractor and see how yours working.

 

[rudegoose]

Yep, been there. done that. got that t-shirt.
Got my new 2920 in early May, it had the height adjustment problems you described starting on Day 1.
I've got the 54" mower deck, had the exact same issues... it was back and forth to the dealer numerous times.. at first, they said Kubota knew about the problem, but didn't have a part to fix it readily available.. so the dealer made an attempt to fix it, it sounds similar to what you did yourself... it still didn't adjust correctly though, but it would at least stay where you put it so you could mow at the same height. I appreciated that the dealer at least fixed it/sort of so I could use it while waiting for Kubota.
Finally got a call from the dealer that the new assembly had come in, so they replaced it....(I think it was early/mid-July) been working fine ever since. Don't know how the 'new part' differs from the 'old part', but it works (knock on wood).

Love my new tractor, but it was extremely frustrating to spend that kind of $$$ and get less than perfection from the start!

 

[Hoosier_Daddy]

I have the B2620.. 60MMM and have not had a problem so far. But, you have my attention.. I have not had the MMM off yet but will soon. Guess I will look around to see what is holding up this heavy mower.

Every new toy has it's bugs. Just glad Kubota fixes the problems..

 

[RRbota]

New member here. Been lurking for the past 8 months or so and finally joined. Man, what a great forum!!!

I bought my 2620 in May, after a lifetime of lawn and garden tractor experience (mostly Gravely). For the most part, I really like it. I've even found that using the diff lock will minimize the number of times I'm frustrated by the common Kubota complaint: "why can't they put the brakes on the other side, so you could actually use them??"

I noticed the "Wal-Mart qualilty" height adjustment method the first time I put the 60" mmm on my tractor, and expected problems. I immediately machined a spacer for the lift shaft, as vinzuki mentioned, and raised the deck wheels so they are a minimum of 1" off the ground. Still, whenever uneven ground is encountered (constantly on my yard) and tension is taken off the adjustment cam, it turns slightly, changing the height adjustment. Maybe this is intentional.....it's made the "brakes are on the wrong side" issue not seem so frustrating!!!! (yes, I am laughing.....the brakes really aren't THAT bad!!! Besides, I knew where they were BEFORE I made my decision to buy!!!)

What I have done the past month, is to change my approach. Instead of expecting the height adjustment cam to hold up the mmm (unrealistic, given the lack of engineering of the components), I'm using it as more of a "position control indicator". With the mmm raised, I set the desired height. Then, slowly lower the mmm, while still holding on to the adjustment knob. As soon as I feel the lifting shaft arm touch the adjustment cam, I stop lowering. Then I close the 3 pt hydraulics lowering valve, using the knob just to the right of the height adjustment knob (in front of the seat). This causes the 3 pt hydraulics to hold up the mmm instead of relying on the Wal-Mart cam, and is working much better. During the 2 hours it takes me to mow my yard, I may need to readjust the height once or twice (probably due to a slight amount of hydraulic leakdown from the weight of the mmm bouncing around), but that is much better than needing to readjust after every lap!!!

I'll have to get in touch with my dealer to see if he knows anything about the "new & improved" adjustment assembly that rudegoose mentioned.

Sorry about the long post, but hey.......it's my first time!!!

 

[Evil the Weasel]

My 2620's problem so far is that the height on the dial does not match the height of the blade from a level concrete floor. It's off by an inch. I posted some info about this in the buying/pricing forum. I mowed about 2 acres tonight and did not notice the mower height change during that, but I will check it out. I don't think they have mine adjusted right. The orange link arms make contact with the height adjustment linkage so I have to go easy when raising the deck (and not use the detent to raise it up quickly). The knob does have side to side play too. I will ask my dealer about this new part. That would be great if it is true.

 

[LBrown59]

It would always fall back to the 1" setting scalping the grass. After reading and studying the manual and looking under the tractor to see how it works it seems to be under engineered. .

What fell back the knob or the deck?
If you had the knob on 1 naturally the deck will drop to 1.

 

[vinzuki]

What fell back the knob or the deck?
If you had the knob on 1 naturally the deck will drop to 1.

I would be mowing at 3.25'',raise the deck and then lower it. You could watch the knob turn when you lowered it back down. Mine had so much play in it what was happening was the clevis in the connecting rod that goes back to the lower link,it was hitting the little nub that sticks out of the stepped cam . (that nub is used to lock the deck in the full up position). Any how I got my customer product survey in the mail today from kubota. They will get an earful on this.

 

[Evil the Weasel]

When the cam is not engaged on the height adjuster spiral gear, there is play in the knob. When I lower the deck to the set height there is no play at all and the deck does not change height during operation. I just mowed 4 acres of lawn tonight and it was fine. My only complaint is that the threaded adjusters are bottomed out (they shouldn't be according to the book), and my height is off by an inch. I can only cut at 3" max with this setup. I'm suspecting the height adjuster is the wrong one. Oh yeah one more complaint, the bracket that replaces the spacer on the left lower link is chewing into my lower link arm. I don't think it should be like that. The mechanic didn't think it was something to be concerned about. I checked the length of the connecting rod and it is spot on. I have a friend with a lot of tractor knowledge and we are going to go through the setup step by step and see if something is amiss down there.

Even though I'm off by an inch on the dial, this thing mows like a BEAST. And I can't believe how maneuverable it is. I have about 45 trees to contend with and I thought the ROPS would be smashing into everything. I have about two limbs total that need to be cut for smooth sailing. Keep me posted and I will let you know what I discover (if anything).

 

[nh_bota]

It's interesting to read the issues that people are having with their 2x20 decks... I had the same issue when I started to mow with mine about 3 months ago (i.e. it was an inch off). I made some adjustments and now have the height almost perfect. Haven't had an issue since. I'll keep my eyes open now that I know people are having problems.

 

[LBrown59]

I would be mowing at 3.25'',raise the deck and then lower it. You could watch the knob turn when you lowered it back down.

It shouldn't do that.