Mowing BX25 mower height adjustment knob

   / BX25 mower height adjustment knob #1  

Chugbug

Silver Member
Joined
Oct 15, 2008
Messages
141
Location
Central Ohio
Tractor
BX25
Has anyone had a problem with the cutting height knob. Mine is difficult (to say the least) to put into the lock position, it moves easily from the 0 to 4 but going from the 4 to the locked up is darn near impossible, I have to raise up the deck to max then rock the lever up and down very quickly at the same time attempting to turn the knob from 4 to lock, eventually it will move to the lock position. When the deck is off the knob moves freely with no problem. I made some adjustments early this year to the deck because it was cutting leaving high low places thought I had it right but the cut was worse so I made adjustments again yesterday but the problem with the knob is not fixed, I will be cutting grass tomorrow so I will know if I got the blades adjusted right (I hope so this MMM is a pain to adjust). Is there something I missed that would affect the height knob?? If I can't get it to work I will have to take it to a dealer to get the adjustment and knob fixed. Any help is greatly appreciated.
 
   / BX25 mower height adjustment knob #2  
Sorry I don't have any fixes for you, but if it makes you feel better, my BX2200 did the same thing after about 8 years of use. I just dealt with it as it was used primarily as a mowing machine, and when I used it for anything else, the MMM was off.
 
   / BX25 mower height adjustment knob #3  
I'm a mechanic at a Kubota dealer, fitted a 60" deck to a BX25 today. The problem you are having with the height adjusting knob is not uncommon. We often find that straight out of the crate they will not lock in and need a bit of adjusting. And if you try to calibrate the deck cutting height to what the knob says you will be disappointed, they are never accurate. You might set your knob to 2.5 inches, but the true cutting height between the blades to the ground will be more like 3.25 inches.
The more you screw those 2 adjusting bolts on the lift links down, the higher the relative deck height will be to the machine's lift arms. So when you raise it right up the deck will butt up hard against the chassis and stop the locking cam mechanism from working because the lift arms haven't reached the top of their stroke yet.
To fix this, you need to forget about the accuracy between what the knob says and the true cutting height to the blade tips to the ground, you will never get it right, you might get it close if you have turf tires which lowers chassis/ground height, but your BX25 will have industrial tires standard so the chassis will sit higher and throw out the calibration of knob height to true cutting height.
Firstly disconnect the rear lift arm links from the deck. Raise the 3PL to it's highest position. The height control knob should be able to lock in to the TOP position. If it doesn't then you need to make an adjustment to the lift rod adjuster behind the Left Rear wheel. Screw the adjuster bolt in a bit and try it again, this will raise the lift arm shaft a touch relative to the 3PL position and give it a higher point on the cam lock pin and should lock in to the TOP position on the knob. If it doesn't, screw the adjuster in some more until you get it.
Next, make sure your rear tire pressures are the same (22psi) and have even tire wear otherwise the machine will tilt to one side or the other which majorly changes your cutting height from left to right spindles.
Park the machine on level concrete. Reconnect the deck to the lift arm links. You need to back off those 2 adjusting bolts on the lift links to allow the relative deck position to lower in relation to the lift arms and keep it off the chassis. You need to lower it down just enough so when the 3PL linkage is at it's highest point the mower deck is just touching, or about to touch the chassis, they should never be butted up hard against the chassis otherwise it won't lock in TOP. Your height adjusting knob should click into the TOP position. If it doesn't then you might need to adjust the rear bolt in a bit more.
Once you have achieved your TOP lock in position, you can then lower it down to approx 2". There is a special blade height tool you can buy that you insert from the outside of the deck and a telescopic arm reaches underneath and touches the blade so you can compare the left blade cutting height to the right blade. If they are out, you need to loosen the adjusting bolt on the lift link of the HIGHEST side, never tighten the lowest side to bring that side of the deck up because it will just hit the chassis when raised again and cause the original problem again of not locking in.
The last thing to do is set your height knob to where you want it, and then adjust the height of your anti scalp wheels so they run 1/2" off the ground.
Just remember these mower decks are not a precision work tool like a golf course cylinder mower, so unfortunately with these "near enough is good enough" as long as the blades give a level cut then it's what you want and ignore what the knob tells you because they are inaccurate.
 
   / BX25 mower height adjustment knob #4  
Great comments onyamatey. Thank you.
 
   / BX25 mower height adjustment knob #5  
I'm a mechanic at a Kubota dealer, fitted a 60" deck to a BX25 today.

Welcome to the forum Onyamatey and thanks for sharing your professional knowledge with us. For every question you answer there are lots more owners reading and learning from your experience. I will be using the information from this thread to make some adjustments to my deck. Your instructions make much more sense than the manual, at least to me.

Sent from my iPad using TractorByNet
 
   / BX25 mower height adjustment knob #6  
+1 What Bob says. Welcome, Onyamatey! Great comment. Hope you can join in some of the more technical discussions from time to time. There are lots of Kubota owners here who share their real life experiences, mostly good, occasionally not so much. Of course, you probably get something like that every day!
 
   / BX25 mower height adjustment knob
  • Thread Starter
#7  
Thanks onyamatey! I spent roughly 3 hours yesterday trying to get the blades at the same height. I knew from the beginning that the height knob would not be the same as the actual cutting height. I set the knob to 4" and leveled it from this height, the cutting height is actually 4 3/4" with the knob at 4. I can freely move the knob with the lift arms off so the problem is with the the 2 adjustment bolts. I will go back out today and start over I know on my 2 adjustment bolts the right side ( looking from the back to the front ) is almost all the way down and the right side is down about half way up the bolt.
 
   / BX25 mower height adjustment knob #8  
:welcome: to TBN, onyamatey.
I can tell you'll be a welcome member with advice like that. Well done! I don't have any complaints on my mower right now, but I might just do what you suggest and see if I can fine tune it some more.
 
   / BX25 mower height adjustment knob
  • Thread Starter
#9  
OK here's what I've done. Started from scratch disconnected every thing Ive turned the fine tuning bolts so they are flush in the linkage. With the height adjustment set at 4" i measured the right side blade and it is 115mm and the left side blade is 95mm is this normal for the mower to be 20mm off. I'm not so worried about the front to back heights its the left to right that's is giving me problems????
 
   / BX25 mower height adjustment knob
  • Thread Starter
#10  
I think I may have the mower set up but I noticed the self balance linkage has about 1/3" play in it. Here is a photo of the left side


image-253242043.jpg


And here is the right side



image-4052961946.jpg

Is this normal?

Thanks
 

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