BX MMM Top Lock questions

[quarencia]

I bought a used 2230 last fall and really like the tractor. I've only had one problem so far. If I adjust the mmm to level, I can't lock it in the Top position with the height adjustment.

I spent some time on my back under the tractor and discovered the problem, and came to an unfortunate conclusion. The only easy fix is new parts. The only good fix is to start welding. I've read several posts on this subject, and none seem to address what I think is the real problem.

Get a cup of coffee, this gets long winded. The shaft connecting the two lift links on each side is pinned to the lift links. The stop bracket that rests on the rotating cam height control is welded to this cross shaft. The pin holes in the shaft and lift links have "wallowed" out over time. This is caused by the assymetric loading of this design between the raised and lowered positions. When mowing (lowered), the mmm load is carried by the tab on the cross shaft resting against the cam stop for controlling height. Both lift links are loaded in the same direction. They also tend to wear in the same direction. When the mmm is raised, the entire load is carried by the right side lift link that is connected to the 3ph. Now the loading on the right hand lift link and cross shaft are reversed from the left side. They wear in opposite directions. Over time, this has the unfortunate effect of preventing the stop bracket from rotating far enough in the raised position to clear "top lock" cam on the height adjustment. These pictures are from the parts manual and may serve to help understand this word jumble.



The long and longer of this post is, has anybody done anything to correct this problem other than buy new parts. I'd prefer to fix the problem rather than throw new parts at a poor design.

 

[toytruck]

I bought a used 2230 last fall and really like the tractor. I've only had one problem so far. If I adjust the mmm to level, I can't lock it in the Top position with the height adjustment.

You've lost me! The "Top" position locks the deck all the way up so you can use the 3 pt hitch. What are you trying to do?

 

[Volfandt]

Good research and topic quarencia.

There was a poster or two a few yrs ago's that posted a fix that seemed to work for some. He (or they) filed (or grinded, (is that a word?)) down the "top" step cam a little bit which was enough to allow it to hold the MMM up. If I recall correctly, his BX wasn't that hold and shouldn't have had too much wear.

Mine worked last yr but I haven't tried it this yr. With the amount of mowing I do weekly I expect I'll be facing this problem soon also.

 

[kevinj]

I bought a used 2230 last fall and really like the tractor. I've only had one problem so far. If I adjust the mmm to level, I can't lock it in the Top position with the height adjustment.

I spent some time on my back under the tractor and discovered the problem, and came to an unfortunate conclusion. The only easy fix is new parts. The only good fix is to start welding. I've read several posts on this subject, and none seem to address what I think is the real problem.

Get a cup of coffee, this gets long winded. The shaft connecting the two lift links on each side is pinned to the lift links. The stop bracket that rests on the rotating cam height control is welded to this cross shaft. The pin holes in the shaft and lift links have "wallowed" out over time. This is caused by the assymetric loading of this design between the raised and lowered positions. When mowing (lowered), the mmm load is carried by the tab on the cross shaft resting against the cam stop for controlling height. Both lift links are loaded in the same direction. They also tend to wear in the same direction. When the mmm is raised, the entire load is carried by the right side lift link that is connected to the 3ph. Now the loading on the right hand lift link and cross shaft are reversed from the left side. They wear in opposite directions. Over time, this has the unfortunate effect of preventing the stop bracket from rotating far enough in the raised position to clear "top lock" cam on the height adjustment. These pictures are from the parts manual and may serve to help understand this word jumble.



The long and longer of this post is, has anybody done anything to correct this problem other than buy new parts. I'd prefer to fix the problem rather than throw new parts at a poor design.

I think from your description that the lift rod from the 3PH need to be shortened a little to raise the carraige slightly.

 

[schrand]

I think I agree with Kevin.
It sounds to me like the 3 point is not raising up far enough. If the little brackets that you adjust to level the mower wear, the mower won't be level any more, but that shouldn't affect the 'top lock'.
There is an adjustment that controls how high the 3 point goes before the control lever returns to the neutral position. If I remember correctly the description for the adjustment is in the manual. The actual mechanism is a shiny rod under the seat on the right side of the tractor.
I seem to recall that when the tractor is properly adjusted, the lift arms (item 080 in your left side drawing) will be 3/16" from the stop bracket on the frame of the tractor (the tab sticking out from the frame half way in between items 090 and 020). Just holding the lift lever in the 'lift' position and not letting it return to neutral may work until you get it properly adjusted.
Good luck,

 

[2002-BX2200]

You have the same problem that I had when I tried to get the mower blade height to match the dial on my BX2200. One of your lift arms is hitting its stop to early because you have one the level adjusters (part #70 on the diagram "LS Mower Link and Height adjust.JPG") cranked down too far and/or the rod (part #40 on the diagram RS Mower Link and cross shaft.JPG) that connects the hitch to the right mower lift arm has been cranked down too far; thus, constricting the hitch mechanism from rising high enough to allow one to click in the “Top” position. On my machine I have to either adjust my right stop in order to be able to crank the right level adjuster down or live with the fact that the mower cuts 3/8" lower than the reading on the dial when the mower is level. There is almost 3/8" of an inch difference between my lift arms and my stops.