M 8540 4wd question

   / M 8540 4wd question #1  

big bubba

Elite Member
Joined
Mar 7, 2007
Messages
2,753
Location
arkansas
Tractor
M8540
my '08 M8540 operates flawlessly including the 4wd. recently, disengaging the 4wd is problematic in that the lever seems to hang up 3/4 downward toward the floorboard, and requires some coaxing to fully disengage.were it not for the 4wd dash light, i wouldn't have noticed... previously, it was very fluid to fully disengage. your thoughts on why it hangs up like this suddenly? is there some clutch/linkage adjustment? lube areas? have yet to crawl under. thanks in advance.
 
   / M 8540 4wd question #2  
gonna sound dumb but check air pressure in your tires. one could be low causing it to bind
 
   / M 8540 4wd question #3  
I suggest to lubricate linkage if you have not already performed that task. Also tire wear can contribute to 4WD gear binding. Have you tried momentarily reversing tractor to relieve stress?
 
   / M 8540 4wd question
  • Thread Starter
#4  
thanks to you both for those suggestions, i will check it out today. :)
 
   / M 8540 4wd question #5  
I have a '10 M8540HD12 and its 4wd engagement/disengagement is not affected by the 4wd bind. Meaning the pull-up/push-down lever will operate smoothly all-the-way even if the tractor is bound and stays in-or-out-of 4wd. (Once the bind situation is resolved, it goes in-or-out of 4wd... wherever the shifter was placed.) This is all normal.

Your dash light tells you whether the tractor is in-or-out-of 4wd, not where the lever is positioned.

The reason I am saying this is, your lever should operate smoothly. I would try the suggestion of checking the linkage.
 
   / M 8540 4wd question
  • Thread Starter
#6  
I have a '10 M8540HD12 and its 4wd engagement/disengagement is not affected by the 4wd bind. Meaning the pull-up/push-down lever will operate smoothly all-the-way even if the tractor is bound and stays in-or-out-of 4wd. (Once the bind situation is resolved, it goes in-or-out of 4wd... wherever the shifter was placed.) This is all normal.

Your dash light tells you whether the tractor is in-or-out-of 4wd, not where the lever is positioned.

thanks for this. yes, the lever engagement of 4wd has worked flawlessly since i've had the tractor (new)....however, this current problem seems to have happened suddenly. tire inflation or linkage lube is not the problem, & there is no adjustment on it..... although there is no problem engaging 4wd, it currently will not disengage (toward the lower end of the lever action) unless i gently release the pedal clutch in reverse. never acted like this before.... this is similar to my older Toyota 4wd gear train, and tells me there is gear pressure that needs to be relieved before disengagement....i certainly can live with this procedure, but it is puzzling why it happened only suddenly. i lifted the ft end to check wheel action in 2 & 4wd and everything is okay. are there synchronizes in the 4 wd system for the lever action since it can be done in motion? hey thanks....
 
   / M 8540 4wd question #7  
are there synchronizes in the 4 wd system for the lever action since it can be done in motion? hey thanks....

I'm pretty sure that it states in the OM, not to engage while the the tractor is not moving but rear the wheels are. Clearly they did not word it the way I did.:laughing:
But to answer your question, no, not synchronized. It engages because both axles are moving the same speed and therefore synchronized, just like a 4x4 pu. or jeep with locking hubs. If the hubs are "locked in" you can shift in and out of 4wd all day long at any speed. If I have the space, I'll just turn the tractor left - right and it'll pop out.
 
   / M 8540 4wd question
  • Thread Starter
#8  
But to answer your question, no, not synchronized. It engages because both axles are moving the same speed and therefore synchronized, just like a 4x4 pu. or jeep with locking hubs. If the hubs are "locked in" you can shift in and out of 4wd all day long at any speed. If I have the space, I'll just turn the tractor left - right and it'll pop out.


hey thanks on this, have already tried that...only by reversing slowly by clutch will it disengage now,where as before, would disengage moving or not in either direction. somehow, a gear bind is now in effect and is puzzling to me. i'll stop in my dealership & if their take might be useful to others on this, will let you know. :thumbsup:
 
   / M 8540 4wd question #9  
thanks for this. yes, the lever engagement of 4wd has worked flawlessly since i've had the tractor (new)....however, this current problem seems to have happened suddenly. tire inflation or linkage lube is not the problem, & there is no adjustment on it..... although there is no problem engaging 4wd, it currently will not disengage (toward the lower end of the lever action) unless i gently release the pedal clutch in reverse. never acted like this before.... this is similar to my older Toyota 4wd gear train, and tells me there is gear pressure that needs to be relieved before disengagement....i certainly can live with this procedure, but it is puzzling why it happened only suddenly. i lifted the ft end to check wheel action in 2 & 4wd and everything is okay. are there synchronizes in the 4 wd system for the lever action since it can be done in motion? hey thanks....

you definitely have axle wrap caused from the air pressure of the tires. They are not spinning at the right speeds which can be cured by adjusting the air pressure.
 
   / M 8540 4wd question
  • Thread Starter
#10  
you definitely have axle wrap caused from the air pressure of the tires. They are not spinning at the right speeds which can be cured by adjusting the air pressure.

thanks art i will put the gauge to them today. hope it's that simple!
 
 
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