BX2350: 4WD appears to lock the rear diff

   / BX2350: 4WD appears to lock the rear diff #1  

fish6942

Gold Member
Joined
Apr 15, 2007
Messages
327
Location
Minnesota
Tractor
'07 Kubota BX2350
When I put the 2350 in to 4wd, the rear tires act like I have the diff lock engaged (inside tire scrubbing during tight turns).

I compared 4wd and no diff lock to 2wd with diff lock and the rears act the same in both cases. At first I thought the diff lock was stuck but then I put it into 2wd with no diff lock and the rears act like I'd expect them to.

Anybody else experienced this?
 
   / BX2350: 4WD appears to lock the rear diff #2  
Very strange, the two systems are not related in any way. I think the diff lock is sticking somehow. try putting it in 4wd and backing it up while turning and see if the the rear tires are still scuffing. Or maybe try stepping on the diff lock pedal repetedly while driving the tractor, that might loosen it up.
 
   / BX2350: 4WD appears to lock the rear diff #3  
I've found this on some tractors. The inside tire will always seem like it is spinning because the outside tire will "freewheel".

What you're seeing is a classic example of why you do not use 4WD on hard surfaces. The front wheels and rear wheels are supposed to go the same distance per revolution of the input shaft of the transmission as they have a direct mechanical connection. The gear ratios are different from the front to the rear because of the tire size differences, so you should get the idea though that 1 engine revolution = x number of feet traveled. This should be the same for the front and the rear. But what happens when you turn the tractor? The rear wheels are now taking a shorter path than the front wheels. Much like how the trailer of a semi takes a shorter path around a turn, your rear wheels do the same thing...it's just not as drastic. So when you turn your tractor, your front wheels are going farther than the rear wheels......so the rear wheels are trying to "push" the front wheels. Since the front wheels are at an angle, it's easier for the inside rear wheel to spin a bit instead of pushing the fronts too fast.

I know it's described in a bit of a "beat around the bush" way......but did it make sense?
 
   / BX2350: 4WD appears to lock the rear diff #4  
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When you turn the front and rear wheels are working against each other.
 
   / BX2350: 4WD appears to lock the rear diff
  • Thread Starter
#5  
PEDALSTOPMER - That does make sense.

BULLITT - I see you have a BX also. Have you ever noticed what I've described?
 
   / BX2350: 4WD appears to lock the rear diff #6  
Jack up the back end so you can spin the rear tires by hand. With the tractor in 2wd, neutral, see if the rear wheels spin in opposite directions when you turn them manually. That's classic behavior for a standard differential and tells you it's working normally. If the diff lock is engaged, it wouldn't do that. I expect yours is fine and just applying power to the inside wheel in a turn.
 
   / BX2350: 4WD appears to lock the rear diff #7  
I am pretty sure its a case of driving on dryer/less forgiving surface that cause you to notice the scrubbing. Mine does it that way when I am on black top turning in 4wd. same goes for turning around in a circle on dry grass and the it doesnt turn as sharp as in 2wd.
 
   / BX2350: 4WD appears to lock the rear diff #8  
PEDALSTOPMER - That does make sense.

BULLITT - I see you have a BX also. Have you ever noticed what I've described?

Yes, the inisde tire on the rear will spin when it is in 4wd.
 
   / BX2350: 4WD appears to lock the rear diff
  • Thread Starter
#9  
Well, it sounds like I'm OK. Next time I have it in my shop I'll try what Grandad suggests and jack up the rear and spin the tires. In addition, I'll try engaging the diff lock when in 4WD to see if there is any difference. All of this testing has been performed on a gravel driveway.

Thanks All!!
 
   / BX2350: 4WD appears to lock the rear diff #10  
As others have said, your machine is fine. The linkages for 4wd and Diff Lock are nowhere near each other. The binding you are feeling is normal and occurs in all 4wd vehicles. It's more noticeable on your BX because you are basically sitting on top of the rear tires.
 
 
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