'New' B6000, 4WD feels like applying brake

[jroen81]

Hi guys, just got myself a B6000 last week. Am busy cleaning it up and refreshing. One thing that has me a bit worried is that the tractor rolls freely when 2wd is selected, but not so in 4wd. As soon as I select that it feels like the brake is deployed.

Has anyone experienced the same and can you get me in the right direction where to start looking? Or is this just normal behavior during 4wd operation?

 

[Motion]

Not familar with your model, I'd suggest checking the fluid level and type, make sure it's in two wheel drive, chock the rear wheels, then jack the front axel and turn the wheels to see how much drag it has. If it'free disconnect the driveline to determine if the problem is on the gear box side.

 

[RBsingl]

Any chance a previous owner seriously mismatched front to rear tire size ratio from how it was originally equipped? There is always going to be some mismatch but a serious mismatch will result in driveline bindup resulting in what you are experiencing.

Rodger

 

[jroen81]

Any chance a previous owner seriously mismatched front to rear tire size ratio from how it was originally equipped? There is always going to be some mismatch but a serious mismatch will result in driveline bindup resulting in what you are experiencing.

Rodger

That's what I was thinking. But the circumfence of the rear is 2160mm and the front 1573mm, so that should be close enough to the stock ratio if I'm not mistaking.

 

[RBsingl]

That's what I was thinking. But the circumfence of the rear is 2160mm and the front 1573mm, so that should be close enough to the stock ratio if I'm not mistaking.

It is good that you checked the stock ratio, I wasn't sure of the original specs.

I haven't ever checked the difference in rolling resistance between 2WD and 4WD with my Deere 955 but I suspect even with fairly closely matched tires it would go up some. I know that it does roll easily in neutral in 2WD but not sure when using 4WD (or what Deere refers to as MWFD or mechanical front wheel drive on their compacts with different size rear and front wheels).

Hopefully someone with your Kubota model checks in with their experience.

Meanwhile I am still awaiting for Kubota to supply a 72" rear discharge mower deck so that the dealer can deliver my new F2690 front mower. Early August delivery has now turned into early November delivery, at this point I will be happy if I get it in time for Spring mowing

Rodger

 

[19thSF]

Hi guys, just got myself a B6000 last week. Am busy cleaning it up and refreshing. One thing that has me a bit worried is that the tractor rolls freely when 2wd is selected, but not so in 4wd. As soon as I select that it feels like the brake is deployed.

Has anyone experienced the same and can you get me in the right direction where to start looking? Or is this just normal behavior during 4wd operation?

Hello Rbsingl and jroen81,

The suggestion of a possible tire circumfence issue is absoluty correct. It the first logical thing to check. When four wheel drive is engaged, the fronts should be covering "slightly more ground than the rears. If this were not the case, the rears would "push the fronts" and you would have poor steering ability. So ........the fronts wind up pulling the rears just slightly, and good steering is maintained.

Kubota refers to the correct ration as the "gear ratio". I asked Kubota Customer Service for the ratio for my B2650, , and the attached is what they sent. I suggest that you make the same inquiry of Kubota, and with that information in hand, you will be able to compare it to what you actually have. Mine is 1.672, which means that the fronts rotate 1.672 times faster than the rears. Changing tire size away from spec changes the amount of Ground covered.
Good luck with the issue
Bob

 

[Henro]

Just to add a thought, but if the resistance was due to binding because of a wrong ratio between the front and rear tires, would not backing up to release the binding, then going forward a bit show increasing binding after one stops backing up.

Point I am trying to make is trying this may help indicate the issue IS with tire size difference from stock design. I would expect that if it were an issue caused by out of speck tire sizes, the issue would gradually get worse when starting forward again, after backing up.

This is something I would probably do as a test if it were me...

 

[19thSF]

Just to add a thought, but if the resistance was due to binding because of a wrong ratio between the front and rear tires, would not backing up to release the binding, then going forward a bit show increasing binding after one stops backing up.

Point I am trying to make is trying this may help indicate the issue IS with tire size difference from stock design. I would expect that if it were an issue caused by out of speck tire sizes, the issue would gradually get worse when starting forward again, after backing up.

This is something I would probably do as a test if it were me...

Hello Henro,
Good question! Here are my thoughts:
If the fronts are too small, they will dig in, and the rears willl have to push them when going forward.
In reverse, the rears will be dragging the fronts.
In either case the ground under the fronts is going to get torn up.
That is my initial reaction. Maybe someone else will see it differently.
Bob

 

[Henro]

Hello Henro,
Good question! Here are my thoughts:
If the fronts are too small, they will dig in, and the rears willl have to push them when going forward.
In reverse, the rears will be dragging the fronts.
In either case the ground under the fronts is going to get torn up.
That is my initial reaction. Maybe someone else will see it differently.
Bob

I suppose this is true. BUT at some point there should be no stress on the system, when moving from one direction to the other.

This would be the mid point between stress developing in either direction, with either tire size combination.

So are you having an issue in both forward and reverse? And when changing directions do you feel any difference?

If you do not see any difference then I would expect the issue is something else other than a tire size mismatch. But what do I know? Just analysis from a distance...

OH! Looking back I see you are not the OP. But the question is a good one and we can see what the OP comes back with if he does...

 

[jroen81]

I suppose this is true. BUT at some point there should be no stress on the system, when moving from one direction to the other.

This would be the mid point between stress developing in either direction, with either tire size combination.

So are you having an issue in both forward and reverse? And when changing directions do you feel any difference?

If you do not see any difference then I would expect the issue is something else other than a tire size mismatch. But what do I know? Just analysis from a distance...

OH! Looking back I see you are not the OP. But the question is a good one and we can see what the OP comes back with if he does...

Hey everyone, did some experiments and measurements, but not conclusive thusfar. I'm not fully familiar with how the system works. As soon as I engage the 4wd I can push the tractor (in neutral, engine off) for a few meters and then it starts 'binding'. Moving forward or backwards does not make a difference.

I took some reallife measurements off the wheels. Front circumfence is 1700mm, rear 2370mm. In my calculations that leads to 1.39 ratio where 1.35 should be 'standard'. That's easily within the 6% margin that is considered normal. So that should not be the problem if I'm correct.

What puzzles me is how the front runs freely when the 4wd is disengaged. Is the whole front axle system indeed functioning in the same way as when 4wd is not engaged? I assume the 4wd lever only flicks the 'connection' between the driveshaft and the rear diff or am I wrong on that one?

 

[jroen81]

Hey everyone, did some experiments and measurements, but not conclusive thusfar. I'm not fully familiar with how the system works. As soon as I engage the 4wd I can push the tractor (in neutral, engine off) for a few meters and then it starts 'binding'. Moving forward or backwards does not make a difference.

I took some reallife measurements off the wheels. Front circumfence is 1700mm, rear 2370mm. In my calculations that leads to 1.39 ratio where 1.35 should be 'standard'. That's easily within the 6% margin that is considered normal. So that should not be the problem if I'm correct.

What puzzles me is how the front runs freely when the 4wd is disengaged. Is the whole front axle system indeed functioning in the same way as when 4wd is not engaged? I assume the 4wd lever only flicks the 'connection' between the driveshaft and the rear diff or am I wrong on that one?

Update on the previous post, crawled under the tractor. Jacked it up and spun the wheels. Everything is spinning with the 4wd disengaged. Nonetheless it still feels like something is binding in the front wheel section as soon as the 4wd is engaged. Hmmm, not conclusive yet... Next up all 4 wheels free from the floor...

 

[19thSF]

Hey everyone, did some experiments and measurements, but not conclusive thusfar. I'm not fully familiar with how the system works. As soon as I engage the 4wd I can push the tractor (in neutral, engine off) for a few meters and then it starts 'binding'. Moving forward or backwards does not make a difference.

I took some reallife measurements off the wheels. Front circumfence is 1700mm, rear 2370mm. In my calculations that leads to 1.39 ratio where 1.35 should be 'standard'. That's easily within the 6% margin that is considered normal. So that should not be the problem if I'm correct.

What puzzles me is how the front runs freely when the 4wd is disengaged. Is the whole front axle system indeed functioning in the same way as when 4wd is not engaged? I assume the 4wd lever only flicks the 'connection' between the driveshaft and the rear diff or am I wrong on that one?

Morning (Guess I should have said good evening) jroen81,

Just curious, where did the 1.35 ratio come from?

Bob

 

[GreensvilleJay]

re: Is the whole front axle system indeed functioning in the same way as when 4wd is not engaged?

yes, had a look at the B6000 dwgs in 'parts', same 'system' as my BX23S where everything up front (drive shaft, axle ,bull gears... all spin as tires are turned.

'something' inside the tranny 'connects' front drive shaft to rear when in 4WD

 

[Dieseldonato]

For what it's worth I was doing some loader work last night and thought about this. Kicked it into neutral and let it run down a little hill in 2wd and 4wd and didn't notice any difference between the two so far as rolling resistance. I would assume it should be about the same for your tractor.
Is this apparent when it's under its own power, or just when your rolling it by hand? (Sorry if you mentioned it, I didn't catch it.)
If your just doing it by hand I would say it's the lead of the front tires, and to see how it reacts under power of the tractor.

 

[jroen81]

For what it's worth I was doing some loader work last night and thought about this. Kicked it into neutral and let it run down a little hill in 2wd and 4wd and didn't notice any difference between the two so far as rolling resistance. I would assume it should be about the same for your tractor.
Is this apparent when it's under its own power, or just when your rolling it by hand? (Sorry if you mentioned it, I didn't catch it.)
If your just doing it by hand I would say it's the lead of the front tires, and to see how it reacts under power of the tractor.

It moving by hand, but also when driving. As soon as I depress the clutch in 4wd it brakes to standstill. If I'm in 2wd it just keeps rolling.

 

[ve9aa]

In my line of work, the first thing I advise my techs is:
"Confirm the customers complaint"

We've been led down the garden path SOOOO many times and found out that:
XX device does NOT even have that function
or
XX device is working perfectly and it's because you've never used this one before, or been used to another model that you think it's broken.

So, I say respectfully to the OP this:
Is this your first tractor?
First Kubota?
First 4WD tractor?
Can another experienced Kubota operator use it and tell you if your suspicions are real and is something actually broken or this "is just the way it is"?

(I'm actually trying to understand why you think the brakes are on, but I'm thick headed and maybe just not "getting it")

<I am not doubting you, but you need to CONFIRM, and yes, it seems like that's what you may be headed towards, thus my questions>


Good luck sir !

 

[jroen81]

In my line of work, the first thing I advise my techs is:
"Confirm the customers complaint"

We've been led down the garden path SOOOO many times and found out that:
XX device does NOT even have that function
or
XX device is working perfectly and it's because you've never used this one before, or been used to another model that you think it's broken.

So, I say to the OP...is this your first tractor?
First Kubota?
First 4WD tractor?
Can another experienced Kubota operator use it and tell you if your suspicions are real or is something actually broken?

(I'm actually trying to understand why you think the brakes are on, but I'm thick headed and maybe just not "getting it")


Good luck sir !

Sorry, but thats not the nicest reaction.

No, it's not my first tractor, yes it's my first Kubota and 4wd tractor, but not my first 4wd.

As I mentioned, it's 'feeling' like the brakes are on, I'm not thinking that they are on, they are not. There is a lot of resistance in the driveline somewhere as soon as 4wd engages. So, I was kindly asking if someone had experienced the same and could help me get the search on. Instead of blindly opening up the driveline to inspect every bit.

Thanks for questioning my mechanical skills, but it would be nice to not assume that they are lacking.

In my mechanical opinion, it is not behaving normal. But, as I stated in the opening post, I was already wondering if this was normal operation, but no one has confirmed so.

So thanks for the reaction, but I'm glad I'm not one of your customers I guess...

 

[RBsingl]

Even with a slight ratio mismatch, it is going to have noticeably more drag in 4WD. IF the front and rear were perfectly matched and the travel path was dead straight, the additional drag would only be from friction and inertia but because the match isn't perfect then force is built up and that is relieved by slippage of one or more of the tires. This is why I do NOT run tractors in 4WD when it isn't needed just like I don't run my pickup in 4WD when not needed. This is one of the very good reasons why vehicles with full time 4WD systems have an additional differential splitting torque between the front and rear axles to allow speed differences between the two axles to be managed as it should be rather than through forced slippage of tires.

I had my Deere 955 out last night doing some loader work and although it isn't a Kubota, its 4WD system is similar with different size front and rear wheels with gearing to compensate. It is much more difficult to push with the front axle engaged (two speed hyrdo in neutral) and comes to a more aggressive stop with the transmission in gear and the travel pedals released. This is with factory style turf tires front and rear.

Try taking your tractor out on a slicker surface (like wet grass early in the morning or after a rain) and compare its behavior on that surface vs 4WD on pavement. I think what you are experiencing is normal behavior.

Rodger

 

[ve9aa]

Sorry, but thats not the nicest reaction.

No, it's not my first tractor, yes it's my first Kubota and 4wd tractor, but not my first 4wd.

As I mentioned, it's 'feeling' like the brakes are on, I'm not thinking that they are on, they are not. There is a lot of resistance in the driveline somewhere as soon as 4wd engages. So, I was kindly asking if someone had experienced the same and could help me get the search on. Instead of blindly opening up the driveline to inspect every bit.

Thanks for questioning my mechanical skills, but it would be nice to not assume that they are lacking.

In my mechanical opinion, it is not behaving normal. But, as I stated in the opening post, I was already wondering if this was normal operation, but no one has confirmed so.

So thanks for the reaction, but I'm glad I'm not one of your customers I guess...

My friend....I meant no ill intent by my post and I think you totally misinterpreted what I was getting at.
You're a new member here and maybe I missed it, but you gave no personal history on your qualifications or experience with tractors or ANYTHING.

You have to realize, something like 90% of tractor owners are first time buyers/owners, so that's why I questioned what I did. Just questions, no accusations !

You seem insulted but at no time did I say anything untoward towards you or call you a name or anything. You overreacted.

Chill...the guys here are trying to help you....and I am one of them. (without the whole story, all we are collectively doing is GUESSING)

I think you'd probably prefer educated guesses, right>?

 

[chim]

I'm on my third Kubota and have a Ford as well. All of them have a certain amount of binding when run in 4WD. I've been taking care of the snow at our church and have been driving the last two (l3200 and l4240) roughly 1-1/2 miles each way to do this. Except for when the roads are completely snow-covered I use 2WD because there's enough binding to somewhat affect how the tractor operates. This is with the factory tires. There have been numerous posts over the years from people who have problems getting their tractors out of 4WD because of the binding. There is no doubt that using 4WD when there's sufficient traction does impart an unnecessary load on the drivetrain.

Of some interest, there's another thread going in which some posters are ridiculing owners for taking a salesman's advice of using 4WD only when needed to reduce wear.