L1501DT front diff

[dawrigley]

I've just rebuilt the front drive units of my L1501DT, straighten the tie rod and fitted new tie rod ends etc. etc. All was going well but when I reconnected the drag link and moved the steering wheel to align the drag link tie rod I noticed the front axle moved - a lot! While I didn't measure the movement it appeared to be around 3/4-1" of movement forward and back in line with turning the steering wheel. I've had the tractor for around 6 years but never noticed any movement, but then I was never looking for such a thing - plus I've always been looking where I was going.

Just wondering if anyone might know anything about this? There are grease nipples on the gearbox side of the propeller shaft and the other side of the front diff. It appears as though the diff is designed to slide but I've never come across such a thing before - it freaked me out when I saw the amount it moved.

I only removed the front drive units and the tie rod, meaning I didn't touch anything else and I have no left over bolts or the like but I'm wondering if a previous owner has fiddled and left me with another challenge I need to fix. (I've had a few to deal with.)

 

[North Idaho Wolfman]

I think you L1501 is set up the same as a L185, and there are bushings and trust washers that sound like they have worn.

 

[dawrigley]

I think you L1501 is set up the same as a L185, and there are bushings and trust washers that sound like they have worn.

View attachment 96719

That's my 'fear'. The bushings and thrust collars on the front of the diff are not too crazy in price but the bushing (19) is certainly pricy. I was hoping Kubota had some funky system in place which means the movement is as it should be...

 

[dawrigley]

That's my 'fear'. The bushings and thrust collars on the front of the diff are not too crazy in price but the bushing (19) is certainly pricy. I was hoping Kubota had some funky system in place which means the movement is as it should be...

I think I'll have to pull off the Center Pin (15) and check the components, I wonder if there's only one bush (20) rather than two. That would account for the amount of movement.

 

[North Idaho Wolfman]

I think I'll have to pull off the Center Pin (15) and check the components, I wonder if there's only one bush (20) rather than two. That would account for the amount of movement.

Yep pull it apart and check it out.

 

[Kubota Max]

I've just rebuilt the front drive units of my L1501DT, straighten the tie rod and fitted new tie rod ends etc. etc. All was going well but when I reconnected the drag link and moved the steering wheel to align the drag link tie rod I noticed the front axle moved - a lot! While I didn't measure the movement it appeared to be around 3/4-1" of movement forward and back in line with turning the steering wheel. I've had the tractor for around 6 years but never noticed any movement, but then I was never looking for such a thing - plus I've always been looking where I was going.

Just wondering if anyone might know anything about this? There are grease nipples on the gearbox side of the propeller shaft and the other side of the front diff. It appears as though the diff is designed to slide but I've never come across such a thing before - it freaked me out when I saw the amount it moved.

I only removed the front drive units and the tie rod, meaning I didn't touch anything else and I have no left over bolts or the like but I'm wondering if a previous owner has fiddled and left me with another challenge I need to fix. (I've had a few to deal with.)

Hi Dawrgley,
I read that you are rebuilding the front drive of your L1501DT and whilst I am unable to provide any advice on that effort, I was hoping you can help me understand how to replace the gear oil in the front assembly of my L1501DT tractor.

I attempted to complete this task on the weekend and successfully located the three drain plugs (one for the centre differential and one on each side for the wheels). I note what looks like a filler plug on each of the axles running from the centre differential to the wheels, but cannot find a filler plug for the centre differential.

I assumed that because each of the axles has a separate filler plug, these are sealed off from the centre differential. Is this correct?

My questions please:

1. Is my assumption regarding the separate axle reservoirs above correct and if so, how do you know when you have added the correct volume of gear oil to each wheel reservoir given there does not appear to be a fill level indicator?

2. Where is the filler plug located for the centre differential and how do you know when you have added the correct volume of gear oil for this reservoir, again I was unable to locate a level indicator.

I appreciate any guidance you can provide and good luck with the rebuild.

Cheers
Pete

 

[North Idaho Wolfman]

I assumed that because each of the axles has a separate filler plug, these are sealed off from the centre differential. Is this correct?

The fill plugs right and left on the axle cases are redundant, one plug fills the whole system.
They did that because the right and left case are the same part on that model.
So no the center diff is not sealed, it shares the oil with the whole axle.
Now on the side cases they have their drain plugs too, and if there is not a second plug higher on that case they too share the same fluid as the upper case.
This can be confirmed super easy:
Leave the drain plug out of the bottom of the case and pour fluid in the axle it should run out the open plug.

 

[Kubota Max]

The fill plugs right and left on the axle cases are redundant, one plug fills the whole system.
They did that because the right and left case are the same part on that model.
So no the center diff is not sealed, it shares the oil with the whole axle.
Now on the side cases they have their drain plugs too, and if there is not a second plug higher on that case they too share the same fluid as the upper case.
This can be confirmed super easy:
Leave the drain plug out of the bottom of the case and pour fluid in the axle it should run out the open plug.

Brilliant. Thanks for your help and good luck with the rebuild.

 

[North Idaho Wolfman]

Brilliant. Thanks for your help and good luck with the rebuild.

Dawrigley is doing the rebuild, I'm just slinging advice.

 

[Kubota Max]

Dawrigley is doing the rebuild, I'm just slinging advice.

Thanks for chiming in. Can you confirm the quantities of oil required for
1. front differential
2. Side cases - I do have a separate filler plug for both the left & right side cases
cheers
Pete

 

[North Idaho Wolfman]

Thanks for chiming in. Can you confirm the quantities of oil required for
1. front differential
2. Side cases - I do have a separate filler plug for both the left & right side cases
cheers
Pete

Center 1.1 liters
Each case .8 liters
You really can't over fill it if you use a little too much.
The side cases sometimes takes some some time to fill, as they trap air.

 

[Kubota Max]

Center 1.1 liters
Each case .8 liters
You really can't over fill it if you use a little too much.
The side cases sometimes takes some some time to fill, as they trap air.

thanks again.

 

[North Idaho Wolfman]

thanks again.

You're welcome.
or
G'day Mate!

 

[dawrigley]

Hi Dawrgley,
I read that you are rebuilding the front drive of your L1501DT and whilst I am unable to provide any advice on that effort, I was hoping you can help me understand how to replace the gear oil in the front assembly of my L1501DT tractor.

I attempted to complete this task on the weekend and successfully located the three drain plugs (one for the centre differential and one on each side for the wheels). I note what looks like a filler plug on each of the axles running from the centre differential to the wheels, but cannot find a filler plug for the centre differential.

I assumed that because each of the axles has a separate filler plug, these are sealed off from the centre differential. Is this correct?

My questions please:

1. Is my assumption regarding the separate axle reservoirs above correct and if so, how do you know when you have added the correct volume of gear oil to each wheel reservoir given there does not appear to be a fill level indicator?

2. Where is the filler plug located for the centre differential and how do you know when you have added the correct volume of gear oil for this reservoir, again I was unable to locate a level indicator.

I appreciate any guidance you can provide and good luck with the rebuild.

Cheers
Pete

Pete,

While there are two filler plugs on the axle supports, 27mm nut/plug on my L1501DT, they fill a common space. Various sources indicate the axle support/diff takes 1.1 litres of 80/90 gear oil. Each of the front drive units takes 0.8 litre of 80/90 gear oil - however mine started overflowing at around 0.7 litre.

The drain plug for the diff is on the very bottom of the diff, well that's where it should be. That was one of the 'surprises' on my tractor, the diff drain plug was missing - who knows how long it had been missing, sigh.

Something I found was that the top bevel housing of the front drive units has no drain or fill plug and appears to have no lubrication methodology. This, I suspect, it what lead to the failure of the open bearings in the top bevel housing and why I decided to fit sealed bearings to the top bevel housing. Further, after talking with a friend who works for a bearing company, I decided to spoon some NLGI 0 grease into that housing so the bevel gears receive adequate lubrication/protection going forward. All I could think of it that in the normal service schedule of the tractor the drive units would be remove and the housing checked/serviced as required. I've written a blog about this on my website: www.inhand.com.au - look for the "Who doesn't love a tractor" heading. I've created a bit of a log of my rebuild with pics.

Happy to help out in any way I can, please don't hesitate to fire in questions.

 

[North Idaho Wolfman]

Pete,

While there are two filler plugs on the axle supports, 27mm nut/plug on my L1501DT, they fill a common space. Various sources indicate the axle support/diff takes 1.1 litres of 80/90 gear oil. Each of the front drive units takes 0.8 litre of 80/90 gear oil - however mine started overflowing at around 0.7 litre.

The drain plug for the diff is on the very bottom of the diff, well that's where it should be. That was one of the 'surprises' on my tractor, the diff drain plug was missing - who knows how long it had been missing, sigh.

Something I found was that the top bevel housing of the front drive units has no drain or fill plug and appears to have no lubrication methodology. This, I suspect, it what lead to the failure of the open bearings in the top bevel housing and why I decided to fit sealed bearings to the top bevel housing. Further, after talking with a friend who works for a bearing company, I decided to spoon some NLGI 0 grease into that housing so the bevel gears receive adequate lubrication/protection going forward. All I could think of it that in the normal service schedule of the tractor the drive units would be remove and the housing checked/serviced as required. I've written a blog about this on my website: www.inhand.com.au - look for the "Who doesn't love a tractor" heading. I've created a bit of a log of my rebuild with pics.

Happy to help out in any way I can, please don't hesitate to fire in questions.

That top bearing would normally have gotten fluid from the center section, which in you case was dry and so was that bearing was dry.

 

[dawrigley]

That top bearing would normally have gotten fluid from the center section, which in you case was dry and so was that bearing was dry.

That's what I had assumed but there was no sign of any oil ever being in those housings. Of course it could be that someone had them off, cleaned them up and upon reassembly forgot to refit the diff drain plug which accounts for why the bevel gear housings were clean as a whistle, apart from metal shavings. If they had attempted to fill the axle/diff housing you'd image the 1.1 litres of oil on the floor would have been a clue. I'm sure I found a drawing somewhere which indicated there was and oil seal behind the outer bearing on end of the axle housing, but I can't locate it now - that would also explain why there was no evidence of oil in the top bevel case. Oil flowing over into the top bevel case makes sense but it begs the question, does 1.1 litres of oil allow both bevel gear cases to fill and leave enough for the diff etc. And why not have a drain plug on that housing, that would be much easier to deal with than having to remove the drive unit in order to change the oil. Lots of questions. Will post the answers as they become clear.

 

[dawrigley]

Was told the bush (20 - part number: 37650-44630) has been discontinued. The thrust collar (22 - part number: 37650-44670) is also discontinued but they had one in stock, which I ordered. I put in a request to Kubota for the specs of the bush which should allow me to go to an engineering company and have some made. (If that turns out to be my problem.) I've also made a request to a company which imports and sells grey market Kubota tractors, here in Australia, and who say they carry all the parts necessary to keep the tractors running. The L1501 is one of the models they brought in some years back and I bought some parts from them around 6 years ago - although my tractor came in via another source.

 

[dawrigley]

I ended up obtaining a couple of the bushes from Pillar Supply in the USA and had them shipped over to me - that ended up taking around a month. (they 'disappeared' in transit for around three weeks and then arrived at my door, thankfully) Today, 15th April 2023, I thought I'd pull the front of the diff apart and investigate. To my surprise the bushings and thrust collar were in pretty good shape, worn yes but more than serviceable. The problem ended up being that the Pivot pin plate (15 in the diagram up near the top) was bent as if the pivot pin had pushed back on the plate making it concave rather than flat. Off to the hydraulic press for some massaging and then back onto the tractor, sorted. The axle no longer moves back and forth when turning the steering wheel. I will see if I can buy a replacement pivot pin plate but if not at least the tractor is back on track again.