Need Help w/ Kubota L3710 Front Axle Bevel Gear Housing Lesak

[whitefacenh]

I hasve a 2000 L3710HSTC w/ approx 500 hours. it has developed a small drip/leak on both sides of the front axle on the bottom of the bevel gear housing. Has anyone had experience with this and how hard it it to repair?

Thanks in advance for any help

 

[rbargeron]

I have worked on both front gear cases of my 1996 L3600 (same as L3710). There are four seals at each wheel where leaks can develop - two are moving lip seals (A, B)and two are static seals (C, D)

A good way to be sure where your leak is coming from is to clean everything up with the wheels off and see where the drips re-appear. With luck it's just the bottom cap C or the o-ring D weeping a bit.

But the A seal is known to be a weak point on these axles. It can let oil out - or worse it can let water in - leading to failure of the bearings. Kubota has redesigned the seal - so hopefully the new one is better. On my rig I replaced the A seals and the C caps on both sides. One side also needed bearings.

The repair job was not hard - it does need a good pair of snap ring pliers. I can give more details if anybody wants them. (sorry didn't take pics)

As always, prompt and cheerful refund if info is bogus. Take care, Dick B

 

[whitefacenh]

Dick, Thanks for the detailed help!

I'll try to narrow down where the leak is coming from this weekend but I'm relatively certain it is from the bottom cup/cover.

Thanks

 

[Jim1764]

Whitefacenh, did you get around to changing out those oil seals? I too have a L3710 GST, (1999) with the same leaks. Haven't attempted to make the repair yet. Would like to know how you're experence was.

Thanks,

Jim

 

[Jim1764]

rbargeron, do I have the correct parts highlighted in these parts diagrams?

Jim

 

[Deerlope]

I just had my dealer replace the "A" seal in my 03, L3830 at 856 hours. I do a lot of heavy lifting with my fel.

 

[rbargeron]

rbargeron, do I have the correct parts highlighted in these parts diagrams?

Jim

Yes - exactly right. Sorry I didn't see this until now - also have your PM asking for some procedure steps - will answer it here and by return PM.

Looking at the diagram I posted above, first step is to take off the wheel and drain the oil from the axle - most direct draining is by prying out the bottom seal cap (C) - it's plastic and there's a notch in the housing to get started.

Next, take off the drive flange and cover (six bolts, 2 nuts on studs) - it takes some prying or tapping (10, 11, 12, & 13 come off together)

Back where cap (C) was, take out the snap ring below the bottom bearing. The lower bearing, small gear (17) and shaft (15) can be worked down by prying down against the small gear through the hole in the housing. Once this is out, you can see another snap ring about halfway up - take that one off and (16) will drop down and off.

Part of the (A) seal will remain on the axle - take this off and clean up the axle with a wire brush so the new part fully seats. For reassembly, I put both parts of the new seal on (16) and pressed it up on the axle until the snap ring would go back on. The o-ring (D) was in ok shape - but I used a little silicone sealant around the flange anyway.

Hope this helps. Good luck and take care, Dick B

 

[repete]

After replacing MANY bearings, seals and two axle housings on my 2550 I finally realized that I was probably putting an extraordinary load on the front end by:

1) carrying more weight than it was designed to do.

2) reversing my front tires (setting them to a wider position).

3) wrapping baling twine around the front axle destroying the wheel seal and taking out the bearing after all the grease drained out in the pasture. Wheel actually fell off... Drove it back to the barn in reverse with the bucket down steering with L and R brakes.

Bottom line in my book is avoid overloading, keeping the wheels narrow and checking for debris on the parts often.

I keep an extra seal for A and B on hand but have never replaced large "O" ring seal.

Treat it nicely. I know from experience that the casting parts are spendy (X2)

 

[Unkownuser]

Just FYI. To the guys that are having front axle leaks. These leaks are most often caused by not properly ballasting your tractor. When you lift a load with your FEL, it picks the back of your tractor up (if the ballast is not correct) and puts all the weight on your front axle. You may not see or feel it but it does. If you do not believe me, have someone stand behind you when you lift a load and watch the bottom of your rear tires. Anyway, I digress. If you want to prevent this problem, put water in the rear tires or get a ballast box. Usually, improper ballast will cause the axle to begin leaking about every 400-600 hours for an 兎very day use, a little quicker for commercial guys. Just a thought.

 

[rbargeron]

Filling the rear tires increases the load the FEL can pick up before raising the back end. So the load on the front axle tends to be increased by adding liquid to the back tires. Only by adding weight behind the rear axle does any load transfer away from the front axle. The answer to front axle failure is better front axle design.

 

[N80]

What do you consider the fault to be in this design? For some reason Kubota seems quite attached to it and I personally like the obvious benefits of this design. Of course I haven't had a leak yet.

 

[rbargeron]

The grand L front axle was a departure from previous designs - which were inherently stronger because the king pin housing was in double shear, with bearings above and below the axle joint. The grand L kingpin joint is cantilevered. I wouldn't go so far as to say it is a faulty design, it just doesn't have as big a strength margin, and with vigorous use it seems to have had a higher incidence of seal and bearing failures.

 

[N80]

Is this true of the other L models?

 

[Ob1kubota]

The grand L front axle was a departure from previous designs - which were inherently stronger because the king pin housing was in double shear, with bearings above and below the axle joint. The grand L kingpin joint is cantilevered. I wouldn't go so far as to say it is a faulty design, it just doesn't have as big a strength margin, and with vigorous use it seems to have had a higher incidence of seal and bearing failures.

Dick please explain "double shear" are we talking stacking pressures on the axis in the joint itself or tensile strength of material? Interesting statement please follow up, Ob1..

 

[rbargeron]

Dick please explain "double shear" are we talking stacking pressures on the axis in the joint itself or tensile strength of material? Interesting statement please follow up, Ob1..

I may not be using the term double-shear correctly - but on the earlier L-series front axles, there's a second shear connection supporting the hub above the axle joint. The first pic shows the arrangement on the smaller models

The next pic is the more robust axle/hub design used on the L3750 & bigger L-3 models - more evidence of why I'm a die-hard L-3 fan. (Have two L5450's)

P.S. To borrow an idea from Curtisfarmer, TWO L5450'S = ONE L10900

 

[N80]

I don't see how that would have an effect on stacking pressure....if I'm understanding stacking pressure as simply the vertical load on the joint.

Let me see if I can think through this: I can see how having an attachment point above and below the axle would give the joint strength in terms of lateral loads... loads that would be in the same plane as 'camber'...for lack of a better word. A 'double sheer' arrangement would give strength resisting forces that would affect camber, and thus spread those forces to bearings above and below the axle, not just below.

These types of loads occur (if I'm thinking about this right) primarily when the tractor is turning. I think in particular when making a tight turn with a full load in the bucket, those forces are very high on the inside wheel. The camber (which is not adjustable) on my L4400, seems extreme to me. The top of the tire sets out wider than the bottom. I'm assuming this provides a tighter turning radius. But, when you have a heavy load in the bucket and make a tight turn, you can see that load's effect on the sidewall of the tire, pushing the bottom of the wheel/tire inward. So it seems to me that in these set ups without the 'double shear' design, a little more neutral camber would put less force on those lower bearings when turning with a load. But hey, I'm no engineer.

Anyway, I may have got this all jumbled up, but it seems to me that for those of us with this type of design, we need to take most care when turning with a load in the bucket.

It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do. But I may be wrong, this is just from looking at the rather poor photos on the Kubota web site.

 

[rbargeron]

..............It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do..................

Yes, the bigger tractors use this stronger design.

I think you are onto something in your ideas about camber and turning with a load. Looking at the cutaway drawing above, it appears to have a lot of camber to accomodate the kingpin angle & large upper bearing. I've noticed the tires on the L3600 get really mashed turning with a load.

 

[Ob1kubota]

I don't see how that would have an effect on stacking pressure....if I'm understanding stacking pressure as simply the vertical load on the joint.

Let me see if I can think through this: I can see how having an attachment point above and below the axle would give the joint strength in terms of lateral loads... loads that would be in the same plane as 'camber'...for lack of a better word. A 'double sheer' arrangement would give strength resisting forces that would affect camber, and thus spread those forces to bearings above and below the axle, not just below.

These types of loads occur (if I'm thinking about this right) primarily when the tractor is turning. I think in particular when making a tight turn with a full load in the bucket, those forces are very high on the inside wheel. The camber (which is not adjustable) on my L4400, seems extreme to me. The top of the tire sets out wider than the bottom. I'm assuming this provides a tighter turning radius. But, when you have a heavy load in the bucket and make a tight turn, you can see that load's effect on the sidewall of the tire, pushing the bottom of the wheel/tire inward. So it seems to me that in these set ups without the 'double shear' design, a little more neutral camber would put less force on those lower bearings when turning with a load. But hey, I'm no engineer.

Anyway, I may have got this all jumbled up, but it seems to me that for those of us with this type of design, we need to take most care when turning with a load in the bucket.

It looks like the MX5100 and the M series tractors have this double sheer set up and none of the L or Grand L's do. But I may be wrong, this is just from looking at the rather poor photos on the Kubota web site.

George I'm going to respond but I'm going to my office to get a couple text books and review mechanics of material and bearing load computation. Double shear to my way of education is putting stress at both upper and lower bearings on the steering axis to the point of possible elastic limits. If I only knew the strength of materials and had a scaled drawing, I could put some math behind where the rubber meets the road. I'm interested because I own an L series with a beveled gear case design and I'm hearing noise at only 200 hours with only 500 pounds in the FEL turning to the left. I don't like replacing part without understanding why. I don't run it very often because my M Series does the heavy work around here.

 

[N80]

You may find out more than I can understand, but I'm willing to give it a try and I appreciate the effort. Also, I guess there are two issue to consider. One is bearings, which some people have had to replace, but the other is just the seals. I'm not sure how the mechanics actually affect the seals.

 

[Barryh]

I hasve a 2000 L3710HSTC w/ approx 500 hours. it has developed a small drip/leak on both sides of the front axle on the bottom of the bevel gear housing. Has anyone had experience with this and how hard it it to repair?

Thanks in advance for any help

Not to get you guys off topic here but, you are talking about axle leaks. Hoping to get a quick reply from someone.

I was wondering if anyone has corrected a front axle pivot leak with a simple adjustment of the pivot nut / pin??

At 450 hours I have a bad leak that just started under the front axle pivot area of my BX 1500. I just received my shop and parts manual.

Has anyone taken this assembly apart if so how straight forward and time consuming did it turn out to be?? It looks like just remove the steering control arm and pull the pivot bolt with some collars and O-rings straight out.

I'm also considering going with 90 weight gear oil instead of the thin SUDT.

I will be working on it very soon. Thanks for any input.