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

[rbargeron]

..........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.

First, to Ob1's point, "double shear" simply refers to the way the part is loaded - not how heavily it is loaded. Double-shear means applying a shear load in one direction at the two ends and in the opposite direction in the middle. The bending moment is balanced in the part. Single shear cantilevered support produces shear stress in the part but the bending moment is resisted by the support - in this case the bearings.

Second, to N80, If the design puts too much load on the bearings they wear and become loose. The flex limit of the seals can be exceeded and they let water in (or oil out). One thing leads to the other. The early A seal tolerated very little wear in the bearing before it leaked. So problems were common before very many hours of use.

And third, to BarryH, no experience fixing a center pivot leak - but I agree it looks straight forward. Can you tell where the leak is (front or back of axle?) I'd be surprised if just tightening the adjuster bolt would affect an oil leak. If the seals are intact, UDT is fine - heavier oil won't leak less, it just takes longer to drain down below whatever is leaking. Cheerful refunds to all if info is bogus. Dick B

 

[Ob1kubota]

First, to Ob1's point, "double shear" simply refers to the way the part is loaded - not how heavily it is loaded. Double-shear means applying a shear load in one direction at the two ends and in the opposite direction in the middle. The bending moment is balanced in the part. Single shear cantilevered support produces shear stress in the part but the bending moment is resisted by the support - in this case the bearings.

Agreed Dick...after several conversations with guys I know in Industry that actually got the priviledge out of college to design axles. ( I didn't ) Kubota is very proud of this design and will share very little with you about BOM and mechanics of materials. I was told the moments are close to neutral at the center of the king pin and that both ends are under shear thus the term double-shear. The effects of moment(s) of inertia during dynamic loading takes years of Stress concentration to reach the endurance limits of the fatigue strength inherent to materials used and thus when solid steel billets are at rest ( neutral stress ) the bearings take the loading and unloading common to FEL cycling. Seals are just what they are and are always the first indicators of wear when the lips (fixed and sliding contact points) reach their elastic limits. I'm told Japan is always looking at 'Economy' and acceptable competative product life cycle with designs and that the parts marketing group has a controlling interest with propriety designs with these bevel gear steering drive axles. I guess we have to be okay with replacing seals and bearings to keep the parts people happy whose profits find their way back to R&D. I'm going to use your statement inclosing out this post, cheerful refunds to all members who know more about this design and for taking time to read it. I know I've learned a great deal from just asking a few questions from the professionals who make their living designing axles. My thanks to all the gear heads out there.

 

[Bigk56]

Barry,
Here was my experience changing the seal that I think you're talking about on my L4350.

http://www.tractorbynet.com/forums/...22-diff-seal-replacement.html?highlight=l4350

 

[rbargeron]

Hi Ken - I just love the mass and ruggedness of the L3's parts - great pics ! The ends of that front axle are what I'm talking about with "double shear" thing - big supports above and below the axle centerline. Very strong. Maybe I should stop harping about this......naaah, I'll keep it up - someobody has to sing the praises of these great machines! Hey is your loader still painted Kubota green? Take care, Dick B

 

[Bigk56]

Dick,
This tractor is absolutely the best tractor I've ever owned. It's incredibly strong and great on fuel. The only problems I've had are seals going out which is probably normal for a 15 year old tractor. I've already got the parts to replace a left rear axle seal and left front axle seal. However these are slow leaks and will probably happen this winter.
As far as the loader goes, I did spray some Kub grey on the lower frame and some orange on the tower, but that is as far as I've got. I'm building a three car garage and it's been quite a project. Here is me using my new green loader. When I get back to the tractor I also plan on adding the supports from rear axle to lower support of loader as you suggested in previous message. Anyway, it's good to have something to do and be able to do it.
Ken

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[RedJeepClub]

First I want to say Thank You for the help in this posting. I had to take my L3130 Front Axle apart to replace the seal that is listed as Part B. in the diagram. I searched hard to find the details for this part of the repair, so I thought I would share some details here..

The outer assembly that has the gear and bearing and seal that I trashed is easy to get apart. It just slides apart with one 1/2 moon clip holding the axle shaft in. I took some video and posted it if anyone wants a visual of the process.

Steps: 1) take the bearing off my using two screwdriver and prying up on the bearing. It is not pressed on so it come off easily. 2) take the gear off using hte same two screw drivers. 3) Take out the 2 parts of the circle clip, two half moon pieces. 4) Tap out the Axle and wheel bolt assembly. 5) Tap out the seal. 6) tap out the bearing. 7) Remove the inner seal part from the axle shaft. This is not very easy. I had to cut it and pull it off. Clean and reassemble.

Hear is a link to the 5 parts of the video I took. Sorta goofy but you get ths idea. [ame="http://www.youtube.com/watch?v=79Z2DMUb8Ic"]Video of my fix.[/ame]

Once again thanks for the help.
Ian

 

[zguillen]

I own a Kubota L3400 and I have a slow leak at the bottom of the bevel housing (the C cap) what tools and parts do I need to get to fix this seal plug myself. regards

 

[frankc]

Sorry in advance if this has been answered, I searched and read all I have found and haven't seen this answered. Can the bottom Seal "C" be replaced without disassemble of any other part of the front hub, other than removing the tire of course? Does it just pry out of the bottom? I have an L2850 that is leaking, I haven't even figured out exactly which seal is bad yet, but if it only gets wet at the bottom, could I get so lucky as to just have to replace this bottom seal? Seams like a seal down low like this would be in harms way, no? Thanks, Guys!

 

[rbargeron]

Clean it off and let it sit a while to see what's leaking. The C seal can be pried out and a new one tapped into place. Tilting the axle up helps keep most of the oil from draining. The C seal doesn't routinely fail - it's somewhat shielded from damage by the wheel. The upper A seal is the most common to need replacement. B is next.

 

[hobonc]

When I do the wheel seals I go for the kill and do the upper and lower king pin seals... The only hard part is installing the seals....