Front tires caused axle failure...?

[thoner7]

I bought a used Kubota m5400 earlier this year. The previous owner had put some 15x19.5 loader wheels and tires in the front. Replacing the original 9.5x22s. it was really nice to have such a wide front tire, for loader work and wet ground.

I double checked online, and the rolling circumference of the original tires was listed as 117". The 15x19.5s was either 118 or 120" depending on which website you believe.

Well not long after I ground up the right side hub and bevel gears, bearings, etc. Parts alone...$3,600!!!!

So now I'm thinking it must have been the tires. But was it? Maybe it was more the width of the tire as opposed to the circumference? Or maybe just the weight? These wheels and tires weight like 150# each.

Anyways I'm not going to leave it in 4x4 anymore, only when it's really needed.

But before I get a new set of front rubber for the old, narrow wheels, I wanted to make sure with the group it was the necessary move.

Thanks

 

[RickB]

Those tires sure didn’t help anything. I’d put something on closer to the right rolling circumference or static loaded radius.

 

[LouNY]

To put a much wider tire on the tractor the rim had to have a lot of offset,that puts a lot of leverage effect on the front axle and hub.
I would expect that plus maybe a lot of maximum loads in the loader would be rough on the front end.
3 inches of circumference is not a lot as Rick mentioned the loaded radius would be the number to work with.That could be adjusted with tire pressure,
also are the rear tires worn out or new?
How did the tractor behave was the front leading by to much, was it hard to get in or out of 4wd?
If you weren't getting excessive lead the loaded radius must have been close.

 

[RickB]

It would be good to know if the bearings failed first or the gears. Gear failure would lead to a drive ratio cause. Bearing failure would point to a wheel offset cause. Probably unknowable at this point. A drive ratio cause would be very likely to affect the front differential before the final drive, but that is kind of a broad based statement.

 

[/pine]

FWIW...A good way to tell if the wheels/tires are not the correct ratio on a 4x4 tractor is...with the engine off and 4x4 engaged and the tranny in neutral...roll the tractor (use a tow vehicle far enough away so you can hear)...listen to the front axle for any friction noise...it does not have to roll fast and a mechanic's stethoscope will help...also pay attention to the tires where the "rubber meets the road"...

On smaller tractors just pushing is enough (no tow vehicle required) any binding etc. will be evident...it is rolls smooth and easy the R.C. is not the problem...

 

[thoner7]

The static loaded radius of the stock tire is listed as 18 inches. The same is listed as 17.7 for the replacement tire. However, the stock tires are so bald, my guess is those are closer to 16" currently. I guess that means I should be within an acceptable range.

However the 4x4 was a tad difficult to go in or out. You had to push down or pull up on the handle (whether engaging or disengaging). And move forward or reverse a few feet. My experience with 4x4s is that's usually normally. Maybe I'm wrong?

If I had to guess, the bearings failed first. Or at least they came out of place. I didn't seem much damage to the gears or bearings themselves, but there was a lot of shredded metal the came out. From the pieces, it looks like some kind of thin metal gasket or retaining ring that was chewed up.

The wheels are currently set to the wider tread . If I swapped sides, the wider offset of the tire would be under the axle, rather than outside of it. Is that any better tho?

 

[/pine]

The issue is with the R.C.'s between the front and rear wheels...has nothing to do with the width (how the wheels are mounted)

 

[LouNY]

The static loaded radius of the stock tire is listed as 18 inches. The same is listed as 17.7 for the replacement tire. However, the stock tires are so bald, my guess is those are closer to 16" currently. I guess that means I should be within an acceptable range.

However the 4x4 was a tad difficult to go in or out. You had to push down or pull up on the handle (whether engaging or disengaging). And move forward or reverse a few feet. My experience with 4x4s is that's usually normally. Maybe I'm wrong?

If I had to guess, the bearings failed first. Or at least they came out of place. I didn't seem much damage to the gears or bearings themselves, but there was a lot of shredded metal the came out. From the pieces, it looks like some kind of thin metal gasket or retaining ring that was chewed up.

The wheels are currently set to the wider tread . If I swapped sides, the wider offset of the tire would be under the axle, rather than outside of it. Is that any better tho?

If they can be swapped without the tire getting into the frame it would reduce any stress from the wider tire and rim offset.

 

[Mat4644]

With factory tires 4wd tractors spin the fronts slightly faster for better steering on non-pavement. Increase the tire diameter and greater stress. How much time was spent on the road or concrete?

I cut a front several years ago and replaced with same number size set (imported I think) but the physical size was slightly larger diameter No nearby people selling Titan plus two more plies and two tires were less cost than 1 Titan. Wondering if this was a bad move now. I never run 4wd until I need it.

 

[JD3520Turbo]

I would not leave your tractor in 4wd all the time no matter what. The reason is because it creates a lot of stress in the driveline every time you turn.
When the 4wd is locked in and you turn, the front wheels are traveling different distances in the turn from each other and different than the rears, so you create bind all the time. When you have a loaded bucket and you are turning in 4wd, you are really stressing the system. Plus you can wear the tires a lot faster.
I am not saying that leaving it in 4wd is what caused your trouble, but it didn't help. I would guess having those wide tires stuck all the way out probably stressed the bearings and one thing led to another. Based on what you said your circumference numbers were, I wouldn't think you would be introducing so much lead that you would break the driveline.

For what its worth, I don't ever use my 4wd unless I need it, and then I lock it in and as soon as I don't need, I unlock it. Actually, for what I do, I seldom need it.