Wheel spacers and broken axles?

[Henro]

The following report was posted in a thread at a related site:

I don’t see anyone here addressing the issue of the added stress on the axles due to wheel spacers.

I have an older BX-23 which I bought used in 2015. For the sake of added stability I bought and installed a pair of 3” Bro-Tek wheel spacers. Five years later I had a very expensive repair. The added bending moment on the axles caused a fatigue failure that not only broke an axle, but snapped the end off the very pricey aluminum housing that the axle rides in. Further, the tractor was jerked sideways by the loss of one back wheel and hit a tree. My employee who was using the tractor said that the impact was such that if he hadn’t been wearing the seat belt, he’d have been thrown off the tractor. (And it wasn’t even going very fast – it was in low range.)

Maybe the newer models have a larger diameter axle and can accommodate the added bending moment, but you really should check with Kubota to see what they recommend.

This was the first report I remember reading where the poster felt damage to his tractor was the result of installing wheel spacers.

Granted, my memory may not be the greatest.

So in this thread I wish to attempt to document cases of people who have experienced tractor damage as the result of installing wheel spacers.

Since the tractor in this case was bought used, the poster obviously has no idea of whatever abuse it may have suffered prior to his purchase. But still, the BX did suffer damage due to a broken axle.

Anyone?

 

[GreensvilleJay]

It's unlikely a STOCK BX23 would have had any damage prior to the wheel spacers being added. My BX23S is one tough lil tractor and I've not been gentle with it in teh past 2 years. I understand the damage due to excessive torisonal forces. The A-C G , a modest 10HP ,were famous for shearing off the axle splines when 'aggressive' tractoring was done.
Have to ask , a 3" spacer kit, is 3" on BOTH axles, or is it 1.5" on each axle ? Frankly, if 3" on each side, that's a big increase in length, and I'm sufe the math wizards can figure out the increased forces that come into play.Als, does Kubota offer any wheel spacers ? If so ,what sizes ?

 

[85Hokie]

This is off Kubota's web site ........ now this is for a B series - B2650 ( did NOT show spacers for BX)

I am with Jay - 3" to each side is a bit much - I have 2" on my BX - but then again I aint pressing it too awful hard - it does carry the backhoe however.

The axles are designed for "X" loads - and as we spread the load out for stability - there is going to be a point of stress outweighing the gain for stability.

Much like a wrench with a cheater bar - every inch we can move away from the pivot point adds a proportional increase to the torque delivered to that point.

Then again - I have seen 6" spacers on tractors - yes they were on the bigger boys like the L and M series .....

Math never lies ...........too much of a good thing, aint always a good thing!

 

[jimh406]

My L spacers from Kubota are only 1 inch. I don’t know if that means that wider is bad, but that’s what they are. It would be interesting to know what width Kubota sells for each model.

Of course, the R1 Ls have the ability to offset their wheels way more than 1 inch. I don’t know if any BXs or Bs have the ability to offset their R1 wheels.

The MX that I saw on the dealer lot seemed to be able to offset R4 wheels. So, it almost seems that bigger is ok with wider which would mean BX should have the least size spacer if that holds true.

 

[dlsmith]

The failure could also be exacerbated due to he tractor having ballast or a heavy attachment on the 3ph.

 

[eserv]

There are some people who can break a crowbar in a sandbox.

 

[DustyRusty]

Spacer dimensions are usually specified in the individual, so a 3" spacer measures 3" in depth. That would add a lot of torsional value to the axle. I wouldn't go more than a 1" spacer on a BX, however, everyone has their own risk / reward tolerances. I also wouldn't pay some of the outrageous prices for spacers.

 

[SDT]

The following report was posted in a thread at a related site:

I don’t see anyone here addressing the issue of the added stress on the axles due to wheel spacers.

I have an older BX-23 which I bought used in 2015. For the sake of added stability I bought and installed a pair of 3” Bro-Tek wheel spacers. Five years later I had a very expensive repair. The added bending moment on the axles caused a fatigue failure that not only broke an axle, but snapped the end off the very pricey aluminum housing that the axle rides in. Further, the tractor was jerked sideways by the loss of one back wheel and hit a tree. My employee who was using the tractor said that the impact was such that if he hadn’t been wearing the seat belt, he’d have been thrown off the tractor. (And it wasn’t even going very fast – it was in low range.)

Maybe the newer models have a larger diameter axle and can accommodate the added bending moment, but you really should check with Kubota to see what they recommend.

This was the first report I remember reading where the poster felt damage to his tractor was the result of installing wheel spacers.

Granted, my memory may not be the greatest.

So in this thread I wish to attempt to document cases of people who have experienced tractor damage as the result of installing wheel spacers.

Since the tractor in this case was bought used, the poster obviously has no idea of whatever abuse it may have suffered prior to his purchase. But still, the BX did suffer damage due to a broken axle.

Anyone?

Having been a design engineer for years in one of my former lives, I am not surprised by this occurrence.

Kubota provides wheel spacers for most of their small tractors but none even approach 3".

There are multiple reasons for this, and the stresses added to the axle and axle bearing carrier are just one.

SDT

 

[OrangeKrush]

I purchased some 2" for my BX but have not installed yet. I've had them for months now but haven't taken the time to put em on, actually keep forgetting about them.

 

[TheOldHokie]

The following report was posted in a thread at a related site:

I don’t see anyone here addressing the issue of the added stress on the axles due to wheel spacers.

I have an older BX-23 which I bought used in 2015. For the sake of added stability I bought and installed a pair of 3” Bro-Tek wheel spacers. Five years later I had a very expensive repair. The added bending moment on the axles caused a fatigue failure that not only broke an axle, but snapped the end off the very pricey aluminum housing that the axle rides in. Further, the tractor was jerked sideways by the loss of one back wheel and hit a tree. My employee who was using the tractor said that the impact was such that if he hadn’t been wearing the seat belt, he’d have been thrown off the tractor. (And it wasn’t even going very fast – it was in low range.)

Maybe the newer models have a larger diameter axle and can accommodate the added bending moment, but you really should check with Kubota to see what they recommend.

This was the first report I remember reading where the poster felt damage to his tractor was the result of installing wheel spacers.

Granted, my memory may not be the greatest.

So in this thread I wish to attempt to document cases of people who have experienced tractor damage as the result of installing wheel spacers.

Since the tractor in this case was bought used, the poster obviously has no idea of whatever abuse it may have suffered prior to his purchase. But still, the BX did suffer damage due to a broken axle.

Anyone?

Lots of variables to consider in a failure like this. Anecdotal failures are not particularly useful. You need to control testing and eliminate those variables before assigning a cause to failures.

For example I have a B7200DT. In the 30 odd years I have owned it I have broken both axles. I have a 1950 Ford 8N and have broken one axle on it. Neither tractor ever had spacers on it but both allow rear tread to be adjusted per the owners manual. I also pushed the B7200 very hard and asked it to do tasks better suited to a larger machine. I may even have (gasp) exceeded its design limits. Does that mean the Kubota and Ford engineers built a tractor with insufficient support for the wider setting and it causes axle failures? Or does it suggest axles are simply the weakest link in most tractor drive lines and simply break when fatigued by hard use or over torqued? I was born into two farming families and tractors of all makes and models have been breaking axles for as long as I have been around them so I lean towards the latter.

My new L3901 has R4 tires with one piece wheels and the tread width is fixed at 45.5". If I put R1s on it the two piece centers and rims can be reversed and allow incremental tread width adjustment from 43.8" to 50.8". I can also bolt 180# of factory wheel weights to both sides which I cant do with the R4s. Does that mean the R4s have some mysterious property that will cause axle failures if I put 3" spacers behind the discs and add 180# of weight to them to set them out and load them just like the R1s? I think not. I think the lack of adjustment on the R4s has nothing to do with loading and everything to do with marketing an "economy" model tractor with limited features. R1 tires are intended for crop tillage where row spacing makes tread width adjustment necessary. R4s are industrial usecwhere a fixed width is fine so no need to go to the extra cost.

So I will be adding 3" spacers and quite possibly the weights to my R4 tractor under the assumption i am staying within the axle design limits of the Kubota engineers. If I then break an axle I will attribute it to heavy use. If i break 2 I will start to wonder if Kubota may have under designed the axles and they are the weak point in the driveline. If I break 4 I will remove the spacers and weights and see if I keep breaking axles. If the failures then stop I will begin to suspect some unexplained causality but I would not consider it definitive.

Dan

 

[leveraddict]

I have to wonder if the spacers may have loosened over time creating more stress on the axle?

 

[Fordtech86]

Lots of variables to consider in a failure like this. Anecdotal failures are not particularly useful. You need to control testing and eliminate those variables before assigning a cause to failures.

For example I have a B7200DT. In the 30 odd years I have owned it I have broken both axles. I have a 1950 Ford 8N and have broken one axle on it. Neither tractor ever had spacers on it but both allow rear tread to be adjusted per the owners manual. I also pushed the B7200 very hard and asked it to do tasks better suited to a larger machine. I may even have (gasp) exceeded its design limits. Does that mean the Kubota and Ford engineers built a tractor with insufficient support for the wider setting and it causes axle failures? Or does it suggest axles are simply the weakest link in most tractor drive lines and simply break when fatigued by hard use or over torqued? I was born into two farming families and tractors of all makes and models have been breaking axles for as long as I have been around them so I lean towards the latter.

My new L3901 has R4 tires with one piece wheels and the tread width is fixed at 45.5". If I put R1s on it the two piece centers and rims can be reversed and allow incremental tread width adjustment from 43.8" to 50.8". I can also bolt 180# of factory wheel weights to both sides which I cant do with the R4s. Does that mean the R4s have some mysterious property that will cause axle failures if I put 3" spacers behind the discs and add 180# of weight to them to set them out and load them just like the R1s? I think not. I think the lack of adjustment on the R4s has nothing to do with loading and everything to do with marketing an "economy" model tractor with limited features. R1 tires are intended for crop tillage where row spacing makes tread width adjustment necessary. R4s are industrial usecwhere a fixed width is fine so no need to go to the extra cost.

So I will be adding 3" spacers and quite possibly the weights to my R4 tractor under the assumption i am staying within the axle design limits of the Kubota engineers. If I then break an axle I will attribute it to heavy use. If i break 2 I will start to wonder if Kubota may have under designed the axles and they are the weak point in the driveline. If I break 4 I will remove the spacers and weights and see if I keep breaking axles. If the failures then stop I will begin to suspect some unexplained causality but I would not consider it definitive.

Dan

wheel weights or loading tires will not add any additional stress to the axles, its unsprung weight supported by wheel/tire not the axle.

 

[NHSleddog]

Around here the BX is a powered wheel barrel to distribute mulch around the mini-mansion. They should NEVER be modified in any way. Kubota should provide additional forward/side and rear impact air bags along with a 5 point harness that locks out the ignition - LOL.

About the story. So a guy running a company buys an older USED bx (no idea of the history). He then puts 3" spacers on it and lets the EMPLOYEES run it. It runs great for 5 years and then one afternoon he THINKS there was an accident (he wasn't there) and he is taking the word of the employee that would possibly fear for his job after destroying the tractor? I am picturing a scene out of the Dukes Of Hazzard.

That is quite the damming indictment on spacers. How about all of the other examples - lol. The questionable story above by a 3rd party via a 3rd party would be the first I ever heard.

FWIW - I had over 4000 hours on my old NH with spacers front and rear (it is still running daily). I have over 700 hours on my Kubota running spacers front and rear - SFSG

 

[SDT]

Around here the BX is a powered wheel barrel to distribute mulch around the mini-mansion. They should NEVER be modified in any way. Kubota should provide additional forward/side and rear impact air bags along with a 5 point harness that locks out the ignition - LOL.

About the story. So a guy running a company buys an older USED bx (no idea of the history). He then puts 3" spacers on it and lets the EMPLOYEES run it. It runs great for 5 years and then one afternoon he THINKS there was an accident (he wasn't there) and he is taking the word of the employee that would possibly fear for his job after destroying the tractor? I am picturing a scene out of the Dukes Of Hazzard.

That is quite the damming indictment on spacers. How about all of the other examples - lol. The questionable story above by a 3rd party via a 3rd party would be the first I ever heard.

FWIW - I had over 4000 hours on my old NH with spacers front and rear (it is still running daily). I have over 700 hours on my Kubota running spacers front and rear - SFSG

Good synopsis of the scenario, Sleddog.

Still, adding 3" to the moment arm of the axle on a BX increases stresses on both axle and bearing support a great deal, especially when combined with BH and who knows what else.

Me thinks that your "old NH" and "my Kubota" are not designed as is the BX.

SDT

 

[TheOldHokie]

wheel weights or loading tires will not add any additional stress to the axles, its unsprung weight supported by wheel/tire not the axle.

Wheel weights will increase the mass (=momentum) acting through that lever arm. It is also an off center mass acting as an overhanging load on the hub. I am pretty sure a properly modeled FEA will show you it adds static stress when the tractor is at rest and dynamic stress to the system when the tractor is in motion and tires are being deflected by ground conditions, turns and changes in speed.

Dan

 

[Henro]

It will increase the mass (=momentum) acting through that lever arm. It is also an off center mass acting as an overhanging load on the hub. I am pretty sure a properly modeled FEA will show you it adds both static and dynamic stress to the system when the tractor is in motion and tires are being deflected by ground conditions and turns.

Dan

No doubt that adding spacers adds stress on the system. but stress is there to begin with.

So the question relates to whether the above described event is a unique event or something that others have experienced.

Things break even if over engineered due to manufacturing issues.

This example is ONE occurrence.

How does one determine, without a sample greater than one, if this is a manufacturing fluke or a real issue?

just fishing for other examples of BX axle failures, especially if wheel spacers were used. BUT if not as well.

Mainly because I recommended my son in law install 2” spacers on his new BX23S. Actually bought them as a gift. Would feel bad if he had issues later...

 

[eserv]

No doubt that adding spacers adds stress on the system. but stress is there to begin with.

So the question relates to whether the above described event is a unique event or something that others have experienced.

Things break even if over engineered due to manufacturing issues.

This example is ONE occurrence.

How does one determine, without a sample greater than one, if this is a manufacturing fluke or a real issue?

just fishing for other examples of BX axle failures, especially if wheel spacers were used. BUT if not as well.

Mainly because I recommended my son in law install 2” spacers on his new BX23S. Actually bought them as a gift. Would feel bad if he had issues later...

We sold a lot of BX's, some with spacers. ( I have 1.5" spacers on my BX and fluid in the tires) and never saw a broken axle! We did have one customer break a rear axle on a Grand L 6040.

 

[TheOldHokie]

No doubt that adding spacers adds stress on the system. but stress is there to begin with.

So the question relates to whether the above described event is a unique event or something that others have experienced.

Things break even if over engineered due to manufacturing issues.

This example is ONE occurrence.

How does one determine, without a sample greater than one, if this is a manufacturing fluke or a real issue?

just fishing for other examples of BX axle failures, especially if wheel spacers were used. BUT if not as well.

Mainly because I recommended my son in law install 2” spacers on his new BX23S. Actually bought them as a gift. Would feel bad if he had issues later...

Widening the wheelbase by reversing wheels or adding spacers adds stress. Pulling a mower adds stress.
Plowing a field adds stress.
Putting a loader on the tractor adds stress.
Just about everything you do with or to a tractor adds stress.

If your son breaks an axle you will never know if it was the spacers, how he used the tractor, or a combination of factors.

Dan

 

[Fordtech86]

Wheel weights will increase the mass (=momentum) acting through that lever arm. It is also an off center mass acting as an overhanging load on the hub.

I think you are combining your 2 scenarios, adding wheel weights and spacers at the same time. I was only referring to the wheel weight part.

Spacers undoubtedly add additional stress to the axles due to moving the wheel line out and additional leverage on the axle. To what extent? Hell if I know.

Adding weight to wheels whether center weights or liquid filled though adds no weight supported by the axle. That weight is supported by the wheel/tire/ground.

Seems many here run spacers and we don’t read many stories about axles breaking. I wouldn’t hesitate to use them if I needed, but I have no need for them.

 

[TheOldHokie]

I think you are combining your 2 scenarios, adding wheel weights and spacers at the same time. I was only referring to the wheel weight part.

Spacers undoubtedly add additional stress to the axles due to moving the wheel line out and additional leverage on the axle. To what extent? Hell if I know.

Adding weight to wheels whether center weights or liquid filled though adds no weight supported by the axle. That weight is supported by the wheel/tire/ground.

Seems many here run spacers and we don’t read many stories about axles breaking. I wouldn’t hesitate to use them if I needed, but I have no need for them.

I am talking about Kubota wheel weights. They are bolted to the center disc and supported by the tire and wheel but they are also over hanging from the hub. That is different than liquid ballast which is filling the tires and is not overhanging.. This bolt on style wheel weight presents a tipping load which is pulling out and down on the hub.

To illustrate get yourself a piece of ply wood and hold the edges in both hands. Set it upright on edge on a table - it requires no effort to hold upright. and the table is supporting the weight of the plywood because it is balanced. Now stack and bolt 3 x 60 pound wheel weights to a 8 inch circle in the center of that piece of plywood and try to hold it in the same position. The table is still supporting "most" of the weight but you will need to exert a lot of grunt to keep it from tipping over. That's the static over hanging load and your wrists are the hub and bearings. Now have some one vigorously shake the table side to side. You will need even more grunt to keep it from wobbling. That's the added dynamic load the hub will see when the wheels and weights start rolling over rough ground.

Dan