Ballast Kubota M7040 front tire ballast

[fleminj2pa]

I recently purchased the tractor pictured below and in order to comfortably handle the 3 pt no-till drill also shown, we had to add approximately 800 lbs. of suitcase weights and brackets along with 400 lbs. of liquid ballast to the front tires only. Prior to adding the weight, attaching to and lifting the drill would bring the front tires up 8-10" on level ground. We first added the suitcase weights and that helped substantially but even then two men could stand on the back of the drill and bounce the front tires. So, we added 20 gal. of rim guard to each front tire and that solved the problem. I used the drill to plant 8 acres of food plot forage on 1.25 miles of gas line in mountainous terrain the very next day and I had absolutely no problems.

However, it's been suggested on another thread that adding liquid ballast to the fronts on the M7040 could lead to problems with the steering, further on down the road. As a tire dealer, we have been ballasting tires for many years and we have never encountered such a problem but I was curious to learn if anyone else had experienced any issues in this regard?

 

[texasjohn]

I've only heard of people having problems with a FEL heavily loaded with low air pressure in front tires and rolling tires off of the rim. Most smaller tractors have small front tires which, if loaded, leaves little air for cushion and reserve in case of a small leak. A larger tire such as you have can hold enough weight to make a small difference, as you report. Smaller tires are not able to hold enough weight to make any real ballast difference.

I know that my Kubota manual says to not put ballast into the front tires. I don't know what yours says. I always carry max tire sir pressure in my front tires because of my heavy FEL loads. Never rolled tires off of rim, but under load the tire certainly squats a lot.

 

[RedNeckRacin]

Does kubota sell a larger front weight bracket? I think JD has two different size ones starting around that size of machine? If your not running a loader and the 3pt will pick up the weight, I don't see any harm in loading the tires. That tractor will never notice the weight difference.

 

[Dave M7040]

The M7040 owner's manual says not to ballast front tires due to effect on steering.
I think a lot of people consider weight in the tires to be the same as weight on a front rack or FEL but they are forgetting the greatly increased gyroscopic forces that come from the extra weight rotating within the tires.
Dave M7040

 

[fleminj2pa]

The M7040 owner's manual says not to ballast front tires due to effect on steering.
I think a lot of people consider weight in the tires to be the same as weight on a front rack or FEL but they are forgetting the greatly increased gyroscopic forces that come from the extra weight rotating within the tires.
Dave M7040

I saw this in the manual and I hear what you're saying but I'm still trying to get my head wrapped around that concept. I'll go back to the issue of inadequate fill level and the associated sloshing that goes with that. We put in 20 gal. of rim guard in each tire, which is all you can get in and still allow room for air pressure. That fills them about to the level of the valve at top dead center. I was watching for any indication of wheel hop or irregular characteristics while operating the tractor the next day and it was smooth as could be...even while operating on the blacktop road at 15 mph.

I think it's interesting that the dealer never once cautioned against adding rim guard. In fact, we discussed it with the setup technician and his only comment was to either fill the rears to the same relative level or leave them unballasted entirely...the issue being trailering weight constraints.

The fact is, as a tire dealer who services ag tires, we've been ballasting tires for years and we routinely fill fronts if requested to do so and to the best of my knowledge there have been no related issues reported, thus far. I'm hoping to hear from someone who has had their front tires filled for some time, with or without related problems.

 

[TomSeller]

That is one downside to taller front tires. The gyro forces are much greater because of the larger radius.

 

[Dave M7040]

Please try this simple experiment. Get the front tire off a bicycle and hold both ends of the axle. Sit in a swivel chair. Have someone spin the tire/wheel as fast as they can. Now try to turn the front wheel like you are steering it. You will find that the swivel chair will rotate and you will be aware of a strong force through your hands.
The heavier and faster the wheel spins the greater the force effect you will experience.
Loading the rotating front wheel with rimguard increases the rotating weight and thus the forces that resist the steering. Gyro's, which is what your front wheel wheel is, want to remain unmoved i.e. don't want to be turned to either side which is why they are incorporated into compasses in airplanes, missiles and ships. The power steering can overcome these forces but only to a limited level and then it will not be strong enough and you will not be able to turn.
Dave m7040

 

[RedNeckRacin]

I think you guys are being overly cautious. The manufacturer is looking out for the general users of the tractors and not specific instances. People have hacked tractors to pieces and once they are out of warranty, its your choice. If the tractor has enough grunt to pick up the seeder and not enough weight to keep it on the ground after adding the max front weights, what options do you really have? If you had a loader, I'd say go find a pile of damp clay and see if that would keep things down but since there isn't one, I don't think that's an option.

 

[skyhook]

Please try this simple experiment. Get the front tire off a bicycle and hold both ends of the axle. Sit in a swivel chair. Have someone spin the tire/wheel as fast as they can. Now try to turn the front wheel like you are steering it. You will find that the swivel chair will rotate and you will be aware of a strong force through your hands.
The heavier and faster the wheel spins the greater the force effect you will experience.
Loading the rotating front wheel with rimguard increases the rotating weight and thus the forces that resist the steering. Gyro's, which is what your front wheel wheel is, want to remain unmoved i.e. don't want to be turned to either side which is why they are incorporated into compasses in airplanes, missiles and ships. The power steering can overcome these forces but only to a limited level and then it will not be strong enough and you will not be able to turn.
Dave m7040

Good point, but I wonder if it would apply to a 16" tractor tire,
remember, these don't turn as fast.

 

[Dave M7040]

Why do you think Kubota puts the caution in their owners' manuals?
Dave M7040