Wheel weights add stress to axles or bearing?

[Superduper]

Hello, I had a conversation with the parts guy at the local deere dealer, in which he talked me out of getting weights for my rear R4 wheels/tires (filled). I inquired about the weights in an attempt to configure my tractor based upon the 300cx loader instruction manual which specifies filling tires AND adding 3 weights per side, in addition to rear ballast. I'm certain that the high amount of ballast is specified for the loader to realize it's capacity potential.

During the conversation, he stated that the additional wheel weights (contradicting the manual) were not needed and would add stress to the axles and bearings. At the time, I didn't want to argue with the expert but on the way home, I got to thinking about it and am skeptical of his assessment. Unlike adding weight to the tractor frame, which will put more weight on the bearings, the entire weight of the wheel/tire assembly rests entirely on the ground and does not transmit to the axle and/or bearings. For this reason, my thinking is that at rest, there should be zero affect on any bearing or axle. In operation, I'm thinking that bearing load increase should be nil but inertia from the spinning tire may induce a slight increase in rotational stress on axle from trying to stop a larger mass from spinning, although I highly doubt that this extra amount of stress would be significant as most forms of automotive related stress is speed induced. 2mph, for all practical purposes is not fast.

What do you guys think?

 

[MikePA]

I'd double check your tractor's Operator's Manual for what is recommended. My tractor (NH TC25D) manual has recommendations for wheel weights, ballast and tire filling. Some people, who want to lift more with their FEL, focus on adding weight to the rear of the tractor and naturally so, since that's the end that gets airborne. But also keep in mind, as you load up the rear of the tractor in order to handle a FEL-full, a lot of stress is placed on the front axle when using the FEL.

At a minimum, ask the guy if they've had to repair tractors that experienced bearing failures after following the manual recommendations.

 

[sandman2234]

Superduper,
I also would question this guys knowledge. Last time I check, gravity was a downward pull, not upwards. Wheel weights would be loading the tires, not the bearings, unless you plan on running it on the ROPS...
David from jax

 

[Fredex]

Also read the thread "Tractor Ballasting, Weight Distribution & Free Body Diagrams." I think that's the title. Very lucid analysis.

 

[Henro]

But also keep in mind, as you load up the rear of the tractor in order to handle a FEL-full, a lot of stress is placed on the front axle when using the FEL.

Mike, that seems contrary to what is normally stated here at TBN. Additional weight on the back end of the tractor tends to take weight off the front, countering the weight of the loader/bucket.

Did you mean to say that extra weight on the back adds stress to the REAR axle? I suspect so...

 

[BobG_in_VA]

Couldn't find out what kind of tractor you have, but, by and large, I hope your tractor isn's fragile enough to stress anything if you add weights. I suspect your axel is at least 2" in diameter and I would expect that the both the inner and outer bearings are very robust. If you find out they are not, you need to definitely find another tractor. I'll go out on a limb and say that your should get 4000 hours out of your engine/clutch with "on time" maintenance and twice that for the trans and axels. BobG in VA

 

[Superduper]

Couldn't find out what kind of tractor you have, but, by and large, I hope your tractor isn's fragile enough to stress anything if you add weights. I suspect your axel is at least 2" in diameter and I would expect that the both the inner and outer bearings are very robust. If you find out they are not, you need to definitely find another tractor. I'll go out on a limb and say that your should get 4000 hours out of your engine/clutch with "on time" maintenance and twice that for the trans and axels. BobG in VA

Hi BobG. Sorry, I've never updated my profile but the tractor in question is JD3120 with R4 tires, 300cx FEL, filled tires, and rear box scraper. Manual for 300cx loader specifies that with R4 tires, I should have rear tires filled, 3 weights per wheel (156lbs) and about 1000lbs of ballast on rear. The box scraper is a little light at 465lbs, but since it hangs off iMatch quick hitch and further back than ballast box, I figure the leverage effect and weight of quick hitch makes up for it somewhat. Since a bit of my property is sloped, and I don't particularly care if my mowing causes marks (weeds), I wanted to at least weigh the tires to manufacturers recommendations for better lateral stability. I'm not sure if you are referring to the axle housing tubes or the axle shaft itself being 2" in diameter but the outside dimensions are something like 6" so a 2" shaft is probably the minimum. I don't imagine the tractor is fragile at all. It feels solid like a rock. This tractor is what deere categorizes as their mid-frame sized CUT. By my calculations, it probably tips the scale at 5000 lbs with my 165lb operator weight. This is my 3rd tractor but my first "real" tractor in the CUT class. Interestingly, I offered the dealership my business and asked for suggestions regarding configurations. For whatever reason, the tractor was suggested in a fairly basic configuration. Now being familiar with the tractor, I find that I would have wanted to have had it delivered with rear SCV diverter valve and weights. If I was the salesperson, I would have taken the opportunity to sell a willing buyer a bunch of options or implements. I don't like begging a salesperson to sell me something.

 

[RobJ]

I wouldn't worry about it either. Just stick with what's in the manual.

 

[ovrszd]

This is a good discussion and should help several in deciding how to weight their tractors.

First, adding weights to the wheels is no different than adding fluid to the tires as far as stressing the tractor.

Second, in the Jeep world, this is what we call unsprung weight. Adding the wheel weight adds no gravitational stress to the tractor chassis. the chassis still weighs the same. What it does add is torque stress to the axles and bearings by giving the wheel/tire more individual traction. Think of it like this. If we set up your tractor on a dyno. Engage your transmission in the lowest (strongest) gear. Add weight to the wheel until it will not slip/spin. Is the axle/bearing assembly strong enough to withstand the highest ultimate horsepower the engine is capable of producing??
So with my Jeep, I add horsepower and then I spin. So I add traction. Will my powertrain stand the strain??? Same with your tractor except you are operating with factory horsepower.

I believe adding the weight to the wheel/tire is the right choice for me. I too am after lateral stability to operate on slopes. Adding a weight box doesn't work as well for that. Same with attaching an implement, just doesn't work as well for lateral stability, might actually make it worse from shifting around or having to raise it high when crossing a ditch, etc.

For your application, you are not going to hurt your tractor from adding wheel weights. I agree the dealer should have taken advantage of the opportunity to sell you the weights. Just understand that he wasn't talking about gravitational stress when he mentioned the axle and bearing situation. He was talking about torque stress from adding traction to that individual tire beyond what the factory specifications of the axle shaft and bearings might be capable of withstanding.

Every time you modify your tractor from how it came from the factory, you have an affect on it's ability to perform without failure. Consider that affect before you modify.

 

[Superduper]

Every time you modify your tractor from how it came from the factory, you have an affect on it's ability to perform without failure. Consider that affect before you modify.

Thanks Ovrszd,

I think I will go ahead and just order the weights without soliciting input from dealer guys. I don't however, consider this a modification, as the weights are clearly specified in owners operational manual and they will be dealer parts, and optionable parts for this tractor. If anything, I consider this one of many variations of factory configuration depending upon how tractor is optioned. As far as overstressing the axles, I am not so concerned that 29hp will snap the axles. From what I can see, this is essentially the same tractor as the JD3720 (44hp) without the turbo. Even the weight is identical. From there, I surmise that the axles are in all probability the same in both configurations, for if the axles were more beefy, the tractor should at least weight a few pounds more. Since the 3720 has 50% more power, then the axle should be plenty beefy to handle the rather lighter power load.