4x4 Question

[sandman2234]

With few exceptions, I think the original question has been answered the same.

Two wheel drive until you need it, and then only on soils that will allow safe spinning of the tires. On anything harder than packed clay, ALWAYS disconnect the front wheel drive, especially if you are loading a bucket or other device that loads the front end with weight.

There are certain exceptions to this rule, such as my lawn mower. It is 4 wheel drive continously, and the only way to change that is with a wrench to disengage one or both drives. It is hydraulic drive, one motor to each axle, so falls under a different class, dispite the fact that it is probably larger than some of your tractors...

The fact that a person operates his own particular vehicle in 4wd full time, is his own decision, and unless he changes tractors every few years, he will suffer for that decision. Hopefully I won't be the new owner of one of those used tractors.
David from jax

 

[CDsdad]

This is straight from my M/F 1533 manual which also covers the 1540, 1547, and 1552.

Page 46 under FIG. 68:

When front axle is engaged, ground speed of front tires will vary from ground speed of rear tires. This is to assist when four-wheel drive is selected.

For this reason, the front axle must be disengaged when the tractor is transported or operated on a hard, dry surface. Failure to do so will result in rapid wear of front drive tires and possible driveline damage.

IMPORTANT: Always disengage front drive axle when operating in conditions with minimal wheel slippage (DRY OR HARD SURFACES).

IMPORTANT: If tire replacement is necessary, identical replacements must be installed to maintain correct front/rear axle ratio.



I typed that as I saw it in the book except I don't know how to italicize the IMPORTANT statements as they are in the manual.

So having a Massey Ferguson, I will follow the recommendation in my Massey Ferguson owner's manual and leave you gentlemen (and ladies if you're here) to debate the burning question at hand. I got to figure out how to italicize.

 

[Timber]

Oh, you are talking about a full-time 4x4 system like was introduced in the mid 70s?? If so, it's using the front and rear axles equally. The T-case is just a splitter like a rear axle splits power to each wheel. Just like the tandem drive on your semi splits power to each rear axle and the one with least traction spins out until you lock the splitter.

There are some systems on new trucks that are traction sensitive like larger Ag tractors use. That's what was referred to back a few posts on this thread which engages and disengages depending on traction needs.

I have had a couple full-time 4x4 pickups. Very dangerous to drive on slick roads because you are unaware they are slick until you tap the brakes, then life changes quickly.

I didn't realize your driving experience or history were in question. Sorry if you felt offended by my questions. I just thought you had something that I wanted to learn about.

Please do not miss understand me. I state my experience to give me some credibility and by no means an authority and take no offense, there are a number of people that have misguided faith in the 4 wheel drive capability of there vehicles

The 4 wheel drive system is a standard feature in most GM trucks for several years now. It is electronic and controlled by the computer' the options are
2 wheel high
4 wheel Auto
4 wheel high
4 wheel low
It is the same feature that a lot of sport cars use full time employed into a truck application. very handy feature. It is not the quad track of the late 70s. The computer has changed everything in that respect

 

[cp1969]

italicize

Just type left bracket, i, right bracket in front of the word you want italicized and left bracket, forward slash, i, right bracket behind it.

 

[N80]

Hmm.. I havn't seent hat spelled out here.. I don't think the front axle is any less durable than any other part of the tractor.. Soundguy

Well, here is the quote I'm referring to:

"Sorry, but your front end driveline is not designed to last as long as the rear driveline, that's just simple physics."

 

[CDsdad]

Thank you cp1969.

 

[ovrszd]

Well, here is the quote I'm referring to:

"Sorry, but your front end driveline is not designed to last as long as the rear driveline, that's just simple physics."

I'll stand by my statement. Refer back to my description of the moving/wearing parts involved between your rear axle and your front axle. Or get out your parts manual and look for yourself.

Also, I think we have already determined that the L4400 has traction sensitive drive which eliminates the "binding" effect of MFWD. That explains why your manual doesn't warn you about driving excessively with it engaged. So for the tractor discussion, we still need to keep the tractors with traction sensitive systems separate from the MFWD tractors. So far in this discussion N80 is the only person I've heard say they have a traction sensitive system??

 

[ovrszd]

Please do not miss understand me. I state my experience to give me some credibility and by no means an authority and take no offense, there are a number of people that have misguided faith in the 4 wheel drive capability of there vehicles

The 4 wheel drive system is a standard feature in most GM trucks for several years now. It is electronic and controlled by the computer' the options are
2 wheel high
4 wheel Auto
4 wheel high
4 wheel low
It is the same feature that a lot of sport cars use full time employed into a truck application. very handy feature. It is not the quad track of the late 70s. The computer has changed everything in that respect

Timber, your description of your truck system is a modern version of the full-time drive system of the 70s. It has no connection to your vehicle computer other than to trigger lights in the dash and engage the front axle disconnect if so equipped.

When in 2 wheel high, that's all the drive you have.

When it's in 4 wheel auto it is functioning as the previous mentioned full-time drive system splitting power to each axle. Similar to your semi rear ends when the power divider is unlocked. To prove this, jack up either end of your truck until both front or rear wheels are off the ground. Engage 4 wheel auto and try to drive off the jack. It will just spin whichever axle you have jacked up and won't move the vehicle.

When it's in 4 wheel high it is locked in 4 wheel drive and demands equal rotation of the front and rear driveshaft. Similar to your semi rear ends when the power divider is locked. If you jack the truck as described above, it will drive off the jack. This is what your B7800 has when you engage MFWD with the lever.

When it's in 4 wheel low it's locked in 4 wheel drive but is operating in low range of the T-case.

 

[Timber]

Well regardless of the technicality's the bottom line and the bigger picture is, It is far better to use your 4 wheel drive on your tractor than not if there is any question as to if you should or not. I would rather see someone use the 4 wheel drive full time than to not use it when they should and get themselves in trouble. You are never going to hurt your tractors 4 wheel drive system as most everyone uses there tractor off road 95% of the time. Then to compare the use of your 4x4 anything to your tractor is a total non issue because the application is completely different. The ground speed and the surface are the factors that damage a 4x4 and that only in abuse or deterioration do to time and wear. If you use a loader for anything regardless of the application and not use your 4 wheel drive is just foolish. The moment you put wt into the bucket or on forks you pivot over the front axle and take the load off the rears and if your front axle is free wheeling your in trouble.

 

[N80]

Also, I think we have already determined that the L4400 has traction sensitive drive which eliminates the "binding" effect of MFWD. That explains why your manual doesn't warn you about driving excessively with it engaged. So for the tractor discussion, we still need to keep the tractors with traction sensitive systems separate from the MFWD tractors. So far in this discussion N80 is the only person I've heard say they have a traction sensitive system??

I did not say my tractor has a traction sensitive system. I have no idea what that is. The L4400 is an extremely basic tractor. Gear drive. Economy model. If it has such a system it is not listed in the specs, brochure, owners manual or web site. Such a system might be inherent to the Kubota bevel gear front axle design, but they don't say anything about it.

I tested my tractor again yesterday, just to make sure I was missing something, and there is no appreciable binding that I can detect. I'm sure there is some, but you can't feel it. If the soil is loose and you turn tightly you can see the outside wheel dig a bit, but you can see that in 2wd as well.

I'll summarize my feelings on this:

My tractor is sold with a front drive system.

Kubota does not suggest anywhere at any time that this part of the tractor is any less durable than any other part of the tractor. There is no documentation that there are any conditions in which it cannot be used.

This tractor is designed to be used in conditions that could require always using the front drive system, even for the life of the tractor. In other words, this tractor could be used for loader operations every day of its life. In this regard, it is highly improbable the Kubota has designed it with a specific area of the drive train incapable of enduring such use.

Leaving it in 4wd during operations in which 2wd is suitable, will lead to more wear than if it were not in 4wd. But I suspect such wear is so minimal as to be trivial.

Using the front drive train at any time the owners manual for that specific tractor specifically says not to, will clearly accelerate the wear on the system.

Question: Is the bevel gear front axle system unique to Kubota?

 

[Neil L]

NH TC29 with Super Steer is in 4 wheel and a sensitive system all the time. You can select fixed 4 wheel when needed.

 

[Keith_B]

Most people on here own CUTs, and any discussion of the 4wd systems will by necessity take that into consideration. The primary reason CUTs come with MFWD as a standard feature is that the MFWD helps to compensate for a lack of weight, in comparison to utility sized tractors.

The line of thinking of not engaging the 4wd until it is needed is faulty. The MFWD is to aid in maintaining traction, and make the CUT safer to operate. An operator negates this safety margin by not taking advantage of the MFWD.

Without the MFWD the CUT can slide more easily on a hill and put you in a turnover situation that could easily be avoided by having the MFWD engaged. A little over a week ago we were cutting a drainage ditch with a potato plow (aka middle buster) that ran down a hillside. We used my BIL's 50 hp David Brown and when he applied the brakes going down hill the tractor would slide 15 or 20 feet, sometimes trying to turn sideways, which put the tractor in an obvious possible overturn situation. We used my Mahindra with the MFWD engaged and did not have that problem. Without the MFWD engaged my tractor would have slid around even more, due to its lighter weight. It would have been ill-advised to have waited until we were sliding down a hillside to engage the MFWD. You engage the MFWD BEFORE you get into trouble, not after.

Obviously, just like the 4wd on a pickup, you do not operate the MFWD on dry pavement, as pavement doesn't allow the wheel slippage necessary for tight turns. My owner's manual specifically says to not operate the MFWD on pavement, or at high speeds as it causes premature component wear.

 

[SPYDERLK]

Most people on here own CUTs, and any discussion of the 4wd systems will by necessity take that into consideration. The primary reason CUTs come with MFWD as a standard feature is that the MFWD helps to compensate for a lack of weight, in comparison to utility sized tractors.

The line of thinking of not engaging the 4wd until it is needed is faulty. The MFWD is to aid in maintaining traction, and make the CUT safer to operate. An operator negates this safety margin by not taking advantage of the MFWD.

Without the MFWD the CUT can slide more easily on a hill and put you in a turnover situation that could easily be avoided by having the MFWD engaged. A little over a week ago we were cutting a drainage ditch with a potato plow (aka middle buster) that ran down a hillside. We used my BIL's 50 hp David Brown and when he applied the brakes going down hill the tractor would slide 15 or 20 feet, sometimes trying to turn sideways, which put the tractor in an obvious possible overturn situation. We used my Mahindra with the MFWD engaged and did not have that problem. Without the MFWD engaged my tractor would have slid around even more, due to its lighter weight. It would have been ill-advised to have waited until we were sliding down a hillside to engage the MFWD. You engage the MFWD BEFORE you get into trouble, not after.

Obviously, just like the 4wd on a pickup, you do not operate the MFWD on dry pavement, as pavement doesn't allow the wheel slippage necessary for tight turns. My owner's manual specifically says to not operate the MFWD on pavement, or at high speeds as it causes premature component wear.

I think the idea is to anticipate the need. It would be nice to have one like this;
Quote: NH TC29 with Super Steer is in 4 wheel and a sensitive system all the time. You can select fixed 4 wheel when needed.

But I think those of us who havnt opted to pay for a sophisticated and near fool proof system are taking responsibility for our choice. For some it is to use the 4WD all the time with its inherent drawbacks of increased; 1) tire and fuel consumption, 2)turning radius with greater surface disturbance, 3)driveline stress, 4) engine and transmission wear, 5) brake wear if used in an attempt to decrease turning radius, 6) etc? - - in return for knowing its on when you need it. For some, in order to avoid these drawbacks, it is trusting yourself and your judgement to recognize the need, and hoping your judgement will be consistent and good. This risk situation, combined with a little luck, turns into the basis for valuable experience in handling a tractor in varying conditions. Possibly, a 4WD NOT ON light would help. It could blink when it detected front vs rear slip?
Larry

 

[whitetiger]

The 4X4 in a 1999 and new GM pickup and SUV's have an optional system (may be standard now) computer controled mode called Auto-something. I can not remember how it is labled right know, mine is a 2500HD which did not offer it.

Timber, your description of your truck system is a modern version of the full-time drive system of the 70s. It has no connection to your vehicle computer other than to trigger lights in the dash and engage the front axle disconnect if so equipped.

When in 2 wheel high, that's all the drive you have.

When it's in 4 wheel auto it is functioning as the previous mentioned full-time drive system splitting power to each axle. Similar to your semi rear ends when the power divider is unlocked. To prove this, jack up either end of your truck until both front or rear wheels are off the ground. Engage 4 wheel auto and try to drive off the jack. It will just spin whichever axle you have jacked up and won't move the vehicle.

When it's in 4 wheel high it is locked in 4 wheel drive and demands equal rotation of the front and rear driveshaft. Similar to your semi rear ends when the power divider is locked. If you jack the truck as described above, it will drive off the jack. This is what your B7800 has when you engage MFWD with the lever.

When it's in 4 wheel low it's locked in 4 wheel drive but is operating in low range of the T-case.

 

[RedRocker]

I hope I live long enough to wear out my tractor. I plan on wearing out all of the drive train at the same time, I don't see much need in having a pristine front drive axle on a worn out tractor. If I'm in the dirt mine is in 4WD.

 

[N80]

For some it is to use the 4WD all the time with its inherent drawbacks of increased; 1) tire and fuel consumption, 2)turning radius with greater surface disturbance, 3)driveline stress, 4) engine and transmission wear, 5) brake wear if used in an attempt to decrease turning radius,

The problem is that the things you have listed are 1) not true for every model of CUT 2) not necessarily true for any CUT and 3) in the cases where they are true they are often trivial to the point of being meaningless.

Tire and fuel consumption: At least one manufacturer says their tractor runs more efficiently in 4wd. Also, if driving on anything but hard dry surfaces, tire wear due to 4wd is going to be meaningless.

Turning radius and surface disturbance. Having the front engaged on my tractor has no effect on turning radius. The outside tire does disturb the ground surface as you mention. When that is a concern, I take it out of 4wd. but that's to svae the grass, not the tractor.

Driveline stress. Opinions vary wildly here and very probably the effect varies between brands and models. But for those who constantly switch in and out of 4wd, if you are switching in only when you start to lose traction, you are probably putting as much or more unneccessary stress on the driveline as the always 'in' crowd.

Engine and Transmission wear. Again, very probably trivial at the most and again, erring on the side of putting it in 4wd too late or too infrequently is likely to be just as costly if not more.

Brake wear. I can see how that might be an issue. For those using one wheel braking it might be a legitimate concern while in 4wd. I don't know.

My point here is that some make the decision sound like its a black and white thing. Maybe you didn't intend it that way but it sounds like you're saying 'leave it in and tear it up'. I just don't think it is quite so simple or so cut and dried.

And in the long run, if each of us follows the owners manual and uses a little common sense, either aproach is likely to be fine and our tractors are likely to out survive their owners, front drive line and all.

 

[Timber]

I leave mine in 4 wheel drive all the time. I don't cut grass with it and I am never on pavement except to put it in the garage. Mine is a little difficult about going in & out of 4 wheel drive anyway. I bought my tractor to dig and to use as an all train fork lift.

 

[whodat90]

Lemme throw my hat into the ring with some facts. First will address some of the later posts; the traction sensing transfer cases in some trucks. GM has autotrack. In this the transfer case has an electronically controlled clutch pack that uses the abs sensors to note a difference in wheelspeed between front and rear wheels and couples the front driveline as needed to equalize the wheelspeeds. It works well, I have it in my yukon. Next (although before chronologically) is the jeep quadradrive system. First iteration used a viscous coupling that drove both front and rear driveshafts. Worked well, but was capable of sending all the power to one driveshaft with the least traction. Next was a different quadradrive, where the power went straight to the rear driveshaft, and the rear front driveshaft was coupled to the rear by the viscous coupling. This created a primarily rear wheel drive vehicle that started adding torque to the front driveshaft as the two driveshafts started spinning at different speeds. Next is the new quadradrive, which uses an oil pump to lock a clutch pack that couples the driveshafts together. If there is any speed difference between the driveshafts the pump pumps and applies pressure to the clutch pack coupling them together.

Next, the comparison between a truck's 4wd system and your tractor's: Unless you have a mower deck and loader on your truck, the comparison is irrelevent. Different applications and different environments.

Next, the pointing out that front drive systems are more complex than rear drive systems: duh. A rock is much less complex than your engine, so should you stop using your engine? If it does in fact add wear that would otherwise not be there, so what? When in 80 years you finally wear out your kubota, do you want to wear it out except the front axle? Have you any actual proof that under normal use of the front drive system the front axle wears out more quickly than any other part of the tractor? If not, then what's the problem? If the tractor lasts 5000 hours and the front axle lasts 5000 hours, then so be it. A properly designed system, regardless of complexity, will last the life of the tractor. Using 4wd on pavement with a full load in the loader will cause damage, but that's operator error rather than normal operation.

Finally, use it if you want to. I've got a little B7200D 4wd with turf tires. Sometimes I need 4wd. Sometimes I don't. I use it when going over rough terrain, not only for the drive traction but for the additional braking available through the drivetrain. I use it when tilling just so that it doesn't throw the tractor around when I hit rocks. I sometimes use it when bushhogging just because it helps offset the inertia of the mower (mower swings side to side and wants to pull the front of the tractor around a bit over bumps and when turning) I use it when using almost any ground engaging implement, largely because I don't typically use the ground engaging implements on pavement. I use 2wd almost all the rest of the time. If it's needed, use it. If it isn't, but it isn't hurting anything, use it. If it's not needed and it's use is either contraindicated or not recommended, don't use it. But most of all, don't be afraid that using it is going to cause your front axle to wear out or break long before the rest of the tractor. Your owner's manual is your best guide.

Edit: Terminology clarification: Jeep's first modern awd system was quadratrack, the second was quadratrack 2. The latest version is quadradrive.

 

[dirtworksequip]

Geez, that snowball rolled from New York clear to Texas. So, to push it back to New York from Texas should I use my 4 wheel drive? Great post by everyone, but did we learn anything?

 

[daTeacha]

Maybe. I did an inadvertent experiment yesterday that might give you guys something else to chew on.

I was working with the loader/grapple picking up fairly big log ends and stumps to take to a burn pile. I was working the wooded pasture, hilly rough ground, driving over arm thick logs and such. I had a heavy load in the bucket -- nothing really huge, but enough so I knew it was a good load, I 5' x 30" or so, wet half rotted oak log with a huge knot.

I was moving slowly uphill, climbing over a small log, and the tractor stalled ou the HST -- engine bogged down, tractor didn't move, tires didn't spin. Then I noticed I was in 2wd, shifted to 4wd, and moved right out, no hint of stalling the hydro.

Point -- there was obviously more strain on the hydro in 2wd than in 4wd. This would also translate to greater strain on the rear axle than when 4wd is engaged and the work load is divided between 2 axles.

So, does using 2wd to save miniscule amounts of wear on the front drive axle system cause a corresponding amount of additional wear on the rear one that would not occur had the front end been engaged?

Have fun!