2wd Always?

[SLOBuds]

Now that I'm an expert after operating my lifetime-first tractor for all of 27 hours ... couple of pretty dumb questions are surfacing at ramdom intervals.

One has to do about when to use 2wd versus 4wd. My first approach was to basically always use 4wd because of its better traction. But now I see the obvious: 4wd introduces added drag/friction/whatever and therefore it is more economical to use 2wd.

Is that an accurate statement? Do you think it's best for me to operate in 2wd as much as possible and only engage 4wd under very limited circumstances when 2wd is bogged down or such?

I think I know the answer to this, but want to know if there are situations when I would use 4wd anyway - even if the tractor isn't slipping around.

Thanks.

 

[Texashayman]

Run 2wd unless the situation dictates 4wd...

 

[Egon]

My little Kubota B7100 rarely ever gets out of four wheel drive.

 

[Runner]

I was having traction problems from lugging around a heavy mower on steep hills. Finally came to the conclusion that it was easier on the tractor to just leave it in 4WD all the time, instead of shifting in and out every 5 minutes.

Another thought is this: since the front hubs are always "locked in" on these things, it appears to me that you are always turning the front differential and driveshaft anyway, whether in 4WD or not. The only difference I can see in running 4WD is that you have the front end and rear end locked together, which might introduce a little more driveline and/or tire wear.

My question is, how much more wear are we talking about? Is it enough to actually cause some kind of problem over, say, a 20 year time of ownership?

The manual is silent on the issue, other than to say "don't run 4WD on hard surfaces" and "disengage MFWD when going to and from the work site to reduce tire wear".

 

[Z-Michigan]

Run 2wd unless the situation dictates 4wd...

Ditto. The situation includes not only you can't move in 2wd, but also moving with excessive wheel slip, i.e. heavy tillage for the size tractor. But be aware that in 4wd you can get so much traction you can damage an implement that gets stuck, when in 2wd it would have just stopped the tractor with the rear wheels spinning (and they don't spin real fast if you were in an appropriate gear).

Overuse of 4wd not only uses fuel but accelerates wear on everything, and on pavement could even cause damage to the driveline, just like with a 4wd pickup.

 

[N80]

Here we go! This has been a hotly debated topic. I'd be surprised if this one went less than 4 pages.

Here's my first thought on this: Don't overthink it, because it really doesn't make that much difference.

Now, some practical issues. First, in addition to better traction, 4wd gives you breaking at all 4 tires which can be very important on hills, etc. As for economy, like evrything else, it just depends. The main thing that 'depends' is how big a deal is it for most of us even with diesel at $4 a gallon? If you have 10,000 acres to plow in Nebraska, that's one thing. If you bush hog with a 30hp tractor on the weekends, well, that's a another. And don't assume 2wd is universally more economical. Pulling a 2-14 plow with my tractor in 2wd requires more rpms and more audible work from the engine. In 4wd, rpms and effort drop considerably.

Now, here's my opinion about wear and tear. Forget about it. If you have a good, modern 4wd tractor, the front drivetrain is designed and built to the same specs as the rear. They are both meant to last the life of the tractor. What good is it to wear out a tractor engine, transmission and rear drive train and still have a pristine front drive train?

Some will also mention turning. My tractor has the same turning radius in 2 or 4wd. It is a bevel gear system and there is no palpable binding or torquing when turning in 4wd. Furthermore, the 4wd model turns tighter than the 2wd model of the same machine.

Okay, so I broke the first rule (don't over think it). Bottom line, use it all the time, never use it, or something in between. As long as you use your head, your tractor will be fine.

About the only time mine is out of 4wd is on the pavement.

 

[Texashayman]

Hey its your tractor, run it or tear it up like you want to..as far as wear and tear, Z-michigan pretty much summed it up! Any time you have more moving parts there is going to be wear! I hardly believe your tractor has the exact same turning radius in 4wd as in 2wd..but hey..its your story! I go back to my original response..Run 2wd unless the situation dictates 4wd

 

[N80]

Hey its your tractor, run it or tear it up like you want to..

And everyone knows that leaving it in 4wd will tear it up.

as far as wear and tear, Z-michigan pretty much summed it up! Any time you have more moving parts there is going to be wear!

That's exactly right. And given that logic, we should be recommending that no one crank their tractors. But in the end, you can't argue with the fact that if its moving it is being worn. So the next question is how much? And the answer to that question is.....not enough to matter.

I hardly believe your tractor has the exact same turning radius in 4wd as in 2wd..but hey..its your story!

Well, you might not believe the earth is round either, but that doesn't make it flat! My tractor has a bevel gear front drive system. There is no difference in feel or turning radius between 2 and 4wd. Sorry if that seems inconceivable, but welcome to the 20th century....Kubota has been making them this way for years.

I go back to my original response..Run 2wd unless the situation dictates 4wd

And that's great advice. But it has absolutely no measurable advantage over the corrolary of always running it in 4wd unless the situation dictates 2wd...such as running on pavement.

 

[jk96]

Now, some practical issues. First, in addition to better traction, 4wd gives you breaking at all 4 tires which can be very important on hills, etc.

Not everyone is aware that at least on most compacts the brakes only stop the rear wheels. Going downhill with a load in the bucket can demonstrate this real quick and is one reason I leave mine in 4wd unless on flat ground.

I personally don't see much reason to worry about having the tractor in 4wd when on softer surfaces.

I hardly believe your tractor has the exact same turning radius in 4wd as in 2wd..but hey..its your story!

Not sure how 4wd would change the turning radius? My tractor turns just as far left or right when in 2wd or 4wd, only difference I see is 4wd will chew up the turf a little more.

 

[wushaw]

I use 4wd all the time unless I need 2wd, I have only been on pavement twice in three years, I can't remember if the 4wd handle goes up or down to disengagement.

I don't care if I wear out the ft. end I will just fix it if and when needed, I need the traction more than worrying about wear and fuel efficiency.

 

[N80]

Not sure how 4wd would change the turning radius? My tractor turns just as far left or right when in 2wd or 4wd, only difference I see is 4wd will chew up the turf a little more.

I guess the forward traction could theoretically increase the turning radius, but that is not the case on my machine. (And for the record, other's have questioned this as well and I took the time to measure it. No difference at all. This was without using a brake.) Kubota designed the bevel gear system precisely for this reason. Other machines may differ.

Saving your turf can be a good reason to take it out of 4wd. However, my ag tires tear up the turf any time I make a tight fast turn regardless of 2 or 4wd. It is worse in 4wd.

 

[tuolumne]

My machine seems to turn tighter in 4wd...it seems as though the front wheels are pulling the front end around where 2wd will let them push forward just a bit. I've never attempted to measure this. With my JD3520 I have followed the protocol of always use 4wd unless the situation demands 2wd (like road travel). I have many steep slopes and it only took one loss of brakes in 2wd with a full loader to decide on this system. Besides, I have no pavement and almost always need 4wd anyway.

 

[Egon]

The front wheel drive on a Kubota should have no effect on turning radius due to the design. If anything the added traction in the direction turned will aid turning.

On my truck with a solid front axle and u-joints its a different situation. It don't like turning tight.

 

[charlz]

My b7100 almost never gets out of 4wd.... just the rare occasion when it needs to go on pavement. Pulls easier in 4wd, fills the loader easier and steers _tighter_ in 4wd. In 2wd the front tires have a tendency to skid and it steers wide. Of course I could use the steering brakes to make it turn tight no matter what but then I'd be wearing out my brakes!

 

[NewToy]

It's quite hilly here in SE Ohio and I rarely am out of 4WD unless on the pavement. Like stated earlier in the thread, the braking in 4WD is greatly enhanced. I feel much more in control of the tractor while pulling my finish mower in 4WD. I just tilled the garden yesterday and did the whole thing in 2WD, no problem. It was dry and flat and 2WD was adequate. If you're more comfortable in 4WD by all means use it, that's what it's for. The last thing I'd worry about is wearing the thing out.

John

 

[border collie]

I guess I'll throw my 2 cents in too; on my NH TC30 with R-4 tires I've experimented numerous times, and found that there is lots less turf damage in 4WD when making tight turns. When pulling a 6ft disc harrow it will dig a hole in 2WD, yet won't struggle a bit in 4WD.(all this is with FEL w/bucket installed). different tractors with different equip. installed may not react the same.

 

[RalphVa]

Biggest reason is safety. With 4wd, you also get 4 wheel brakes. On my tractor, it has to be just so (all tension off the gears, etc) to get the thing in and out of 4wd. If I left it in 2wd, I can see myself getting into a ticklish situation needing 4wd and not being able to get the lever to go. I leave mine in 4wd unless I go all the way down my driveway. Half way? It stays in 4wd.

Ralph

 

[brandoro]

I find my tractor slips in and out of four wheel quite easily so I often do shift it in and out. Sometimes I forget but don't worry about it too much. If I am manouvering in close quarters with a full bucket and the counterweight on the back in 4 wheel then it tends to bind up the driveline a bit, the rest of the time I don't notice that it stresses the tractor very much. Some jobs I WANT it in 4 wheel, going downhill with a full bucket for instance. When snowblowing on the other hand, I like to run in 2 wheel so I don't bend/break things if I encounter something in the snow. The back tires will lose traction easily enough that the tractor will stop before hurting anything.
Basically, use your own discretion depending on the work situation and attachement in use. My last tractor was over 20 years old when I dealt it off, no problems with the front drive and the tires would have rotted off long before being worn out.

 

[PILOON]

Someone mentioned 4 wheel braking.

May I correct that statement?
Most tractors that I know of only have brakes on the rear wheels.

However (from experience) when braking downhill you are most often actually 'on compression' ie the engine compression is slowing you down + brake application.

Example braking downhill with the FEL loaded often proves to be quite hairy as the rear can easily lock up due to the upfront weight kinda lifting the rear and therby causing the pucker reaction.

My prime vehicle is 4 x 4 and when on very icy roads (like my drive) one tactic I use is 4wheel + low range + low gear and coast on compression.
However even the slightest tap on the brake peddle and off road skid will I.

 

[SPYDERLK]

Well, you might not believe the earth is round either, but that doesn't make it flat! My tractor has a bevel gear front drive system. There is no difference in feel or turning radius between 2 and 4wd. Sorry if that seems inconceivable, but welcome to the 20th century....Kubota has been making them this way for years.

None of my 3 Kubotas, nor any of my tractors have as tight a turning radius in 4wd as in 2wd. The difference is in the 5-10% range unless you use the brakes in 2wd. Then you can get a 20 or 30% improvement in 2wd if the front end isnt too heavy.
larry