4x4 Question

[ovrszd]

Everyone who intends to use 2WD on pavement, but has forgotten to disengage the 4WD a time or two...raise your hand! I hope mine isn't the only hand raised.

One of the many times I've forgotten resulted in catastrophic front axle damage...Maxing out the loader forks with a partial pallet of bricks I needed to move a half mile on asphalt. At the end of the trip I noticed fluid leaking onto the pavement. The lower spindle shaft bearing had "exploded" and broke a hole in the cast iron spindle housing.

The front axle MFWD drive train on my tractor doesn't look to be built nearly as heavy as the rear drive train. I believe the front axle is relatively delicate compared to the rear and certain "bonehead" situations will make that weakness painfully clear.

My intent, even before the accicent, was to use MFWD whenever needed, but only when needed. ie 2WD unless MFWD is required.

OkieG

Do Jeeps count???? My Hand Is Up!!! Sorry for your breakdown!!! Ouch!!!

 

[JerryG]

Correct on ALL counts.

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD. For all the newbies, MFWD stands for Mechanical Front Wheel Drive. Technically, unless the front and rear wheels are the same size, like on a truck, or large ag tractor, it's not 4X4 or 4 wheel drive (6 times a year).

Fact: The MFWD system is designed to give added traction in sub standard conditions. Using MFWD in on high traction surfaces, including dry lawns and packed gravel and dirt, WILL result in added driveline stress, and premature failure. Chances are, this failure will occur when you are decending a steep hill with a heavy load, or stuck up to the axles in heavy mud becouse you went into the mud with the MFWD locked in, and kept going, hoping it would also get you out. My 4 wheel drive ag tractor has pulled out MFWD tractors almost as many times as it has gone out to the field to disc.

Fact: Using a MFWD tractor to do more work than the tractor was meant to do, just becouse it has MFWD, will cause serious saftey issues and premature wear on the tractor.

Fact: The most important part of a tractor is an operator who knows how to operate the tractor, and when to use each of the features on the tractor.

Fire away boy's and girl's....

 

[SPYDERLK]

Good posts guys.. nice and lean too.. no fat.

Soundguy

You guys have it right. One added thing - - the tractor takes more HP just to move when the 4FD is engaged - - not so much due to spinning added parts, but from the stresses on these parts due to the overdriven front wheels. The fronts are clawing their way along a little faster than the backs so the front/back drives are loaded against each other. Lots of drive friction - HP converted to heat. Those w/o the fancy systems will definitely notice that the tractor coasts to a stop quicker when in 4WD. Also youll notice this when your tractor engine can barely pull a gear in some field task. Shifting into 4FD will bog it due the extra HP used by the fighting components.
Larry

 

[ovrszd]

You guys have it right. One added thing - - the tractor takes more HP just to move when the 4FD is engaged - - not so much due to spinning added parts, but from the stresses on these parts due to the overdriven front wheels. The fronts are clawing their way along a little faster than the backs so the front/back drives are loaded against each other. Lots of drive friction - HP converted to heat. Those w/o the fancy systems will definitely notice that the tractor coasts to a stop quicker when in 4WD. Also youll notice this when your tractor engine can barely pull a gear in some field task. Shifting into 4FD will bog it due the extra HP used by the fighting components.
Larry

I tried to make that point but got shot at several times. Maybe your viewpoint will get along better!!

 

[Timber]

I don't think comparing you Pickup truck to your tractor is a fair argument at all. The applications are completely different. I have always owned 4 wheel drive trucks. They are apples and oranges. Your pickup is designed to run on asphalt and your tractor is designed to run in the dirt. You will never generate the speed out of a tractor you can with a pickup and a tractor is a work horse and designed for that purpose and run it how you use it, The soil will give long before your drive line and if you use you loader your just a fool not to use it in 4 wheel drive. The only reason I see for not using 4 wheel drive is transporting down the road or grass cutting and then only for tire ware and lawn care. Abuse anything and you will tear it up. I have 2 trucks now with a limited slip option on 4 wheel drive and another with 150 thousand miles on it. I cant tell you how many times I have run it in 4 wheel at 60 miles an hour on pavement in the winter and never a problem. If you tear it up it is usually on you

 

[ovrszd]

I don't think comparing you Pickup truck to your tractor is a fair argument at all. The applications are completely different. I have always owned 4 wheel drive trucks. They are apples and oranges. Your pickup is designed to run on asphalt and your tractor is designed to run in the dirt. You will never generate the speed out of a tractor you can with a pickup and a tractor is a work horse and designed for that purpose and run it how you use it, The soil will give long before your drive line and if you use you loader your just a fool not to use it in 4 wheel drive. The only reason I see for not using 4 wheel drive is transporting down the road or grass cutting and then only for tire ware and lawn care. Abuse anything and you will tear it up. I have 2 trucks now with a limited slip option on 4 wheel drive and another with 150 thousand miles on it. I cant tell you how many times I have run it in 4 wheel at 60 miles an hour on pavement in the winter and never a problem. If you tear it up it is usually on you

I guess I don't know what a limited slip option on 4 wheel drive is??

If the hiway is slick enough in the winter to need 4x4 is it safe enough to drive 60 mph? Does your truck stop quicker on ice slick hiways when it's in 4x4??

 

[Timber]

There is a period of time after a storm were some roads a clear and some are not so 4 wheel drive is the safest option to leave my truck in. You should also know I am a professional driver and have logged well over 1 million miles in full season weather driving running 80,000 pound semis in the mountains.
A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages. My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

 

[ovrszd]

There is a period of time after a storm were some roads a clear and some are not so 4 wheel drive is the safest option to leave my truck in. You should also know I am a professional driver and have logged well over 1 million miles in full season weather driving running 80,000 pound semis in the mountains.
A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages. My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

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.

 

[cp1969]

A limited slip 4 wheel drive option is where your in 4 wheel drive but your rear wheels have power and your front wheels free wheel till the rears slip and then your front axle auto engages.

How does this work? I'm not familiar with any kind of transfer case/power divider that will do this, with the possible exception of a viscous coupling made by VW back in the 80's. I didn't know anybody had adapted that to their vehicles. Anything that is full-time 4wd (with a power divider, such as tandem axle trucks or full-time 4wd), both axles are receiving power all the time unless one wheel spins. Then all the power is wasted on that one spinning wheel until you lock the power divider.

My driving experience exceeds in less than 5 years more than what most people will do in a lifetime

There is a lot of experience to be gained from years of driving, too, not just miles. In five years, you could have no more than five winters under your belt.

 

[N80]

How about I inject some facts into the thread, sort of kicking the bee hive.

Fact: Buy a tractor from a company who knows tractors, like John Deere, and they will tell you, right in the "operating the tractor" section of the owners manual, to only use the MFWD when needed for added traction and braking. The proper way to use MFWD.

I consulted my Kubota manual. It says nothing of the sort. It lists a _wide_ range of areas in which 4wd is helpful. It says that running in 4wd on pavement _could_ result in premature wear of the tires, but it doesn't even say not to do it, and believe me, this manual is packed full of things _not_ to do. The only other warning regarding the 4wd system is not to engage and disengage it at road speeds.

So either your "Fact" only applies to JD or it isn't a fact at all, which seems to be the largest part of the problem here. There are very few facts going around.

In addition, at least one poster mentioned that his manual (Mahindra?) indicated that 4wd was the more efficient way to operate.