To all the macho men with 4x4s...

[bc-chris]

i only use 4x4 when it's really snowy and icy... mind you, i run 34" mud tires all year round!!! ... soooo much fun in the snow



maybe it's just me, but i bet TylerSVT has a youtube video of himself doing brakestands in one of these!! ....but i guess it should be purple!

Originally Posted by PsnaP

[Johnny Canuck]

Originally Posted by 3 Justin 3

When my dad had one he rarely used it, only if he was stuck or the ground was ice/really bad.

+1

I do the same thing.

[speede5]

Originally Posted by Pinner

You're diff's are trying to turn all the tires the same, unless you're driving in a straight line you are wearing on the clutch plates, diff's and or transfer case. On ice, the tires can slip reducing the wear.

Shouldn't cause any problems with your diff's, they are designed to allow your wheels to turn at different speeds, hence the name.

I would love an automatic, I try to leave mine out as much as possible but the roads in town are so bad, ice and rutts, that I have it in 4 wheel most of the time. On the highways, she's 2, but I'm not on the highway long enough so it's kind of a pain switching back and forth.

[Pinner]

Originally Posted by speede5

Shouldn't cause any problems with your diff's, they are designed to allow your wheels to turn at different speeds, hence the name.

Most, if not all diff's are limited slip, hence the name.

If you drove around with a smaller tire on one side, the diff would wear out very quickly and only one axle would be powered by the diff.

[Clarkey]

I put 100,000kms on my jeep cherokee all in 4x4 with no ill affects. The transfer case would rattle in 2wd so I just left it in 4x4. Didn't seem to affect the fuel consumption much either.

[Pinner]

Originally Posted by bc-chris

i only use 4x4 when it's really snowy and icy... mind you, i run 34" mud tires all year round!!! ... soooo much fun in the snow

It should be against the law to run mud tires in the winter, in fact mud tires are dangerous year round and have no use other than mud.

They're no good on snow, ice, rain and probably have significantly longer stopping distance on dry pavement. They are good in mud tho

[kevman]

Originally Posted by Pinner

It should be against the law to run mud tires in the winter, in fact mud tires are dangerous year round and have no use other than mud.

They're no good on snow, ice, rain and probably have significantly longer stopping distance on dry pavement. They are good in mud tho

I would agree that they're no good "on snow" but they're pretty damn good in snow or slush...

[speede5]

Originally Posted by Pinner

Most, if not all diff's are limited slip, hence the name.

If you drove around with a smaller tire on one side, the diff would wear out very quickly and only one axle would be powered by the diff.

My truck only has posi in the back, the front is open. Unless I'm mistaken this is pretty much par for the course with factory 4x4's, as not many people really need full locking systems and, like you said, it is very hard on the drivetrain if the system is full locking. I know some toyota's (my friends 4runner for example) have full locking 4x4's. Big difference in driveability.

[Pinner]

Posi trac is GM's brand name for a limited slip diff.

[kevman]

Originally Posted by speede5

Shouldn't cause any problems with your diff's, they are designed to allow your wheels to turn at different speeds, hence the name.

Yes, the diff's in the front and rear axle's are designed to allow slipping. In a true 4x4 the centre diff is locked. Since the front wheels and rear wheels take different paths when cornerning leaving the vehicle in 4x4 on roads with good traction causes drivetrain and tire wear. Ever forgotten to take your truck out of 4x4 and pull into a tight parking spot? Feel that steering wheel shimmy? That's the drivetrain and tires fighting each other.

Originally Posted by Pinner

Most, if not all diff's are limited slip, hence the name.

Actually most axle diff's are completely open. They deliver power 50/50 to both wheels when you have equal traction. As soon as one side loses traction all of the power transfers to the side of least reistance and spins the tire. Modern cars make up for this with brake limited slip systems that use a computer to brake the spinning wheel and transfer power back to the wheel with traction.

A limited slip uses a hydraulic pressure (think torque converted) to apply power to the wheel with traction when one wheel begins to slip. These are usually found in trucks, SUV's and rear wheel drive sports cars. Rarely are limited slips found in the front end of 4WD or AWD vehicles.


There seems to be confusion about the word "differential". A 4WD or AWD vehicle has 3 differentials. Front, centre and rear. The more of these differentials you lock the more driveline wear you're going to do to your vehicle if you drive on roads with good traction.

An AWD vehicle applies power to all wheels BUT as soon as you lose traction you deliver all of your power to the wheel with least resistance. Ignoring modern traction and control and hydraulic limited slips, it is possible, even in an AWD vehicle, to get stuck with only 1 wheel spinning.

A 4x4 combats this by locking the centre differential. In this case it is possible to get stuck by losing traction on two wheels, 1 in the front and 1 in the rear.

Driving around in 4x4 on dry pavement WILL cause drivetrain wear since the front and rear axles are not allowed to spin at different rates. In this case it doesn't matter if the axle diff's are open or locked. Driving around in AWD will NOT cause drivetrain wear for all 3 diff's are open.

[kevman]

Re: Fuel Economy

Driving your vehicle in 2wd vs. 4wd in a modern 4x4 to save fuel economy is largely a myth. This idea comes form the days of locking hubs. With a locking set of hubs when you disengage the hubs and take the vehicle out of 4wd you essentially remove all input to the front driveline. This would leave the front drive shaft to sit still and not spin. Since rotating mass has a great influence on then stationary mass this would increase your fuel economy.

In today's trucks most* hubs are left locked all the time. Probably a result of cost cutting and better bearing technology. When you take the truck out of 4wd you disengage the front driveline at the transfer case but since the wheels are still locked to your driveline it is still spinning. Since it's still spinning the rotational mass of the driveline remains the same and you really gain no efficiency.

[kevman]

Originally Posted by Clarkey

I put 100,000kms on my jeep cherokee all in 4x4 with no ill affects. The transfer case would rattle in 2wd so I just left it in 4x4. Didn't seem to affect the fuel consumption much either.

Did your Jeep have the NP242 transfer case?
ie, did it look like this?
2FT
4FT
4PT
N
4L

If that's the case then 4FT, is an open centre differential, which is essentially just AWD. All modern Jeeps have permantly locked hubs and as such your fuel economy is always the same whether you're in 2wd or 4wd. Unless of course you've installed aftermarket manually locking hubs...

[Madman]

Originally Posted by kevman

Re: Fuel Economy

Driving your vehicle in 2wd vs. 4wd in a modern 4x4 to save fuel economy is largely a myth. This idea comes form the days of locking hubs. With a locking set of hubs when you disengage the hubs and take the vehicle out of 4wd you essentially remove all input to the front driveline. This would leave the front drive shaft to sit still and not spin. Since rotating mass has a great influence on then stationary mass this would increase your fuel economy.

In today's trucks most* hubs are left locked all the time. Probably a result of cost cutting and better bearing technology. When you take the truck out of 4wd you disengage the front driveline at the transfer case but since the wheels are still locked to your driveline it is still spinning. Since it's still spinning the rotational mass of the driveline remains the same and you really gain no efficiency.

That may be the case in AWD vehicles, but there is no way true 4WD trucks leave the hubs locked all the time. New 4WD systems have a vacuum system that locks the hubs when 4WD is engaged and subsequently unlocks them. My truck actually has an "Auto" setting on the hubs, but I can physically lock them to ensure they are locked or if the vacuum system fails.

I'm still from the old school 4WD mindset that even in my 08 F350, I prefer to back the truck up after disengaging the 4WD just to make sure the hubs are fully unlocked.

[Pinner]

Oh man that is old school

[FlamesAddiction]

I have a 4x4 vehicle because my job requires that I drive down back roads and remote areas in all types of weather condition - not because I am trying to be a macho guy or anything.

I rarely ever use it on pavement. Only when I am moving slow or when I might get stuck. In fact, I heard it is harder on the transmission to use it on pavement or fast speeds.

[Titan]

We found out the hard way. My truck was in 4x4 and the wife drove it in a parkade. Round and round on dry cement. It was in the shop the next week replacing the front diff. I can't be too mad as she was taking me to the hospital due to kidney stones. I would have driven the truck off a cliff to make that pain go away!

[troutman]

Quien es mas macho? Lorenzo Lamas o Ricardo Montalban?

[Cowperson]

Originally Posted by Titan

We found out the hard way. My truck was in 4x4 and the wife drove it in a parkade. Round and round on dry cement. It was in the shop the next week replacing the front diff. I can't be too mad as she was taking me to the hospital due to kidney stones. I would have driven the truck off a cliff to make that pain go away!

It's always an "oh crap" moment when I realize I hadn't turned off the 4X4 when trying to do a tight turn in my city underground parking. Dry pavement + tight turns + 4X4 = doesn't work.

We live in the country, southwest of the city, and I've found through the years a 4X4 capability is pretty essential through the winter for getting around on lightly travelled roads early in the morning . . . . . my Durango is a lot of fun in wintery situations, dodging Elk on my snow-covered gravel road like I was this morning, or gunning it down a snowy Smith-Dorrien Trail in the mountains.

But the 4X4 is off on drier pavement or most of the summer.

Cowperson

[Locke]

Originally Posted by DuffMan

My Jeep grand Cherokee makes the decisions for me, like AWD.

Haha! Ditto. Theres no options for me so its All Wheel Drive, All the time!!!

ANd for the 'You're going to ruin you're drivetrain!!' crowd, this thing is a 1996 with 290,000 on it and going just fine.

[Boblobla]

edit: nm, I was like the 4th person to make the same joke...