Downsides two four-wheel drive engaged?

17 years ago I had a Volvo v60. Loved that car. All-wheel drive Rock solid. Drove like a tank. Leaky power steering fluid slowly caused the steering to fail over the course of about 6 months. I didn't notice it until someone else told me they could not park the car. They could not turn the wheel at all. I had learned to aim for the wet spots. And built up gorilla arms and shoulders without realizing it.

I've had a 2006 GMC Yukon for 3 years. Some type of tow upgrade and possibly transmission fluid cooler edition. I'd have to really look at it and it's cold out so I'm not going to right now.

Rarely drove it except for required errands. Love the height, love the comfort, love love love love love. Hate the gas mileage. Dislike the loose steering as compared to my Kia Niro but accepted it as something from 2006. All my cars back then had loose steering. My hands auto corrected for it.

It snowed last night and M wanted to meet at the diner in town for breakfast when she got off work. Great, I'll see you there at 7:00.

Turned it on at 6:00 to let it warm for a bit, did a walk around with a thin wooden board to knock all the snow off and was on my way. I used the high gear four-wheel drive for the first time other than testing.

Yes I know not to believe you can stop because of four-wheel drive or that you won't skid. If I can feel g-forces on a curve I'm going too fast.

So I'm cruising along at anywhere between 15 and 25 down a curvy snowy mountain road and the four-wheel drive locks me in perfectly and maintains whatever downhill speed via gear/engine braking for the most part and the steering is perfect. As good as my Volvo if not better. All the sudden this thing became the best vehicle in the world.

Regular slightly wet highway was just as good, if not better.

Right now it gets terrible gas mileage so I drive it rarely anyway but when I do it seems to me that it's worth it just to leave it in four-wheel drive for normal driving.

So what else do I need to pay attention to concerning usage and maintenance? I will not be doing any four-wheeling on any muddy hillside. This is simply 20 minutes to and back with an occasional wander around.

I'm no expert, but I don't think that you'll be wearing anything out more than it's already worn out.

[ Thinking out loud... ]

In olden days, you didn't want to leave trucks in 4WD mode because they didn't have clutches, etc., to handle the wheels turning at different speeds for long periods of time. They needed to be able to slip the wheels.

Ever since the days of Audi starting to put 4WD in everything, since the advent of cheap clutch systems for 4WD, I think [but see below!] it's been less of an issue.

AFAIK, the only issue with keeping newer things in 4WD mode is potentially greater tire wear, maybe more noise, and maybe a little worse mileage.

Let's see what the actual experts say... GMC.com:

HIGH-RANGE FOUR WHEEL DRIVE

High-range four-wheel drive, marked as “4↑” on most transfer cases, is designed for use on loose or slippery surfaces. In this setting, the front axle is engaged, and the transfer case then sends power to both the front and rear axles and to all four wheels.   

This mode forces the front and rear axles to spin at the exact same speed. Due to minor tire size differences and track length differences when turning, the front and rear axles can ‘fight’ against each other on high-friction surfaces and results in a condition sometimes known as ‘crow hop’ as tires are forced to slip to the ground. 

Since GMC’s transfer cases are designed to be “shifted on the fly,” drivers can shift between high-range two-wheel drive and high-range four-wheel drive without bringing the vehicle to a halt. On electronic transfer cases, an indicator on the selector knob will flash while the shift is being performed and turn solid once it’s fully engaged. For trucks equipped with a manual transfer case, an indicator within the gauge cluster will illuminate.

  It’s important to note that high-range four-wheel drive is not intended to be used on dry surfaces or roads with good traction. Doing so may place undue stress on axles, transfer cases, and other drivetrain components which could lead to damage. It’s important to remember to shift out of 4 HI as soon as road conditions improve.

So, they apparently don't have the clutches and smarts that Audis have had for years, and you don't want to leave them in 4WD mode all the time.

HTH!

Best wishes,
Scott.

Post #445,353 by crazy 2/4/25 1:07:16 PM 2/4/25 1:07:16 PM Reply	Downsides two four-wheel drive engaged? 17 years ago I had a Volvo v60. Loved that car. All-wheel drive Rock solid. Drove like a tank. Leaky power steering fluid slowly caused the steering to fail over the course of about 6 months. I didn't notice it until someone else told me they could not park the car. They could not turn the wheel at all. I had learned to aim for the wet spots. And built up gorilla arms and shoulders without realizing it. I've had a 2006 GMC Yukon for 3 years. Some type of tow upgrade and possibly transmission fluid cooler edition. I'd have to really look at it and it's cold out so I'm not going to right now. Rarely drove it except for required errands. Love the height, love the comfort, love love love love love. Hate the gas mileage. Dislike the loose steering as compared to my Kia Niro but accepted it as something from 2006. All my cars back then had loose steering. My hands auto corrected for it. It snowed last night and M wanted to meet at the diner in town for breakfast when she got off work. Great, I'll see you there at 7:00. Turned it on at 6:00 to let it warm for a bit, did a walk around with a thin wooden board to knock all the snow off and was on my way. I used the high gear four-wheel drive for the first time other than testing. Yes I know not to believe you can stop because of four-wheel drive or that you won't skid. If I can feel g-forces on a curve I'm going too fast. So I'm cruising along at anywhere between 15 and 25 down a curvy snowy mountain road and the four-wheel drive locks me in perfectly and maintains whatever downhill speed via gear/engine braking for the most part and the steering is perfect. As good as my Volvo if not better. All the sudden this thing became the best vehicle in the world. Regular slightly wet highway was just as good, if not better. Right now it gets terrible gas mileage so I drive it rarely anyway but when I do it seems to me that it's worth it just to leave it in four-wheel drive for normal driving. So what else do I need to pay attention to concerning usage and maintenance? I will not be doing any four-wheeling on any muddy hillside. This is simply 20 minutes to and back with an occasional wander around.
Post #445,354 by Another Scott 2/4/25 7:13:50 PM 2/4/25 7:13:50 PM Reply	2006? I'm no expert, but I don't think that you'll be wearing anything out more than it's already worn out. [ Thinking out loud... ] In olden days, you didn't want to leave trucks in 4WD mode because they didn't have clutches, etc., to handle the wheels turning at different speeds for long periods of time. They needed to be able to slip the wheels. Ever since the days of Audi starting to put 4WD in everything, since the advent of cheap clutch systems for 4WD, I think [but see below!] it's been less of an issue. AFAIK, the only issue with keeping newer things in 4WD mode is potentially greater tire wear, maybe more noise, and maybe a little worse mileage. Let's see what the actual experts say... GMC.com: HIGH-RANGE FOUR WHEEL DRIVE High-range four-wheel drive, marked as “4↑” on most transfer cases, is designed for use on loose or slippery surfaces. In this setting, the front axle is engaged, and the transfer case then sends power to both the front and rear axles and to all four wheels.    This mode forces the front and rear axles to spin at the exact same speed. Due to minor tire size differences and track length differences when turning, the front and rear axles can ‘fight’ against each other on high-friction surfaces and results in a condition sometimes known as ‘crow hop’ as tires are forced to slip to the ground.  Since GMC’s transfer cases are designed to be “shifted on the fly,” drivers can shift between high-range two-wheel drive and high-range four-wheel drive without bringing the vehicle to a halt. On electronic transfer cases, an indicator on the selector knob will flash while the shift is being performed and turn solid once it’s fully engaged. For trucks equipped with a manual transfer case, an indicator within the gauge cluster will illuminate.   It’s important to note that high-range four-wheel drive is not intended to be used on dry surfaces or roads with good traction. Doing so may place undue stress on axles, transfer cases, and other drivetrain components which could lead to damage. It’s important to remember to shift out of 4 HI as soon as road conditions improve. So, they apparently don't have the clutches and smarts that Audis have had for years, and you don't want to leave them in 4WD mode all the time. HTH! Best wishes, Scott.
Post #445,355 by crazy 2/4/25 8:58:24 PM 2/4/25 8:58:24 PM Reply	That's the type of stuff I needed to know Thanks.

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