AWD vs. 4WD, which is preferable?
12-18-2007, 10:50 PM
#21
SeaRay Sundancer
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Well tell ya' what, you define "locking" for me. I'm pretty sure I understand the difference between the transfer case splitting power to the front axle and "locking" the front axle. When 4WD is activated, it's pretty obvious when you turn that the front axle is locked.
As for the rear diff, GM's unit isn't a clutch type, at least not what I think of (like an Auburn) when I think clutch type diff. It's made by Eaton, and it's totally open unless you spin a wheel below 20mph. If you spin a wheel at slow speed, it spins weights inside the diff to "lock" both wheels. The axle will stay locked until you go over 20mph. The engagement is about the worst I've felt, and in my truck it's pretty easy to spin a wheel over the "disengage" speed before it ever engages.
As for the rear diff, GM's unit isn't a clutch type, at least not what I think of (like an Auburn) when I think clutch type diff. It's made by Eaton, and it's totally open unless you spin a wheel below 20mph. If you spin a wheel at slow speed, it spins weights inside the diff to "lock" both wheels. The axle will stay locked until you go over 20mph. The engagement is about the worst I've felt, and in my truck it's pretty easy to spin a wheel over the "disengage" speed before it ever engages.
How does GM define front axle locking....you have now locked the front diff into 4WD. Feel free to look it up yourself....there is nothing in the factory front diff of your truck. Its an open 8.25" aluminum case POS. I have the same thing. Would break if a locker was in there. What you feel when you put it in 4wd is the weight of your truck and input torque from the motor. Both tires will spin/pull with equal resistance on them....its the way an open diff works. You can turn b/c its open, otherwise your tires would chirp, and the axles would chatter about and you would kinda plow forward. The rear G80, govlock, or whatever, is called a locker and it does sometimes lock under 20 mph. But it takes one wheel spinning, the other not, and nothing over 20mph to do it. Overall its a very week unit. A real auto locker like a detroit, that has weights too, should always engage when power is applied, and free wheel when not, so you can turn easier. Badabing
12-19-2007, 11:50 AM
#22
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What they mean by locking front axle is how the axles are locked to the diff.
Chevy's do not have locking hubs, the axles are directly attached to the break rotors/wheels. The disconnecting of the axles from the diff is done at the differential by an electric sleeve. Auto locking means you don't have to get out and manually lock the hubs (axles to the diff). There is still just an open differential.
Ford uses auto/manual hubs on its trucks, a much better design IMO.
I prefer 4x4, not all wheel. AWD takes a lot more power to turn, uses more fuel and compromises on 4wd function. Plus, if I want to light up the rear tires and put the truck sideways, it just isn't happening on AWD. Thats why I hate the trailblazer SS.. could have been such a cool truck, but they put AWD in it.
Joe
Chevy's do not have locking hubs, the axles are directly attached to the break rotors/wheels. The disconnecting of the axles from the diff is done at the differential by an electric sleeve. Auto locking means you don't have to get out and manually lock the hubs (axles to the diff). There is still just an open differential.
Ford uses auto/manual hubs on its trucks, a much better design IMO.
I prefer 4x4, not all wheel. AWD takes a lot more power to turn, uses more fuel and compromises on 4wd function. Plus, if I want to light up the rear tires and put the truck sideways, it just isn't happening on AWD. Thats why I hate the trailblazer SS.. could have been such a cool truck, but they put AWD in it.
Joe
12-19-2007, 02:30 PM
#23
SeaRay Sundancer
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What they mean by locking front axle is how the axles are locked to the diff.
Chevy's do not have locking hubs, the axles are directly attached to the break rotors/wheels. The disconnecting of the axles from the diff is done at the differential by an electric sleeve. Auto locking means you don't have to get out and manually lock the hubs (axles to the diff). There is still just an open differential.
Ford uses auto/manual hubs on its trucks, a much better design IMO.
I prefer 4x4, not all wheel. AWD takes a lot more power to turn, uses more fuel and compromises on 4wd function. Plus, if I want to light up the rear tires and put the truck sideways, it just isn't happening on AWD. Thats why I hate the trailblazer SS.. could have been such a cool truck, but they put AWD in it.
Joe
Chevy's do not have locking hubs, the axles are directly attached to the break rotors/wheels. The disconnecting of the axles from the diff is done at the differential by an electric sleeve. Auto locking means you don't have to get out and manually lock the hubs (axles to the diff). There is still just an open differential.
Ford uses auto/manual hubs on its trucks, a much better design IMO.
I prefer 4x4, not all wheel. AWD takes a lot more power to turn, uses more fuel and compromises on 4wd function. Plus, if I want to light up the rear tires and put the truck sideways, it just isn't happening on AWD. Thats why I hate the trailblazer SS.. could have been such a cool truck, but they put AWD in it.
Joe
Ahhhh...you can get the TBSS in both AWD and RWD. I test drove on 08 RWD the other day (very bad azz.) Im getting an AWD for my wife.
12-21-2007, 09:56 AM
#24
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As quoted from my 2001 Yukon XL owner's manual:
So GM's 4WD front axle will indeed LOCK via electronic device. The rear axle is GM's excuse of a "locking" diff, but it does work at low speeds and throttle input, like a slippery ramp. A true limited slip would be great; do they make one for the 14-bolt axle?
So GM's 4WD front axle will indeed LOCK via electronic device. The rear axle is GM's excuse of a "locking" diff, but it does work at low speeds and throttle input, like a slippery ramp. A true limited slip would be great; do they make one for the 14-bolt axle?
My suburban had auto locking front hubs. When you put it in 4x4 and hit the the gas, the front hubs would lock. This would likely be referred to in the manual as the axle locking up, becuase the manual is usually pretty well dumbed down.
In my S10, there was a vacuum switch on the transfer case that actuated a function similar to a locking hub, except it was at the front differential. The axles always spun with the wheels (IFS, so halfshafts actually) but the front driveshaft would not turn with the front halfshafts unless this little vacuum switch told it to. I'm not sure if this locked the halfshafts to the diff, or the axle to the diff, but one way or the other it "locked up" the front axle. And it was most certainly an open differential, whether it was "locked" or not.
Lots of confusing use of the term "locked" floats around. It takes some experience with different vehicles to really understand what's going on.
12-22-2007, 10:47 AM
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As quoted from my 2001 Yukon XL owner's manual:
So GM's 4WD front axle will indeed LOCK via electronic device. The rear axle is GM's excuse of a "locking" diff, but it does work at low speeds and throttle input, like a slippery ramp. A true limited slip would be great; do they make one for the 14-bolt axle?
So GM's 4WD front axle will indeed LOCK via electronic device. The rear axle is GM's excuse of a "locking" diff, but it does work at low speeds and throttle input, like a slippery ramp. A true limited slip would be great; do they make one for the 14-bolt axle?
The GM rear is a complicated locker that sometimes works and sometimes doesen't. It is much less noticable on the street than a detroit, lockright, etc. and that is the purpose. There are plenty of Limited slips available for the 14 bolt but they are no better than what you have and will not completely lock. YOu can get lockers that actually work for the 14 bolt, but you probably won't like them on the street.
There are way too many different AWD systems out there to lump into one category. The quadradrive in Grand Cherokee's works very well on the street and off road and will actually lock the differentials, even the front. The denalli is setup for slick roads and works great for that, but offroad you will be disappointed. I drive a navigator and it has AWD 4 high and 4 low, and I very seldom touch the switch. I get a little better mileage than my dads f150 without AWD too.
If any of you guys want a demonstration of locked and unlocked let me know.
This is locked at both ends
Last edited by 320es; 12-22-2007 at 10:56 AM.
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