All wheel drive engaged?

[scooter]

I've noticed there seems to be no visual indicator that all wheel drive has engaged - meaning torque has been redirected in part to the rear wheels.... Am I missing something, or does this (indicator) not exist? I know on some other FWD cars that have traction control, there is an indicator that will alert the driver when traction control is activated.... I am starting to question whether or not my AWD is functioning. Could just be my imagination, but I seem to have less traction this year at times then I remember having in the past few winters....

[Petrucci914]

traction control and AWD are different, as well as 4WD. AWD is all wheels, ALL the time. Why would you need an indicator?

[millster]

Quote, originally posted by Petrucci914 »traction control and AWD are different, as well as 4WD. AWD is all wheels, ALL the time. Why would you need an indicator?Incorrect (in this case).The Vibe uses a viscous coupler on the rear driveshaft to transfer power to the rear wheels when the front wheels lose traction.It is an on-demand system, not a full-time system.

[Digger]

there is no indicator light or bell. It just engages

[zionzr2]

i light would be nice...

[djb383]

Does this mean that if all four corners on an AWD were jacked up off the ground and it was then placed in gear, that only the front wheels would turn? Just curiuos. Thanks.

[millster]

Hard to say, but I would think not.I'm not sure how the system determines loss of traction (probably by comparing wheel speed). But given the lock of a limited slip differential only one wheel would spin and I would think would trigger the AWD system.

[djb383]

Somebody here needs to lift all four corners off the ground, put the car in gear and post back how many wheels are turning. I thought AWD was four wheels with power all the time with the driver having no input. 4WD was four wheels having power, only when activated by the driver. In other words, 4WD can be disengaged by the driver and AWD cannot be disengaged by the driver.Some AWD Viber needs to set us straight. Thanks.

[joatmon]

The power transfer to the rear differential is by a viscous coupling. One description of a viscous coupling is at http://auto.howstuffworks.com/differential9.htmIf you jacked up all four wheels, and ran it in drive, I think all four wheels should spin. The transaxle would spin the front wheels and also the shaft to the rear differential.; The viscous coupling on the front end of the rear diferential would experrience difference in spin between the two shafts, and the friction of the viscous coupling would transfer torque to the rear differntial. Depending on the differential slip however, you might see one front wheel spinning faster than the other front wheel, and one rear wheel spinning faster than the otherr front wheel, but there shouldbe at least one front and one rear wheel spinning. If anyone tries this, please be sure the car is secure, we don't need any Bueller moments.If you truly are having traction issues due to the rear wheels not getting enough power, then it could be caused by a viscous coupling, especially if the coupling wasn't as viscous as it should be. Before suspecting that as a cause of traction issues, I'd check the tires first.

[BlueCrush]

Quote, originally posted by silverawd26 »Rear wheels only engage when the front wheels are slipping on the 03 + Vibe/Matrix.Now, if the Vibe had a TRUE AWD system like Subaru, then if you put the vehicle up on blocks and hit the gas, then you would see all the wheels spin. As of right now, the Vibe/Matrix AWD system does not work that way. When up on blocks or lift and in drive if the front wheels are spinning and the rears are not it will automatically engage the rears so all 4 will then be spinning. Same as when you are driving in snow and the front wheels start spinning the the rears will engage. I tried it while on a lift last spring and yes all 4 wheel were spinning after about a second of just the front wheels spinning.

[zionzr2]

Quote, originally posted by BlueCrush »When up on blocks or lift and in drive if the front wheels are spinning and the rears are not it will automatically engage the rears so all 4 will then be spinning. Same as when you are driving in snow and the front wheels start spinning the the rears will engage. I tried it while on a lift last spring and yes all 4 wheel were spinning after about a second of just the front wheels spinning.FINALY a confirmation!!!

[djb383]

I think Joatmon has the right idea. The front and rear wheels are constantly connected to each other by a viscous coupling and therefore all four would turn. Under dry road conditions, both front and rear wheels are applying equal driving force to the ground. When unequal front to rear traction occurs (wheel slip) the viscous coupling changes the driving force from 50/50 to lets say 70/30, as an example. Both front and rear are always connected by the viscous coupling, maybe not 50/50 but still connected, thus making the system full-time AWD. There are different ways to connect the front and rear wheels together, and a viscous coupling is just one way to accomplish this. Just my $0.02.

[ToolGuy]

I better statement of an AWD system that is not really true All Wheels Driving are 4X4's... For example my Blazer and Cherokee, if stuck, one front and one apposing rear wheel would sit and spin, not ALL 4 wheels. Sure if you added or the vehicle had the option of a locking diff, that would be different but most 4x4's out of the showrooms do not.

[joatmon]

I think that under dry road conditions, the driving force is provided entirely by the front wheels. The rear wheels would be rotating at the same speed as the front wheels, there would be no slip between front and rear, there would be no shear inside the viscous coupling, so there would be no torque coupled viscouslsy to the rear differential, the rear would be floating along.I just noticed this was scooter's first post, so Hey scooter, welcome to genvibe!

[jasonvibe]

Bluecrush, that all sounds good. But in reality that is not what happens. I watched my left front and right rear spin in the snow on my ski slope driveway. NEVER will all 4 wheels drive for more than a second. After that just one front and one rear. ONLY When I gased it hard would all 4 wheels dig in. Then only for a second. THESE do not have limited slip or posi-traction. AWD means there is the potential for any wheel to be driven. Nothing more.. Otherwise only front wheel(s) receive power.....I do not know how a Subaru is better as others mention.

[djb383]

And a lot of 4WD vehicles have a traction enhanced rear diff but have an open front diff.

[jasonvibe]

so what's your point. Don't compare apples to grapes. Both are fruit...that's it.