2003 Chevy Tracker with F***ed up 4-wheel Drive

[spirited09wrx]

So my gf is driving a 2003 chevy tracker, and when you engage 4x4 (uses the lever behind the shifter) turning becomes very difficult, jumpy, and it almost feels like one of the front wheels is being dragged sideways. Its been taken for an alignment check, and also to fill up the oil in the transfer case. Nobody seems to be "finding anything wrong"

Does anyone know why this is happening or what would be causing this?

Thanks ahead of time.

[Donkey]

And the Chevy forum had what to say about this problem?

[spirited09wrx]

Didn't post on one yet, just thought there enough people here with a decent mechanical aptitude of cars and their problems to at least point me in the right direction. I guess that direction is to post it on a different forum...

[Trainrex]

Is this happening on dry pavement when you turn?

[dbya rx]

the reason no one is finding anything wrong is probably because there is nothing wrong. subaru wrx's are all wheel drive, which means a computer is constantly figuring out which drive axle needs power based on calculating slippage, yaw rate, and probably hundreds of other things. Your transfer case 4X4 chevy tracker has nothing like the subaru system. when the 4X4 is not engaged, the motor is sending power to the rear axle, and probably to just one side since rear wheel 4X4 vehicles like that usually have one main drive wheel on the rear axle. When you shift that transfer case into 4X4, the power is then split between the front and rear axles.

now, when you turn the wheel of your vehicle and are moving forward (or backward for that matter) the wheels that are on the outside of the turn you are completing travel a further distance than the wheels on the inside of the turn, which is why we have differentials, which allow drive wheels to spin at different rates based on turning radius.

when you lock that front axle transfer case and put the car into 4X4, it puts more pressure on the differential because now it actually has power to it, and it feels like it is binding when you are turning.

I had a toyota tacoma 4X4 with locking hubs and a transfer case, and it did the same thing. especially when i was turning the wheel going slowly, like trying to get into a parking spot.

thats the best explanation I have, and I think its normal, unless this is something that JUST started happening.

[Trainrex]

the reason no one is finding anything wrong is probably because there is nothing wrong. subaru wrx's are all wheel drive, which means a computer is constantly figuring out which drive axle needs power based on calculating slippage, yaw rate, and probably hundreds of other things. Your transfer case 4X4 chevy tracker has nothing like the subaru system. when the 4X4 is not engaged, the motor is sending power to the rear axle, and probably to just one side since rear wheel 4X4 vehicles like that usually have one main drive wheel on the rear axle. When you shift that transfer case into 4X4, the power is then split between the front and rear axles.

now, when you turn the wheel of your vehicle and are moving forward (or backward for that matter) the wheels that are on the outside of the turn you are completing travel a further distance than the wheels on the inside of the turn, which is why we have differentials, which allow drive wheels to spin at different rates based on turning radius.

when you lock that front axle transfer case and put the car into 4X4, it puts more pressure on the differential because now it actually has power to it, and it feels like it is binding when you are turning.

I had a toyota tacoma 4X4 with locking hubs and a transfer case, and it did the same thing. especially when i was turning the wheel going slowly, like trying to get into a parking spot.

thats the best explanation I have, and I think its normal, unless this is something that JUST started happening.

Well, you're close. Regular WRX's don't have any of the fancy electro-doodads. Just a limited slip center diff. The Tracker has a fully locked transfer case acting as the center diff when 4wd is engaged. Both vehicle's front and rear differentials are capable of slipping from left wheels to right. If the front diffs weren't capable of slipping, you wouldn't be able to steer due to the difference in wheel speed from left to right when steering.

Now, when you steer your WRX in a tight turn, the inside front wheel is spinning faster than the rear wheels, and your outer front wheel is spinning slower. When this happens, the center diff slips to allowing it to steer without binding.

When you put the Tracker in 4wd, it locks the transfer case (center diff). No slip at all. So if you are tring to turn tight on dry surfaces, the front wheels are trying to go different speeds than the rears and will skip, jump, and lurch. You don't notice it in slippery conditions because the tires can slip a little on the slippery surface.

[spirited09wrx]

Dry, wet, everything...the explanation about the transfer case/differential makes sense( or at least sounds legit lol). It just seems stupid that it affects the driving so much that her 92 escort wagon was better in snow :/

[zax]

subaru wrx's are all wheel drive, which means a computer is constantly figuring out which drive axle needs power based on calculating slippage, yaw rate, and probably hundreds of other things.

Uh, no. Unless you are referring to the STi drivetrain, the computer is not even involved -- everything is mechanical. Even the DCCD is only an electromagnetic clutch that varies the center diff's propensity to lock. The 4EAT is the closest to what you've suggested but still far removed. If you want all the things you've listed, you'll have to spring for Haldex, Acura's SH-AWD, Mitsu's SAWC, BMW X-drive, or just about any other AWD system on the market. Subaru AWD is as basic as they come...

[dbya rx]

i guess i was close. "you were on the right track" as they say...

thats why i should stick to crap that i know about, body work hahaha

[teflon_jones]

My truck was doing the same thing this morning because I was in 4WD on dry pavement (snowy at my house, dry by the time I got to day care). Perfectly normal, but not healthy for your front diff.

I wouldn't blame the 4WD for the Tracker not handling well in snow. I'm betting it's running crappy all-season tires right?

My truck has a very simple old 4WD system. I drove it up a steep, icy/snowy hill and over a 4' snowbank onto the road this morning from where it was parked and it never even slipped. Good tires make all the difference. With all-seasons, the truck never would have made it anywhere.

[spirited09wrx]

My truck was doing the same thing this morning because I was in 4WD on dry pavement (snowy at my house, dry by the time I got to day care). Perfectly normal, but not healthy for your front diff.

I wouldn't blame the 4WD for the Tracker not handling well in snow. I'm betting it's running crappy all-season tires right?

My truck has a very simple old 4WD system. I drove it up a steep, icy/snowy hill and over a 4' snowbank onto the road this morning from where it was parked and it never even slipped. Good tires make all the difference. With all-seasons, the truck never would have made it anywhere.

I keep meaning to check the tires, Im assuming thats what are on there. I wouldnt doubt if they were all seasons and running low on tread too...

[KHP]

Uh, no. Unless you are referring to the STi drivetrain, the computer is not even involved -- everything is mechanical. Even the DCCD is only an electromagnetic clutch that varies the center diff's propensity to lock. The 4EAT is the closest to what you've suggested but still far removed. If you want all the things you've listed, you'll have to spring for Haldex, Acura's SH-AWD, Mitsu's SAWC, BMW X-drive, or just about any other AWD system on the market. Subaru AWD is as basic as they come...

Hmm.. from what I understand the newer WRX's have a limited slip center differential and fully open rear and front diffs. Subaru then used a part of the brake distribution system to make up for the lacking of front and rear limited slip diffs. They partially activated the brakes on the slipping wheels to redirect power to wheels that have traction. I maybe completely wrong on this, but I'm pretty sure I remember reading about it somewhere.

[dbya rx]

this is from subaru's website about symmetrical all wheel drive:

"MODELS WITH FIVE-SPEED MANUAL TRANSMISSION – CONTINUOUS ALL-WHEEL DRIVE: A viscous-type locking center differential and limited-slip rear differential help distribute torque – normally configured at a 50/50 split front to rear. If wheel speed differs between front and rear axles, the center and/or rear differentials lock up to help distribute power to the wheels with the most traction.

MODELS WITH FOUR-SPEED AUTOMATIC TRANSMISSIONS – ACTIVE ALL-WHEEL DRIVE: An electronically controlled variable transfer clutch and limited-slip rear differential distribute power to where traction is needed. Sensors monitor parameters such as wheel slippage, throttle position, and braking to help determine torque distribution and direct it to the wheels with optimum traction.

MODELS WITH FIVE-SPEED AUTOMATIC TRANSMISSION – VARIABLE TORQUE DISTRIBUTION ALL-WHEEL DRIVE: As with Active All-Wheel Drive, an electronically controlled variable transfer clutch distributes power, but through a planetary-type center differential and a viscous-type limited-slip rear differential. Torque distribution is normally configured at a performance-oriented rear-wheel-biased 45/55 split front to rear. Sensors monitor the same parameters as for Active All-Wheel Drive.

WRX STI, WITH SIX-SPEED MANUAL TRANSMISSION – DRIVER CONTROLLED CENTER DIFFERENTIAL (DCCD) ALL-WHEEL DRIVE: The STI uses an electronically managed multi-plate transfer clutch and a mechanical limited-slip differential in conjunction with a planetary-gear-type center differential to control power distribution between the front and rear wheels. Featuring manual and three automatic modes, DCCD is normally configured at a 41/59 split front to rear. Sensors monitor parameters such as wheel slippage, steering angle, throttle position, and braking to help determine torque distribution and direct it to the wheels with optimum traction. DCCD also features a limited-slip helical front and Torsen® rear differential."

I was kind of correct in my explanation

[zax]

Ah, that is correct. The older (2002-2007) used viscous locking center diffs and viscous limited slip rear differentials. In 2008+ the limited slip rear diff was replaced with an open diff and the brake force distribution system was used to mimic the behavior of the limited slip rear diff. Good stuff. Guess I'm wed to the past