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Jeep

Grand Cherokee SRT8 2006-2009 - pro-active automatic all wheel drive. In normal conditions, 100% of torque is transferred to the rear axle. This system is sold under the name of Quadra-Trac I, however it is not a full-time all wheel drive, as on the other Grand Cherokees.

Grand Cherokee WK 2005-..., Commander XK 2006-... - Equipped with one of the following four wheel drive systems:

Quadra-Drive II - full-time all wheel drive system. 48/52 percent torque split (front/rear). Electronically-controlled multi plate clutch pro-actively locks the center differential. 2.72:1 low-range mode. Electronic Limited Slip Differentials (ELSD) front and rear.

ELSD is the Eaton EGerodisc - a hydraulically-operated electronically controlled limited slip differential that is capable of providing variable torque up to full axle lock:
Quadra-Trac II - Same as Quadra-Drive but without the ELSD. Instead, an electronic traction control - Brake Traction Control System (BTCS) - is used to transfer torque from left to right.

See: WK Grand Cherokee 4x4

Grand Cherokee WJ 1999-2004 - Equipped with one of the following four wheel drive systems:

Quadra-Drive - automatic all wheel drive (standard on "Limited", optional on "Laredo"). Normally rear-wheel drive vehicle. The differential is the hydromechanical system based on geroter oil pump and clutch pack, located within the transfer gearbox between the driveshafts that carry power to the front and rear axles. One part of the pump, the rotor, is driven by the front driveshaft while the other part, it's case, is attached to the rear driveshaft. The system reacts faster than the viscous coupling unit of the previous Jeep AWD system. The reaction time is about 40 milliseconds. The transfer box can be also locked in low-range mode to provide equal power to the front and rear axles.
Progressive Vari-Lok gerodisc differentials front and rear, using the same geroter pump system. Almost 100% of torque can be transferred to any wheel.
NV247 AWD transfer case with lever-operated 2.72:1 low-range gear.
Dana 30 non-disconnect live axle at front, aluminum central section Dana 44 at rear.
Quadra-Trac II - automatic all wheel drive. NV247 transfer case. The same as Quadra-Drive but without the Vari-Lok differentials.
Quadra-Trac I - automatic all wheel drive. NV140 - a version of the NV247 transfer case lacking neutral and low-range modes (2004 only).

Figure: Jeep Grand Cherokee Quadra-Drive transmission

See: WJ Grand Cherokee 4x4

Grand Cherokee ZJ 1993-1998 - Equipped with one of the following four wheel drive systems:

Command-Trac - part-time all wheel drive with shift-on-the-fly possibility (used until 1996). 2.72 low range.
Selec-Trac - selectable all wheel drive. NV242 transfer case.
Quadra-Trac - full-time all wheel drive system. A viscous coupling locking center differential.
In 1993-1995 the viscous coupling was used to lock the differential when in low range (NP249 transfer case). In 1996-1998 the differential is mechanically locked when in low range (NV249 transfer case).

Figure: Jeep Grand Cherokee Quadra-Drive II (? not sure, needs verification)

See: Four wheel drive systems by vehicle

See: Wikipedia

Last updated: 2010-04-18 10:57

There are 4 comments

mike

July 27, 2010 - 00:11

Subject: 1998 jeep grand cherokee 5.9 limited (quadra-trac) and 4.0 laredo (selec-trac)

The most basic question:

AWD=four tire replacement policy

4x4=does not

How do I know -- FOR SURE -- whether or not a vehicle is a pure 4x4 or an AWD?

Do I have to replace all four tires on either of these vehicles (see subject line)? An AWD requires all the tires to be near exact. However a 4x4 does not (as I understand it). From what I have read, I think the quadra-trac requires all four tires to be exact. And the select-trac would also, if placed in the full-time four wheel drive.

Am I correct? Please help me understand the reason why I am or am not.

I have been unable to locate any site that indicates which vehicles have the four tire replacement policy.

Thank you.

Reply to mike

awd.ee

July 28, 2010 - 10:36

Subject: Re: 1998 jeep grand cherokee 5.9 limited (quadra-trac) and 4.0 laredo (selec-trac)

Hi, let's move away from using the "4x4" and "AWD" terms, because noone knows what they mean for sure

The answer for your question is yes, you must use all four tires of the same model and the same wear for both quadra-trac and select-trac systems.

In theory, you can use different tires for select-trac if you know what you are doing and you are not planning on using the four wheel drive mode.

Reply to mike

George

August 17, 2010 - 02:19

Subject: What you looking to do?

Worn tires? Slightly different tire sizes?

The NVG249 transfer case utilizes a viscous coupling clutch to power the front axle. I would keep the axle speed difference at less than 2% [putting the new tires on the rear]

The NVG242 transfer case has a center differential, 48/52 split. I would keep the axle speed difference at less than 1% (assuming you are actually using four wheel drive, not just the rear drive setting) again putting the new tires on the rear axle.

George

October 31, 2009 - 22:14

Subject:

Chrysler still offered the NVG242 transfer case in the WJ Grand Cherokee.