Nuts & Bolts: Solved! Jeep Grand Cherokee Bind
Nuts & Bolts
I recently bought a 2007 Jeep Grand Cherokee with a Hemi and the Quadra-Drive II system. It’s in great shape and only has 72,000 miles on it. The morning after I bought it, I was pulling out of my driveway and turning into the street when I heard this binding/groaning noise coming from the front end, almost like the Jeep was in four-wheel drive when it wasn’t. This noise continued every time I turned for maybe 10 minutes and then suddenly went away. It does this just about every time it’s cold, but the noise goes away once the Jeep warms up. Everything looks to be in great shape on the front end, with nothing visually wrong. No lights or codes. The only thing I can figure is maybe something is wrong with the transfer case. Any ideas?
We recently had the same issue on a 2005 Grand Cherokee. According to several forum threads, it is somewhat common to this generation of Grand Cherokee. The forum jockeys blame everything from the wrong oil in the differentials to bad bushings, while it appears that a few shops and dealerships have misdiagnosed the issue as the transfer case and have handed customers a repair bill for a couple grand while not fixing the problem. With such low miles it is highly doubtful that the transfer case is the culprit. Here’s hoping your fix is as easy as ours—under $80. Read on.
The Quadra-Drive II is a pretty neat but rather complicated full-time 4WD system. The NV245J transfer case has full-time Hi as well as 4-Hi and 4-Lo. In full-time mode there is a clutch pack in the transfer case that sends varying amounts of power to the front and rear axles depending on traction conditions. This is the same transfer case that’s in the Quadra-Trac II systems in the earlier WJ Grand Cherokees, but what makes the Quadra-Drive II system different is the electronically controlled front and rear limited-slip differentials (ELSDs). Both the clutch in the transfer case and the ELSDs are hooked to the traction control system, which can regulate the amount of slip between the front and rear outputs while also varying the amount of slip allowed between the tires on each axle. According to factory literature, the ELSDs can be entirely unlocked just like an open differential and can add varying amounts of resistance to the point that they can even lock up, making them act like a locking differential. That’s a lot of moving parts and electronic gadgetry, but as long as everything works, the system is pretty slick.
The ELSDs are controlled by a solenoid that regulates the amount of slip allowed between the tires. This solenoid can start sticking, which causes the limited-slip to tighten up when it shouldn’t. The traction control system doesn’t know that the solenoid is stuck, as there is no feedback to the electronic nannies, so it often doesn’t throw any codes or lights. For whatever reason, once the oil in the differential starts warming up, the solenoid frees up and starts working as it should. For equally unknown reasons, these sticky solenoids usually happen on the front axle. It could be simply because the front tires spend more time rotating at different speeds, or it could be that the front sticking is simply more noticeable.
Let the vehicle sit overnight. Then with the vehicle in Park, jack up the front end so that both tires are off the ground. The front tires should spin opposite each other with very little resistance, just like an open differential. If they don’t, lower the vehicle and drive it around until the binding noise goes away. Jack the vehicle up again and see if the front tires spin freely. If they do, you have a sticky solenoid. If they don’t, disconnect the pigtail on top of the front differential housing and spin the tires again. If they free up, then there’s likely a wiring or electronic issue.
Fortunately a genuine Mopar ELSD solenoid can be had for about $60. The service manual calls for removing the front differential to change it, but that’s not necessary. Unbolting the front mount allows the differential to rotate enough to remove the inspection cover on the front axle without tearing apart the whole front end. The solenoid itself is a simple R&R. Don’t forget to add friction modifier to the gear oil when you fill it back up, and be sure to use 75W-140 synthetic.