2015 Jeep Renegade Trailhawk: The Renegade Rumble is Not a Dance
by Dan Edmunds, Director of Vehicle Testing on October 1, 2015
I've heard it every time I've taken our 2015 Jeep Renegade Trailhawk for a spin. It doesn't happen all the time, but it happens regularly in certain circumstances. And it stands out to me because it was totally absent from the early press sample I drove a few months ago.
What am I on about? I call it the Renegade Rumble, a low-level grumbling sound that comes from down low behind the driver's seat under the back of the vehicle somewhere. It's not terribly loud, but the low frequency nature of the thing hovers on the edge of being an outright vibration.
No one could ever accuse the Renegade of being a quiet vehicle. It's not like this is the only noise it makes. The exhaust is fairly buzzy, there are a few rpm ranges where it drones in certain gears, and it's a shoo-in for the Nobel lack-of-peace prize when it comes to the production of idle vibration.
But unlike those sounds, the rumble doesn't seem to correspond to anything that should be going on. It doesn't feel right.
The noise is most obvious when cruising steadily at or above 30 mph. If you forced me to pick, I'd say 32 mph is prime time.
I'm getting good at inducing it on command, especially on quiet residential streets. Starting at 25 mph, I'll slowly edge up my speed. It'll come on suddenly at 32 mph, accompanied by the gentle lurch of a shift. But it's not a shift because the rpms don't budge.
Sometimes I think I can still detect it when cruising at faster road speeds, but the higher background levels of wind and road noise make it hard to tell. Sometimes it reappears if I coast down gradually enough into the 30-35 mph speed range, sometimes not.
It would be easy to confuse this with a downshift mixed with the aforementioned raspy exhaust, a muffler resonance of some sort. But that's more of a thing when I'm on the throttle more aggressively, not poking along on level ground.
Besides, a simple test eliminates this possibility.
Remember, it comes on with the feel of a shift but the rpms don't change. That's one clue. Another is when I slip the tranny into neutral. The engine speed falls away, but the grumble lives on at the same frequency.
It didn't seem like a tire issue, but we had Stokes check them on their road-force balance machine to make sure. It's best to eliminate the easy stuff first. Everything checked out. They didn't even charge us.
At this point I visited a forum dedicated to the new Renegade and struck gold. There's a thread on this very issue, and a couple of posters were describing the same symptoms. One of them pointed out a further diagnostic step I hadn't thought to try, something that resonated with me because it lined up with a theory I had about the possible source: the rear differential or the four-wheel drive coupling that's mounted on its nose.
It's a simple check. Press the 4WD Lock button while the noise is present and force the coupling to engage. You're not supposed to do this on dry asphalt, but it doesn't hurt if you're driving straight ahead at residential speeds. The noise disappears pretty much entirely as the 4WD clutch engages. You can't drive around like that, but it's a supremely useful clue.
The rumble is still with us, but our Renegade seems OK to drive. The 4WD system works and the intermittent noise doesn't interfere with routine commuting. But it's not something we plan to ignore, especially since we have some idea of the source.
A dealer visit is our next move. We'll tell them what we know and see if the factory has seen enough of this to have engineered a fix. Fingers crossed.
Dan Edmunds, Director of Vehicle Testing