Drive line vibration

darryl2005

My son noticed a vibration problem with our grand Cherokee 3.7 awd. And starts once the speed is 65 or more under acceleration. This only happens on the highway traveling 70-80mph. We have been advised that the transfer case needs to be replaced and the drive shaft balanced. From what I have heard the drive shaft for this car cant be balanced. Any feedback as to the actual cause is welcomed so I can avoid spending money needlessly replacing one part and finding the problem still exists.

0patience

Have you had the tires balanced first?
Driveshafts don't just come out of balance, unless you hit something, knocked a weight off or the u-joints are bad.

Before replacing the driveline or transfer case (have no idea where they came up with that), check the u-joints and see if they are tight and no play in them and see about having the tires balanced.

My bet is you have a tire balance problem or broken belt.

Question though, who advised you to balance the driveshaft and replace the transfer case?

darryl2005

The mechanic at midas. My son has taken the jeep off road onto to rutted roads when hunting. I had been thinning maybe they bottomed out and bent it slightly which your response seems to confirm. did not realize they have weights on them. If the u joints were bad would they result in vibration or a clicking noise which is not being heard, only the vibrations and lack of power when going 68+ thank you for taking the time to help out with this issue as we want to repair the car and do it right the first time,

PF_Flyer

Since it's a very specific circumstance when you have the vibration, an out of balance SOMETHING would seem to make sense. It's like you're hitting a resonant frequency at 68+ and accelerating. Start simple and inexpensive. Check tire balances and work your way up from there.

You also added lack of power in your last post but not the first. Is that a definite symptom or something that you sort of feel/sense. You know how it is when noises or feelings in your vehicle get into your head

PF_Flyer

Another thought came to mind as well, highly unlikely, but it got stuck in my head... you said your son took it off road. If you have aggressive tread on the tires, a semi large stone could get wedged (although you'd hear that usually and it likely would fly out at highway speed) or a chunk of tread getting knocked off might make a tire feel out of balance. Just think that you're not feeling this until fairly high speeds, so if it WAS a tire, the amount is was out of balance might be pretty small

Just ideas...

darryl2005

I noticed when I drove it and floored it at 60-65 it did not have the same get up and go. The tires are standard AWD tires

PF_Flyer

What year is it, how many miles? Lots of variables could lead to the perception of not having "the same get up and go". Just trying to keep MY head from making leaps of logic. Sort of like when I had a wheel bearing go, and the noise it made colored my judgement of noises I'd hear in cars for quite a while.

0patience

A person can jump to conclusions all day long, but until you eliminate the likely, tires, you cannot go much further. Because you don't have the vibration at lower speeds, the drivetrain probably isn't responsible. 
Drivetrain vibrations, tend to be constant, growing in severity as the speed increases. 
Tires tend to like to show up between 45-70 mph as a problem. 

So, if a visual inspection of the driveline doesn't show anything obvious and the u-joints have no play in them, then start with the likely suspect and work from there.

And since you discussed the power loss, there is a possibility that a misfire is the cause of the vibration and power loss. This would cause a high rpm vibration and a power loss. 
When was the last time it had the spark plugs changed?
When was the fuel filter last changed?
If it has one, not sure if that has the screen or actual filter.
Remember, we are working with the info you provide, so if the answers seem incomplete, it is often hard to see the whole picture from words.

capriracer

If the problem is only there under acceleration, that is most likely U joints. Acceleration changes the pinion angle and that frequently reveals imperfections in U joints. By contrast, a tire vibration would be there all the time - steady speed, accelerating, braking.

0patience

U-joints can vibrate/shake just as much on deceleration as acceleration. They aren't just gonna show up at 65 mph. 
Normally, I don't see tire,balance problems show up until at least 45 mph, with 60 mph being the most common point. I have one truck right now that one tire was way out of balance, it started shaking at 61 mph. 
I've never seen tires show problems on braking though, but anything is possible.

Chilll

I'm going thru the same problem. 2017 Jeep Grand Cherokee drive shaft was unbalanced according to dealer. Dealer told me it's defective. They just replaced it but still vibrates especially when going over 65 mph to 80.it gets worse. I feel the vibration in the seat & under my feet. I know it's not the wheel balance. U joint is next. Luckily this is warranty work..Once they figure it out I will post it..

PF_Flyer

Be sure to let us know. I had a U joint go bad on my '66 Newport. Being rear wheel drive, I skipped the vibration and went right to the drive shaft banging against the bottom of the car. Definitely got your attention!

thecardoc3

There are new tools and techniques for diagnosing such conditions. GM has issued this to all of its dealers, as has Ford and Toyota. I do not know if Fiat/Chrysler/Jeep has gotten on to this and trained their techs to use it or not. https://www.picoauto.com/products/noise-vibration-and-balancing/nvh-overview

Chilll

Just called the dealer(Jeep) they told me the rear driveshaft & u joints were replaced as an assembly. Going back to dealer on Monday 24th I will keep you updated.I will definitely ask them about the kit (diagnostic testing) thanks @thecardoc3

Chilll

Update Took it back to the dealer they said they found nothing ( I honestly think they just let it sit & did nothing). Going back tomorrow 7/18 at 7am for the same problem. You think they have the equipment to test for vibration. This is the 3rd time. Next I'm calling corporate. Then if this doesn't get resolved I'm selling it and will never buy a Chrysler/Jeep again. I only have 26k miles on it...This seems to be an ongoing problem with jeeps dating back before 2010

thecardoc3

How many times have you ever heard or seen someone say that the dealerships and most repair shops "charge an arm and a leg" for what they do? There is a cost for every service a shop offers with regards to tools and training/experience that has to be recovered by what the consumers end up having to pay. Adding the tooling that I described creates an additional cost that the shop down the street probably isn't exposed to so that creates a disadvantage on the street for the ones that do. In the dealer world they are forced each year to add essential service tools as part of their franchise agreement and that is expensive so unless Jeep has made the PICO and it's accelerometers an essential tool and created a class on how to use it they aren't likely to have it.

Try this. Go to Goggle play and search for a vibration frequency diagnostic app. Then post the speed you are traveling when you feel the vibration, the engine RPM and the frequency that the app reports. Try measuring the vibration with the phone in different locations and report where it senses it the strongest. Aka the top of the dash, the floor both the left and right side as well as the rear seat area, center console if equipped .....
Here is a sample app. There are many others. https://play.google.com/store/apps/details?id=pl.alitec.mvibe&hl=en_US

JeepownerSonoma

Following....I have the same issue with a 2012 Grand Cherokee - vibration when accelerating beginning around 35-45mph and continuing intermittently until around 60mph. My first instinct was to check the tire balance, which turned out to be fine. Many consults later, I had the axels replaced followed by the UJoints when that did not solve the problem. Then, Jeep service techs got involved and said it's definitely caused by the engine mounts and front right bushing. Luckily, the last two were covered by the shop owner but it did not settle the vibration. Jeep is now suggesting it may be transmission or transfer case but the tranny runs fine! At a total loss.