Hello all. I have a 2001 Jeep Cherokee 4.0 Automatic. I’ve been chasing a 35mph and up vibration for the last couple months. Most recently in the journey I have removed both front and rear driveshafts from the transfer case and ran it in drive. The vibration was still present with no driveshafts. It does not occur with trans in neutral. It occurs while in drive, 3rd, and 1-2. I replaced the transfer case and still have the same effect. At this point I’m quite certain it is related to the transmission/flex plate/torque converter. The harmonic balancer is not loose or walking around.

The odd thing is when sitting in the car you can REALLY feel the vibration in the seat and hear the vibration. But outside the car it is difficult to feel anything. The engine doesn’t flex from side to side. I swapped in new trans mount from SFR with now change. The motor mounts do not move a fraction. With the car on Jack stands I can feel the vibration gets much more significant going from from 1st into 2nd then doesn’t change from 2-4th.

It has seemed to get worse over time. I’ve been chasing the vibration the past 2 months. Finally dropped the car off at a transmission shop. Waiting to hear back from them. Initially the tech at the shop called me saying he was going to pass, had too many cherokees that the vibrations couldn’t be found. Explained to him why I thought it was transmissIon so he said he would take a look. Has anyone ever experienced something similar to this?

 

Are either the motor mounts or tranny mount made of poly instead of rubber? That could definitely make vibrations.

Also, make sure there isn't metal on metal contact anywhere. A popular spot for this to happen is the exhaust hanger on the crossmember holding up the transmission.

 

Trans mount is SFR super soft poly, stock rubber motor mounts. Going to swap out motor mounts. I spent 30 minutes last night looking for ANY metal to metal contact. Adjusted TV cable which helped shifting points but vibrations still present. I did pull the serpentine belt and used a long screw driver to put some pressure on the harmonic balancer and easily moved the pulley in relation to the hub so it has started to separate. Would the HB cause vibes throughout the speed range?? Im going to swap it out regardless.

Trans shop said they didn’t think it was transmission related but they weren’t willing to dive farther. Might end up trying another shop or two.

 

Certainly a bad HB could cause a vibration and I agree..... replace it before continuing on with the transmission.

 

So wasn’t the HB. It ended up being the SFR trans mount. I put in the SFR motor mounts and that multiplied the problem. Went and got some duralast stock engine mounts (actually seem to be great quality) and a trans mount from Napa. Totally transformed the jeep at idle - no more annoying vibes at all. The 30-40 vibe is gone. Now just back to the very mild 60+mph vibe. Probably just wheels and tires - tire shop had to put like 3-5 weights on each wheel to get them balanced. They’ve been balanced twice and I’m pretty sure they still aren’t right.