Brady733

I have a 2001 Jeep cherokee sport with about 170000 miles on it. I just put a 3" lift on it and about a few days after i noticed that whenever i get above 40 there is a weird vibration when i accelerate. The weird vibration only happens when i get above 45 and its not constant it happens only when i barely push down on the gas pedal. For example if i floor it it'll only happen when i initially push down on the pedal and then stop. Then the vibration comes back when i release the gas pedal. So if i barely hold the pedal down and hold it there then the vibration will stay constant. Another thing i need to add is i do need a new pinion seal and but i don't know if that would have anything to do with it. Another thing i need to add is that the noise is kind of a vibrating grinding noise and it sounds like its coming from right from under me but more towards the middle. Sorry if this isn't a very good description but if you need anymore further explaining then let me know. Thanks for helping me

TRCM

sounds like you need a SYE due to the lift

Brady733

A slip yoke eliminator??

TRCM

yes...sye

Bugout4x4

I know everyone is going after the SYE angle with this because of his 3 inch lift and even though it is very logical... This symptom sounds more like a bad motor mount from how he is describing this.

Brady733

could it be that?? It only started after the lift??

Bugout4x4

I'm probably wrong but I would check just to make sure. Because you are describing the absolute classic symptoms of a bad mount, and the new configuration may be causing it be worse and easier to feel now.

Martlor13

eh, to me that's the absolute classic symptoms of driveline vibes haha....you can feel motor mount vibes at idle and every other speed in my experience, not just at 40mph. But of course never hurts to check and it is easy to do.

Brady733

could you explain how to do this? Or link a video? Never done that before

TRCM

The best way to check the motor mounts is to use 2 people...1 power braking the engine enough to torque the motor but necessarily spin the tires....the 2nd watching the motor mounts for excessive movement.



Or, you can pull the hood off and watch the engine yourself for excessive movement while you power brake the engine.......

Bugout4x4

Thank you... I got pulled away yesterday and couldn't get back to continue this conversation. I highly suggest the first two person method to check it "under load".

Bugout4x4

Every motor mount I had go bad first showed signs it was "getting bad" with exactly the same symptoms he described "as written". At 40 when you just start to apply load with throttle "feather" but not bad enough yet to do it from take off. They are not noticeable in no load or take off conditions until they get worse past this point. They find that "sweet spot" where they vibrate under only this particular condition when they first start to go bad.

Like I say, I'm probably wrong, but this has happened to me so many times that I can tell when I am starting to get a bad mount by these same symptoms. Rubber mounts don't last long in the hot dry desert so this is a very regular and common maintenance issue for us out here and happens much more often than other environments.

SexyDexy

Brady, I installed a 3" a few weeks ago and all I had to do to resolve it was to drop the cross member down about 1/4" (About 3 washers per bolt).

Brady733

you had had the same problem I have?

SexyDexy

For the most part "yes"...but if you have the d35, I am worried that the "vibrating grinding noise"you are hearing is coming from your pinion bearing as its the same symptoms that I heard on the d35 on my TJ when I found the pinion bearing was bad. With your harsher driveline angles now, it may be exposing the bad bearing.