So. I have a 98 sport. It's my second 98 and I decided to take the 2 inch lift off my old one and replace the saggy leafsprings from the newer one. Unfortunately, I picked up a vibration, from under the floor, center of the Jeep.
I initially thought the rear ujoint had adjusted to the old crappie springs and replaced that. The vibe got worse. I then changed to rear driveshaft front u joint as the sound seemed to have moved farther forward. The sound lessened, but was still there.
It sounds like when I had my KM2 tires on it. Like a hum. Only generally between 25 and 35 mph.
So... then I decide, since it's a Michigan jeep, to change the transmission mount. It was crappy, and worn, but not too horrible.
This lessened the vibration intensity, but it's still there.
I'm beginning to feel like I'm just throwing time and money at this thing and getting nowhere.
The motor doesn't really clunk or move too bad when I change from park to gear so I was not really thinking motor mounts but wasn't too sure.


Any advice or suggestions? I'm drowning here.
Thanks.

 

Also, my last jeep did just fins with a 2 inch lift and no drop kit for the Trans case. This one's springs were in just about as bad condition. I also changed the rear pumpkin fluids and rechecked all the bolts n nuts to make sure nothing wiggled loose. Nothing did. Any help would be a Godsend. Thx!

 

New info...
Just drove it to work.
Now I get to feel the vibration at ALL speeds. Even when going 65.

 

Would the motor mounts do this?

 

I don't have experience with lifts and whether 2" without dropping the case will cause vibration.

I was getting some vibrations at all speeds, replaced the transmission mount because my transfer case seemed to have a lot of play and the rubber on the mount seems old and spongy. Right after replacing that, my drivers side motor mount went on me. (or was already gone and became noticeable) I replaced both motor mounts and the vibration was gone.

There was a "break in" period with the new mounts. I had some vibrations for a couple of weeks and then things settled in.

 

About how long does a motor mount job take?

 

Any pointers? Are the bolts sure to break or strip?

 

If it seems like it's right under you, you may check to see if your slip yoke is greased. Sometimes they dry out.

 

I did them at separate times. Trans mount took me an hour and the engine mounts took me a little longer as I have never replaced motor mounts before.

No issues with bolts breaking or stripping. You'll need to support the engine before unbolting on the oil pan. Use a piece of wood in between. When putting the new mount in you may need to adjust the height of the engine using the jack. Also put the long bolt that goes through the mount first. Don't tighten bolts all the way until you get both installed.

However before doing all of this, inspect your mounts to see if they need replacing. Youtube is your friend on how to's etc.

 

Motor mounts aren't to bad. Just make sure you have everything you'll need. Here's a video I did on changing the mounts in my 1990. There will be a couple of differences (Air box, oil filter), but should be pretty much the same beyond that.

 

Found the issue... thx guys!

 

Glad you got it worked out.

 

Yep. Was about to say that was probably it. My driver side mount was completely busted. I replaced them and has vibrations for a couple of weeks but they have settled out.

 

Drove it to work. Minimal vibes now. You say it'll break in? Anyone agree with him? Seems like there should be none at all.

 

The rubber in the mounts is super stiff new. They'll wear and then become a little looser and allow it to absorb the vibrations.