Vibrations after lift

[NMjeeptj1986]

Hi everyone.

I've been in the process of building up a 1998 Jeep TJ sport, manual, 4.0, 3.73 gears the last few weeks and have found so much info on this site that I haven't had to post yet till now.

I've installed the below list to date:
OME 2" heavy duty springs and shocks
All 4 ball joints - Yukon - wow those were rough
Rough Country adjustable lower control arms front and rear
Rough Country Heavy duty steering kit with drag bar and tie rod
JKS Sway bar links front and rear
JKS Adjustable front and rear track bar
JKS 1" motor mount lift
JKS 1.25" body lift

I'm scheduled to get 33" tires installed in August and the shop putting on the wheels and tires will be doing an alignment as well.

I've completed a very rough alignment myself.

First time I took the Jeep out I had some vibrations which I thought was due to having skipped lowering the transfer case. I skipped that since I was doing the motor mount lift and figured I wouldn't need to lower the transfer case. Since I had vibrations on the test ride I decided to go ahead and lower the transfer case using the OME lowering kit that came with the 2" lift.

After dropping the transfer case I still have vibrations which seem to happen at all speeds above 15 mph or so but haven't tried it at highway speeds yet. Vibrations happen while coasting in neutral as well.

Any ideas what could be causing the vibration? It for sure feels more like drive line and not front end steering/suspension/wheels.

I'm looking into installing a SYE but wanted to figure out the vibration first which was why I figured I'd try lowering the transfer case since I had the lowering kit anyway.

Lowering the transfer case was more difficult than I expected. It seemed like the drive shaft was pushing the transfer case forward which made it very difficult to get the bolts in. I had to put a ratchet strap around the skid plate to pull the transfer case toward the rear to get the bolts in which seemed odd to me and not sure if that has something to do with the vibrations. Maybe the lower control arms need to be adjust a bit too?

Any ideas are appreciated....sorry for the long post. Pic after lift complete attached.

Thanks!

 

[JMT]

What’s your actual lift amount? Not interested in what’s advertised.

What does your rear driveshaft angle look like? Post a pic. I want to see what you did there.

 

[cpwolf]

I'm with JMT, can you take pics of your rear DS, your output, and the angles. When he says what's the real lift, measure the springs perch to perch, front stock is 12" anything above is lift, and rear is 8" anything above is lift. So measure and take a pic, see if it's really 2" or what.

You shouldn't have to fight so much to get that skid up, at least I never have.

Personally, I'd pull the front drive shaft, and see if the vibes are there. Then you can pull the rear, and put the front in, and see if it's still there. That way you know which end you're working on.

And how are your U joints, have you checked them? You're lifting and putting some stress on them, just curious if they're worn.

Also, what was so bad about the ball joints? With a ball joint press, that's really not that difficult of a job. Did something happen to make that so hard?

 

[NMjeeptj1986]

I'm with JMT, can you take pics of your rear DS, your output, and the angles. When he says what's the real lift, measure the springs perch to perch, front stock is 12" anything above is lift, and rear is 8" anything above is lift. So measure and take a pic, see if it's really 2" or what.

You shouldn't have to fight so much to get that skid up, at least I never have.

Personally, I'd pull the front drive shaft, and see if the vibes are there. Then you can pull the rear, and put the front in, and see if it's still there. That way you know which end you're working on.

And how are your U joints, have you checked them? You're lifting and putting some stress on them, just curious if they're worn.

Also, what was so bad about the ball joints? With a ball joint press, that's really not that difficult of a job. Did something happen to make that so hard?

Attached a pic of the rear drive shaft.

Front springs are sitting at about 14" and rear springs about 10" so 2" seems about right. I did add 15mm spacers to the front to level out the jeep. Bottom of the body below driver door is at 21.75" sitting on the stock tires.

Honestly this is the most automotive work I've ever done so not sure about the U joints and what they should look like and their current condition. I can try pulling the front drive shaft out but have never attempted that so may be a learning curve haha. Seems like they're simple enough to get out.

Ball joints were just really stubborn to get out. I actually bent and ballooned out the sleeve of the press getting the lower passenger one out but it finally broke loose.

Just measured angles. Transfer case is 8 degrees, drive shaft is 18, pinion is 5. So maybe it's my rear pinion angle throwing it off?

 

[cpwolf]

Attached a pic of the rear drive shaft.

Front springs are sitting at about 14" and rear springs about 10" so 2" seems about right. I did add 15mm spacers to the front to level out the jeep. Bottom of the body below driver door is at 21.75" sitting on the stock tires.

Honestly this is the most automotive work I've ever done so not sure about the U joints and what they should look like and their current condition. I can try pulling the front drive shaft out but have never attempted that so may be a learning curve haha. Seems like they're simple enough to get out.

Ball joints were just really stubborn to get out. I actually bent and ballooned out the sleeve of the press getting the lower passenger one out but it finally broke loose.

Just measured angles. Transfer case is 8 degrees, drive shaft is 18, pinion is 5. So maybe it's my rear pinion angle throwing it off?

View attachment 539431

You have adjustable arms, get the rear pinion to 8 like the output and drive it. I'd do that before doing anything else. Those should match in that setup.

 

[cpwolf]

Attached a pic of the rear drive shaft.

Front springs are sitting at about 14" and rear springs about 10" so 2" seems about right. I did add 15mm spacers to the front to level out the jeep. Bottom of the body below driver door is at 21.75" sitting on the stock tires.

Honestly this is the most automotive work I've ever done so not sure about the U joints and what they should look like and their current condition. I can try pulling the front drive shaft out but have never attempted that so may be a learning curve haha. Seems like they're simple enough to get out.

Ball joints were just really stubborn to get out. I actually bent and ballooned out the sleeve of the press getting the lower passenger one out but it finally broke loose.

Just measured angles. Transfer case is 8 degrees, drive shaft is 18, pinion is 5. So maybe it's my rear pinion angle throwing it off?

View attachment 539431

Personally, I'd make the change to get pinion to 8 to match output. If it fixes it....I would take out the TC drop, and see what the output measures, and match it with the pinion. You might not need the TC drop at 2", I wouldn't think so...especially with a MML.

 

[NMjeeptj1986]

Personally, I'd make the change to get pinion to 8 to match output. If it fixes it....I would take out the TC drop, and see what the output measures, and match it with the pinion. You might not need the TC drop at 2", I wouldn't think so...especially with a MML.

Thanks! I'll give that a try and see what happens.