Ohwow

So I just bought a jeep and installed a rock krawler 3.5 inch x factor lift kit on it. I'm having a bad vibration at all speeds and I can't seem to figure out what it is. The jeep drove fine from what i can remembet after the install but as soon as I had it aligned I got the vibration. So I returned and had them align it again. And everything is in spec except for the caster is off. So I pulled the front drive line but the vibration is still there. So I called up rock krawler and spoke to them and looked over some stuff they thought might be the problem. He told me that my caster being at 2.5 degrees instead of the 4.2 to 5.5 they recommend shouldn't cause a vibration. I checked all the bolts and joints on the lift and there all tight.my pinion angle is good. Stock shafts front and rear. I checked the back joints, tierod and draglink. I even jacked uo the jeeo on stands and put it in drive and the vibration goes away. The only thing I've noticed is that my rear springs have a bow in them and I looked into and realized I installed my rear springs on the shim with the tail facing to the rear of the jeep and I read that facing those forward makes a difference. I'm gonna correct that tomorrow and see what happens. Does anyone else have any idea or something i missed or could do to see whats going on? Im at a loss here and would appreciate any help I can get Thanks.

Mr.T

Presuming you have stock control arms, only the toe-in is adjustable for alignment. If toe-in is off a little, it won't cause vibration. When you say the vibration is at all speeds, how slow will it happen? When you had it on jack stands, did you check how true the tires were turning? One reason for asking is that there are some clips on wheel studs that have to be removed for aftermarket wheels so they mount flush to the hubs.

Ohwow

the vibration starts around 15 mph and you can feel it in the steering wheel and brake and gas pedal. Once you get up to 20 to 40 mph and around 65 mph it will vibrate and cab hear the dash vibrate and feel it in your seat. I have fully adjustable upper and lower control arms and all the clips used to hold the rotors on during assembly have been removed for wheel spacers and I've check the torque in both the spacer and the tires.

Mr.T

It sounds like you've already done a lot of the usual troubleshooting, so it's not going to be easy to figure out. Yep, I'm a master of the obvious.

When you ran it on jack stands, it was just the rear turning -- correct? I'm thinking it's the front where the vibes are coming from, especially since you mentioned the steering wheel vibration. Here's a few troubleshooting thoughts:

Swap your spare tire to each front position and see what happens. Spin the fronts by hand, and look for true running or bearing noise. Check for looseness in the unit bearing and ball joints using as much force as practical. Recently worked on a friends Jeep that appeared like the unit bearing was loose/bad, but the bolts were actually not tight. Drive on a lonely road with another car observing and listening at each of the four wheels. Drive with a GoPro or cell phone camera mounted in various places. Try running in 4WD on jack stands or a lift. This method has obviously got a boat-load of safety issues -- You already know that, just mentioning it for others that read this.

TrailBadger

Just an observation, I'm wondering what shocks are being used within this setup.
Also, has anyone mentioned swapping the factory bolts for the grade 8 or 9 bolt setup.
I would rotate the wheels just to see if this clears up as an unbalanced wheel or unevenly worn tire could create this issue.

resharp001

You do realize these two statements are conflicting right? Your pinion angle is NOT good, which is why your caster is very low. It’s a fixed relationship. I would suggest the very first step needs to be correct your caster, then reassess. If you know something is wrong…..which it is, your caster is way low, then correct that issue before moving forward. I’m a little confused why your caster is so low. You have adjustable arms, and instructions should have included a suggested length to set them…..which should have gotten you much closer to proper caster. Absolutely no reason you should be at 2.5” caster with that lift.

I’m not saying that is going to make your vibe go away, but you need to get the arms adjusted appropriately before trying to determine your next coarse of action. There are a lot of variables in play. If it were me, I’d start by correcting caster, rotate the tires front to back or confirm they are all balanced at a tire shop, and double check all steering component joints and bolts/jam nuts to make sure torqued to spec.

jedg

Yeah. resharp001 is correct on your caster. No reason for it to be that far out given that kit comes with adjustable control arms. It's not going to correct the vibration, but in the end it will correct flighty steering that you'll feel after you fix the vibration.

On the vibration, I'm betting you have a tire out of balance.

pdurio

One thing no one has mentioned yet, you have the x-factor kit with control arms that use joints on each end that are tight and precise, no more soft rubber stock arms. You will feel more noises and vibrations transmitted through to the chassis.

Ohwow

Sorry it's taken me so long to reply I've been super busy at work and finally got to the jeep this weekend. So i got the vibration fixed it ended up being a tire I had was coming apart and couldn't see it from the outside of the vehicle. I didn't think it was the tires due to them rotating them when I had the alignment done. Goes to show how much you shouldn't trust others or possibly it happened right after the alignment who knows but glad it's taken care jeep drives great now just gotta have the caster adjusted. Thanks for all your guys support on this.