So I have an 07 2 door with 42,000 miles. ONly have a 3 year old 2" BB with skyjacker nitro shocks - just switched form 33x12.5 baja atzs to toyo Mts because I was essentially forced to... So obviously it's a stiff ride however with the bata atzs - I finally lowered the tire pressure after 3 years to accommodate for the ride quality, however, since then, I started to get a constant vibration which, after constantly going to jeep and mavis, I was told I needed new tires because they were "warped." So i finally got new tires about a month ago, who road forced the tires and aligned them, at the custom jeep shop I go to, who does about 10+ JKs a day - jeep was driving well for about 2 weeks, however I was playing with the tire pressure to accommodate the bumpy ride and even tread wear. In the past 2 weeks, the vibration has reoccured, and is driving me crazy. I finally brought it to mavis (since the jeep shop is quite far away) who used their tire balancing machine, and claimed all the tires were off - one by half a LB! Since then, the car has been progressively driving worse and worse. (CONSTANT vibration which Mavis claims is the knobs on the tires, however, when i bought them, they drove very smooth, and now feel essentially the same vibration I had with the old tires, which were supposedly causing this problem. I was told, after reviewing the specs with the custom jeep shop, that the camber is off, which is wearing the inside of the tires unevenly. I am currently running the tires at around 29 PSI HOT and have found that to be the smoothest ride with the least vibration. I am posting the alignment specs below. I don't have adjustable tracks bars, cam bolts, adjustable control arms, etc. ANy idea as to what is wrong with my jeep??? Also, I have had the front end replaced and looked over repeatedly in the past 3 months, assuring every ball joint, tie rod end, etc is good. Also had a new steering stabilizer put in. The alignment specs are posted below... Any experience/ advice? Do i need to buy lower control arms/cam bolts or a new track bar to correct the geometry?

 

Here are the alignment specs for the JK:

Front Caster: preferred +4.2 degrees, can vary by +/- 0.5 degrees
(no more than 0.65 degrees difference between LT/RT)
Front Camber: preferred -0.25 degrees, can vary by +/- 0.37 degrees
(no more than +/- 0.5 degress difference between LT/RT)
Front Total Toe In: preferred +0.20 degrees (0.10 degrees each front wheel), can vary by +/- 0.03 degrees
(no more than 0.04 degrees difference between LT/RT)

Rear Caster: N/A
Rear Camber: -0.25 degrees, can vary by +0.0 degrees to -0.5 degrees
Rear Total Toe In:+0.25 degrees, can vary by +0.0 degrees to -0.5 degrees

 

How do I fix this??

 

Your caster can only be fixed by adj control arms, caster correction brackets, etc. Your camber isn't too bad, but can be fixed by adj ball joints.
Have you checked your front driveshaft lately? Possible weight was knocked off or the joint may be going. Any racheting sound. Does your vibration go wrrrrrrrrr, wrrrrrrr, wrrrrrr.Increase with speed? My Toyos did this till they were properly balanced. They also did it when I bent one of my C's, and again when a unit bearing went out.

 

I don't think its the driveshaft - no ratcheting sound? Feels like its most likely the tires vibrating being that it went awaway with the new tires then came back? Would adjustable lower control arms correct this? or do you mean both? what exactly do I need to buy?

 

Your castor wouldn't be affecting your tire wear. If your happy with 3 degrees and the drivability. Adj lower control arms would give you better castor, but you really dont need them with a BB. With adj ball joints they would be able to correct your camber and as an added benefit they would be able to adjust your castor a little too. BUT, your camber is really not that bad off. .5 offset adj ball joints would put at .0 and .1 on camber. And as I said they can make a small amount of castor change with these aswell. Being as that your new tires rode well for a couple weeks, then started the same thing and the tire shop says they're wearing on the inside, that means one of two things, camber is off or too much toe in. I would first try to toe it out a little, say, total toe .12 or . 15, see if it helps

 

Hmm..... I feel as if adjustable lower control arms would be the right thing to do being that I just got new ball joints... In theory, would lower control arms improve handling and ride quality? Also, in regard to fixing the vibration, would this help along with road road force balancing? Lastly, Im interested in switching to either am old man emu or a 2.5" custom lift of some sort to improve ride quality at some point... Im interesting in these -http://www.quadratec.com/products/16189_2115.htm

 

Those would be good

 

If your going to be changing your lift, front lowers would be a great addition. Not sure if it'd fix your vibe though. Ride quality /handling would improve though.

 

what do you think is causing the vibration? - I suspect is has to do with the tires but not 100%...