Wobble when breaking at higher speed (45-50+).

Hello all! Let me apologize for the length of this post up front, I just wanted to make sure I put everything we have done to/for the Jeep so you all have the full picture and can hopefully help me.

I am new to Jeeps ( but learned a lot the past year and half) I have been lurking and reading for months and finally joined. Bought the 2006 TJ a little over a year and a half ago. Pristine, garaged kept by a nice older lady who barely drove it with only 20k miles on it. Always wanted one growing up so I bought it for "my son" (HA). Anyway, earlier this year put a 4" lift kit and 1.25" body lift and went from 15" wheels to 18s with 32's ( had them balanced before putting them on). Immediately afterward we got vibration when accelerating and the death wobble at 45+ (the magic number I've come to find out). Went back and read the info on the kit and of course in the small print it said you will probably also need adjustable rear upper control arms, a new CV joint and SYE kit. Got a Teraflex SYE kit w/ a 1310CV (short) and some heavy duty adj RUCA's. Also put on a new steering damper. Bought a lifetime alignement at Firestone and have had it aligned every time we have done some work on it; after the lift, after the SYE, CV and adj rears. Found we had some warped rotors so replaced those and new front brake pads ( had it aligned again-love the lifetime). Still have a very little vibration (very little) when accelerating and get to around 20-25mph then it goes away. No DW, but when I took it for a test drive I was beating it a little and was driving approx 45-50 and had to hit the brakes quick a little hard due to a car slowing in front of me and the front end started wobbling?!?! I have driven it several times and tested it out and about 80-90% of the time when over 45-50 and I hit the brakes ( not slamming on them or locking them up) the front starts to wobble. It happened to my son for the first time the other night and I can't have him driving a Jeep that was perfectly fine until Dad decided to live his dream of a Jacked up bad A** Jeep. Anyone have this problem??? I searched and could not find anything relating to "wobble while braking". It seems to be the only issue ( right now). When we lifted it, a buddy of mine that owned a Jeep (and I thought was a Jeep guy) had his slightly lifted), until I drove his to get some bolts while we were lifting mine and his jeep was wobbling and pulling all over the road (yikes!), helped me and when we were reconnecting the upper control arms we had to use the strap/come along and it was extremely hard, and to me it seems like the front end may be "too tight" ( again, dont know anything other than what I have learned along the way). Was thinking about buying adjustable lower control arms ( front and back) and adj upper control arms to loosen, or settle, the car?!??!?! I don't even know if I'm making any sense with what I'm saying, so I will just say any help/advice would be greatly appreciated.

Jeff

 

I would buy adjustable control arms all around as you're already thinking to get the axle back into a perfect alignment. I would also check the track bar, balljoints, tie rod ends. Swap your new tires with the tires in your buddies jeep and see if that helps the problem at all.

 

I agree with Paul on the DW. It looks like you have 2 issues, 1. DW and 2. Rear vibration.

1. Track bar is the number one culprit, but usually preceded by other worn loose steering/suspension components. When this happens I spend a full day and replace ball joints, steering dampener, and sometimes the tierod ends to both the draglink and the centerlink.
2. Your rear drive shaft is it a double cardigan drive shaft (also know as a CV shaft) or a regular shaft? If it is a regular shaft, even with the SLE at 4 inches of lift you will probably have some vibration on acceleration. If it is a double cardigan shaft you probably don't have your pinion angle right. I know every one says to point the pinion at the Tcase tail, but if you are getting a lot of flex under acceleration you may feel vibration, and to decrease the vibration you can lower the pinion down a little so that under acceleration the pinion is not raising up to high causing your vibration. Check out this article on CV drive shafts: http://www.billavista.com/tech/Articles/High-Tech_Driveshafts/index.html and this one on general information: http://tomwoodscustomdriveshafts.com/ click on tech information on the right side of the page. This article titled the "Drive Shaft Bible" is probably the best I have read on the subject: http://www.billavista.com/tech/Articles/Driveshaft_Bible/index.html

 

Thanks to both of you. It appears I was kind of on the right track. After doing some research I was going to look into replacing the track bar, ball joints and tie rod ends in addition to the adjustable control arms all around. Peter, I did replace the drive shaft, put on a Teraflex SYE kit with a 1301 CV ( short) that I purchased from Adams Driveshafts. It reduced the vibration by 90%. Only small vibration when jeep reaches 20-25 mph then its gone. It was constant and horrible at high speeds ( highway) right after the lift, but then I replaced the CV and added the SYE kit. I also put a new steering damper on.