Hey guy,

Having some vibration issues after installing an Adams rear driveshaft after lifting my 2012 2 door automatic with a rock krawler 2.5 max travel.

I got an alignment, and it's still vibrating, not so much on the highway, but more street driving in 2nd and 3rd , I wanted some opinions on my driveshaft angles if possible. Sorry for the bad pictures!

Thanks!
Jason

 

Your drive shaft angle at the rear axle definitely looks too great in that third pic. Get yourself an angle finder from harbor freight for a couple dollars and check it. Should be about 1-2*

 

So I need adjustable uppers to adjust the angle of the axel correct?

 

I suppose you could shorten your lower control arms to adjust the angle, but I think you'll run out of room pretty quick and probably run into the pinch seam at the front of the fender well.

Not sure if it's because you have a two door and mine is a four door, but I recently dealt with this and ended up not needing to make any control arm adjustments at all. I just lucked out. I also have the RK 2.5" max travel lift. I didn't install it though, so I can't say for certain what length my rear lower control arms are set at. All I know is I had to replace my drive shafts recently and I went with the Adams driveshafts both front and rear. I bought Teraflex rear upper control arms fully expecting that I would need to make an adjustment for the rear pinion angle. That ended up not being the case. My pinion angle happened to be perfect at 2* and I have zero vibrations. Again, I didn't install my lift, so I'm not certain what length my rear lowers are set at, but I'm assuming they adjusted the arms pretty short. That would explain why I had to trim my pinch seam at the rear wheel well when installing my 35's. I returned the rear upper arms that I purchased.

Just for your knowledge, you can't use the standard RK rear upper arm that they sell with the rear lower arms you have now. You'll either have to buy longer (3.5" lift) RK rear lower arms along with the RK upper arms, or get RK to make you a custom set of rear uppers for the rear lower arms that you have now, or just go with a different manufacturer's arms like I did. Reason being is RK's rear upper arms are only sold in one length, and they are too long to be able to use with the arms that come with your 2.5" max travel lift you have now. RK's rear upper arms are designed to be used with the rear lower arms from their 3.5" lift kit.

I ended up going with Teraflex rear upper arms. They sell rear uppers in two lengths. You'll need the shorter arms called the "JK Extra Short Rear Upper FlexArm Kit" SKU: 1654840. Going with rear uppers allows you to adjust your pinion angle while keeping your rear axle centered in the wheel well. Give Northridge 4x4 a call. They had them on the shelf at a great price plus free shipping.

 

Awesome! Thank you so much for your post. I realt appreciate it. Let me look tomorow if my tires are centered under my wheel well. If they are ill order the uppers. If not , ill tweak her accordingly! Thanks! I have a place to start now! The Adams shafts are great, heavy duty and I know they'll take the abuse I throw at then

 

No problem... glad I could help.

Just to be clear, if you have enough room between the pinch seam and the front of your rear tire, I would try to shorten your rear lower arms to adjust the pinion angle. That's only because I'm a cheapo and don't like spending the money if I don't have to, plus your pinion angle doesn't look too far off and you might get away with a small adjustment. I know full well that I'm going 37's eventually, and so it's only a matter of time until I have to adjust my rear lowers out further and buy those rear uppers again. Good luck, and I hope that this solves your vibration issues.

 

Yeah I plan on running the 2.5 with flats for 33s off the bat, then possibly larger everything later. One step at a time. Thank you again. I will let you know the outcome!

 

So I removed the rear driveshaft and drive in fwd. issue remains. So I can rule out it being an issue with the rear. Also when I did the lift I rotated the tires. So we tried rotating them back. Still remains. Any further ideas guys?

 

You mention it happens when driving in 2nd or 3rd... is it at a certain speed, or at a certain RPM. Also, where do you feel the vibrations? Is it in the steering wheel, in the gas pedal, in the seat of your pants?

 

Typically second and third around 1300-2300 Rpms . Automatic. The vibration is in the seats and the steering wheel. Rotating the tires didnt fix the issue. I'm going to rip off my skid plates today to see if maybe that's causing anything.