Hey guys, Just wondering if someone can lead me in the right direction here, i searched the forums on this and really didn't get a straight up answer. so here we go.

I bought my jeep with pretty much inverted stock leaf springs sitting on a 3" block lift. So, i bought Pro Comp 2.5 inch spring packs for it.

After I fought with them over a day to put them in, I finally got it on the road, it sits considerably higher now in the rear and rides pretty stiff which i don't mind at all lol.

Here's the question, after im driving it, my jeep vibrates so bad at at about 25mph that i can't even see out of my mirrors. It goes away after 30mph though, so i'm ruling out an SYE kit because it should get worse with speed.

I'm gonna check out my U-joint for the rear driveshaft today, hoping that will solve my issues, but if not would a T-case drop work out for me? I have a shim in place to help with the driveshaft angle too.

Thanks guys

 

Im going through the same thing. I went and got the shims yesterday but now after reading about it, there is no guarentee the shims will work. I am going to Iron Rock offraod and getting this SYE. End it once and for all.
I am going to use my front driveshaft until i get another front driveshaft. I lowered my transfer case 1 inch, waste of time and money.

http://www.ironrockoffroad.com/Merch...egory_Code=XDT

 

Rear driveshaft u-joints are binding, causing the vibration. This tends to be speed specific, or even throttle specific (as in, it only happens when you let off the throttle). An SYE (IRO's Hack-n-Tap is amazing) will fix it for you. Shims help, t-case drops help, but the SYE is the best fix. If you don't want to go that route, start investing in U-joints for the rear drive shaft.

 

an SYE seems a little extreme just for a 3" lift and expensive non the less. I'm going to investigate the situation in a little while and start small before dishin out coin on an SYE.

 

IRO SYE(hack n tap) and new-refurbished driveshaft is $199.....

but driveline vibes at 3" is not uncommon. check pinion angle and the like as well as driveshaft angle.

but vibes will kill u-joints quick... and when they do here is a write up I did on how to change them:

http://www.cherokeetech.com/VBull/sh...nging-U-Joints

 

Granted I am sitting at 6.5 now but I had the exact same vibe after my lift. Only showed up from 27-32 an then it was gone an drove perfect. SYE an a front shaft in the rear cured it completely. Tc drop might help but you can get a the hack n tap kit mentioned above an save slot of headache. Plus you will already be set up WHEN u go higher lol.

 

Like has been said (by me and others) go with IRO's HnT kit. It's only $200 and for a 3" lift, is not over kill at all. I'm at 3.5" and am shimmed and have a tc drop, and still get some small vibes. I'm ordering the HnT kit from IRO soon as it's well worth the money, not expensive at all, and is the proper way to fix the vibration problems.

 

I already did the spacers and i was going to put the 6 degree shims, then you need longer u bolts, forget all that and get the SYE because you will end up getting in the long run if you are particular at all. Nobody likes or wants a vibration at any speed.

 

had same problem check uj seating point on rear pinion should be little stop mine had worn away and uj gave way on mway destroyed transfer box casing when it fell out may need a tiny spot weld so it sits right

 

I had the same thing with my 3" lift.. Just because the vibes don't get worse as you go faster doesn't mean that it isn't drivine vibes, it is. For a 3" a sye isn't really necissary, unless you really want to and have the money. I put a 1" tcase drop and 2* shims and fixed my vibes.

 

Thanks for the advise guys. I'm leaving it the way it is for now and i have a slight suspicion that the U-joint is pretty beat up. Due to the weather I was not fortunate enough to be able to rip it down today.

 

I just bought and installed the same 2.5"'s by pro comp, put them in, I have some very teeny weeny vibes from about 25-30 as well. Going to T-case drop and do new U-joints. My vibes are nothing compared to yours, but I'm hoping the new joints and a drop to adjust driveline angles will do it, or lessen the effect.

 

Biggest complaint about Jeeps from the factory is the slip yoke and NON CV drive shafts on a 4x4. These should have been standard equiptment. But the company decided to save money. Because of this fact ANY modifcation away from stock height can and does cause drive line issues. There are cheaper "fixes", but the SYE is the proper solution.