Vibration when accelerating

Matt1707

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Apr 13, 2017
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Bel Air, MD, United States
04 tj with a 4 inch lift and a 1 inch t-case drop. I have a very noticeable vibration when accelerating from 15mph and up. It shakes the dash and vibrates the steering wheel ( but a buzzing type vibration that travels through the steering column not a steering wheel shake). Its there when accelerating and gone when coasting.

Repairs done- new clutch, flywheel ( was warped a bit), pilot bearing, release bearing. Drove with front driveshaft off and still there. Removed rear driveshaft and thats good. Adjusted rear pinion angle and its near -3 degrees. Checked trans mount and it looks fine. Engine mounts look fine.
 
If vibes are gone when you remove rear driveshaft. Check u-joints and the spline in the driveshaft make sure there is no play. Also 1" TCase drop might be too little I had some vibes on mine when I had 4" lift and the 2" TCase drop. Pinion angle is another possibility but not all TJ's behave the same from my experience. For me all the vibes were eventually solved when I did the SYE.
 
I don't have an sye. I have realized that will be my next step. I did find out that I have a 11 degree angle in the tcase to driveshaft. And 5 degrees at other end to diff. Its all way too much. Jeep states only allowed a max of 3. My next question is what is a good set up. Like what sye and rear shaft is good together?
 
Vibes only while accelerating are often caused by the rear pinion angle being too high. Accelerating raises the rear pinion angle so if it's a little too high to begin with, accelerating can raise it further to the point it causes the rear driveshaft to vibrate.
 
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Reviving something of a dormant thread here, but I have a related question: What if I'm getting the same kind of driveline vibration (vibration on acceleration, not so much when coasting), but it's come on quite suddenly, as in last weekend, when I did some very light off-roading, mostly just running forest trails (I'm scared to death to crawl or subject it to real punishment with a stock 35 rear). What should I be looking for.

I have a 2.5" lift with a 1" tc drop. Vibrations haven't been an issue until this week. I've looked at the U-joints on the drive shaft, and don't appear to be loose. I have not yet checked the angle on the pinion yet, but since I still have the stock control arms, I don't know how much I can do with pinion angle.

One other observation. This weekend, I was on one of the forest roads in 4 high, and when I got back on to the highway and switched back to 2wd, it sounded like it had a little bit of a problem engaging. Yesterday, I tried switching from 2wd to 4hi, and then lightly slamming (oxymoron?) it back into 2wd. The vibration seemed to stop for a brief time after that, but I don't know if me switching transfer case gears had any bearing. I'm going to try adjusting the linkage, but I have no solid evidence that the tc is the problem.

I'm also going to check to see if maybe one or more of the front or rear brakes might be seizing up, but a steady MPG calculation and no real pull to either side makes me think that it's not getting any drag from there.

Any suggestions?
 
I agree with Jerry above^^^. As for a new all of a sudden thing for no reason, I would start with the easy stuff first. Any debris stuck in a rim or rotor? Could a wheel weight have been ripped off? Keep track of how much and where each tire is balanced with. From there check for a bend or twist in any control arm, track bar, etc. Could drive shafts pick up a bend? Knocked off balance? Some driveshafts have a weight added for balance. U-joints ok? Loose or bent?
 
An added observation...I drove home today the last several miles at low speed in 4wd, and the vibration on acceleration was almost non-existent. I'm still heading some unexplained missed up front, though. Running and the occasional clank, so multiple issues are likely in play.
 
Saturday update: Adjusted the linkage, and in the middle of it, something fell out of the assembly. I never saw it, but I felt it hit me in the shoulder. When I looked on the ground, I couldn't find anything but driveway gravel. All I can figure is that a small rock or pebble got thrown up in there and was lodged somewhere in the assembly from last weeks off-roading, and was keeping the lever from completely going far enough to go into 2WD. Either that, or the adjustment just slid out of place at some point when I was shifting from 2WD to 4HI or 4HI to 4LO. It seems to be behaving now, but that's only after taking it around the block. I haven't completely road tested it yet.
 
Well, found the other part of the problem. The 4WD solution only worked because it was taking the load off of the rear driveshaft. The "well, THERE'S your problem" moment came courtesy of the pinion-side rear driveshaft U-joint:

97636


The needle bearings were pretty much dust, and there was no grease left in the cap. I forgot to take pictures of the joint itself, but it was scored up pretty good. One new Spicer 5-1310X later, and all is right with the world.

One important thing to note is that even with the rear wheels off the ground, it refused to indicate to me that there was a problem. It wasn't until after got the driveshaft off that I saw what was going on. The bad cap was underneath the strap on the pinion yoke, and bound up in such a way that there wasn't much give in it. When I took the straps off, that cap just dropped away, along with tiny pieces of needle bearings and road gunk.
 
Just to add to this in case anyone else has a similar vibration. I replaced some u-joints and had the same vibrations mentioned above. Got under and looked at the rear pinion u-joint and sure enough the strap bolt broke off and let the u-joint move out a bit. Waiting for the new strap and bolts to arrive but pretty sure this is my problem!
 
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I'm having the same issue it's only under hard acceleration that I get to vibration as soon as I let off the gas the vibrations gone I took the front drive shaft out and it helped a little bit I have the transfer case drop some rough country with a 6-in lift aftermarket control arms new 488 gear package new rear diff with a master overhaul kit Master overhaul kit in the front bulletproof motor mounts prothane TC mount knew you joints in the rear drive shaft it helped a little bit when I took a front one out the only thing I haven't changed as my front u-joints but since my rear drive shaft is the only one in I would have to guess that my opinion angle is wrong..ps also on good flat level pavement from fender to tire on the right it's 7 and 5/8 of an inch and on the left side it's 8 1/4. But my control arms is adjusted at exactly the same length any ideas?