Alright well ive spent hours researching this issue on this site as well as others but i cant seem to shake my driveline vibes completely. As of right now my xj has a 2" lift (spacer/full AAL) on 235's. When i installed the lift last year i had bad vibes from 20 through 45 mph. So i installed a 3/4" TC drop. Then right after that the rear ujoints went and the vibes came back so i replaced them. That worked pretty good for about 7 months then the vibes came back between 30-40 mph. Ended up being another blown ujoint (end cap seal gave out). So in anticipation of going to 4.5" in about a month and being fed up with driving a trojan vibrator around i removed the TC drop, ordered an AA hd sye and installed that. I then took my front shaft over to a shop and had them do a once over and put all new u joints in it so i could use it in the rear without worrying about it. I also picked up some 4* axle shims and got my pinion pointed within the the 2*'s below the output shaft like i read on here to do (its pointing at about the bottom of the oil seal). Now it drives like a dream...until i get around 60mph and up. The vibes i used to get were like a high frequency vibration, almost like a buzzer. This vibration is more like a lower frequency pulsation type of vibration. Its also weird that this vibration varies. My drive to work is basically a straight 40 mile cruise between 60 and 70 mph. Maybe its my imagination but it seems that the vibes are worse on newly paved roads with no bumps (maybe this is just because i cant feel them when bouncing around, idk), but honestly, i dont know what else to do here. Should i have my shaft completly rebalanced? Should i go with some 6* shims and point my pinion directly at the output shaft? Im getting these new vibes only running 1 driveshaft, no driveshaft going to the front axle. Any input here would be appreciated before i go with the stick of dynamite remedy. Thanks fellas

 

have you looked at having the wheels balanced?

 

how are your tranny, motor mounts?...i had the same issue...chased the vibes as you did...shim,tcase drop etc...replaced all my mounts and vibes got worse...took shims out then tcase drop and now no vibes at all...a worn mount (s) can cause this...hope this helps
Cameron

 

My TC chain was worn and causing vibes.
Probably not your issue, but worth a check...

 

maybe your rear u-joints are worn?

 

Vibes get worse on smoother newer roads? Have you have your front end alignment checked recently? Maybe you have too much toe in. On the smoother roads the tires might grab better and try to work against each other. Could also be just good ol tire noise.

 

Does it happen at highway speeds if you coast and take the load off the driveline? If the vibes are only there under load, i.e. acceleration or deceleration, it's probably something in the driveline still, but it sounds like tires or wheels causing that vibe since it's a different "sound" and timing. If it's there regardless of whether there is a load on the TC/driveshafts or not, it sounds more like wheels out of balance or bad ball joints or something in the front end. From the sounds of it you've eliminated everything in the driveline except the motor/tranny mounts so try rotating your tires and having them balanced mebbe and see if there's any change? Also check for play in the hubs and tie rods/ball joints mebbe?

When my ball joints went bad, it caused uneven wear in my tires and I got pretty bad vibes above 55mph even if I put it in neutral and coasted. Same thing happened when I threw some wheel weights. Definitely sounded different from the driveshaft vibes I'm dealing with currently.

 

well i think ive fixed it. Once tranny mount got mentioned i already knew it was there but it looked like hell, so i called in a reserve at the napa by my work and picked it up after. Just got done installing the new mount and it seems to have dulled the vibes almost entirely. i still feel some very light grumbling under me at various speeds, like it wants to vibe, but its nothing compared to the "pulsate the skin on ur face" vibes i had before. I did seem to get a worse case of the angry sparrows out of this though. I still have to look up any remedies for that. The wierdest thing that i got out of this though is that with the new uncollapsed mount putting everything back in the right place, my ebrake cable now is pushed against my cv joint on the rear shaft, which in case you were wondering makes a horrible noise if you try to drive it like that
i have it redneck ziptied right now so i can go to work tommorrow but i have no idea what im going to do about that yet. Thanks for the multiple replies though. And if anyone has any experience on the sparrows or the ebrake cable i would love to hear.

 

EDIT: i lied, vibes are still there.... it now feels like theyre vibrating through all speeds. just the worst at 50-70. worst of the vibes is always when i have a light foot on the gas holding a speed. Guess ill see about getting the shafts balanced. Im wondering if i put a small tcase drop back in that it would help.

 

Rear ujoints are 2 weeks old. front ujoints are 2 days old.

 

Just inspected my tcase chain a month ago when i installed my SYE and there were no signs of wear. Looked good to go

 

Tires tires and tires. What kinda tires do you have? Are they belted tires? I thought I had driveline vibes too, but turned out to be an unbalanced wheel and a belt that was tearing.

 

Angry sparrows usually are caused by the centering ball in the CV joint of the driveshaft. When you had yours rebuilt, did they do ujoints only, or did they replace the $60 centering ball joint also? If not then you should get it done asap and try to swap to a different driveshaft in the meantime. Angry sparrows quickly lead to that joint seizing up, which if you are going highway speed and the driveshaft stops turning then the next thing that usually happens is your tcase rips in half.

Edit: This ball being dry and worn could also be the cause of your vibes.

 

really....i specifically asked them about the centering ball and they told me it was just fine and didnt need to be replaced. great one mre thing to worry about. when i was using this shaft as my front shaft i would get angry sparrows whenever i got home from a wheeling trip, even if it was just a trail ride. it would squeak for about a week and then go away. it only squeaks with my foot off the gas at over 10 mph and under 35 mph, and higher speeds and it fades out to nothing. this is the same thing that its doing now, but i was on a light trail this past weekend so im not sure if its going to follow the same pattern. I really dont feel like its my driveline angles, with the 4* shim theyre not much at all, im considering swapping my front shaft with my rear to see what happens tonight, but i just got the front shaft out a donor xj and i feel like its going to be unbalanced and just cause other vibes.

 

right now im running 235/75/R15 Goodyear Duratracs with about 25% tread left. the reason i feel that its not my tires is that these high speed vibes were non existant hours before i installed my SYE (pre ujoint blow), and then were There immediately after installing my SYE (same day). i can try rotating them tho if the shaft doesnt change anything