My "vibration issue" thread

History of my situation (kind of long):

I bought my '96 about 7 years ago...totally stock (4.0 HO, AW-4, Chrysler 8 1/4").....from day 1 I always had a slight driveline vibration.

Intalled a Pro Comp (I know) 3 1/2" lift, 31" BFG ATs, 1" wheel spacers and ran it that way for a year or so......no real change in vibrations.

Found and installed a D44 that I adapted Ford Explorer discs to....still had vibrations.

Put together a (around 4 1/2"-5") lift from various parts I had been stock piling over the years ie: custom made adjustable lower arms with flex joints, drop brackets, 4 1/2" RC leaves and shackles, yoke style hack and tap SYE and front CV shaft in back, 33x10.50 BFG ATs...still stock gears.....slight increase in vibes (not too bad though) because I needed to point the pinion up more.

Regeared to 4.88, No Slip in back, ARB in front (picked that up for $250 ), took me a couple of years to gather up all these parts.....vibes about the same but, shifted because of increased shaft speed.

Had my tires rebalanced, changed oil.....in preparation for a trip to Cedar City, UT (I'm moving there). Leave the house at around 11PM (I have an appointment with a title company at 9am). A couple of hours out, vibrations intensify to the point of getting violent (holy crap!) but, I'm forced to keep going because I have to keep my 9am appointment.
After I signed all the paperwork, I get under my Jeep and discover that the bolt holding the yoke on, is loose (as is the yoke!) tighten (and Loctite) the bolt but, I still have bad vibes but, not as severe as before.

Been trying for the last week to figure this out. Shimmed the pinion up to ideal angle and had it on my buddies lift, ran it up to speed....sounds like it's coming from the rear end but, could be telegraphing, opened up the rear end to reverify pattern and backlash and all seems fine (my buddy is a certified mechanic and very experienced in gear set ups). I also replaced all the u-joints and repacked the CV joint centering ball. I'm (we're) stumped.

I bought a Rugged Ridge shaft style SYE (smoking deal) and will install that tomorrow, thinking that maybe my trip to Utah with a floppy shaft might have damaged the t/c output shaft bearing so, might as well upgrade.

So, if this dosen't cure it, anybody have any ideas?.....could a bad wheel (axle) bearing act this way. I'm about to put a bullet in it (or me)!

Just to clearify, vibrations are speed/load sensitive....ease up on the gas and they lessen or go away.

HELP!

Hans

Have you made sure it's not the front shaft?

I used to have vibes from 70 mph plus, even with a properly shimmed sye.

I regeared to 4.56's on my 32 inch tires... Oh my god I couldn't go over 45 mph.

Long story short, turns out it was the front shaft. (It was smooth with the part removed)

I changed/ adjusted-
-Front pinion angle, above, below, and at zero degrees
-2 different junkyard driveshafts (one got rebuilt and balanced)
-A new Tom Woods shaft
-Front axle regeared/ with new bearings, gears, everything
-New motor/tranny mounts

I upgraded to 33's, and the slower DS speed helped, so it was more manageable. Vibes started at 67 mph, so i gave up, and called it good enough.

Then about 2 months ago, the vibes got violent again. I was pissed. So we went underneath, and checked the front pinion yoke... The nut was barely tight.

It was wobbling on the shaft, so we inspected everything, and retorqued it, and the vibes are GONE. Check your pinion nut.

Took the t/c apart to install the SYE and noticed a lot of very fine aluminum "dust" in the case and fluid....hmm.

Couldn't see any evidence of the chain or anything else making contact with the case but, the output shaft bearing was very loose in it's bore, allowing it to walk back and forth and rock up and down as well.

I believe the "dust" in the case and fluid was from the bearing wallowing out the bore in the rear casting.....in any event, it's dead smooth now and a lot stronger as well.

Hans