Rear axle death wobble?

**Richmond88yj** · 04-03-2007, 10:46 AM

I had the top and doors off today going to work and think I finally figured out my vibe issues. Looks like DW from the rear.

As it would start to vibe about 60 mph or so, with no door it was easy to look at the rear and front tires. Seems the rear (no rear trackbar) is getting wobbly and shuttering the whole rig. (I'd been chasing the front)

I've got a RC 4" lift with about 1" longer shackles in back. Think adding the track back on would stop this?

First time I've heard of DW (although much less than true DW) coming from the rear and not the front.

93YJfalcon · 04-03-2007, 10:59 AM

Bent axle, bad bearing, rear driveshaft u-joint, loose u-bolts, tire slipped a belt????

I just can't see the trackbar being the cause

yjing · 04-03-2007, 11:03 AM

all i can say is that when it happened to me, i'd get it around 45 mph and it was a faulty rear u-joint. Happend so violently once, that the rear driveshaft just blew off and put a hole in my muffler. Check that out frist

drexelsteve · 04-03-2007, 11:45 AM

i'd guess it's the ubolts being loose. I know you're not using aluminum shims for the rear pinion angle right? Trackbar won't fix the problem, it might bandaid it but it'll still be there.

**Richmond88yj** · 04-03-2007, 12:00 PM

Yeah, no SYE and I'm chewing through rear U-joints about every 600 miles. Should I start with that?

I've eliminated the tires and wheels (swapped with a bud, problem still there)

**atomicmoose** · 04-03-2007, 12:22 PM

I am going to guess that it's the u-bolts as well. Are they tightened to spec?

chupacabrah · 04-03-2007, 12:23 PM

could you actually SEE the wobble?

maybe that's the deal w/ my vibes too...but i dont think i'm so lucky

do you think getting an SYE would correct it? maybe somethings funky there.

I'm going to get an SYE and try that out, then progress if it continues

**Richmond88yj** · 04-03-2007, 12:46 PM

Quote:

Originally Posted by atomicmoose

I am going to guess that it's the u-bolts as well. Are they tightened to spec?

U-bolts are tight to spec although I have sinned and pulled them off and on a few times farting around with driveline angles.

I could literally see the tire <--|--> vibrating left to right about an inch when it got really bad.

I've been chasing this forever thinking it was front end, but the wobble was always managable, but annoying. Plus it shakes the entire rig, stressing everything. I is/was definately not the simple driveline bzzzzz vibe you feel in the seat due to bad angles.

**atomicmoose** · 04-03-2007, 12:56 PM

Quote:

Originally Posted by Richmond 88 YJ

U-bolts are tight to spec although I have sinned and pulled them off and on a few times farting around with driveline angles.

I wonder if that has fatigued them to the point that they are allowing movement?

Another thing...

Centering pins are in place?
No movement in the leaf springs themselves?
What torque are your shackles bolts at? Anything under 25-30 ft, lbs. could be a problem...

chupacabrah · 04-03-2007, 01:10 PM

i reused my front ubolts and nuts when i changed out my front axle. would this be a problem at all? they were only about 1 year old.

that's really scary seeing the wheel move back and forth like that......
what else could cause that kind of movement/
a bad u-joint wouldnt do that right?
u-bolts....maybe they've stretched and can allow that, like atomic said

**Richmond88yj** · 04-03-2007, 01:54 PM

Quote:

Originally Posted by atomicmoose

I wonder if that has fatigued them to the point that they are allowing movement?

Another thing...

Centering pins are in place?
No movement in the leaf springs themselves?
What torque are your shackles bolts at? Anything under 25-30 ft, lbs. could be a problem...

Centering in as far as I know, will pull em tonight and doublecheck.

The shackles were about 40 and I wrenched em up to 90 in the front and it really helped, will check the rears tonight. (have to pull the hitch, total PIA.

**atomicmoose** · 04-03-2007, 01:59 PM

Quote:

Originally Posted by Richmond 88 YJ

Centering in as far as I know, will pull em tonight and doublecheck.

The shackles were about 40 and I wrenched em up to 90 in the front and it really helped, will check the rears tonight. (have to pull the hitch, total PIA.

Whoa, 90 is high! I run mine at right about ~45 ft.lbs. I find that to be a happy medium between stability and flex.

zman · 04-03-2007, 02:09 PM

Quote:

Originally Posted by atomicmoose

Whoa, 90 is high! I run mine at right about ~45 ft.lbs. I find that to be a happy medium between stability and flex.

and I run mine at 15ft lbs.

Couple things here. If you truly see the wheels moving I could see bent flange on D35, bad shackle mounts, bad spring mounts, bad bushings in springs or spring hangers or missing centering pin. A missing TB is definately not your problem. I bet the problem is quite obvious to the eye when you find it. Also some people don't know that the frame spring bolts are 9/16 and the shackle side are 1/2" bolts. I saw this on my last jeep I bought that had bad vibes at 45mph plus. BTW, I would not classify this as DW. DW is in the front and has to do with the steering wheel violently shaking.

zman

LandRover · 04-03-2007, 02:51 PM

Quote:

Originally Posted by zman

If you truly see the wheels moving I could see bent flange on D35, bad shackle mounts, bad spring mounts, bad bushings in springs or spring hangers or missing centering pin.

X2. I had a wobble in the back of my 89 that I never found until I had to pass smog and saw it running on a dyno...it was a bent flange on the D35. What Axle are you running?

chupacabrah · 04-03-2007, 03:13 PM

Quote:

Originally Posted by LandRover

X2. I had a wobble in the back of my 89 that I never found until I had to pass smog and saw it running on a dyno...it was a bent flange on the D35. What Axle are you running?

what flange? where ?

04-03-2007, 11:03 AM	#3
yjing Registered User Join Date: Aug 2005 Location: long island, NY Posts: 324 Profile Gallery Classifieds My Jeeps	all i can say is that when it happened to me, i'd get it around 45 mph and it was a faulty rear u-joint. Happend so violently once, that the rear driveshaft just blew off and put a hole in my muffler. Check that out frist __________________ 89er 4banger [COLOR="Red"]Red Jeep Club Member #360[/COLOR]

04-03-2007, 12:22 PM	#6
atomicmoose Just call me Moose Join Date: Nov 2004 Location: South Jersey Posts: 3,978 Profile Gallery Classifieds My Jeeps	I am going to guess that it's the u-bolts as well. Are they tightened to spec?