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Unread 11-10-2011, 09:02 PM   #1
grule1988
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Xj death wobble diagnosis

I have a 98 cherokee with a rustys 4.5in lift..1.5in transfer case drop kit and drop pitman arm. I've been trying to chase down this annoying death wobble and can't figure it out..just recently changed the front axel ujoints and trac bar bushing but still soon as I hit 45mph and on I get the horrible death wobble..caster angles are dead on all front end components are tight and I believe it has an OE replacement steering stabilizer...rides perfectly fine from 0-40 but god awful after that..any other ideas? Please help!

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Unread 11-10-2011, 09:15 PM   #2
CJ7-Tim
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Get rid of the Drop Pitman Arm. Cherokees don't need a DPA until you have 6-8" of lift.


DW is usually caused by a combination of worn parts on the list of usual suspects, not one single part that. Here is some good info on DW.

If you are having a shop align your modified Jeep or diagnose Death Wobble, make sure they regularly deal with lifted 4x4's, understand the printed alignment specifications are for stock Jeeps, and that a good Pinion Angel is slightly more important than your Caster Angel. Lifted Jeep should have Neutral Toe or a slight Toe In.


Death wobble isn’t similar to a wiggle from an unbalanced tire. It is by far worse. When death wobble hits you will know… it’s a violent shake from the front end that feels like the Jeep is about to fall apart. Usually when it happens the only thing you can do to stop it is to slow down.

The first steps to eliminate death wobble should be a visual inspection of each component, check the bushings, tire balance and an alignment. These are some common things you must check anytime you lift your Jeep. Death wobble is experienced mostly on lifter Jeeps, however it is not uncommon for someone without a lift to experience the dreaded DW. Listed below are a few things you can check.

Check your Track Bar, play in this can cause the axle to shake.
1. Bushings - check to see that they are not worn. Looks for cracks, and excessive play)
2. Angles - this angle should be the same as your drag link. Use an angle finders you can get at sears to determine this, don’t just eye-ball it.
3. Bolts – Make sure all bolts are tightened down to spec (some lift components have a different torque spec then)
4. Axle Bracket - Make sure the bolt hole is not enlarged allowing the bolt to wallow around.


Check the Axle, your mounts may be worn
1. Check the axle mount. Here is a good write up on a wallowed out bolt hole
http://www.jeepin.com/features/trackbarfix/index.asp
2. Check your Universal joints, a binding or lose U-Joint can cause DW
3. On the frame end if you still use the conventional Tie Rod End or (TRE) make sure that there is no play in this, as play can cause DW.
4. Look/Check for worn/torn boots on ball joints/tie-rod ends.

Check your Tires
1. Out of balance tires can cause shaking in the front end, which can lead to death wobble.
2. Make sure all of your lug nuts are tight, (Sounds elementary but it happens to the best of us)

Check your Frame
1. Small cracks in the frame can cause the steering box to feel loose, Shaking from DW can only make this worse. 33’s and larger should have some form of Steering box brace, or frame brace in.
2. If you have upgraded your frame mount, make sure its cranked down nice and tight. (best to use an impact gun)
3. A busted Frame Mount can cause play in the front end causing DW (Keep a watchful eye on the welds as welds in sheer can break over time.

Make sure you have a good alignment
1. After you get an alignment done, have them print out the numbers for you. An XJ should have a 7* positive caster angle. A lifted XJ can’t always have that high of a number because the pinion would become out of alignment with the front driveshaft. Pinion angle takes precedence over caster.
2. Make you sure you go to a place that will adjust the caster if necessary (either by shims in the frame side of the LCAs, or adjustable LCAs).

The more adjustable parts the easier it is to tune in your suspension.
1. Adjustable Track Bar
2. Adjustable Upper and Lower Control Arms (upper ones above 4” of lift). Not only are they adjustable, but they are stronger.


Things to remember:
1. After any lift, get your Jeep professionally aligned, this is a REQUIREMENT, not a suggestion.
2. A Steering Stabilizer (SS) is not a quick fix for DW.
3. Make sure that the lift you purchase comes with all the required parts for a safe driving vehicle. (as long as its going to be a DD)
4. PLEASE ALWAYS DRIVE WITH YOUR FRONT SWAY BAR CONNECTED!

Entire list of everything that can cause death wobble:

-Front tires out of balance
-Front alignment out of spec
-Loose track bar
-Worn track bar bushings
-Worn track bar end
-Needing an adjustable track bar
-Bad bushings/joints in control arms
-Worn/damaged steering stabilizer
-Worn/damaged shocks
-Worn/damaged tie rod end
-Bad U Joint
-Bad ball joint
-Loose frame mount
-Steering box looseness
-Need drop pitman arm
-Driveshaft(s) not balanced
-Bad front hub assembly


Torque specs:

Item ........................................ Ft. lbs. ................... Nm

Lug nuts (1/2 X 20 w/ 60* cone) .... 85-115 .............. 115-150
All tie rod ends .....................…..... 55 ...................….. 74
Steering (both ends) ..............…..... 55 ................….... 74
Shock absorber upper nut .............. 16 ................….... 22
Shock absorber lower nuts ............. 17 ................….... 23
UCA frame end .....................…...... 66 ..............…..... 89
UCA axle end .........................….... 55 ................….... 74
LCA frame end ......................…..... 85 ...................... 115
LCA axle end .........................….... 85 ...................... 115
Track bar frame end ..............…..... 60 .................…... 81
Track bar axle end .................….... 40 ..................…... 54
Track bar bracket bolts ..........…..... 92 ...................... 125
Track bar bracket nut .............….... 74 ....................... 100
Track bar bracket support bolts ...... 31 ....................... 42
Hub bolts (3) ............................…. 75 ....................... 102
Hub- axle bolt ..........................….. 175 ..................... 237


Some information provided by Jeeps Unlimited
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Unread 11-10-2011, 09:18 PM   #3
The_Blacksmith
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x2 the drop pitman arm is hurting you a ton.

I'm asuming the track bar isnt stock, because if it is, your dif is horribly off centered at 4.5'' lift.

after 40mph wobble, is more than likely wheel balance, which you notice after 40mph more times than not.

if the shop who balances your tires dosent have a digital balancer, and you cant watch them balance the tires to 0.00 go somewhere else.

I watch my tires get balanced everytime.
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Unread 11-10-2011, 09:30 PM   #4
grule1988
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Quote:
Originally Posted by The_Blacksmith
x2 the drop pitman arm is hurting you a ton.

I'm asuming the track bar isnt stock, because if it is, your dif is horribly off centered at 4.5'' lift.

after 40mph wobble, is more than likely wheel balance, which you notice after 40mph more times than not.

if the shop who balances your tires dosent have a digital balancer, and you cant watch them balance the tires to 0.00 go somewhere else.

I watch my tires get balanced everytime.
It's a non adjustable trac bar that's on there I bought the jeep with the lift already in it only things i put in are the TC drop kit and pitman arm cuz my buddy w a 2dr xj looked over it and told me to install them. And the trac bar bushing cuz the old rubber one was junk and would clunk when id turn
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Unread 11-10-2011, 09:48 PM   #5
CJ7-Tim
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Does the track bar have a relocation bracket on the axle end like the silver one in the pic ?

.
trackbar-relocation.jpg  
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Unread 11-10-2011, 10:04 PM   #6
grule1988
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Quote:
Originally Posted by CJ7-Tim
Does the track bar have a relocation bracket on the axle end like the silver one in the pic ?

.
No it doesn't
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Unread 11-13-2011, 08:05 AM   #7
twm3000
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Here are 2 articles about the death wobble:

http://www.jeeparticles.com/technica...ath_wobble.htm
http://www.jeeparticles.com/technica...e_shooting.htm
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Unread 09-13-2013, 08:34 AM   #8
yukonie
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Sorry, this is for a WJ but...
Omix-Ada 18205.06 Track Bar (Automotive)
WARNING, When easy fixes go wrong...
I removed the old bar, reused the original bolts because it didn't come with any new bolts. After install, during test drive the death wobble became worse at 42 mph. At slow speeds, I could feel the play in the track bar. When hitting potholes, ones I hit normally in my street, I could feel the wheels wiggle. I didn't do that before, this was different, it was a 'death wiggle'. I had a feeling the new bar end bushing inner diameter does not match the old bolt diameter. I saw a you-tube video before I did the install that showed this same thing. I was removed the new one, laid it on the floor next to the old one and put the old bolts in and there was a very slight wiggle that should not be there. The old bolts fit very snug in the old bar.

I measured each side of the inner sleeve, at each end ->

Old inner diameter: 48/64, 48/64, 48+/64, 49/64 (inches)
New inner diameter: 48+/64,49/64, 48+/64, 49/64

I cant use this bar with these bolts, and they seem like they wont be easy to find to fit a bigger bore hole.

It makes me wonder if part of the death wobble (for me) could be play caused by using parts that are not quite exactly right in size.

Anyone else have this issue?
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Unread 09-13-2013, 11:31 AM   #9
habbyguy
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Quote:
Originally Posted by The_Blacksmith View Post
after 40mph wobble, is more than likely wheel balance, which you notice after 40mph more times than not.
I'd just add that it's not likely that JUST an unbalanced wheel - unless it's grossly out of balance - should be enough to induce DW in an otherwise mechanically correct Jeep. If the problem is traced to a wheel that's only a little out of balance and/or it comes on when a particular front wheel hits a bump, suspect a bad shock absorber. That was the ultimate cause of a VERY difficult to fix DW my XJ had - turned out there was a big dent on the shock that would intermittently cause the shock to act like it wasn't even there, so any excitation of that front wheel could build into DW.
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