Occasional Violent Shaking, 1990 Jeep Cherokee

[jyl]

My father is having a problem with his 1990 Jeep Cherokee (2-door, 6-cyl, stick, about 100K miles).

Every now and then, when driving around 55-65 mph on the freeway, the vehcle will suddenly and without warning begin to violently shake.

I mean really violently, it feels like the wheels are jumping off the road, the gear shift lever is bucking, your vision is blurry.

The only solution is to slow to about 15 mph, when the shaking suddenly stops. Putting it in neutral, lifting off the gas, applying brake, none of that makes any difference. Then you accelerate back to cruising speed and everything is fine again.

It doesn't happen often - I drove 200 miles today from the Bay Area to Laguna Seca and back, and experienced this shaking only once. The front tires have been balanced, the vehicle drives extremely smoothly. When it happened today, I was on a smooth stretch of freeway, might have been recently resurfaced actually,with no particular bumps that I recall.

Any ideas? One mechanic said the front end was worn out, $1,000 please. Another said the front end was okay. My father doesn't want to blindly throw $1,000 at the vehicle, without some good idea what is causing the problem. This is a "spare" vehicle.

[Dantilla]

I would check the tierods first. Something in the front end is worn out way beyond limits.

[JeffO]

Replace the stearing damper. Its cheap, just a shock absorber that takes the shakes and shimmys out of the front end. Why it would be intermittant is odd.

[Dantilla]

Yeah. The 1990 Cherokee had a straight front axle. I dont know if they came from the factory equipped with a steering damper, but it sounds like you need one now.

Common upgrade on straight-axle four wheel drives after they rack up the miles.

[Don Ro]

Do a Google on "Jeep Death Wobble", John.
The consensus is that it can be caused by any number of issues.
Never had it on my '92 XJ (just bought it last Oct.), probably because she's pretty snug up front.
I'm not experienced in the matter, but I've read that a new stabilizer can just mask it.
If you go w/a new stab., this one is highly recommended: OME SD40 stabilizer
.
http://kevinsoffroad.com/sstabilizers.html
.
Anyway, good luck.
.
BTW, I hear DW gives good pucker.

[MotoSook]

I have a 2001 XJ..and I got the shakes once, never again..'though I did nothing since it happened once going 30 MPH.

I figured it was the combination of bumps and a damper that was going bad..

I never did replace the damper which is the stock unit. Random combination of events/factors that seem to be a problem for a solid front axle (shrug)

[jyl]

Good pucker - well, my father warned me about it so I wasn't too shocked. But it was violent, felt like you blew both fronts at once or something.

I simply took my foot off the gas and eased over to the shoulder as the Jeep slowed to 15 mph. If there hadn't been a shoulder, like if this happened on the Bay Bridge, that would have been dangerous. And if this had happened on a curve, that would have been dangerous too (but my dad says it never does).

This Jeep will be for my wife and I to use when we visit the Bay Area, so my wife will sometimes be driving it with the kids. I think she wouldn't be as sanguine at the "Death Wobble". Got to get this fixed.

[lm6y]

Don hit it on the head, Death Wobble.

More often than not, it's the front control arm bushings going bad. Look the bushings over for splitting, and rot. If the bushings are bad don't even try to change them, it's a PITA. Just replace the arms, they are only about $10 more for the whole thing, with the bushings already in place.

http://www.quadratec.com/products/56015_004.htm (uppers)

http://www.quadratec.com/products/56015_001.htm (lowers)

You'll need two of each.

While you are checking the bushings, check the balljoints, and tierods.

Solid front axles are VERY sensitive to alignments too.

If the front end is tight, you don't even need the stabiliser. My best friend and I run with a local Jeep club (on designated trails only, TREAD LIGHTLY!). we built a 98 Chero with 8 inches of lift, running 35 x 13.50 tires, no stabiliser, and no death wobble.

[Rot 911]

I too agree that it is the infamous "Death Wobble."

[Superman]

I once had a death wobble develop on a motorcycle at a triple-digit speed. That was exciting.

[Rot 911]

All the info you need on an XJ Death Wobble:

Death Wobble (front end tire wobble/shake) Info --
The following information was provided by JU Members:

Jason (XJay96)
Chris (SilverXJ)



Curing death wobble is defiantly a reality. Death wobble isn’t similar to a wobble from an unbalanced tire. It is by far worse. When death wobble hits you will know… it’s a violent shake form 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 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. There 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.

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

Alingment specs (stock):

Angle ............. Preferred ........... Range ............. Max R/L diff.

Caster ............ +7.0* ........ +5.25* to +8.5* ......... 1.25*
Camber ........... -0.25* ....... -0.75* to +0.5 ........... 1.0*
Total Toe-in .... +0.25* ....... 0* to +0.45* ............. .05*
Thrust angle .... 0* to ± 0.15*



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 draglink. 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)

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
-Need 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



Information provided by JU Members:

Jason (XJay96)
Chris (SilverXJ)

[jyl]

This is great information, guys. Thank you!