death wobble still

[mvusse]

The biggest cause of death wobble is the track bar being loose at one end or the other. the second is that the track bar and tie rods are no longer aligned due to lifting the truck, but this normally just results in bump steer. J B Cuz

 

Yes, JB, but he already replaced his track bar (see picture above), so he eliminated that cause. The only thing left to do is balancing, as far as I can see. :cheers:

 

-Tom

 

He replaced the track bar, but I wonder about the track bar bracket. Not uncommon for the hole to be wallowed out allowing the track bar to move.

[skidoo_j]

the holes on the trac bar mounts were snug, not oblong.

I used the stock uppers because the geometry for a 4" lift should be right at stock length, one of the reasons i was okay with 4" because less than 4" should not really be a stock length upper.

 

I did not replace the upper mounts though, not sure if that could cause issues... I did replace motor mounts and tranny mount. the alignment shop said all my rod ends were solid.

[skidoo_j]

Have your wheels "Road Force" balanced. It will make a world of difference. If you have replaced all of the front end components, and your alignment is on spec, that should fix your problem. :thumbsup:

 

-Tom

 

 

what is a road force balance??? Is it different than what les schwab normally does, they are open country toyos

[skidoo_j]

i'll check to make sure the track bar bushing holes are snug on the bolts. i know the bolts are solid in the mounts...

 

 

as per all suggestions the .75" pitman arm drop was not used. as the alignment guy said they way it is currently chaning in the different arm may cause bump steer. He told me they checked my caster and i'd adjusted the arms correctly. thank you all for the advice over several searches. he also said i'd centered the axel with in spec and they did not need to adjust it. I don tknow if they just said all that so all they had to do was adjust the toe.

[skidoo_j]

The biggest cause of death wobble is the track bar being loose at one end or the other. the second is that the track bar and tie rods are no longer aligned due to lifting the truck, but this normally just results in bump steer.

 

J B Cuz

 

I'll take a pic from the front of the steering y and trac bar maybe it's not right.

[HellCreek]

what is a road force balance??? Is it different than what les schwab normally does, they are open country toyos

 

"Road Force" balancing is done on a machine that applies pressure to the tread as the tire is being balanced. It is much better than regular spin balancing. Your expensive tires will last longer, too. I also highly recommend inflating with Nitrogen instead of air. Again, your tires will run cooler and last longer. These two things cost a little more initially, but are well worth it in the long run. :thumbsup:

[carnuck]

Nitrogen is a crock! The air we breath is mostly nitrogen anyways (almost 80%)

[skidoo_j]

Now i'm confused beyond.

 

at 55 when accel no wobble.

can get all way up to 85 no wobble.

 

 

then 5 miles later when at 60 and took foot off gas and slowed to 55 bad wobble.

 

tried to repeat no wobble. then drove over a bump at 50 and wobble..

 

so it seems completely random, but only at speeds higher than 50...

 

any ideas. it appears to be unpredictable and i'm not able to reproduce under control

[Eagle]

Now i'm confused beyond.

 

at 55 when accel no wobble.

can get all way up to 85 no wobble.

 

 

then 5 miles later when at 60 and took foot off gas and slowed to 55 bad wobble.

 

tried to repeat no wobble. then drove over a bump at 50 and wobble..

 

so it seems completely random, but only at speeds higher than 50...

 

any ideas. it appears to be unpredictable and i'm not able to reproduce under control

Just to be contrarian, I disagree completely with previous posts saying the usual cause of death wobble is loose track bar, loose tie rod ends, loose ___. It doesn't work that way. I drove my '88 XJ for an entire winter with a track bar that was so worn out I had over a quarter of a turn of free play at the steering wheel before it actually began to turn the vehicle. Those things being loose can allow death wobble to escalate, but they cannot cause it.

 

The usual cause is wheel balance. Next most usual cause is wheel alignment, typically insufficient caster angle. You have already been advised to have the wheels rebalanced, and I second that. It's ironic that as the balancing equipment gets better, the people doing the work get worse. The result isn't even a wash -- I've gotten better balance jobs in my own garage using a 30-year old J. C. Whitney bubble balancer than some of the expensive and high tech "professional" balance jobs I've had recently from shops with the latest and greatest equipment. Also have the alignment checked, paying particular attention to the caster angle.

[Chillstar]

 

death wobble is a horrifyingly violent shaking of the front end that makes you slam the brakes and pray to god that you don't hit something. Is that what you're experiencing?

 

Yes... I am experiencing this.

 

I just got my MJ up and running and when I accelerated fast above 40 mph, I experienced the dreaded "Death Wobble." My problem is that I haven't even lifted it yet and have death wobble. My plans are to put a 4.5 inch lift on it, so I don't know if I should address this problem now or after the lift.

 

I also just picked up my Rubicon wheels. When I get my tires, I will have them balanced and then see if the death wobble still exists. If it does, what are your recommendations?

 

Thanks

[Pete M]

find the slop in the front suspension and steering and replace those parts. :thumbsup:

[Eagle]

I also just picked up my Rubicon wheels. When I get my tires, I will have them balanced and then see if the death wobble still exists. If it does, what are your recommendations?

What are your alignment specs?

[SW86]

ive got DW also but one day after doing a little offroading, i didnt reconnect my sway bar. drove a good bit before i remembered i was supposed to be death gripping the wheel a long time ago. i know ive got issues up front but hell i just creep around town anyway. so i said @#$% it with the sway bar for now :nuts:

[Eagle]

ive got DW also but one day after doing a little offroading, i didnt reconnect my sway bar. drove a good bit before i remembered i was supposed to be death gripping the wheel a long time ago. i know ive got issues up front but hell i just creep around town anyway. so i said @#$% it with the sway bar for now :nuts:

Yep.

 

Several years ago one of the original members of NAXJA said the same thing. He then rolled his Cherokee in a city street, two blocks from home, at under 30 MPH when he had to make a sudden swerve. I think he was dodging a kid who ran out into the street, but the actual cause isn't important. What's important is that the factories don't throw metal on vehicles for no reason. It costs money, and it adds weight. If they didn't think it was absolutely necessary, you can bet it would not be there.

 

And that's for a stock height vehicle.

[skidoo_j]

I'm not sure what the alignment specs were. I'm assuming the shop set it to factory specs??? All i know is I still have death Wobble at 45 on a rough road (county maintained), but on freeway 60+. I actually had to come to a complete stop to get it to go away yesterday. and it came back even faster... I guess i'm gonna have to get under there and look for loose/ broken parts.

 

I really don't know where to go from here. even though i replaced the steering stabilizer could i need an aftermarket one because of the lift?? I just replaced it with new OEM spec.

 

Tires are out as a possible as i put the wheel/tire combo that was on before the lift and still wobble. I was thinking to remove front drive line just incase the u-joints were so bad that the wobble could start there??? then i guess it's all the ball ends? in the steering?? would you replace the knuckle ones first or the ones in the steering?

[skidoo_j]

any one know of a good off road shop in portland, oregon area??? one that could rid me of this death wobble???

[skidoo_j]

With front drive shaft removed and vac disconnect disconnected this violent shaking still occurs. It's random. I got up to 75 with no problem. bounced it through some rough gravel road w/ pot holes at 30 mph with no problem, but on way home at 50 mph just remove foot off gas to slow for speed limit and there it starts. Entire truck shaking. I did notice however that it does not feel as though the tires are jerking just the truck violently shaking all over to the point you think its going to explode. First time the wife rode and experienced it and she stated if felt as if it was a side to side movement..

 

 

 

So is it possible rear drive shaft is causing this??? I will be measureing my pinion to shaft angle tomorrow on level ground and also my shaft to transfer. I don't know if the yoke is to far out of the transfer case maybe w/ accel and decel it's pullling out??? but then there's no popping or grinding noise. the drive line angle looks okay. Here's a photo...

[mvusse]

What you describe sure sounds like DW, and the wife would be correct. No, this is not a driveline problem. This is a front suspension/steering problem. Somewhere in there something is just lose enough for a harmonic oscillation to start. Most likely track bar, but could be 50 other things as well. A new/better/bigger steering stabilizer can successfully hide DW, but would not fix the underlying issue.

 

And yes, Eagle, a REALLY loose track bar allows too much movement for DW to occur, with the end result just being that you move the steering wheel half a turn while the truck shifts sideways before finally turning.

[shelbyluvv]

I also see a CRusty's track bar. Take that POS and throw it as far as you can.

 

I fought DW on my WJ for over a month after I put a new CRusty's lift on it. It turned out to be the bushings were too soft in the TB. I put a Rock Krawler TB in it and it cured the DW.

 

This

[Eagle]

And yes, Eagle, a REALLY loose track bar allows too much movement for DW to occur, with the end result just being that you move the steering wheel half a turn while the truck shifts sideways before finally turning.

That has nothing to do with death wobble. Death wobble is elusive precisely because it is a harmonic. A loose track bar neither contributes to the harmonic nor takes away from it. There is no such thing as a track bar that is "too loose" to result in death wobble.

 

The early 1999 Grand Cherokees (the WJs) had a DW problem ... with the export suspension only. I think the Up Country suspension was the same, because I had a totally stock '99 WJ go into death wobble cruising on a state highway in New Hampshire. The vehicle was totally stock and had less than 10,000 miles on it.

 

DW can be cured by changing to different rate front springs. That's what Jeep did with the WJs. It may be cured by changing to harder (or softer) rubber bushings. It may be cured by changing to different shock absorbers. It may be cured by rotating the tires.

 

The key point is that it is a harmonic. In order for death wobble to occur, one front wheel starts to wobble or bounce, and then the other front wheel starts to wobble at the same frequency. Once that cycle starts, they feed on each other and it escalates. That's why the only way to stop it is to slow the vehicle virtually to a stop. But the harmonic takes place as a result of a number of factors being "just right." Change any one of the factors, and the death wobble is eliminated. On my '88 MJ, at one time it would go into DW when going around sweeping right hand curves, but not when going around sweeping left hand curves. Go figure.

 

That said -- the wheels/tires of any motor vehicle are individual gyroscopes. If you can remember playing with a gyroscope as a kid, when spinning they do NOT like to be moved out of their plane of rotation. So a vehicle tire/wheel inherently resists wobble, and there has to be something seriously wrong to allow the first wheel to wobble enough for death wobble to be initiated. And that's why I remain of the opinion that the primary cause is wheel balance. I just put new tires on my wife's (all stock) Cherokee. The tires were mounted and balanced by a friend, using a "road force" balancer. There is a shimmy at exactly 55 MPH. Fortunately, it doesn't escalate into death wobble, so I won't ask him to rebalance the tires. It's only a small shimmy. But ... the balance was done by a guy who cared (he knew these were for my wife's Jeep), using the very latest and best equipment ... and the balance is off. If you think you can have the high school drop outs at Pep Boys balance oversize off-road tires and have them done right, you are only fooling yourself.

 

Rotate your tires and see if the death wobble goes away, or changes the speed at which it starts.

[Incommando]

My death wobble was a bad track bar. Re-assembled with same tires in the same positions = No D.W. woo hoo.

[skidoo_j]

Tire balanced again, still DW.

 

However somthing promising to remedy...

 

Had Les Schwab in Hillsboro, OR do a pre alignment shake down and they found both passenger upper and lower ball joints to be bad. It has about 3/4" vertical play. So I plan to change those, now I know they could be a result of the DW or they could be the cause, Will keep posted. Thanks for all suggestions so far.

[skidoo_j]

Passenger side ball joints replaced in 4.5 hours, working on driverside now. On test drive after passenger side DW seems to have gone away, but a pop during turning now, hopfully it's the driverside ball joints that's why they're underway now.

[Incommando]

Passenger side ball joints replaced in 4.5 hours, working on driverside now. On test drive after passenger side DW seems to have gone away, but a pop during turning now, hopfully it's the driverside ball joints that's why they're underway now.

 

Track bar will also make a pop. Check for play at the top mount with the weight off of the front axle. :thumbsup:

[skidoo_j]

Driver side upper and lower ball joints in 2.5 hours.... Hell yeah

 

 

tools that make job go way fast.

 

Get a slide hammer with hub adapter

Ball Joint press from auto zone

then go to harbor freight and buy the ball joint adapter set i got it for 50ish on sale 66958

 

and a joint tool that looks like scissors suggest front end service set 66686

 

13 mm 12pt socket w/ 1/2” drive to remove hub

24” breaking bar

Small ball peen and a large ball peen.

 

 

When pressing in or removing the joints it was help full to rap on the axle C when pressing.

 

Moog joints are larger in diameter than the auto zone life time warranty ones. I installed the auto zone brand in my brothers and ordered mine through amazon and got moogs. Hence the press set from harbor freight is vital as the pieces that come with the press are not used except the press rings.

 

 

 

 

Now to chase the pop. I'm thinking i'm gonna buy some water disolve paint and spray everything up front when it pops pull over and look for what moved. any other suggestions. i don't have a lift to get the truck up high enough now to see what is loose while not under stress.