passthrujr

Okydoke, where to begin?..... I've got a 92' cherokee, nothing fancy, 4.0L with the basics. Its my trail rig, and daily driver. I was driving it home the other day and noticed a funny vibration coming from the front end. It more or less felt like a flat tire (going down the highway at 55mph). I pulled over to check. Everything looked fine, so i procceded on my way. Quickly, it got much worse, and soon began to feel like the brakes were grabbing or somthing of that effect. I limped my way home. Jacked it up and found both front calipers locked up. (strange that both were locked). I replaced both callipers that day, after much cussing and frustration i got them both on correctly. Bled the brakes and took it for a spin, got on the highway and hit 45, it was like the whole front end was falling off. At first it felt like it was lagging out and it was an engine problem but no rpm drop... went back home. spent 3 hours looking over everything... I rotated the tires (front to back), Double checked callipers and rotors. Oh, forgot to mention the callipers fixed my brake delima... Anyway, both drive shafts looked fine, I've resently replaced the front U-joints (past couple months), all components look fine. I tightened the wheels on evenly, touqed them to 110 and hit the road again. STILL NO CHANGE... im very frustrated at this point. i was hoping someone could help me out.

Byro

The good old death wobble. Check out your track bar, youll need another hand for this. Have a friend sit in the Jeep with it off and shake the wheel back and forth slowly, the track bar goes from the axle to the body, one end is a rubber bushing, the other is a ball joint. As your friend turns the wheel back and forth you should check for play in the ball end.

tjwalker

In one line, you mention "feels like the whole front end was falling off". I agree that you are most likely suffering from "death wobble". Here is more.
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My understanding of “death wobble” is this. Somewhere in the vehicle, one or more components is worn beyond tolerances, and when oscillation initiates from a suspension “traumatic” event or when a vibration reaches a certain point and harmonic at a certain speed, it causes the other components to react. It is called the “multiplier effect”, where one component affects one or more other components as the event travels through the system.

Death wobble is not uncommon with the XJ. Finding the worn component or components is not always easy. It can sometimes be downright difficult. Sometimes it’s obvious, other times everything appears to be okay when you perform an inspection on a hoist, but getting the vehicle up in the air and going over everything with a fine tough comb is always a good first step. It is very helpful if you know or have a technician that knows how to perform a comprehensive inspection.

Possible causes of DEATH WOBBLE are listed below. Isolating death wobble is a process of elimination and the root cause is not always obvious.

Note: It can oftentimes be due to a combination of things!

Check out this link if you want extensive reading on “death wobble” causes and cures.From my research, Kevin is among the sharpest with tracking down root cause of D.W. He offers hardware that can be helpful with D.W, but even if you don't order from him, you can benefit from his knowledge base on this condition.

http://www.kevinsoffroad.com/how-to-...-death-wobble/
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-Front tires out of balance (try swapping fronts to rear; see if symptoms change)
-Tire pressure. Don’t laugh. Experiment with lower tire pressure to see if it helps. Higher tire pressure can help in a small% of cases
-Improper lug nut torque on wheels
-Front alignment out of spec
-Loose track bar
-Worn track bar bushings
-Worn track bar end
-Bad bushings/joints in control arms
-Worn/damaged steering stabilizer (not generally a cause in and by itself)
-Worn/damaged shocks
-Worn/damaged tie rod end
-Bad U Joint
-Bad ball joint
-Loose frame mount
-Steering box loose
-Bad front hub assembly

passthrujr

Sorry guys i probably should have been more specific about the condition.

@Bryo- I've actually had Trac bar problems in the past. When a rotated the tires I discovered that the bolt in the lower bushing was too small and was allowing about a 1/4" of play. (i know, really bad) With a 7/16" bolt from homedepot i fixed that problem and I double checked all tie rod joint while i was doing that. When i took it for the spin the problem still prosited.

At this point I am leaning away from "death wobble" like condition only becasue the vibration is worse when i am accelerating.

@tjwalker- Much appreciate the research, thank ya. like i said above i probably should have been more specific. The "vibration" is only when accelerating at a little above 45mph, and it takes a little while from the problem to begin once i get to 45mph. It seems to be to that more more i drive it after it gets to that point the worse it gets. It feels more like the jeep is lagging or skipping.


Does anyone think that warped brake rotors could cause this?

passthrujr

Anbody have any ideas?????????????????????????????????????

tunermiket

For starters, lagging and skipping are two different things. A lag during acceleration takes my mind beyond suspension to engine/fuel delivery. A lag could be due to a dirty injector, operation at wrong voltage, loose vacuum, or many other culprits to this effect.
But what you said sounds like the infamous death wobble. If nothing is worn and causing that domino-type effect, not sure. I think we need to be more clear on exactly what its doing. Is it lagging under acceleration or skipping (up and down)?

xjbeans

All bs aside check the bolts in the trans mount i swapped my trans torqued all my bolts down with the impact some how they still fell out had weird vibration also check motor mounts the go bad its not good they will snap the bolts off in the block

tunermiket

A more in-depth thread on DW. Hope this helps a little more:

https://www.cherokeeforum.com/f51/di...-wobble-55021/

passthrujr

awesome, thank ya!!!! i did some work on it last night. the track bar seemed fine, and the tie rod end are ok. it probley seems goofy but i went and had the brake rotors turned. i figured that if i warped the rotors i can rule that out.

passthrujr

im guessing it isnt something with the engine, because there is no drop in rpm. Just for $h!t$ and giggles i went over everything in the motor. Fuel preasure was fine, and all vacuum lines were on ok. To be more exact, when i hit 45mph on the highway after a few seconds the jeep starts skipping. Almost like the brakes are being tapped really really fast. When i start to accelerate over 45mph it gets worse. When i let off the gas and coast it gets better. after a while of driving, it seems like it starts to do it at 35-40mph.

tunermiket

yeah, it really does sound like death wobble. the slightest vibration can cause it under the right conditions. go through all the bushings and tighten all the bolts.. pretty much what the link says to do. id say youll pinpoint it when you do all that, man.

Red82

Did it start after wheeling? Check your toe in. Maybe you knocked it out of alignment? Or maybe you bent a rim and its not properly balanced?

passthrujr

okydoke guys, I think i might have finally gotten it figured out.


first off, ive got two bad tie-rod ends. Secondly there is a u-joint in the steering colum that has a top piece in the center of the joint and its worn down a bunch so it causing a ton of play in my steering. If anybody wants, i can post pictures. Im not really sure of the specific name of the joint though.

Also i discovered ive got two bad plug wires that are causing the first two cyclinders to misfire.

Thank you all for your help!