1988 Comanche

[kirk]

Hello, this is my first post on CC, and hopefully not the last.

 

I located an MJ for a fair place from a local dealer, and I planned to purchase it with my dad today.  It's an 88 MJ 2WD with the 4.0 I6 and a 5 speed Peugeot.  It has around 173,000 miles and has no major rust on the underbody, just a few tiny tiny spots on the tailgate and such.  It has good paint.  The interior is ok, but the bench seat is terrible and needs to be swapped either with a clean bench or some buckets.  So I went this morning with my dad and mechanic friend, but the dealer would not sell it to us because he said it would get heavy shakes around 50 mph...with my loads of Comanche research I have done, I immediately recognized it as "Death Wobble".  The dealer said he was going to get it checked out at his tire shop and see what happens.  I've read up and heard all about "Death Wobble" but there never seems to be a definitive cure.  My good mechanic friend could probably diagnose it but apparently it could be a multitude of problems.

 

So, yall, do you think we should purchase this truck even if it has "Death Wobble", and how hard is it to fix?

[cruiser54]

Don't shy away from it.

 

 

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 (hitting a bump or a pothole) or also when a vibration reaches a certain point and harmonic at a certain speed, it causes theother components to react.  This is called the “multiplier effect”, where one component affects one or more other components as the event travels through the front end of the vehicle.

 

Death wobble is not uncommon with the XJ.  It is even more common with a lifted 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 exactly how to perform a comprehensive inspection of every single front end part, looking for abnormal wear and or play in that hardware. If you do not know how to do this type of inspection, pay an experienced professional to do it. Be sure to ask them if they are familiar with “death wobble”, as not all technicians are versed in this…..   

 

Check out the below link if you would like some extensive reading on “death wobble” causes and cures. From my research, Kevin (the author of this tutorial) is possibly the best in the business with tracking down root cause of death wobble.  He does offer hardware for sale that can help resolve death wobble, but even if you don’t buy any parts from him, you can still get some excellent ideas on what to look at in resolving your death wobble. 

 

http://www.kevinsoffroad.com/how-to-fix-your-own-death-wobble/

 

Possible causes of death wobble are listed below.  Isolating death wobble is a process of elimination and the root cause is not always obvious and it can often be caused by a combination of things! From my personal experience, I would first concentrate on the track bar and the control arms and associated bushings.

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-Front tires out of balance (try swapping fronts to rear and see if symptoms change)

-Tire pressure.  Don’t laugh. It’s not a root cause but can exaggerate the problem.  Experiment with lower tire pressure to see if it helps

-Improper lug nut torque on wheels
-Front alignment out of spec
-Loose track bar
-Worn track bar bushings
-Worn track bar (check for play!!)
-Bad control arms and associated bushings
-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

 

Tom Walker

[GirsMJ86]

I'd pick it up. Make it known you know all about DW and what it can entail and try to get a good deal for taking it off their hands. A dealership doesn't want to pour money into a used car.

[Eagle]

Yes you should purchase it.

 

The death wobble may or may not be easy to fix. If you have read a bunch of posts on the subject, you must already know that very few of us agree on what causes it. Many people claim that a loose tie rod end or a bad track bar "causes" death wobble. Having driven to work daily with a very bad track bar for a period of several months when it was too cold and snowy to crawl under my XJ to replace it, I know absolutely for a fact that a loose track bar does NOT and CANnot cause death wobble. Nor does a bad tie rod end.

 

I have experienced true death wobble twice in my life. Both times it was terrifying, even though I knew what it was instantly. The first time was in a brand new (less than six months old, under 10,000 miles, never driven off-road) 1999 Grand Cherokee. What triggered it was touching the brakes lightly on a long downgrade, when the front rotors were warped. But ... the rotors had been warped for awhile, and I had just driven over 100 miles on that trip alone. That was the ONLY time death wobble kicked in.

 

Why that one time? My best guess is that I had never before encountered those exact conditions. Usually, I use the brakes to stop, not to regulate speed at 55 MPH. Even with warped rotors, when you step on the brakes hard enough to stop, the calipers clamp the rotors tightly. I think that light touch, possibly combined with the weight of the vehicle being shifted forward due to the grade, created a different reaction. The calipers (or at least one of them) got knocked back and forth by the rotors, that got transferred to the tires, and from there on it was Katie bar the door.

 

What IS death wobble? Death wobble is a phenomenon that takes place when one tire starts to shimmy and, for whatever reason, instead of the one wheel just bouncing happily along (which can happen -- I've been beside cars on the Interstate where I can see one front wheel bouncing up and down at least two or three inches and the owner seems totally unaware there's anything happening), the shimmy gets transferred to the opposite wheel as well. That wheel starts to shimmy, and they create a harmonic, where each oscillation of one wheel send a reinforcing vibe to the opposite wheel. It keeps escalating until you either stop the vehicle ... or you crash.

 

So they key is to stop tires from shimmying. In theory, a tire in motion should be self-stabilizing, like a gyroscope. But a gyroscope has to be perfectly balanced to run true. That's our clue -- if a tire is a gyroscope, then a tire has to be perfectly balanced to run true. Often, they aren't. And too many shops are perfectly willing to charge you full price for a half-assed job, and send you home with tires that are NOT properly balanced.

 

The only other time I had death wobble was just after I had swapped a different set of tires onto the '88 MJ. I set off on a short drive, got about ten miles up the road, went into a sweeping right hand turn that took some weight off the right front wheel, and BAM! I stopped, caught my breath, turned around and drove home, and took those tires off. Never had death wobble again, even running 31" tires. (The ones that caused the problem were stock size.)

 

My answer, obviously, is: TIRE BALANCE.

[HOrnbrod]

The only other time I had death wobble was just after I had swapped a different set of tires onto the '88 MJ. I set off on a short drive, got about ten miles up the road, went into a sweeping right hand turn that took some weight off the right front wheel, and BAM! I stopped, caught my breath, turned around and drove home, and took those tires off. Never had death wobble again, even running 31" tires. (The ones that caused the problem were stock size.)

 

My answer, obviously, is: TIRE BALANCE.

 

Must have been Goodyear tires. Possibly Wranglers GSA's? They make them square. 

[Eagle]

 

The only other time I had death wobble was just after I had swapped a different set of tires onto the '88 MJ. I set off on a short drive, got about ten miles up the road, went into a sweeping right hand turn that took some weight off the right front wheel, and BAM! I stopped, caught my breath, turned around and drove home, and took those tires off. Never had death wobble again, even running 31" tires. (The ones that caused the problem were stock size.)

 

My answer, obviously, is: TIRE BALANCE.

 

Must have been Goodyear tires. Possibly Wranglers GSA's? They make them square. 

 

Yeah, now that you mention it I believe the WJ did have GSAs.

 

Don't remember what the ones were on the MJ.