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-   -   The dreaded DW (http://www.jeepforum.com/forum/f96/dreaded-dw-1557228/)

suspensionguy 08-02-2013 11:12 PM

The dreaded DW
 
Im new to the forum and like reading all your posts.Its great to see a bunch of guys so passionate about their rides.This forum is a testiment to human ingenuity and the will to do it yourself if nobody else can or will help you.
I have been in the alignment and suspension industry for the past 15 years and have coma across all kinds of issues on all kinds of vehicles.
I would like to give my opinion regarding the dreaded DW.
DW is not a balancing issue and can not be caused by a tire.Balancing will be a vibration on the steering wheel at speeds upwards of 40mph.
DW can best be explained by looking at what happens when you drop a pebble into a pond,the ring it makes in the water becomes bigger and bigger untill it filss the whole pond.Now,I have read all the statements made on DW and to some extent agree,but,I would like to ask this question.If DW is a problem on straightdiff coilsprung suspensions,why is it that it doesnt occur so frequently on LandRover or Toyota LandCruiser?I have done lifts on all kinds of 4x4 vehicle and it is only the jeep that I have had to deal with DW.
Back to the pond.When you hit a bump in the road,the suspension reacts to the bump by transferring the energy to the shock absorber.The shock must absorb this sudden influx of energy and by moving up and down in a controlled manner that is determined by the shocks recoil and rebound settings it must get rid of the energy.But there is always some of the energy that passes to the rest of the suspension,and that is where DW is born.That bump to the steering becomes bigger and bigger untill it fills the whole suspension and you need new shorts.But there is a way to fix this.I heve been doing it with great success for years.

tydp 08-02-2013 11:17 PM

Ok????
 
But there is a way to fix this.I heve been doing it with great success for years.

So, "splain Lucy":kiss:

Filthy-Beast 08-03-2013 12:32 AM

I'll play: I'm talking about true death wobble not a bad shimmy or vibration. If you have true DW it's a stain making event, you will think the entire front end is coming apart and you have to come to a complete stop to get rid of it. My was violent enough to rip a brand new stabilizer from it's mount.

Agreed true DW is not caused by tire balance or steering stabilizer. Plain and simple something is loose or worn and many times it's multiple things that are loose or worn.

The reason some people think it is tire balance is an out a of balance tire can trigger DW in the loose or worn part. My LJ would get DW if there was even a little mud in the wheel, but when perfectly balanced I'd only get a slight vibration from 52 to 65, above 65 it was smooth as glass.

I checked everything with me under it and somebody moving the wheel, I had 3 shops check it everything seemed fine. Took an old-timer to figure it out, he jacked up the front so one wheel was off the ground, then wedged a 6' 2x4 under the tire and lifted up. the unit bearings were shot, the spindles moved a good 1/2".

You had to have the leverage of the 2x4 to see it. the out of balance tire going was the trigger not the cause. Had I not found it I believe my tire would have come off within a 1000 miles.

Bottom line: if you get true DW, find the part or parts that are loose or warn don't just apply the bandage of tire balance or stabilizer, as these will only hid the problem while it continues to get worse.

1222 08-03-2013 03:50 AM

Quote:

Originally Posted by suspensionguy (Post 15751084)
...
DW is not a balancing issue and can not be caused by a tire...

:welcome: to the forum.

Yeah well I’m not so sure of that. I had some tires that were cupped very bad on an ’04 Rubi that I had and when I left the tire shop with brand new tires and got on the freeway I swear I thought I was about to die (DW). Long story short it turned out to be a combination of extreme psi differences in the 4 tires along with improper balancing.
:cheers2:

suspensionguy 08-03-2013 04:17 AM

The main problem on all Jeeps are the steering damper.In my opinion a damper does not hide or mask the problem but actually prevents it.I think you refer to it as the stabilizer?
It is a design flaw on the part of chrysler and I cant beleive that they havent picked up on it yet.The damper on all Jeeps mounts to the toe bar on one end and the diff housing on the other.
I have a bolt on kit that I make in house that mounts to the toe bar on one end and the chassis on the other end.The simple fact is that for a damper to be effective it Must mount on the chassis.If it mounts on the diff it becomes a part of the moveable suspension parts that cause DW.So by mounting it to the chassis you are not masking death wobble,but preventing it from happening in the first place.You are stopping the circle the peblle makes in its tracks if you understand what I mean.
I still run the stock damper as well.

suspensionguy 08-03-2013 04:31 AM

I agree that improper PSi and tyre wear could cause a vibration,but DW is not a vibration.The defining character of a vibration is that it can be cured by correcting the balancing,be it a propshaft a tyre or even a ceiling fan(i have balanced all mine at my house)
DW is a movement of suspension parts that builds up moment and transfers its energy to any and all available parts in the system.I do agree with Beast that worn out suspension parts do play a huge part in the cause of DW but replacing said parts wont always correct DW.I have been resaerching DW since it reared its ugly head on my Jeep and have had about 30+ sattisfied customers since I started with my kit

1222 08-03-2013 05:43 AM

I can tell the difference between a shimmy and full on DW. What I experienced was full on DW, no if's ands or buts about it.
:cheers2:

suspensionguy 08-03-2013 06:02 AM

Point taken 1222.Im only trying to explain from my point of view what DW is and from my experience how to correct it.Im not trying to say that what you experienced was not DW,and improper balancing could set it of.
By the way,do you guys have shops that offer highspeed or on car balancing.I recommend it especially on a aftermarket tyre and wheel setup.

1222 08-03-2013 02:58 PM

Quote:

Originally Posted by suspensionguy (Post 15751497)
...By the way,do you guys have shops that offer highspeed or on car balancing.I recommend it especially on a aftermarket tyre and wheel setup.

I’m sure we do although I’ve never been to one myself, I think. I did have my tires “shaved” on a CJ7 of mine many, many years ago though. It was done by spinning my wheels/tires while they were still on my Jeep. Not sure if it could have also done a “high-speed” on car balance or not; just been too long ago to remember.
:cheers2:

Prot 08-03-2013 03:13 PM

I think a lot of people have misconception about the purpose of the steering stabilizer. It's to prevent bump steer on uneven terrain.

Common causes of death wobble on solid axle vehicles like the JK:

Worn suspension or steering components, usually track bar, trackbar bracket, ball joints, tie tod, and sometimes wheel bearing (sometimes called unit bearings) contribute.
Loose hardware.
Incorrect caster (this applies mostly to vehicles with modified suspensions)
Incorrect tow can also cause steering abnormalities but not really death wobble.
Bad mismatch of coil springs with shocks (yes, that was my contribution to the stickies after chasing this down for four freaking years)
Axles not centered. This is very common and is caused by tightening up the track bar, brackets, and other suspension components when the vehicle is still in the air instead of setting on the ground on it's own weight.

Another thing that is not as specific, is the higher the suspension lift you install, the more components it takes to get it right. A a couple of inches of lift doesn't require much. A lift of several inches requires adjustable control arms, and a high steer kit or Reid knuckles to return steering to parallel geometry. Without parallel geometry, steering on a JK is horrible. The higher you go, the more it gets to be not parallel.

My set up was built over time, replacing faulty and cheap components and learning what was the next thing causing problems. It ended up costing me a lot more than it should have. Then again, in 2007 the knowledge base was somewhat limited.

Key components to get my steering and suspension to work right are, chromoloy tie rod (stock one is useless), high steer kit, and all eight adjustable control arms. Rancho 9000XL adjustable shocks also helped.

SubAtomicGenius 08-03-2013 05:27 PM

Quote:

Originally Posted by suspensionguy (Post 15751436)
The main problem on all Jeeps are the steering damper.In my opinion a damper does not hide or mask the problem but actually prevents it.I think you refer to it as the stabilizer?
It is a design flaw on the part of chrysler and I cant beleive that they havent picked up on it yet.The damper on all Jeeps mounts to the toe bar on one end and the diff housing on the other.
I have a bolt on kit that I make in house that mounts to the toe bar on one end and the chassis on the other end.The simple fact is that for a damper to be effective it Must mount on the chassis.If it mounts on the diff it becomes a part of the moveable suspension parts that cause DW.So by mounting it to the chassis you are not masking death wobble,but preventing it from happening in the first place.You are stopping the circle the peblle makes in its tracks if you understand what I mean.
I still run the stock damper as well.

Not to be snotty, but you're a little misguided about this IMHO. Fact is that a properly torqued front-end solid axle assembly can work perfectly fine without a steering stabilizer. Sure, they act to absorb bumps/jolts in the steering when you're driving around, but in most cases they only mask the underlying problems until it only gets worse and you have full-blown DW. As a matter of fact, most 4x4 vehicles with solid front axles don't even use a SS.

What prevents DW in the first place is a torqued track bar with solid mounts (not ovalled), servicable ball joints, proper diameter fasteners instead of the stock Mopar metric ones, etc. See Planman's thread for DW, that sorts out all the details.

ncb 08-03-2013 05:47 PM

This thread sounds like a sales pitch for the bracket the OP mentioned.

SubAtomicGenius 08-03-2013 06:28 PM

Agreed, something strange about it.

brianjw 08-03-2013 07:27 PM

Same here.

Lets see this magical fix you have created. ;)

TheBoss 08-03-2013 09:19 PM

BS is what comes to mind when I try to draw the concept of what is being described by the op.


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