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Need help, death wobble, can't drive much longer.....

Re: Need help, death wobble, can\'t drive much longer.....

The caster brings up a comment from my old suspension class in college. Reference was made to the mid'70s monteCarlos. They had higher amount of caster than say the malibus. They required a steering stabilizer to prevent a steering shake. If trying different caster, I'd recommend lowering it to the 4-5* range and see what happens.
 
Re: Need help, death wobble, can\'t drive much longer.....

I think the true "DW" is a D60 related problem as it seems to happen when changing from D44/10 bolt to a 60 when everything else remains the same. in my case it once it started the only way to stop it was by comming nearly to a complete stop or keep hard in the gas but you have to let off sooner or later and it comes back as soon as you let off. if you eliminate the parts of the steering system that were on the truck before the D60 swap steering box, drag link, frames/ braces etc... the only difference assuming the truck the axle came from with stock tires didn't have DW is the tie rod and the way the knuckles pivot king pins vs. ball joints I'm wondering if the king pin has less resistance to pivot in conjuction with the big lug tires we run to start a side to side motion that just snowballs? I can start my blazer and pivot the 39.5's by just grabbing the tires
 
Re: Need help, death wobble, can\'t drive much longer.....

<TWIZTED> hey hey no name calling needed , he is just like my brother so im used to it ....anyone run a trac bar / pan hard bar ? OH OH brainstorm , could it be bcuz our trucks are shackle reversed ? phard pooper doodies are backwards and they run a trac bar that i know of ...i think .... am i way off base ?
 
Re: Need help, death wobble, can\'t drive much longer.....

K10ANDYKHAMNIC (Dude, you need a shorter name/forums/images/icons/smile.gif)
Your not off base at all. Your thinking the axle houseing is walking side-to-side (corrrect?). Thats totaly possible, we could be looking at it as steering related, when in reality it could be suspension related. Who knows....
I've seen D/W on a Jeep, with the shackles on the front, so I don't think what end the shackles are on matters much.

DieselDan
Too much caster? I'd agree with that as a possibility as-well. Remember when we we're kidds, rideing our bikes way-too-fast, and running over a rock- You' would end up with the D/W on the bike. and a Bike has alot of caster built into the front forkes.
Could be the same-thing we're dealing with here.
BTW, Some IFS trucks run steering dampners too.


There are way too meny different combination to find a sure-fire, fix-all for this problem. I think a guy just needs to creep up on it and hope for the best.
 
Re: Need help, death wobble, can\'t drive much longer.....

I installed a D60 in my K5 about a year ago and I have never had D/W. I did have Dynatrac cut and rotate my nuckles thoe. They recomended 3 to 5 degrees positive caster.
 
Re: Need help, death wobble, can\'t drive much longer.....

I think that caster is as good a guess as any. (Don't get me wrong, the stabilizer is very important to keeping the shake in check.) If you shim the axle to reduce the caster, you will also improve the front driveshaft angle. But intuitively, it seems like more caster would reduce DW because it would be harder to turn the wheels side to side. Maybe the movement actually stores energy in the front springs since the axle reallly has to move upward a little bit to allow the wheels to turn to the side. This could be the ultimate explanation. A D60 has more mass...
 
Re: Need help, death wobble, can\'t drive much longer.....

Only have a couple new things to add here. One is my own DW experience. 1st time was with the 8 lug 10 bolt. Converted my front to crossover with the track bar and a heim jointed tie rod and ditched my stabilizer. running Q-78 swamps at the time on 3" backspace wheels. After about 3K miles DW occurs so I balance tires with little or no effect. Put on stock replacement rancho steering stabilizer, problem gone. That axle was running about 8 degrees castor at the time. The only thing that could have happened is then ends loosening up a little.
Then I bolt in a stock D60 front with stock stabilizer in unknown condition. Crossover steering. Drive several hundred miles with 35" radials and no problems.
Then I build the Tera60. Set castor to 8 degrees, bearings, etc all used but good. New tie rod ends,
etc. Drive a while and get DW. This is with the rock ram system also. So I back off the caster and some of it goes away. Put a better tire on the LF and more goes away. Now at 5 degrees or so of castor it's livable.

So I think:
Wear makes a difference, if the front starts to ocillate for some reason that makes it worse. Maybe NEW TRE's can have some slop in them? I know they're not supposed to but.........

Dampers seem to be a fix.

Castor can be a factor. Most fronts are probably running too much. It does make them track nice which is why I set mine up to run 8* but I think I was wrong. I'd shoot for less now. I think it has to with the vertical motion of the axle when the kinpin axis is kicked forward. More castor means more vertical motion as the tires ocillate which could add energy to the system.

Slop can come from unexpected places, I would have taken a long time to think of the spring pressure as a point to check but as all D60's (GM) use king pins maybe the springs are a maintenance item?

Crossover could be a factor in exciting the motion since any vertical motion of the front will induce a side to side motion at the wheel. All crossovers with leaf springs and no track bar have bumpsteer to some degree. With factory steering it's a bit more independent of the right wheel's motion and can be better in bumpsteer motion than crossover. So that can be a contributing factor.

I'm a little up in the air on the tierod stiffness thing, from what I could tell with my DW the front tires seemed to be moving together, not independent of each other. Which would indicate looseness in the box, draglink or frame. That's when the stabilizer would be most effective also since it dampens the motion of the tie rod compared to the axle.

How about this for a possible fix in extreme conditions: bolt a stabilizer to each knuckle arm with the other end of each cylinder mounted to the housing. That way you're ruling out any tie rod effects from the system. This would apply best to systems using heim jointed tie rods or high steer systems because it's easier to fasten to the knuckle.

I should get back to work now but thought I'd pitch my bit in here too.
 
Re: Need help, death wobble, can\'t drive much longer.....

Stephen is right about this:
<blockquote><font class="small">In reply to:</font><hr>

I'm a little up in the air on the tierod stiffness thing, from what I could tell with my DW the front tires seemed to be moving together, not independent of each other. Which would indicate looseness in the box, draglink or frame. That's when the stabilizer would be most effective also since it dampens the motion of the tie rod compared to the axle.

<hr></blockquote>

Remember too that the tires themselves act as springs. The bigger they are, the more energy they can store. And too much spring is underdamped, hence the oscillation. That's why the stabilizer works, to a point.
 
Re: Need help, death wobble, can\'t drive much longer.....

do you run a steering stabilizer?
 
Re: Need help, death wobble, can\'t drive much longer.....

I dont run a stabilizer and I never will.THOSE things are way out of style!
Im into the chrome shocks and triple swaybars and 6 shocks per tire!
Nah just kidding,anyways I believe I spoke something of caster angle ALONG time ago and everyone was like NO-WAY MAN YOU'RE WAY OFF ON THIS ONE!DUDE...............................Now that everyone else brings it up its like Oh Ya that sounds good! Well Shiver me timbers you
land lubbbin lugs!
All I know is DW sucks and Im gonna do something about it before you guys do so I can market the solution and make my million!
 
Re: Need help, death wobble, can\'t drive much longer.....

ok just to make you feel better
I still think the caster deal is hogwash
feel better now?
 
Re: Need help, death wobble, can\'t drive much longer.....

Well after replacing my wheel bearings and stablizer I went wheeling to break in the new parts .And I am happy to say that the DW did not return .I think it starts with the new stablizer and tighter front bearings.My old stablizer was a rancho 5000 that was about a year old I replaced it with a 29$ autozone one and end of problem Maybe the ranchos wear out to fast Which starts DW .............
 
Re: Need help, death wobble, can\'t drive much longer.....

ill take off my stab today and see if it does anything ....
 
Re: Need help, death wobble, can\'t drive much longer.....

No I dont feel better!You are a meanie!
Anyways From what has been stated over and over again,chevy uses 8 degrees caster on (all) their front axles.
What does other brands(ie dodge furd toyota etc.....) run?
Apparently DYNATRAC Runs about 4-5 degrees on their axles with no DW problems.Think they know anything about axles and caster angle?Just wondering??????????
 
Re: Need help, death wobble, can\'t drive much longer.....

Here you go mudddog91

'71 bronco. - 2.5 degrees casrter
'72-77' Bronco - 3.5 degrees
'97-'98 Wrangler TJ - 7 degrees
Wrangler YJ - 6.5 degrees


Checked those out too.../forums/images/icons/smile.gif
 
Re: Need help, death wobble, can\'t drive much longer.....

took off my steering stab tonight and no DW .
i run ORD old 1/2 ton axles . not quite sure what all he did to them .... but i like it without the stab steers easier ....
 
Re: Need help, death wobble, can\'t drive much longer.....

i never had stabs on my 44 either
got some quick after the 60 went in
 
Re: Need help, death wobble, can\'t drive much longer.....

You also don't have a D60.../forums/images/icons/tongue.gif

Rene
 
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