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is this too much caster, and could it cause my wobble????

01maroonz71

01maroonz71

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well, i've been trying to track down this crazy wobble that i have so i figured i'd go check my caster angle on my D60...i've searched and searched and searched and im about torn b/t saying it's too much, or it's perfect. haha. maybe ya'll could help.


i am running longer shackles, and the 8in BDS springs had shims already on them when i installed them. right now, my truck has about 7.5degrees of negative caster(pointed to the back of the truck) keep in mind this is a kingpin D60. any thoughts???? thanks
~Dave:D
 
I looked all over the place for a spec and I finally found one, the service manual says "8* nominal, no adjustment provision."

I don't think your caster angle is causing your death wobble.
 
awesome...thanks alot guys. this is killin me. i geuss im gonna have to swap tires and see what happens.
 
01maroonz71 said:
well, i've been trying to track down this crazy wobble that i have so i figured i'd go check my caster angle on my D60...i've searched and searched and searched and im about torn b/t saying it's too much, or it's perfect. haha. maybe ya'll could help.


i am running longer shackles, and the 8in BDS springs had shims already on them when i installed them. right now, my truck has about 7.5degrees of negative caster(pointed to the back of the truck) keep in mind this is a kingpin D60. any thoughts???? thanks
~Dave:D
Click to expand...

I don't know how soft those 8" BDS springs are, but the longer front shackles could be promoting lateral instability. I went through the same hell after installing 6" Alcan's and longer front shackles. The solution as I see it is to add a panhard bar up front, or drop back down to a somewhat shorter front shackle. If you can find a way to tie both halfs of the shackle together that would also help.

In my case I had been driving the truck daily with the D60 and 39.5" TSL's and never had a lick of death wobble problems for over two years. Once the Alcan's and the longer re-located shackles were in it was a death wobble nightmare.

Rene
 
How much do you know about death wobble, and what causes it? What have you checked?

Here are a few things that can cause it in no particular order.

Worn components: TRE, balljoints(I didn't want to just type BJ), worn kingpin, worn kingpin bushing, wheel bearings(loose wheelbearings can cause it also)

Bad spring bushings

Alignment(toe adjustment)

The only real way for your caster to be off is if the axle tube is bent. Are you sure that is what you mean?
Example: look down at your feet, with them parallel. If you bring your toes closer together, that is like the "toe" adjustment called toe-in. If you move your toes apart, that is toe-out. Looking from the top down onto yor tires, toe in looks like / \ , toe out would look like \ / Kinda simple isn't it. If you try to move your ankles closer together or farther apart, that is like the camber adjustment. If you look at the tires from the front they look like the examples above. Kinda leaning in or out.

Some questions for you.
 
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How wide are your tires?
How long have you been having this issue?
Did anything change, right before this started to happen?
Do you run a steering stabilizer?
Do you run hydro assist?
What kind of lockouts do you have?
How are the TREs?
How are the balljoints?
How are the kingpins and bushings?
How are the spring bushings?
Have you lifted the front of the truck and checked them?
Have you checked bolt tightness?
Do you know about the fender washer trick?
Do you have the knowledge to "toe-in" your truck a quarter of an inch?
 
ok, leper..let me try here....haha

in your 1st post....
i figured the caster could be off from shims/axle swap/longer shackles/lift springs, i could be wrong though, but it isn't just a bent housing that could cause that.

in your second post, here's the answers...

15inch wide tsl's
had issue for a while, slowly getting better as i shim kingpins, add SS(see next)
nothing changed, im just trying to eliminate it completely
yeah, dual brand new stabilizer
no hyrdo asssist, but plan on it VERY SOON
i have superlift premium hubs
brand new TRE's
Kingpins in my 60 are fully rebuilt about 3months ago, new bushings,springs,pin,caps,etc.....
spring bushings are brand new about 3months ago also
i've checked EVERYTHING in the front end for loooseness/wear
ubolts,shackles,steering,wheels,steering arm, etc... is 100% tight/to specs
i am running two washers on each side right now
i have tried towing in about 1/8 of an inch at a time (about 4times now) with no results...the 1st spot i had it was the best by far.

thanks alot guys....i appreciate ya'lls help.
 
Have someone saw the steering wheel left a ways and then back right a ways while you watch what your springs are doing. If they are soft laterally it should be evident...

On my truck if I hit a good bump while holding the steering wheel it'd trigger a bit of shimmy even with new bushings, king pins, springs and two washers under each cap (new TRE's, New DLE's, caster at spec). If I hit the same bump at the same speed but let go of the steering wheel the steering wheel just moves a little and I get less shimmy or spookiness. I think my springs are so soft laterally that even a little bump steer causes them to deflect laterally...which used to trigger a DW episode. As it sits now, I don't get Death wobble, but the steering/handling is spooky.

I think a panhard or track bar would make a huge improvement. That or stiffer front springs.

Rene
 
Is it still as bad as that video you posted that one time?
 
To clarify caster, it is the wheels not being lined up. Easy to do with IFS, as the wheels are indepent of each other. On a solid axle, the only way for it to be an issue, is if the axle is not at a right angle to the frame. Look at the shackle angles on both sides and make sure they look the same.
Now, i did manage to do that when I installed my 56" rears. The center pin is not centered. There is a long side and a short side from it. But, the axle looked so off, it was kinda easy to see. One tire was 4" closer to the body than the other.

I would suggest that you pull your hubs, and make sure your wheel bearings are torgued properly.
I have never seen a truck that needed two fender washers under the caps. Also, make sure the caps are tight. That happened to me once. One loosened up, and BAM, I was all over the place.
Running those washers and dual stabilizers and still having a problem would lead me to believe your steering box is loose, or the frame is cracked behind it. With your truck sitting still, have someone turn the wheel from lock to lock and look real close at your steering box. It should not move at all.
 
Ijusr re-read your first post. I really need to see a picture of your front axle from the front and the rear. If you have drastically rotated your front axle, that may be your problem. Also, tell me more about the shims the springs already have, that you mentioned. Is it possible that they are backwards on one side?
 
Did you get this worked out? It was bugging me today.


I did a bit more research on your problem, and my definition of caster, and I have come to the conclusion that you problem almost has to be your axle degree of rotation, provided there is nothing worn out or loose.
 
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