Topic: Caster question

[jrock]

So I've been fighting a death wobble and shaking problem fro a while. I've narrowed it to the tire or the caster. I haven't had an alignment shop look at my truck yet but plan to next week.

My question is, my caster is +5*, +-.5*, and I have a wobble between 45-55mph, do I increase the caster or decrease the caster?

37" tires with 8oz BBs inside.

[daniresch]

I'd first try to balance get the wheels static balanced, no BB.
what 37s? and what steering setup?

[jrock [OP]]

37x12.5x15 Irok radials. Xover steering with hydro. 4" MC fronts. 1" drop front hanger pushed forward 3/4", 4.5" shackles.

Knuckle preload ~14-15lbs. Top knuckle studs are Magnums, 100ft lb., bottoms are stock, 70ft lb.

I talked with a Les Schwab tech yesterday and he truly believes its the tires. He recommended I try 16oz in the tires

[brainlessfool]

my caster is +5*, +-.5*,

you have positeve caster? I think it should be negative? so it wants to track. I could be talking out my  

[jrock [OP]]

The top of my tire is leaning towards the rear, positive or negative

[brainlessfool]

it's round, how can it be leaning anyway? now the flat sides can lean in or out.
cater is found at the "king pin" angle. now a toy don't have a king pin butt a solid axle does have king pin angle and not cater,
butt I'm getting nit-picky. take it to the front end shop they will fix it up and if thats the truble you'll be all better.  

[Snowtoy]

This Toe, Caster and Camber explanation might give you some more information.

If yours is leaning back towards the passenger compartment, it would be positive camber, which is what you want according the article in the link. 

Is it true deathwobble where you could actually loose control, or just bad viberations with the steering wheel moving back and forth?  Out of balance, out of round, or seperated tires can also cause violent vibrations.  If you haven't tried it yet and want to before heading to an alignment shop, swap the tires front to rear and see if the problem goes away, or persists.

Does it go away over 55?  I don't think death wobble is works itself out with higher speeds like a balance issue does

[jrock [OP]]

I have swapped tires front to rear. I did it like 8 months ago and it was better but gradgually got worse. I again, swapped them front to rear, bout one month ago, and it got better. I'm sure it's the tires but I wanted to be sure.

The caster/camber question is to see if anyone has experience with too much angle causig DW.

I would love to borrow someones 35-37" tires to test my theory but up in Humboldt I don't know anyone with the size of tire and on the correct bolt pattern I need. At least not with decent tires. I think I could find someone with boggers but that won't help any

[brainlessfool]

are you sure theres no play in the steer linkage? I mean REALY sure.

[jrock [OP]]

None that I can see, I'm 99% sure. I haven't had someone else steer while I look yet but I will today.

[brainlessfool]

None that I can see, I'm 99% sure. I haven't had someone else steer while I look yet but I will today.

thats a must. have them hold there foot on the brake while turning the wheeel.

[junya92toy]

Caster wont really cause that, toe will.

[TacoRunner]

I guess this is a bit old now, but I run 6* of caster in mine. And I never let the alignment shop do my toe in because they all F it up. They always set it to factory spec which is a 28" tire but I'm on37"s so the toe in needs to be adjusted.

First I'd align the front for the tire size you have. After than I'd try different tires. I had this same problem with Noahrod after he linked his truck. His what the steel bead locks and bias Irocks. The bead locks aren't balanceable and bias Irocks get flat spots in them. And he felt the shaking between 45-55 too.

If want you have is the same as Noahrod's problem then its not death wobble, its just the tires and/or wheels that wont balance. Death wobble typically only stops when you stop the vehicle. A good way to tell this is, toss on a different set of tires and wheels. If the problem persists then you know your tires and wheels aren't the problem.

[jrock [OP]]

Thanks Taco, I have wanted to swap tires and see if that fixes the problem but I havent found anyone local with similar tires. Currently I have 8oz airsoft BBs in only the fronts and it drives pretty good above 55mph. Shaking steering wheel is between 35-50mph and thats thru the hydro assist. The shaking is not bad, probably just a balance issue, like you said.