WTF....Wobble at 40 MPH

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I have a wobble in my steering wheel when I hit 40 MPH. Once i get over 40-45, my rig drives fine. Wondering if my steering box could be the issue, have a little play in the wheel anyways..... My FJ80 has a new Iron Man 4" lift with coil springs, foam cell shocks, steering stabilizer and panhard rods. 35" new Falken Wildpeak tires. Knuckles are redone and good, so trying to see what else it might be to cause the wobble at 40 before I just end up swapping the steering box for a new one.
 

mudgudgeon

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Steering box may be a contributor, but it's not the most likely suspect, and there's lower cost items higher on the list before you start shooting the parts cannon at it

Search death wobbles

Usual suspects . . .

Wheel bearings
TREs
Tire balance
Panhard rod bushes and bolts
Radius Arm bushes and bolts
Trunnion bearings
Shock absorbers
Cracked frame around steering box and/or panhard rod brace
 
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Have you checked the wheel bearings? Jack the truck up and grab the tire at 12 and 6 and rock it back and forth. If there is play, adjust as needed.
thx, so if there is play then replace the wheel bearings?
 
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landtank

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If there is no correction as of now you need to install some.

At 4” of lift you have 2 choices. I offer caster plates that provide 7* of correction and others offer new arms.

A Properly aligned pinion angle will require a DC drive shaft

Other things you failed to mention is sway bar drop blocks, bump stop drop blocks, extended brake lines, adjustable panhard bars or equivalent, adjustable rear control arms or equivalent, extended rear sway bar links or equivalent.

If your list of what you have done is accurate, you have a ways to go to get it to drive correctly.
 
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If there is no correction as of now you need to install some.

At 4” of lift you have 2 choices. I offer caster plates that provide 7* of correction and others offer new arms.

A Properly aligned pinion angle will require a DC drive shaft

Other things you failed to mention is sway bar drop blocks, bump stop drop blocks, extended brake lines, adjustable panhard bars or equivalent, adjustable rear control arms or equivalent, extended rear sway bar links or equivalent.

If your list of what you have done is accurate, you have a ways to go to get it to drive correctly.
This FJ80 is new to me. Was done up right before I bought. Drove fine with the aluminum wheels and 35" on her until I put the heavier steelie rims on a few days ago. New tires are balance. Think the wheel bearings might be my issue with the heavier wheels now and that big ole heave Cummins 5.9 in her!
 

landtank

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This FJ80 is new to me. Was done up right before I bought. Drove fine with the aluminum wheels and 35" on her until I put the heavier steelie rims on a few days ago. New tires are balance. Think the wheel bearings might be my issue with the heavier wheels now and that big ole heave Cummins 5.9 in her!
Do you even have 4” of lift?
 
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Do you even have 4” of lift?
ah yea

Cummins.jpg
 
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New wheels and 4x4 Labs bumper just added

IMG_7699.jpg
 

mudgudgeon

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thx, so if there is play then replace the wheel bearings?

Depends on condition of the bearing. If bearings are good, regrease, re-torque and good to go.

If its a new rig to you, be prepared to replace them
 
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Depends on condition of the bearing. If bearings are good, regrease, re-torque and good to go.

If its a new rig to you, be prepared to replace them
ordered a set of Koyo's just now to replace
 

jfz80

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Before throwing parts at it id simply check that they are tight. Snug the inner adj but down to 35 ft\lb then tighten outer to spec. 45 or 47 IIRC.
 

ppc

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If there were no issues before you replaced rims and tires then that is your starting point. Just because they are new doesn't mean that they aren't causing a problem. A wheel may be bent, welded incorrectly, or have some runout issues. A tire could also have defects in production.

I would start by rotating tires from front to back and observe any changes that occur.
 
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LOL, like a picture is proof. Measure the distance from the hub's center to the underside of the flare and subtract 20.5
What does that mean Yoda????
 

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