WTF....Wobble at 40 MPH

mudgudgeon

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Dec 17, 2007
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Across the pond, and upside down
What does that mean Yoda????

A picture alone can be very decieving for others to guess at how much lift you actually have. Wheel and tire size make it hard to judge.

4" springs could get you anything from 3.5" - 5.5" lift.

Measuring as above is a simple way to check lift.
Standard lift, you'll have 20.5" from centre of hub, to the lip of the wheel well in the fender.

This measurement doesn't change if you change wheels or tyres.
 
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Center of wheel [hub], measured vertically, until you hit the underside of the fender flare. Factory measurement is roughly 20”, give or take. If you have a 4” lift, you would be around 24”
 
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@NYIronPig

Take your wheels to a shop that can do road force balancing and make sure you got at least 35 psi. You would be amazed how many shops can't balance a big mt tire.

Whenever my tires are out of balance or low on air I get the same 40mph wobble that gets better with speed. First thing I always check is tire pressure and proper balance.


Check your rig for caster correction. The iron man 4" lift should have come with drop brackets to address caster.

Here is what they look like, they will be located on the frame under the front doors where the radius arms attach to the frame.



You should verify that your rig at least has all these parts installed.


If all those parts are installed and the tires are road force balanced and you still got the wobble than change all the old bushings and check your tie rod ends. Especially the radius arm bushings.
 
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@NYIronPig

Take your wheels to a shop that can do road force balancing and make sure you got at least 35 psi. You would be amazed how many shops can't balance a big mt tire.

Whenever my tires are out of balance or low on air I get the same 40mph wobble that gets better with speed. First thing I always check is tire pressure and proper balance.


Check your rig for caster correction. The iron man 4" lift should have come with drop brackets to address caster.

Here is what they look like, they will be located on the frame under the front doors where the radius arms attach to the frame.



You should verify that your rig at least has all these parts installed.


If all those parts are installed and the tires are road force balanced and you still got the wobble than change all the old bushings and check your tie rod ends. Especially the radius arm bushings.
well went to a pro tire shop today and had all 4 wheels balanced with all new wheel beads and 35 PSI all the way around. Castor correction and all the Ironman parts are intact and nice and tight. Still a wobble at 40 mph..... Thinking next I should either look at the front wheel bearings and possibly replacing them or the steering box (still a lot of play in my steering wheel)...

Ugh
 
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balanced with all new wheel beads

That's probably your problem, balance beads probably are not what you should be using.i think weights would be better for your scenario. I have never heard of balance beads being used on a modern 35" mt. They are usually used on big super gnarly mt's like super swampers and such.
 
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@NYIronPig

Definitely check your wheel bearings but wait on replacing the steering box. You need to make sure all the bushings and tie rods are good before swapping a steering box.

Get a big pry and get under the truck. Use the pry bar to pry on parts and check the radius arm bushings and pan hard bushings.

Have a buddy turn the wheel from side to side while checking these bushings and also check the tie rods.

Also make sure you check the frame for cracks where the steering box and pan hard mount to the frame while your under there.

The actual steering box would be the last thing on my list to suspect for a death wobble.

Make sure all your control arb and pan hard bolts are properly torqued. Also make sure your steering stabilizer and all steering links are torqued and good.
 
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If the truck was fine with the old rims and tires then more than likely you have a bad steel rim, why not put your old ones back on. My experience with some aftermarket Steelies was the same way got rid of um put factory wheels back on and no issue.
 
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Twin cities Minnesota
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.
Mine did this when my 35’s were balanced poorly with Beads, had them rebalanced with weights and it’s gone
 
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Kansas City
That's probably your problem, balance beads probably are not what you should be using.i think weights would be better for your scenario. I have never heard of balance beads being used on a modern 35" mt. They are usually used on big super gnarly mt's like super swampers and such.
I have had great luck with the ceramic beads, as well as piss poor luck. It all depends on the inside of the carcass of the tire. I've ran dynabeads in my SAS 4runner on 37's with multiple different tires and had great luck. By great luck I mean I used the beads in my sets of tires for over 15 years and many thousands of highway miles and it was always like driving on glass. I used the beads with beadlock wheels as well as regular steel and aluminum variants. The moment I purchased my 100 series and added 33" tires from general tire with brand new aluminum forged wheels I used the same brand beads, and it was like driving egg shaped tires. I re-mounted and tried multiple things including different sized beads to mitigate the issue and could not rectify the issue. Eventually I dismounted all of the tires and vacuumed out the beads and noticed that the inside of the General ATX tires had this scalloped pattern inside the tire which would "Hold" pockets of beads and not let them freely scatter about seemed to be causing my issues. Either way I have not used the ceramic beads since then. I would not recommend them in a daily driver or trail truck anyways as they limit the serviceability of your Cruiser.
 

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