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Discussion Starter · #1 ·
NTB w/ a problem.

What: 1985 standard cab 4x4. Hysteer w/ axle moved 1.5" forward. Downey 3" springs w/ 1.5" longer shackles. 1" body lift.

Problem: Truck has a bad vibration/shimmy under braking. It also vibrates at 55 & 70 mph. The truck seems to wobble at low speed(5mph) almost like a bounce. I can see the drivers side tire shimmy under braking. The ride is horrible-feel every bump x10.

Things checked: steering is tight, U-bolts are tight, springs appear to be in good shape, new bushings, steering box adjusted, recently rebuilt FA with the proper preload on the trunion and wheel bearings, runout on both the rotors and wheels are within the limits, steering stabilizer functional, toe set at 0-1/8"-1/4" with no change.

There is a little bumpsteer, but barely any brakesteer.

Does anyone know an easy way to check caster? I believe it to be about 3-4 degrees at the moment, but I want to be sure before I start shimming(don't want to pay an alignment shop $$$ just to tell me that the caster is out!)

Has anybody here ever experienced/fixed a similar problem?
 

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The low speed wobble is a dead give away.
You probably have a seperated tire. Lift the front end and spin the tires by hand. you will see a lump on one. If you dont see anything,rotate the tires to the rear and see if the vibration changes.
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[ 09-15-2001: Message edited by: zags ]
 

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What kind of tires are you running? Sounds like mine with 38" SX's. I wobble at take off and braking, used to wobble at 65 mph until I added golf balls to the tires. I'd say it's your tires too, especially if they're Swampers.
 

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Discussion Starter · #5 ·
Zags, I swapped front-to-rear with no change. I also could not see any high/low spots in the tire itself.

pmurf1, the circumstances at the time are excuse enough for the P.O.S Kelly A/T's that are presently disgracing the hard work and money that went into this truck. Simply put this is the second set of the same tires(first set were clearly out of round) but these look to be from a different lot and are round <IMG SRC="smilies/rolleyes.gif" border="0"> imagine that! Although I still have not ruled them out. I haven't tried the golf ball trick--lost them all to <IMG SRC="smilies/beer.gif" border="0"> and <IMG SRC="smilies/mad.gif" border="0"> but mostly to <IMG SRC="smilies/beer.gif" border="0"> .
 
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