I have a 86 4Runner, I recently completed a 4" SAS kit from Marlin. In the process, I rebuilt the front axle (1985) with a full service kit as well. I set the toe angle on stands to 1/8" in, between the front and back of the tires and down the road I went. Wanting to protect my new tires I decided to go have the alignment checked by a pro.

Their machine said I was nearly .5* toe out, and the caster was nearly 4* between both sides. I chalked up the the toe being wrong to me just having measured wrong or something, so I had them set the toe and I left thinking my caster was perfectly fine.

Not a half mile down the road I got the death wobble for the first time. Because I though a tire was about to fall completely off the truck, I went right back to the shop...Long story short, after returning from the shop which was unwilling to help figure it out. I set the toe back to 1/8" in, and the problem was gone unless I tried topping 70-miles per hour, then it would shake pretty bad. Knowing I hadn't really fixed the problem, and not wanting to drive with a bad toe angle, I started reading about the death wobble. After seeing that nearly everyone agrees that the caster angle should be between 6-8*, I installed a 4* shim and took it to a different shop this time. They also said I was toe out, but now my caster angle was 7* on the left and 8* on the right. With that much caster, this thing should be almost hard to turn. So I had them re-set my toe again...and once again, the death wobble came right back.

I have put the truck on stands and shaken the tire vertically and horizontally, and can't find anything even a little loose anywhere. Any ideas why the toe angle would change that much just because the weight of the truck is on the tires? (.06 in to .45 out) Or why the toe angle could be causing the death wobble? Obviously the weight of the truck puts more force on the front end than I can by shaking the tire...could something be loose and not be able to tell when shaking it by hand maybe? And is there anything else that can cause the death wobble aside from caster angle? Maybe I have too much caster; but would that make the death wobble return? I do run my shackles a fairly loose to keep them from binding at the bushing, how tight should the really be though?

Any help would be great, as I'm running really low on ideas aside from welding that IFS back onto the truck.

TIA!
-Dan.

 

Have you considered installing a steering stabilizer ?.

 

Never done anything but an alignment on the ground with the front of tires 1/8" toe in and never had any issues.

Steering stabilizer might help. Try balancing the tires too.

If you are good to 70mph I'd call it good.

 

X2. Also since this is a new install re-tighten all the steering knuckle bolts, or anything with steering. Sometimes a new install will kinda undo a little.

 

You can see some toe-out movement when setting the toe-in with the tires in the air after you lower the weight back down. Why? Crossover steering has the tie rod above the center line of the wheel (and in front) and if there is any play in the knuckle bearings, the wheel is going to tip inward under load. Tie rod length stays fixed so if the wheels tip inward, that tie rod pushes the front of wheels outward. I find that if I set mine with weight on the tires works best, or if I measure the toe on the ground then again up in the air and noting any change in toe and accounting for that.

Also, might try cutting back on caster angle a little:
-http://www.4crawler.com/4x4/ForSale/Shims.shtml#FAQ1

 

Yup, I did install a stabalizer from the front of the drag link to the driver side frame rail. The tires are 35x12.50r15 Baja Claw radials from desert rat. I did have the tires balanced, although they were supposed to be pre balanced, all but one of them wanted between 1 and 2 1/4 pounds of weight if balanced dynamically, static balancing put left them all with at least 10 oz. Of weight. However balancing them didn't help things at all. The tires only have about 500 miles on them, one bad tire...maybe two, but 4 out of 5?? Kinda makes me wanna call and try to get a different set from them if it hasn't been 4 months since I bought em.

I suppose I could call it good, and keep it under 70. Since it isn't a car and not realy meant to go fast. However, as soon as I hit about 70 the right front starts to shake bad enough to make me think the tire is hopping completely off the ground at speed. Today after work I am going to tear at least that side of the axle back down and check for anything that may be bad.

I did just think to check for any play by leaving the wheels on the ground and shaking the truck side to side as hard as possible to try and apply more force than possible with the wheels in the air. Doing it like this revealed no play at all anywhere...untill I had my hand on the tire while it was being shaken. Then I could feel a slight ammount of movement that feels like maybe wheel bearings on both sides. Time to double check that bearing preload again aloong with torque on everything in there. Still, it feels pretty slight and not enough to cause anything like the death wobble...still worth a look though I guess.

 

Oops...I don't see where to delete the duplicate post when I try and edit it out?

 

Fixed your duplicate for you. Google Davez No Death Wobble Shackles. Long thread on Pirate about them. $75 here...they are amazing http://www.davezoffroadperformance.c...c.php?f=3&t=19 The one and only time I dealt with wobble on my truck it was because of the shackles. After toasting about 4 sets of cheap bushings I installed these and the front end is way tighter now.

 

I had the death wobble. Toe is at 0, Caster is at 6*, Tighten up your shackles, bolts on the springs GOOD. Don't worry about the binding. It'll be whole new truck :-)

 

It was the shackles. Thanks for your help guys. I tightened them up until it compressed the bushing partially and you are right Stace...it's a whole new truck.

In all the reading I've done about this, this is the first time I've heard that the shackles could cause the wobble too.

 

Glad to help. I was chasing it for a while, and found an OLD post on a TTORA board. Figured it couldn't hurt to try. Bingo!

 

My right front tire still feels like it wants to bounce clean off the truck at about 70mph. I'm wondering if its a bad tire. Less than 500 miles on it, on a new wheel...it wanted 37 ounces of weight to balance dynamically. I can't use weights on the outside of the wheel, and wouldn't want the required 24 ounces on the outside anyway so we balnced it static and it needed 15 ounces.

I used to be a tire mechanic for a few years and can't ever remember a tire taking that much weight, not even the huge semi truck tires.

Ahh, the joys of buying tires online.

 

My right front tire still feels like it wants to bounce clean off the truck at about 70mph. I'm wondering if its a bad tire. Less than 500 miles on it, on a new wheel...it wanted 37 ounces of weight to balance dynamically. I can't use weights on the outside of the wheel, and wouldn't want the required 24 ounces on the outside anyway so we balnced it static and it needed 15 ounces.

I used to be a tire mechanic for a few years and can't ever remember a tire taking that much weight, not even the huge semi truck tires.

Ahh, the joys of buying tires online.

 

Can you try swapping that tire to the rear to see if that makes a difference ?.

 

x2 - good advice. Mine death wobbles also (when my hydro assist steering isn't hooked up). It's a combo of bad tires, loose shackles, loose steering arms, & play in the tie rod ends. The death wobble gets masked with the hydro assist and the makes my 4Runner drivable

 

I have it also but not until I reach about 68. Reach 73 and it stops. I top out at about 80 and dont reach any of these numbers much so not a biggie to me.

 

you might wanna check your wheel bearing preload if they loosen up a little even a little play can cause the wobbles, or you might have an out of round tire, i ran a set of 33'd and one was out or round and as soon as i hi 65 it got bad and got worse with more speed

 

I have new tires on mine also. Where are these things made at? China?

 

no tires should take that much weight to balance.

that's a problem with the tires for sure.

 

put it on stands and let it idle in fourth gear and look at the tires. do they turn concentrically or eccenctrically or are they turning completly round and true or do they have a high spot. if they have a high spot you can take them to a semi truck tire shop that does tire truing they can take an out of round tire and make it true. then once its perfect it wont take much to balance. on my retreads i had an out of round tire i put a jack under it until just the high spot touches and the rest just drags on the ground then i wound it up in fourth and burned off the high spot, seemed to work ok but be careful and use a good jack you dont want it to falkl off at 60 mph