I have a 72 FJ40 and I just recently did a motor swap and power stearing with a scout box and pump. When I drive down the street the tires will start to vibrate violently. this is what I have done to try and stop it. new stearing stablelizer,new tie rod ends,tigtened the wheel barings, tigtened the nuckles, adusted the tow in, and out, put new wheeles and tires that are ballenced, and bought a new scout box this morning and it still does shakes.

If anyone has any other ideas please let me know.

thanks Travis

It is caused by slop or wear in anything that has to do with the location of the wheels. What do you mean "tightened the knuckles"? If they are loose, you replace the knuckle bearings. Besides the knuckle bearings, the tie rod ends, steering box, wheel bearings, spring bushings, U bolts, spring hangers and/or a cracked frame can all contribute to the "death wobble". Negative or zero caster also contributes to the tendency to initiate the wobble.

ask BellyUp about the death wobble. He has had it 4-5 times. He's got a tj but he maybe to help anyway.

thanks for your help ill try and change my spring bushings there alittle wore out Thanks again Travis

Keep us posted if you find a soultion!

The best strategy is to find out what is loose first. Have someone get in the cab and rock the steering wheel back and forth violently like in the death wobble while you look at all the parts from the outside. Look for anything that is moving that shouldn't be. Try jacking up the wheels and yank on the wheel at top and bottom to check the knuckle bearings and side to side to check the tie rods and linkage. Pry the spring ends back and forth to check the bushings, spring hangers and U bolts.

I dont know what front axle you use but could it be slightly bent from hard core crawlin? Also what tires do you run if you run big swampers good luck getting it to go away.:smokin:

I had an experience once commuting with a good friend in his 52 chevy pickup. We were traveling down 101 at about 60 when his truck started to shacke like a lying newbie. Then all of a sudden the steering wheel was free and the shaking stoped. Yep the pitman arm ball sheered off and we were going 55 without steering in the middle lane. Fortunately there weren't any cars next to us and we sauntered up the median where my buddy slamed on the brakes and we stopped. Turned out the problem was cheap ass tires that weren't balanced proberly. Soooo you might want to check your tires, That is if you don't like adventures and lawsuits.

try a search im sure there enuf about DW to keep you reading for a month.

Originally posted by Pin Head
Negative or zero caster also contributes to the tendency to initiate the wobble.

Originally posted by trailhawg
try a search im sure there enuf about DW to keep you reading for a month.

yep, do a search in the cruiser section.....is addressed there several times also.

The difficultly in diagnosing this problem of wobble is the fact that prior to the installation of the scout P/S steering there was no wobble. He adjusted the wheel bearings which were a little loose, checked and tightened all nuts. The tires were major toe out, thought that was the problem. Adjusted them to a 1/4" toe in with no improvement. He eliminated the possibility of the steering pump causing the problem. We have rocked the steering wheel back and forth and everything appears tight. As Travis stated, he even replaced the box with a new one and it feels tight.
There are two u-joints between the wheel and the steering box. There isn't a rag joint. Could this be a problem. Thanks for the advice.
Mike

After you have tried to replace/adjust everything, do what I did, go to hydraulic-assist steering. Zero death wobble a.k.a violent bumpsteer and plenty of power to turn those big tires in the rocks. Best of all, you don't have to go with AGR's rock ram, you can do it yourself like I did. Talk to "The Lakerat" or "66CJDean" (I think that is his name on pirate.
I can send you a link to my setup if you would like.

Check the u-bolts.

that happened to me about 3 months ago my fj is sprung over with a shackle reversal. it turned out that my shackles were way to loose. they are just 2 pieces of steel nothing in the middle and they were allowing the springs to shake wich made the axle shake wich made the tires shake out of control. might check your shackles.

running front bald bias-ply's and rear radials will give you a death wobble, too!

...not that I would know from experience....

38 bias ply (swamper sx) and i can blast down the highway at 65, check for slop, then double check, triple check for the right caster at the knuckle, that was my prob. its no problem now that i got rid of the cheepy rod ends.............they are all the hype, but they are only as good as the money you spend. :usa:

We made sure everything was tight, adjusted the toe out condition to toe in, he even replaced the steering box, front spring bushings and put different tires and wheels on. Yesterday he put an additional shock on the drag link and started adjusting the toe out. He finally seems to have got it settled down. Last night we measured the toe out and it is 3/4" difference! Doesn't make sense to me. When we checked it earlier in this process it was 1" difference and I thought that was the problem. Well, at least it is drivable.
Mike

Originally posted by flexing40
When we checked it earlier in this process it was 1" difference and I thought that was the problem. Well, at least it is drivable.
Mike

still sounds like something is bent or loose from that statement alone.....did anyone mention wheel bearing adjustment also?

Caster is a biggie. Did the frame height change due to a weight diff in motors. If so, maybe the caster is off.

Originally posted by macgyver


still sounds like something is bent or loose from that statement alone.....did anyone mention wheel bearing adjustment also?
One of the earlier adjustments he made. Also forgot to mention in first post that althought not a new mod, this truck is SOA with crossover steering. A friend suggested that the steering arm on the knuckle should be longer, which would put the drag link arm futher ahead of the tie rod. Mentioned something about the Ackerman steering principle. I will search on that term for more information.
Mike

Originally posted by flexing40
We adjusted the toe out condition to toe in... Last night we measured the toe out and it is 3/4" difference! Doesn't make sense to me. When we checked it earlier in this process it was 1" difference and I thought that was the problem.
Mike

If your toe-in keeps changing each time you measure it, something is loose. Sometimes you have to pull, pry, get mean and cuss it to find the loose stuff, especially if it is the spring bushings, hangers and U bolts. Very little of this stuff gets tightened by just turning a bolt; you have to replace the worn parts. Checking your caster can help too, but I would not expect that to change just by changing your steering box. If you changed springs or shackles, that could mess with your caster. The fact that it didn't do it before the steering box swap is a big clue: it is most likely something you replaced or messed with in the swap.

how much toe are you running? Sounds like too much to me. How are you measuring the toe? Marking and turning the tires?
Are you measuring with the rig on the ground?
The tires will toe in when you move forward, and toe out if you move back. I would mark the tires, and put it in a spot where you can push it forward quite a ways, so you can take a few measurements. Dont measure after a backwards movement, always forward.
If you dont do it this way, you can get all kinds of different readings.

And Pinhead, how can the toe change because of worn bushings and hangers? :confused:

Originally posted by Pin Head


If your toe-in keeps changing each time you measure it, something is loose. Sometimes you have to pull, pry, get mean and cuss it to find the loose stuff, especially if it is the spring bushings, hangers and U bolts. Very little of this stuff gets tightened by just turning a bolt; you have to replace the worn parts. Checking your caster can help too, but I would not expect that to change just by changing your steering box. If you changed springs or shackles, that could mess with your caster. The fact that it didn't do it before the steering box swap is a big clue: it is most likely something you replaced or messed with in the swap.
The toe condition was not changing on its own. What I was trying to say about the toe condition was this: Originaly it was toe out. We adjusted it to a toe in condition which made no improvement. On Sunday he put an additional stabalizer on the drag link. And started adjusting the toe to a toe out condition and driving it. He finally elimanated the wobble with a toe out condition.
I, like you figured that as there was no wobble prior to the box swap that this problem should be easy to diagnose.
Mike

Originally posted by Keith
And Pinhead, how can the toe change because of worn bushings and hangers? :confused:

I didn't mean to imply that spring bushings/hangers/Ubolts will cause the toe-in to change, but slop in the tie rods and knuckle bearings/king pins/ball joints certainly can.

I didn't understanding what he said. I thought that he said in the first post that the toe in was set correctly, but 1 inch toe in is WAY TOO MUCH and this can help initiate the death wobble too because both tires are trying to center themselves. You don't generally encounter this unless you have bent something as it is easy to eyeball the toe in to better than about 3/8 inch, so there should be no reason to have that much toe in. Having it 1 inch toe out is not good either. You want to get 0 to about 1/4 inch toe in. If you can't eyeball that accurately, jack up the tires and spin the tires and scribe a chalk line around them. Then put the tires back on the ground with the wheels straight ahead and measure the distance between the lines at the front and the back. The difference in the distance is the toe in. Still though, it won't wobble like death if everything is tight.

You said that you got new tires and wheels. How were the tires balanced? If they were statically balanced that could be your problem. Just for peace of mind I would take your tires to a shop that sells big truck tires and have them put your tires on a computer balancer and have them check the DYNAMIC balance. A friend of mine has a TJ and he went round and round with the death wobble thing for months. He also replaced everything from tierod ends to ball joints to adding twin stabs to adjusting everything on his front suspension in all kinds of extremes to find out that the 38.5" TSL/SX's were balanced wrong. After the correct amounts of weight were put in the right places on his rims, his Jeep rides and drives like new again. Hope this helps, I know how scary DW can be on a crowded road.

Originally posted by xjxtreme
You said that you got new tires and wheels.............
No,he put on a different set of tires to see if that would help. I am going to send him down to an alignment shop. Additionally, when he is out today I will have him pull the tires and wheels off and we will do some close up checking on the wheel bearings and knuckle.
Mike