1970 Ford Bronco - Death Wobble

[tonytony9]

Hi Everyone,

I am experiencing death wobble between 40-55+ mph, somewhat consistently. A bit of a pull to the right on a hard stop.

I want to redo all of the steering components. I will upload pictures in a bit. Is there a kit? Any recommended components? I have the stock dana 30, and its all quite rusty.

To clarify, I am feeling a vibration in the steering wheel and it will shake violently. I can sometimes accelerate through it or decelerate down to right below 40 and it disappears. I had real death wobble in my Jk Wrangler years ago, it felt like the entire vehicle was shaking and you almost had to come to a complete stop for it to go away. Usually after hitting a pothole or bump. My EB does not get this from a bump, it is typically simply from getting up to that speed.

Best,
Tony

 

[DirtDonk]

That’s an interesting variation. What you describe your jeep as having sounds like an actual Death Wobble. The shaking you’re having now, sounds a little different in that it might be something different as well.
But I always recommend the same thing. First and before changing any components, rotate the tires front to back.
You can do one at a time to see if it’s actually a single tire causing it, or you can do both at the same time. Up to you.
if it goes away, then you can have those two tires checked and replaced if necessary. Maybe a rebalance, maybe a tire pressure change. Maybe whatever. But it’s free and easy and you don’t have to go to much work to do it.
It’s a good first test.

 

[DirtDonk]

Another thing you can do for free, while you’re jacked up and ready to remove the tires, is to check for looseness in the wheel bearings and kingpin bearings.
Certainly doesn’t help things when those are loose, but the initial dynamic for the vibration and shaking still has to be coming from the tires to begin with. They start the motion, but loose components make it worse.
As you are suspecting.

 

[Oldtimer]

And check date code on tires. Old tires, regardless of miles, can cause all kinds of issues.

Befor you "redo all of the steering components", take it to an alignment shop and ask them for a printout of the current alignment. Usually cost me $20-$30, and well worth knowing start angles when ordering 'C' bushings.

 

[tonytony9]

Another thing you can do for free, while you’re jacked up and ready to remove the tires, is to check for looseness in the wheel bearings and kingpin bearings.
Certainly doesn’t help things when those are loose, but the initial dynamic for the vibration and shaking still has to be coming from the tires to begin with. They start the motion, but loose components make it worse.
As you are suspecting.

And check date code on tires. Old tires, regardless of miles, can cause all kinds of issues.

Befor you "redo all of the steering components", take it to an alignment shop and ask them for a printout of the current alignment. Usually cost me $20-$30, and well worth knowing start angles when ordering 'C' bushings.

Thanks for the advice, I will start here.

Thinking ahead here, and apologies for the lack of my comprehensive knowledge, I would like to do a disk brake conversion (front only) down the line. I do have a Dana 30, would any of these potential components I would be changing have to account for the conversion?

 

[DirtDonk]

Not really.
Because the Dana 30 conversions retain everything from the steering knuckle inward, you’re good to change any steering linkage or renew kingpin bearing and shim set ups.
The only thing you replace with the disc brake conversion kits are the spindles, sometimes the bearings, and adding the disc brake components outside of those.

 

[DirtDonk]

Great question by the way. You definitely don’t want to put a bunch of bucks into renewing old stuff, only to toss it out later!

 

[tonytony9]

Great question by the way. You definitely don’t want to put a bunch of bucks into renewing old stuff, only to toss it out later!

What pressure are you running in your tires, ~33?

 

[HoldMyPocket]

The easiest thing to check first is with the truck off, have someone get in the driver's seat and turn the wheel back and forth quickly while you observe the track bar mounts on the axle and the frame. I wouldn't be surprised if the first thing you notice is that the mount on the axle is where the track bar fits loosely, or the mount on the frame is wobbling.

Then turn your attention to the pitman arm off the steering box and the draglink there. Then follow the draglink down to the axle end and observe that.

Finally, observe where your steering box mounts to the frame, is the frame twisting? is the steering box moving?


If you're lucky, you just need new trackbar or draglink bushings.

Other potential problems:
- frame cracked at steering box mounts, or the steering box holes on the frame are ovaled out
- track bar mount at the axle is ovaled out, there's a repair kit for that to replace it with a stud.
- track bar mount at the frame is loose, maybe a crack, maybe ovaled out, would have to see it.
- steering arm on the axle where the drag-link attaches could be ovaled out, there's a way to repair that as well.

I would do this simple check before diving into the other checks as it's the easiest to do. You can then jack the truck up, grab the top of the tires and try pushing/pulling to see if there's excessive play in the wheel bearings as a quick and easy check.

Usually though, it's track bar related.. mounts, length, angle.

 

[DirtDonk]

So, 33 pounds? For some of us that’s perfect. For others it’s too much.
You could easily play with tire pressures just to see if it changes where and when the Wobble comes into play, or if it changes the severity.
Another easy and free test.

 

[Madgyver]

I've experienced death wobbles.
recently it was a bad ball joint.
loose bolts on steering box.
tracbar bushings.
loose tie-rod ends.
bad tires.
bad alignment.

 

[tonytony9]

So, 33 pounds? For some of us that’s perfect. For others it’s too much.
You could easily play with tire pressures just to see if it changes where and when the Wobble comes into play, or if it changes the severity.
Another easy and free test.

33 is what I ran on my Jeep, seemed to be the best middle ground. Thats what I am running on the Bronco now, it has helped every so slightly with the shake. Or, might be a little sugar pill syndrome. Either way, going to use the above suggestions and report back.

The easiest thing to check first is with the truck off, have someone get in the driver's seat and turn the wheel back and forth quickly while you observe the track bar mounts on the axle and the frame. I wouldn't be surprised if the first thing you notice is that the mount on the axle is where the track bar fits loosely, or the mount on the frame is wobbling.

Then turn your attention to the pitman arm off the steering box and the draglink there. Then follow the draglink down to the axle end and observe that.

Finally, observe where your steering box mounts to the frame, is the frame twisting? is the steering box moving?


If you're lucky, you just need new trackbar or draglink bushings.

Other potential problems:
- frame cracked at steering box mounts, or the steering box holes on the frame are ovaled out
- track bar mount at the axle is ovaled out, there's a repair kit for that to replace it with a stud.
- track bar mount at the frame is loose, maybe a crack, maybe ovaled out, would have to see it.
- steering arm on the axle where the drag-link attaches could be ovaled out, there's a way to repair that as well.

I would do this simple check before diving into the other checks as it's the easiest to do. You can then jack the truck up, grab the top of the tires and try pushing/pulling to see if there's excessive play in the wheel bearings as a quick and easy check.

Usually though, it's track bar related.. mounts, length, angle.

Thank you for the thorough list. I will check back after I go through it.

 

[tonytony9]

So, 33 pounds? For some of us that’s perfect. For others it’s too much.
You could easily play with tire pressures just to see if it changes where and when the Wobble comes into play, or if it changes the severity.
Another easy and free test.

I've experienced death wobbles.
recently it was a bad ball joint.
loose bolts on steering box.
tracbar bushings.
loose tie-rod ends.
bad tires.
bad alignment.

The easiest thing to check first is with the truck off, have someone get in the driver's seat and turn the wheel back and forth quickly while you observe the track bar mounts on the axle and the frame. I wouldn't be surprised if the first thing you notice is that the mount on the axle is where the track bar fits loosely, or the mount on the frame is wobbling.

Then turn your attention to the pitman arm off the steering box and the draglink there. Then follow the draglink down to the axle end and observe that.

Finally, observe where your steering box mounts to the frame, is the frame twisting? is the steering box moving?


If you're lucky, you just need new trackbar or draglink bushings.

Other potential problems:
- frame cracked at steering box mounts, or the steering box holes on the frame are ovaled out
- track bar mount at the axle is ovaled out, there's a repair kit for that to replace it with a stud.
- track bar mount at the frame is loose, maybe a crack, maybe ovaled out, would have to see it.
- steering arm on the axle where the drag-link attaches could be ovaled out, there's a way to repair that as well.

I would do this simple check before diving into the other checks as it's the easiest to do. You can then jack the truck up, grab the top of the tires and try pushing/pulling to see if there's excessive play in the wheel bearings as a quick and easy check.

Usually though, it's track bar related.. mounts, length, angle.

And check date code on tires. Old tires, regardless of miles, can cause all kinds of issues.

Befor you "redo all of the steering components", take it to an alignment shop and ask them for a printout of the current alignment. Usually cost me $20-$30, and well worth knowing start angles when ordering 'C' bushings.

I wanted to send a thread update; I got my alignment report back from FireStone. They recommended starting with steering stabilizer and tierods. Does this report help any of you narrow down the cause?

 

[nutnbutdank]

If you have not replaced the tie rod and drag link yet, then that's a good start. If you are on old tires, that's a must. One of the first things I had to do, was to replace mine on my 70 when I first got it back in 1998. You can tell when it's bad, those ball joints get loose. Dust caps dried out and gaps.

Pulling to one side on hard stop, sounds like brake adjustment.

 

[tonytony9]

If you have not replaced the tie rod and drag link yet, then that's a good start. If you are on old tires, that's a must. One of the first things I had to do, was to replace mine on my 70 when I first got it back in 1998. You can tell when it's bad, those ball joints get loose. Dust caps dried out and gaps.

Pulling to one side on hard stop, sounds like brake adjustment.

Tires are solid. Good point.

Is it worth upgrading to a Heim setup?

 

[Madgyver]

Tires are solid. Good point.

Is it worth upgrading to a Heim setup?

No, some counties is a hit/miss with Heims for steering components to pass annual safety inspections. (i.e. Honolulu, Hi.)

 

[tonytony9]

No, some counties is a hit/miss with Heims for steering components to pass annual safety inspections. (i.e. Honolulu, Hi.)

Luckily no inspections for me

 

[HoldMyPocket]

I take it you didn’t perform the various checks I listed. A steering stabilizer hides the problem, tierod ends is probably a guess and just selling labor. How do they look? Perform the tests. Firestone doesn’t know how to troubleshoot death wobble.

 

[tonytony9]

Long time coming, thank you everyone for all of the advice. I went through the various checks, ball joints, track bar/steering lineage, idle/pitman, and steering box all seem good. Order up all of my suspension parts including new radius arms from North East Classic Ford. Going through the job over the next few days. Will let you know how everything progresses. Thanks.

 

[DirtDonk]

Well, it’ll all be new up there then. Except for the tires…
Did you try rotating the tires yet? If not, I would do so before going through all the installation of the other stuff. Looking solid does not mean they are.
You’re gonna have the tires off anyway for the install, so you might rotate them, accidentally on purpose when putting it all back together.
In that case you would never know if it was all the new components, or a change in the tires.
So if you have not, I still say rotate one side front back, drive it, see what happens. Then rotate the other side front to back, drive it, and see what happens.

Even if you want to replace all those items with new anyway, it would still be nice to know if the tires had any part in it.