death wobble

[Jimmy Pirtle]

Hello there. This is my first time EVER to join a chatroom or do a post on a forum so please bear with me. I am a dinosaur. In order to get the headers I wanted, on the bucket, I had to move some things regarding my steering, resulting in a violent death wobble about 30mph. I lengthened my pitman arm by 2" and swapped the tie rod and the hoop style steering arm. so my hoop style steering arm is on the bottom after much heating and bending, and the tie rod on top after much grinding. I know there are endless issues that can cause a death wobble. what are the most common? Thank you all

 

[Neshkoro]

The famous death wobble!
On my T I tried toe in, toe out, caster increase/ decrease.
The final numbers were:
Toe in: 1/8”
Caster: 5° positive
The biggest improvement came when I reduced the tire pressure to about 15 psi.
That’s my car. Each car is different. Yours probably will be, too.
I also installed a steering damper. I don’t think that did much of anything. a
After 40 years of driving it, the car still wanders, but no death wobble!!

 

[guilld]

German engineering. Volkswagen have steering dampers and from experience of owning one when those dampers wear out you will get a similar thing to a death wobble.

 

[thebearded1]

As Neshkoro stated it's different for every car. I had a similar issue and reset my toe to 1/8" in and that seemed to help. I was even able to race at an 1/8 mile drag track and didn't have issues even without shocks so try some small adjustments on the toe and see if that helps. I'm running about about 7 degrees lean back on the front axle and using friction shocks. Unsure of my tire pressure on the front tires.

 

[PotvinGuy]

This can be so frustrating! I never have had it, so can't speak with personal experience. But one thing that seems to come up often is toe-in, and 1/8" is a typical number. I can't imagine toe-out working at all. I run 30# tire pressure and have fooled with that, but it doesn't seem to make a difference.
I can't see how your modifications would trigger a wobble. Check all steering connections for any slop. Do you use ball joints like this:



..or spherical rod ends (heims) like this:

The heims are much tighter and minimize slop in the steering system

And how do you center the axle? Panhard? Any side-to-side movement of the axle will really give wobble.

 

[Indycars]

If you don't find a quick solution, then it might be time to drop back and start from the beginning. Do a String Alignment for the car, this will make sure that the rear end is square in the car and also help you get the front end square and measure the the toe-in. It's a very accurate method and only has to be done once or until you make a major change in the suspension. Then all you will need to do is the Caster angle.

I used the two videos below when I did my string alignment.

I used the video below for setting up the string border, so you only need to watch the first 16 minutes.

 

[lincolnuT]

No panhard bar, 1/8th toeOUT and 6 degrees back at the Kingpins along with 32 lbs of air in the front tires & I now have Halfrack steering............Many Miles without a Death Wobble...........

 

[Neshkoro]

LincolnuT is a prime example that all cars are different. There’s probably something unique in each that dictates what the front axle settings should be!
Imagine, we build our chassis on the garage floor or some crude jig. Car manufacturers use precise jigs and robotic welders to make theirs frames/
Chassis as perfect as they can be and they still have a number of adjustment points and areas that need shims to align their front ends. And they have precise alignment tools to adjust. We have string, tape measures and pencil marks on the ground. With all that crudeness, we’ve done pretty damn good! Give yourself a round of applause!!

 

[lincolnuT]

Clap Clap Clap............................LOL.........