Death wobble

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straightaxledar

straightaxledar

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Running a all new speedway gasser front end and new shocks launch the car real hard and shakes like crazy till I jump on the brakes also running 15x5 inch cragar steelies with et fronts any ideas ??? All was installed by a professional fabricator and long time drag racer
 
thanks for the idea I've been wondering if maybe a steering stabilizer or stronger shock never thought of caster thanks so much
 
set your caster at +1 +2 degrees, sounds like your caster angle is to high,
it will probably be +5 or more if you check it. you will have to shim it between the axle and spring. I have 2 2 degree shims if you need them.
Brian
 
No shims or anything now the guy just pretty much bolted everything up it only does when I launch real hard other than it rides great brand new cragar rims and et fronts drag tires I don't think they r balanced I paid a guy to do the whole front end set up I just bought the parts me and geometry don't mix
 
Working on buying new radial front tires I've heard from some old timers that mixing bias and radial is a bad idea ???
 
And for the shims do u put them in the front side or from the back very new to the gasser world thanks again guys
 
Install the shims wherever you need to in order to lay the top of the tire back a few degrees. Not sure how that particular front end is done, but sometimes you can shove the cradle forward a little bit to move the lower control arms forward. This does the same thing as shimming to top. Sometimes it is easier to adjust the cradle and be done with it.
 
I used used rear axle shims in the front they come in 2deg. up to 10 deg you want to tilt the axle back to the fire wall. I started with 2 degs in mine ended up with 8degs. some shim are made to stack most are not. 8degs. stopped the wobble and the squealing in the corners
 
Got any pics of the front end? It would probably make things easier for us to diagnose.
Generally a street driven straight axle car would run anywhere from 6* to 9* of positive caster without issue, a track only car can get away with more positive caster, more caster is more stable at high speeds it helps make the front wheels track straight ahead.
You can check your caster angle by putting an angle finer or digital level on the steering knuckle right above the king pin, it should be at least 6*
A steering stabilizer would help in your situation especially is the front tires are coming off the ground on launch.
How is the steering box linked to the axle? More importantly what kind of angles are involved? If the tie rod going from the steering box to the axle isn't parallel (or close to it) to the axle your going to have bump steer issues which can also cause death wobble.

Did the tie rod tubes also come from speedway?

When I put a straight axle in my 46 Plymouth using speedway stuff I noticed the tie rod tube seemed very thin and flimsy and would flex pretty easily. Luckily I haven't had any death wobble issues with mine but I did have some bump steer because of too much angle from the steering box to the axle.
 
daliant said:
Got any pics of the front end? It would probably make things easier for us to diagnose.
Generally a street driven straight axle car would run anywhere from 6* to 9* of positive caster without issue, a track only car can get away with more positive caster, more caster is more stable at high speeds it helps make the front wheels track straight ahead.
You can check your caster angle by putting an angle finer or digital level on the steering knuckle right above the king pin, it should be at least 6*
A steering stabilizer would help in your situation especially is the front tires are coming off the ground on launch.
How is the steering box linked to the axle? More importantly what kind of angles are involved? If the tie rod going from the steering box to the axle isn't parallel (or close to it) to the axle your going to have bump steer issues which can also cause death wobble.

Did the tie rod tubes also come from speedway?

When I put a straight axle in my 46 Plymouth using speedway stuff I noticed the tie rod tube seemed very thin and flimsy and would flex pretty easily. Luckily I haven't had any death wobble issues with mine but I did have some bump steer because of too much angle from the steering box to the axle.
Click to expand...

30203.jpeg
 
daliant said:
Got any pics of the front end? It would probably make things easier for us to diagnose.
Generally a street driven straight axle car would run anywhere from 6* to 9* of positive caster without issue, a track only car can get away with more positive caster, more caster is more stable at high speeds it helps make the front wheels track straight ahead.
You can check your caster angle by putting an angle finer or digital level on the steering knuckle right above the king pin, it should be at least 6*
A steering stabilizer would help in your situation especially is the front tires are coming off the ground on launch.
How is the steering box linked to the axle? More importantly what kind of angles are involved? If the tie rod going from the steering box to the axle isn't parallel (or close to it) to the axle your going to have bump steer issues which can also cause death wobble.

Did the tie rod tubes also come from speedway?

When I put a straight axle in my 46 Plymouth using speedway stuff I noticed the tie rod tube seemed very thin and flimsy and would flex pretty easily. Luckily I haven't had any death wobble issues with mine but I did have some bump steer because of too much angle from the steering box to the axle.
Click to expand...
All speedway parts
 
Can deffenatly tell steering box needs rebuilt or replaced it was tight when we started now have almost half of turn of steering wheel play
 
do you have a pic of the car finished at ride height, I ask because from the looks of pic #13
it looks like the caster is close to 0 and lifting up the back leveling out the car the caster will go negative.
 
daliant said:
Got any pics of the front end? It would probably make things easier for us to diagnose.
Generally a street driven straight axle car would run anywhere from 6* to 9* of positive caster without issue, a track only car can get away with more positive caster, more caster is more stable at high speeds it helps make the front wheels track straight ahead.
You can check your caster angle by putting an angle finer or digital level on the steering knuckle right above the king pin, it should be at least 6*
A steering stabilizer would help in your situation especially is the front tires are coming off the ground on launch.
How is the steering box linked to the axle? More importantly what kind of angles are involved? If the tie rod going from the steering box to the axle isn't parallel (or close to it) to the axle your going to have bump steer issues which can also cause death wobble.

Did the tie rod tubes also come from speedway?

When I put a straight axle in my 46 Plymouth using speedway stuff I noticed the tie rod tube seemed very thin and flimsy and would flex pretty easily. Luckily I haven't had any death wobble issues with mine but I did have some bump steer because of too much angle from the steering box to the axle.
Click to expand...
I'll get better pics of the steering setup today
 
The further you lift the back, as is bigger tires, arch the springs the more negative the caster goes, make sure the last thing you do is set the caster angle.
 
brian6pac said:
The further you lift the back, as is bigger tires, arch the springs the more negative the caster goes, make sure the last thing you do is set the caster angle.
Click to expand...
Makes sense with the way the car is sitting would u recommend more positive castor I really like the stance but have noticed a lot of guys make the cars sit level front to back is that a preference thing or is there a reason they do that
 
straightaxledar said:
Makes sense with the way the car is sitting would u recommend more positive castor I really like the stance but have noticed a lot of guys make the cars sit level front to back is that a preference thing or is there a reason they do that
Click to expand...
And for positive castor u add in the shims from the back correct to push the back side of the axle down ?
 
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