Death Wobble - speedway tie rod may be suspect

This happen to me years ago turned out to be caster, check the king pins make sure they lay back a least 7 degree's, on the steering dampner check out the VW's of the 60's 70's they had a small unit that worked well, check out your tires, if you mounted the driver side to the passenger side the casing and tread may have seperated and you're picking up a wooble from that............

 

Very interesting. Not that I am doubting you, but it seems unlikely that a person could flex the tierod by reaching out extended to each front tire.

Just a thought, but what do you have for steering arms on each spindle? If they are bolt-on types, are they tight? Maybe if a steering arm is loose it makes it look as if the tie rod is flexing?

If your steering arms are the Speedway flat plate ones, that could be what you see flexing. Those are really pretty easy to flex because they are bent flat plate. Some bolt-on forged ends would be a much stronger choice.

Just a couple thoughts, keep us posted on what you find...

Dan

 

Check your caster also. To little caster will help cause the death wobble.

 

I doubt this very much.
Tubing is stronger than solid bar.

 

post pics

 

I'm running Speedway draglink with heims and their flat steering arms with no problems. Going on Two years now and never did put shocks on the front, the roads here are pothole infested too. I have no shakes or wobbles with my setup, had bias plys on steel rims and now have radials on aluminum slots but have no problems here.

 

I had a swell case of death wobble in my A coupe. I also noticed that when I ran 10psi in the fronts it was all but gone, but one set of RR tracks by my house would always set it off. I also run speedway tierod and draglink, but with real tie rod ends. IMO there will be a little flex to these 7/8" links. I dont think its the end of the world, and I dont see the need to run around a 2000 lb car with tie rod links that belong on a rock crawler.

Long story short, a VW steering dampner and now everything is great with the tires at 30 psi.

Im not saying its gonna fix worn out parts or improper caster etc. BUT it worked for me.

Rob

 

Another thing to try is the Toe in or out. Alot of guys will toe out 1/8-3/16" and have good results. I ket it toe-in at 3/16". Bias plies.

Rob

 

we've used theirs on a couple builds...no issues. was it powder coated when you got it..? got a pair once that where black coated. we did have a draglink around here off of a old fed...the car would go into SEVERE shake if you hit a bump . it ended up being a worn axle and bad steering geometry.

 

The piece I cut off measured .14 wall thickness - That's in the threaded portion. I am not sure if they drill them prior to tapping them.

I have tried the steering dampner and it changed nothing -it is back off now.

It was not powder coated when I got it.

 

its the blower, take it off and send it to me.

 

Tudor, over on the NTBA message board is a recent discussion about how a death wobble was cured by replacing defective M/T tires. Lots of good info on all the things that were checked before the tires were finally found to be the cause.

 

send me your address! Hey I am going to be in Leavanworth for the October fest coming up. Should I just bring it then? Will you be close? Hope we can see you and Stacey.

I have an 1/8" toe in.

Caster is at 7 degrees.

 

Harry - I've had two different sets of tires and wheels with the same effect. I just happen to have some small radials I am going to try with stiffening up the tie rod.

 

only tudor has mentioned caster, that i noticed. what's yours?

 

I think this guy hit the mark its not the dia thats the issue .
we run sprint cars and experence this from time to time and its always toe first then caster . on some cases we will install a wood dowel through the tie rod and that will take the flex out but wont fix the problem just hides it . if we can use small dia alumunum rod and just trash it on dirt a little old streeter wont need some gorilla sized fix all .just my thoughts .

 

Tire pressure and side wall flex will effect the wobble but wont fix it just mask the problem its not the tires , wait till you drive in the rain its a rodeo .

 

Even if your a strong guy, I doubt you're actually flexing the tie rod proper.

What may be happening is a defective Heim may be allowing the tie rod tube to rise and fall as you push back and forth.



Do you have bolt on steering arms?
Are they tight?

Are your steering arms and pitman arm tapered for tie rod ends and you're using bolts instead of a tie rod end's tapered end that goes into the tapered holes?


The hot rod aftermarket generally supplies tie rods and drag links that are made from 7/8" OD x .156 wall thickness for standard Ford 11/16-18 thread tie rod ends.

I believe Speedway's tie rods etc. are the same.

 

As far as the tie rod flexing, is it bent or bowed at all. Once a piece of tubing gets out of line it loses much of it's compressional strength. Think of it like a big push rod.

 

Sorry C9 - they are bolt on and tight. The steering arms are not flexing and the Heims are new and they are high end Aurora units. They have no slop. Lock nuts on the heims are tight. The tie rod bows up when I pull and dips when I push on the tires. I have the radiator off so I have my face right in front of the center of the tie rod looking at it. I welded a small angle on the rod about 36" long and doesn't flex near as much, but still moves slightly when I push or pull on the tires.


My draglink is disconnected. The steering arms have straight through holes and are not tapered. I have shouldered bolts.

Like I said below, the piece I cut off measured .14 wall thickness but that was in the theaded portion. If they don't drill them before they tap it then that is prettyclose to the wall thickness. they may drill them prior to tapping. I don't know.

Trust me the tie rod is bowing up and down.

 

It is not bent that I am aware of. I have never jacked up on it or anything. It was as straight as the angle iro I welded to it.

 

so are you going to take it off and send it back to them?

oh scratch that..i see you already welded an angle to it..so just toss it in the trash and carry on

than go out and buy a 50" stick of 7/8" DOM and make your own tie rod..at least you will know what you got than

Im thinking maybe you got a defective tube? maybe wall thickness thin in the middle? (it is possible isnt it)..do a post mortum ..and see if it is thin cut that bugger in two

than if you still have the wobble you know your not going to wrap up another tie rod and can focus on where the wobble is coming from

or you may have solved your problem right there

 

what are you running for shocks...?

 

Tudor:

What you are describing is a classic positive feedback system:

When you hit a bump, you are getting a toe in situation. I know you claim zero bump steer, but that would be rare.

When the one wheel toes in, it compresses the tie rod and in effect turns it into a sping. The tie rod will staighten out and push the wheel back out, now what you have isa weight on the end of a spring. The forward motion of the car keeps adding energy to the system and you end up with a system that will increase its oscilation until energy is subtracted.

You claim this was a developed situation. I would look at the tie rod and make sure it is arrow straight. Toe in would contribute to this problem and most rear drive cars are toed in.

Bottom line, you have an oscillating system; find out what is storing the energy and ou solve the problem. The underinflated tires are acting as dampers and masking the problem.

 

Pro 1 chrome hotrod shocks - they are new and at about a 25 degree angle from vertical. They are mounted to the bottom of the axle at the bottoms of the perches.

Thanks Nohome. I'll say the car doesn't dart or change direction when I hit bumps.

VonFink - I think I am going to see if the angle I added made any difference. I may make a new one or sleeve this one. I think it should be stiff and not flex. Then I am going to try toe out, then I have some 135 15 radials I am going to try. If it still does it after all that I am going to shoot myself.

I was mainly curious to see if anyone else had a flimsy tie rod. I think it flexing and springing back is what is causing the wobble to occilate out of control.

 

Will you put me in your will..if you decide to shoot yourself?

I'll figure it out, and in honor of you ..I'll drive it in your funeral procession

J/K..you'll get it..im sure once you get that flex out of the tie rod..it will either show you that it alone was your problem all along..or at least a big contibutor to it..
let us know how you come out of this

 

or you could stare at this and it will straighten your rod out

 

Really? We talking resistance to bending? Got a tube bender, or know someone who does? Take, for example, a piece of 1 1/2" .120 wall tube and put a 90º bend in it. Now take a solid 1 1/2" solid bar and put a 90º bend in that. Check back with me.

Bob

 

you need to start from one end of your car to the other end. I've had several cars do this same thing and it turned out to be a bad u-joint on the driveline. look at everything.

 

Nice picture - I think she would prefer the solid bar

Thanks guys- I'll keep ya posted. I have been screwing around with this now for a while -