The dreaded drag radial wobble
 

Looking for pointers on how to fix my issue. 68 dart with stock front suspension and four link rear. BB motor with 821hp and a 727. The tires are Goodyear 31.5 x 31 x 15 with 18psi. Car makes it to the 1/8th mile then the steering wheel starts moving left and right and the car wobbles really bad. Ran bias tires for years and no issues. Switched to radials and adjusted the shocks and this happened. Any thoughts on how to fix this. Thanks for the advice.

Re: The dreaded drag radial wobble
 

How much caster do you have? Ray

Re: The dreaded drag radial wobble
 

No Fun!

Having been there and done that with different cars over the years I can tell you that many answers are found in the front end not the rear.

The lower psi of the bias ply masks underlying issues already in play. I have seen the following cause radial wobble....
* Bad front shock
* Bad rear shock
* Loose Idler arm
* Cracked steering box mount

Hope you find it easily

Re: The dreaded drag radial wobble
 

do you have radials front and back? Mixing them made my car drive terrible on the top end.

Re: The dreaded drag radial wobble
 

Anti roll bar might help with the 4 link. Try running the same pressure in the radial as the bias for a staring point. I run mine a 12 psi and have minimal problems with the wobble. Make sure everything is tight in the suspension and no slop or loose bolts. Radials need to dead hook. No wheel speed as some call it.

Re: The dreaded drag radial wobble
 

I do have bias front tires. There on a four inch wide wheel and an anti roll bar in the rear. Front end was setup for racing but that was a long time ago and I don’t remember the specifics.

Re: The dreaded drag radial wobble
 

Like said above - anti roll bar does wonders. A must have with big radial tires.

Re: The dreaded drag radial wobble
 

I do have an anti roll bar. It’s not helping.

Re: The dreaded drag radial wobble
 

I had a similar problem on my old third gen Camaro...... put a steering stabilizer on it and never happened again. I had to make some mounts, but wasn't to much trouble. I don't remember what the original application was for the steering stabilizer, but it looked like a standard shock.

Re: The dreaded drag radial wobble
 

Don't know if a steering damper is the fix, but the commonly used one is from and old VW bug , and make your own mounts for it

Re: The dreaded drag radial wobble
 

As someone else said, solving the problem can be a major task. If you just want it gone with no drama, switch to Phoenix radials, in the size you need. Call Mike Crutchfield and he will give you the scoop. Bottom line, Phoenix tires work and they absolutely get rid of the wobble.

Re: The dreaded drag radial wobble
 

Have had that problem several times when putting radial tires from bias - tighten front shocks to keep car from rocking back and forth . should work

Re: The dreaded drag radial wobble
 

I'm curious if anyone that was experiencing "wobble" ever tried a set of radial front runners and what the results were.

Re: The dreaded drag radial wobble
 

Does anyone make a radial front tire with that small a width?
Thanks for all the input and keep them coming. Hope to figure this out.

Re: The dreaded drag radial wobble
 

I googled "drag radial front runner" and found a mickey Thompson tire that I'm sure is heavy but it would be interesting to try on a car that was having problems.

Re: The dreaded drag radial wobble
 

Have a buddy that chased this issue in the past for 2 years,changed just about everything on the car..finally talked to a chassi builder (well known to this forum) he asked what tire he was using and then said you cant use that one,use brand /size XX instead wich he did and then problem was gone.
Sometimes it's the easy things,

Re: The dreaded drag radial wobble
 

ok, what was the mystery tire brand?

Re: The dreaded drag radial wobble
 

Front or rear tire?

Re: The dreaded drag radial wobble
 

how wide are the wheels the OP is using?

Re: The dreaded drag radial wobble
 

I’m using a 14” wide rear wheel and 4” fronts.

Re: The dreaded drag radial wobble
 

I would not like to go there for a number of reasons :
1. It was not my problem so I never heard it from the chassie builder myself

2, Since it was not my car I was not interested enough to maybe remember what I heard correctly if what I heard now was correct!

3. This was in the beginning of wider Radials so "the problem" has most likely moved around between brands since then with moving factory's and outsourcing etc.
also it could have to do with what car or combination you have?
only a reputable chassie builder would probably gathered enough info to know about this.

Free info is what all expect and often get on the internet, and it's usually worth what you pay = nothing:D

Well Ok...here's the free advice : If I remember it correctly I think he was told to get Mickey's :rolleyes:

Re: The dreaded drag radial wobble
 

Talked to the Goodyear representative and he said to raise the front tire pressure to 40psi and try that.

Re: The dreaded drag radial wobble
 

And does Mickey Thompson even make a 14” wide radial?

Re: The dreaded drag radial wobble
 

I am not a radial expert but I have worn out a few sets of similar sized Hoosier radials. I will offer what I do and don't do. I only have about 600 hp first of all. I think radials are more sensitive to track temp and prep. I never run more than 13 lbs of air, at 18lbs the outside 2 inches of tread doesn't contact the track. Maybe you are running about 5 or 6 lbs too much air pressure ,that's a lot. I have a four link , no anti roll bar, bias ply front tires and I routinely switch from radials to bias ply with basically no change other than air pressure. I would consider where your four link is also ,perhaps shorten it up some so it keeps the tire planted and a shorter setting has more triangulation and thus less roll tendency. I believe that as the tire unloads and slips is when this problem happens. Most of the cars with lots of gear and weight transfer seem to work fine. Good luck!