The dreaded drag radial wobble

kevinlc · 06-15-2023, 11:27 PM

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.

dragracerray · 06-16-2023, 07:13 AM

How much caster do you have? Ray

Mark Howes · 06-16-2023, 07:52 AM

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

novassdude · 06-16-2023, 09:20 AM

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

Mike Pearson · 06-16-2023, 09:43 AM

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.

kevinlc · 06-16-2023, 10:30 AM

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.

Dyno · 06-16-2023, 01:44 PM

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

kevinlc · 06-16-2023, 03:00 PM

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

kirk · 06-18-2023, 05:31 PM

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.

Dave Casey · 06-19-2023, 08:58 PM

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

06-15-2023, 11:27 PM	#1
kevinlc Junior Member Join Date: May 2013 Posts: 7 Likes: 0 Liked 0 Times in 0 Posts	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.

06-16-2023, 07:13 AM	#2
dragracerray Member Join Date: May 2017 Location: Webster, New York Posts: 157 Likes: 311 Liked 122 Times in 57 Posts	Re: The dreaded drag radial wobble How much caster do you have? Ray __________________ Ray Bassett I/SA 1687, SS/DA 1687 "SuperPro is both", unknown

06-16-2023, 07:52 AM	#3
Mark Howes Member Join Date: Nov 2001 Location: Saint John, NB Canada Posts: 117 Likes: 299 Liked 68 Times in 22 Posts	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

06-16-2023, 09:20 AM	#4
novassdude Senior Member Join Date: Mar 2002 Location: usa Posts: 746 Likes: 203 Liked 133 Times in 49 Posts	Re: The dreaded drag radial wobble do you have radials front and back? Mixing them made my car drive terrible on the top end.

06-16-2023, 09:43 AM	#5
Mike Pearson VIP Member Join Date: Mar 2007 Posts: 2,321 Likes: 546 Liked 1,629 Times in 502 Posts	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. __________________ Mike Pearson 2485 SS

06-16-2023, 10:30 AM	#6
kevinlc Junior Member Join Date: May 2013 Posts: 7 Likes: 0 Liked 0 Times in 0 Posts	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.

06-16-2023, 01:44 PM	#7
Dyno Senior Member Join Date: Dec 2002 Posts: 870 Likes: 920 Liked 605 Times in 177 Posts	Re: The dreaded drag radial wobble Like said above - anti roll bar does wonders. A must have with big radial tires.

06-16-2023, 03:00 PM	#8
kevinlc Junior Member Join Date: May 2013 Posts: 7 Likes: 0 Liked 0 Times in 0 Posts	Re: The dreaded drag radial wobble I do have an anti roll bar. It’s not helping.

06-18-2023, 05:31 PM	#9
kirk Junior Member Join Date: Dec 2002 Location: Kalamazoo Michigan Posts: 35 Likes: 1 Liked 5 Times in 4 Posts	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.

06-19-2023, 08:58 PM	#10
Dave Casey VIP Member Join Date: Dec 2002 Location: Hampden, MA Posts: 1,151 Likes: 198 Liked 581 Times in 127 Posts	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 __________________ Dave Casey 1330 STK