Radial tire "wobble" with the Super 10

[Dragsinger]

The first test outing with M/T bias tires [#3074s 32 x 14] went smoothly, handling was as expected.

This weekend at D 4 Race with #3073R M/T[31.25/12.2R15W] Radial I had the "wobble" near the finish line.

About 200 feet before the finish line it does a very uncomfortable feeling "wobble dance"

Not out of control but it feels unsafe and I think has potential to be trouble.

The truck weighs 3170, 15" wide wheel, 18 pounds air pressure, about 125 MPH

Any suggestions for a cure?

[Angelo DiTocco]

Radials are more sensitive to everything -- like bumps on the track, shock settings, etc. But..... If your wobble is developing down track, definitely check the balance of the tires before you do anything else, next check the shock settings - make sure they're set the same from side to side... If you get a wobble developing closer to the starting line, like after the car settles down from the wheelstand then jack the front end up and check your suspension travel.... meaning how far your front wheels drop. Make sure that is the same on both sides.... If it's off... do what you got to do to correct it. Cars with uneven front end travel will go into that wobble when one side's front wheel touches down ahead of the opposite side and then continue for the run. With bias ply tires you'd never notice it.... but with radials the imbalance gets transferred right to opposite side rear wheel and then across to the other rear wheel. It sometimes happens past the finish line when you let out of it. But in your case - if it's fine until half track or 1000ft, and there's no bumps in that area of the track..... then I'd rebalance the tires first and see if that does the trick.

[Mike Pearson]

Drop the tire pressure to what you were running in the bias ply tires. Then work your way back up until you find a sweet spot. I had the same issue and this is the method I used. I have never been able to use more than about 14 lbs in my tires and have consistency. I run Hoosier and they seem to be more forgiving than the M/T tire. The M/T seemed to be just a bit faster but did not last very long. As Angelo said check all of your shock settings. Certain tracks will act differently if they have bumps.

[Jeff Jewell]

Just a couple of suggestions to add...

I had a top end radial wobble issue a couple of years ago. It turned out that the corner weights were off. It was most evident when I would lift off the gas. I had too much weight on the driver's side front corner, causing the car to go into wobble.

I would also check to make sure you have as much positive caster in the front end alignment as possible. We're having an issue with my father's car where it doesn't have enough positive caster and it will get into high gear wobble on some tracks. My car has a lot more positive caster in it and doesn't have the same problem, using the same wheels and tires. We're going to make some front end changes on his car this winter so we can get more positive caster in it.

Hope this helps.

[1320racer]

Originally Posted by Angelo DiTocco

If you get a wobble developing closer to the starting line, like after the car settles down from the wheelstand then jack the front end up and check your suspension travel.... meaning how far your front wheels drop. Make sure that is the same on both sides.... If it's off... do what you got to do to correct it. Cars with uneven front end travel will go into that wobble when one side's front wheel touches down ahead of the opposite side and then continue for the run. With bias ply tires you'd never notice it.... but with radials the imbalance gets transferred right to opposite side rear wheel and then across to the other rear wheel.

THIS^^^^ is the #1 cause of radial wobble.

[Dragsinger]

Notes:

*15" wide wheel

*M/T #3073R 31.25/12.2R15W

*first 15 pounds then 18 pounds

*about 1.25" on each side of each tire has never touched the track

*3170 race weight

*nice smooth wheelie down before 60' clocks

*1.39 - 60 foot

* 10.40 ET

[Dragsinger]

the truck setup is good

*front end properly aligned

*same travel on each side both front and rear

*four link has 1/4 flat pre-load right upper bar [just take the slack out from neutral]

*anti-roll bar is neutral with slack taken out

*new AFCO shocks all four corners by Randy Mans of Fast Shocks. Shocks adjusted per our collaboration.

An above post suggest running the same air as I ran with bias tires [10 pounds] and judging by the photos that is good advice.

Truck is smooth and straight with bias tire.

[Mark Markow]

my truck is 2915 race weight. and I run 13.5 psi in the radials 3074r on 15'' wide rims no wobble.

[rk3800]

Try adding a couple lbs. of air to the front tires.
Worked for me and it was cheap.

[Dragsinger]

front tires are M/T 26" front runners at 30 pounds