IRS need power to the ground.

[tbirdtess]

Hello

I am having trouble with a loose condition coming out of the corners.

This is for my oval track car. I race a Factory stock 1990 Thunderbird.

Sorry, not a cobra. This is in my Thunderbird. I know alot of you run the IRS in your Cobras. I must run a open rear gear.

I had a push until I connected the rear-sway bar. Now she is loose. I lowered
the rear springs. helped some. I was thinking of using a lighter rear sway-bar.

Any help is appreciated

Paul

[Naumoff]

Why do you have to run an open rear and not a limited slip?

[mylesdw]

If I read your symptoms correctly they are consistent with too much rear roll stiffness so a lighter rear sway bar should help. Increasing rear roll stiffness unloads the outside front tyre which decreases understeer and adds load to the rear outside tyre which increases oversteer.

[tbirdtess]

Hello

I run an open rear do to the rules.

Mylesdw, That sounds right. The RR was the hottest tire after the feature.
What about even lighter rear springs? Or more rear weight?

My car is heavy already. So adding weight not direction I want go.
The handling was good until I changed the 302Ho to the 351W.
The extra weight in the 351W & more HP completely changed the car.

I need all the Help I can get. I have mid to lower finishing car. I want to improve that fact. I also run the Only Ford. Stubborn Frenchman I guess.

Here are some of the rules:
V-8 2bbl carb 8.5 compression + stock lift w/mec fuel pump, Automatic Trany, 15" DOT 70 series tires, open rear gear with max 3.73(I am aloud 3.90) all on a min 3400lb car & only 51% left side weight.
Did I mention No Racing spring or shocks(Most ignore this rule), I can't.
I can't find racing shocks for my car.

Paul

[mylesdw]

Originally Posted by tbirdtess

Hello
Mylesdw, That sounds right. The RR was the hottest tire after the feature.
What about even lighter rear springs? Or more rear weight?

I can't see that either of those two would help, the ARBs (anti-roll bars) convert body roll to loading on the outside tyres and the balance between front and rear roll stiffness effects understeer/oversteer. You need to decrease rear roll stiffness or increase front roll stiffness. Moving the ARB pick-up points gives the best adjustment since changing its diameter gives a very large change; the stiffness of a torsion bar goes up with the 4th power of its diameter, or to put it another way, if you double the diameter the bar will be 16 times stiffer! An alternative is to lessen the car's tendency to roll in the first place by lowering the centre of gravity.

[Jac Mac]

Rather than an anti-roll bar have you thought of trying a 'Z' bar at the rear, this would transfer some of the roll induced right rear weight to the left rear to reduce wheelspin on the LR which should give more overall rear grip as well in the turns.
Since I assume you only turn left by having several pickup points on the suspension arms you could vary the amount of leverage obtainable.

Jac Mac

[tbirdtess]

Hello

I swapped the rear sway bar. from a .98" solid bar to a 1.04" hollow bar.

I also swapped the rear springs. Now LR 300 RR 275

Want about rear toe. It measures even. Should I try toe in at RR of 1/8"?
There is movement in the rear K. There are ware(motion) marks in the bushings.

Rear weight? I have about 47% rear weight. Should I add?

Thank you
Paul