Cal Tracs and Instant Center????

[Phillip marvetz]

Whatcha using for a clutch?

[3pedals]

11" Ram Single iron. it is at about 550lbs static right now, has no counterweight added to the CW levers.
I have tryed the static down so low to where the car wont even move when you let out the clutch, only when revs come up to about 1800, and it still BLOWS the tires away, even with launch rpms as low as 5000rpm. In fact the 60ft improved when I forgot to turn on the 2step, and left of the 7200 high side limiter lol, that was the 1.60, all others were 1.64 - and up, sometimes way up.
I am convinced the problem is in the rear suspension??????

[Phillip marvetz]

Have you tried another set of slicks? I have set that just wont hook for some reason. Switched them out and picked up big time.

[3pedals]

this is the second set of M/T et street bias 28x12.5's. 1rst set was an older pair, this set is NEW. EXACT results with both

[TOSTO RACING]

Put slicks on it et streets just won't cut it. You need a stiff sidewall slick.

[Phillip marvetz]

Ding, Ding, Ding, We have a winner!

Stiff sidewall slicks will be much better.

[3pedals]

Originally Posted by TOSTO RACING

Put slicks on it et streets just won't cut it. You need a stiff sidewall slick.

OK , I plan to try that type tire next
Do you have any input on the original question - does the cal tracs change the effective Instant Center of a leaf spring suspension?

[Phillip marvetz]

I think your putting the cart in front of the horse.
It will be pretty hard to make your car work consistently with what you have. The traction bars will help but are not the answer.

[Tony Curcio]

[QUOTE=
Do you have any input on the original question - does the cal tracs change the effective Instant Center of a leaf spring suspension?[/QUOTE]

CalTracs most definitely change the instant center. The rear attachment point (the one directly under the axle tube), is much lower so that the angle is more acute through the the front attachment point (the one below the spring-eye), in other words, pointing upward.

I have to agree with what Dinsdale said. In back to back testing on two different cars, we found the lower hole on the front mount resulted in less separation between body and wheels, as you would expect from a lower Instant Center. The resulting hit was softer, and that enabled the cars to hook on hot tracks. In better conditions, the upper front hole sometimes resulted in better 60 foot times, but it was not nearly as consistent. These were both automatics.

But what really made it work was finding the right shock setting. Controlling the rate of separation, as you already mentioned, is key, and ADJUSTABLE SHOCKS CAN POINT YOU IN THE RIGHT DIRECTION WITHOUT SPENDING MONEY. Don't assume that it's a harder hit that you need. Try going both directions with the shocks. If a stiffer shock (when extended) improves your 60 foot, then you'll know the IC needs to be lower. If a looser extending shock helps, a higher IC. It's also possible that the shock adjustments alone will be enough.