East Tennessee Region SCCA

Anyone know if any of the "good" tires will be made in a larger than 305 - 19"? I would love to go 18" for selection and weight reduction but the brakes are to big.

I will be changing the rear gear soon and I didn't think tire size and rain would have such a huge difference. I'd like to do it once.

Another question, what is a reasonable max speed in second gear for a CAMC car. As the car sits right now it is 77. 3.91 = 74. 4.09 = 70. 70 feels really low except on a really small local.

On CAM Nation it looks people were doing 77 or so through the finish on the West course at Nats.

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Do you have a torque curve at the wheel? You can use that with the gear ratio, axle ratio and tire radius to calculate acceleration. IMO there's no point in gearing for more acceleration at full throttle in second than the tires can take, which in a rear wheel drive car is an acceleration around 0.8-1.0 g. IIRC, JY's car does ~90 in second. Mine only does something in the mid 60's, but I don't have a supercharger or a huge engine.

Berry, with my factory 3.90 and 315/18 I topped out at 59mph. However..with the 3.09, I easily hit 79 twice in Huntsville when we were there.

I dont have much desire to go any faster on an AX course.. lol

Using the gear chart that I believe Disney posted in anther thread was very helpful

Also... the 3.09 made the car sooooooo much faster out of a corner,simply because I dont have to worry as much about wheel spin..I just mash the throttle like a Miata.

John Brown wrote: ↑Sat Nov 04, 2017 6:33 am Also... the 3.09 made the car sooooooo much faster out of a corner,simply because I dont have to worry as much about wheel spin..I just mash the throttle like a Miata.

I'm tempted to replace the 3.55 gears in my diff with 3.15 or 3.08 gears for exactly that reason. You also have to have the suspension set up with some understeer to be able to get on the power early.

The car is defined out of the power band when under 40mph. It can over power the tires but that has been on slick lots and not too bad.