more gear or less gear in the slick

[dirtracr33]

lets hear it..ive heard both ways...whats everyones thoughts on this..thanks for any input.

[Kwoods25]

Same gear and throttle control

[bob75]

When it's slick the track gets slower we've always put more gear .if you take gear away you will have to much wheel spin, you will have to back pedal

[dirtracr33]

reason I post is weve always went w/ less, tried more before but w/ no luck and im smooth on throttle, over 20 yrs racing... but ive got guys who swear by more gear....

my thoughts are when slick, you'll hear guys changing link on carb, taking timing out, etc....to eliminate some of the "shock" to the tires, that was my theory w/ taking gear out, roll into it and let the motor do the work pulling you off...I can see where more can help on entry but when you're in traffic trying to get under a guy and get him coming off seems like you would get more spin with that lower (higher number) in there...

so am I thinkin it wrong..not trying to start any arguments, just trying to get some theories, thanks for the input..

[billetbirdcage]

reason I post is weve always went w/ less, tried more before but w/ no luck and im smooth on throttle, over 20 yrs racing... but ive got guys who swear by more gear....

my thoughts are when slick, you'll hear guys changing link on carb, taking timing out, etc....to eliminate some of the "shock" to the tires, that was my theory w/ taking gear out, roll into it and let the motor do the work pulling you off...I can see where more can help on entry but when you're in traffic trying to get under a guy and get him coming off seems like you would get more spin with that lower (higher number) in there...

so am I thinkin it wrong..not trying to start any arguments, just trying to get some theories, thanks for the input..

I really depends on several things, but the big 2 are:

1. The engine itself
2. The driver

Personally, more gear (IE higher number) too me made it easier to control wheel spin. If the engine is a large engine with large stroke, you may find it's better to take out gear and with a smaller short stroke engine its better to add gear.

The idea behind the add gear deal is basically this: It takes a certain amount of time for the driver to sense the wheel spin and then react and move his foot, lets say this is an average of .5 seconds. Lets also say your engine, when it goes into wheel spin and the driver can sense that it gains RPM at a 1000 RPM per second.

Just throwing out those random numbers to show something here:

Less gear: 26" tall tire and 5.0 gear and wheel spin occurs at 6000 RPM off corner. MPH of the tire is 92.86 MPH. The MPH of the tire .5 secs later when the driver can react is 6500 RPM = 100.60 MPH. You gained 7.74 MPH at the tire before you can react.

More gear: 26" tall tire and 6.0 gear and wheel spin occurs at 6000 RPM off corner. MPH of the tire is 77.38 MPH. The MPH of the tire .5 secs later when the driver can react is 6500 RPM = 83.83 MPH. You gained 6.45 MPH at the tire before you can react.

While that 1.5 MPH may not seem like much, when you trying to back pedal and rehook the tires it actually makes a fair difference, IMO.

Next thing is the engine and it's torque curve. More gear allows you to run on the back side of the torque curve, meaning your likely already past torque peak and any increase in RPM the torque is going down not increasing. If your running below torque peak, you can hold the throttle steady and it incur wheel spin from the increase in torque from the engine. Even if you're not on the back side of the torque curve, you are at least closer to torque peak where the engine isn't making large gains in torque like if your way below the torque peak.

Example: Engine torque peak at 6000 RPM and gains 10 FT pounds for every 100 RPM above or below that RPM (again fake number, just using something easy). Say you are running a 6.00 Gear and torque peak is 600 foot pounds.

So at 5000 RPM the engine has 500# and is on the verge of wheel spin so you are holding the throttle steady and waiting. Then engine is slowing gaining RPM as it comes off the corner, so once it gains to 5200 RPM it's now at 520# of torque (520# X 6.0 gear = 3120# at wheels vs 500 X 6.0 = 3000#). This gain of 120# at the wheels is enough to induce wheel spin even though you didn't push on the gas any harder.

If your already past the torque peak by adding gear then the # at the tires isn't going to increase cause the torque of the engine is actually going down and thus reducing the # at the tires.

I over simplified this and took some liberties to get the basic idea across, but you should get the point.

[adamsraceshocks]

Above posts are good. Two other factors that play in are setup and how well the car is working, and the type of track. If you are already suffering from a tight loose condition adding a higher gear ratio is only going to make it worse, if your car is good in and through the middle keeping the engine in the power band will make the car faster and more consistent. If you are on a stop and go track I think it comes down to driver ability and preference what gear to run not spinning the tires becomes the main concern. On a momentum track I think you want to gear for how fast you are going to keep in the power-band.

[swartzman]

I know years ago, I asked Jerry Inman that very question and he had told me at that time to go up a couple of points that way you use the engine to slow you down and it would keep you off the brakes. But I think it's driver preference.

[kenwoodjeff]

I have always used "Use track times to determine gear direction".

Lower lap times = less gear
Higher lap times = more gear

[swartzman]

I know alot of times it would depend on where I started the race from. Up front I would pull a few points of gear out of it and more to it if I was midpack..