Physics of max lateral G's based on tires Options

[98_1LE]

I seem to recall that max lateral G's of friction is 1 G, and that to go above that adhesion is required.

If true I interpret this to mean that typical street tires would be limited to 1.0 G.

Am I nuts, close, or correct?

[Ojustracing]

I seem to recall that max lateral G's of friction is 1 G, and that to go above that adhesion is required.

If true I interpret this to mean that typical street tires would be limited to 1.0 G.

Am I nuts, close, or correct?

I have seen street tires go over 1g. Just look at what Danny P did. The track was not completely dry either.

OLOA 06 Dry skid pad

those results were done on a 2 lap average and one of his lap was above 1.12. On street tires that had seen 4500 miles of use.

John

[John_D.]

I have seen street tires go over 1g. Just look at what Danny P did. The track was not completely dry either.

OLOA 06 Dry skid pad

A little off-topic, but I found it interesting that a Viper and a Vette scored below a Grand Cherokee (24th place)... (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

On topic, I think one factor is going to be the interaction of irregular surfaces. The rubber can deform into pits/crevices in the track surface and create a bit of a shearing effect on a small scale.

[killer_bluebird]

I have pulled 1.02g on all season street tires at the track. So with a good summer tire or or Nitto II's you should be able to pull quite a bit more.

[Ojustracing]

I have seen street tires go over 1g. Just look at what Danny P did. The track was not completely dry either.

OLOA 06 Dry skid pad

A little off-topic, but I found it interesting that a Viper and a Vette scored below a Grand Cherokee (24th place)... (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

On topic, I think one factor is going to be the interaction of irregular surfaces. The rubber can deform into pits/crevices in the track surface and create a bit of a shearing effect on a small scale.

John you are very observant. Yes certain cars did better than others. Basically it came down to driver at these events. Just because A car is capable of X in a magazine doenst mean that the car owner can reach x also. These events were done with a 2 lap clock/counterclock wise average. Some people have never been on the skid pad before other its there job. I personaly did really good counterclock wise because you can see the edge of the track. I screwed up going clock wise and went a bit wide and lost a ton of time. Spinning the car intenially between a direction change might not of been the best thing to do, because I was laughing like a little kid in my helmet. (IMG:http://www.frrax.com/rrforum/style_emoticons/default/rolleyes.gif)

Here's another look at cars during a wet-skid pad, Look what is first a 92 dodge daytona (IMG:http://www.frrax.com/rrforum/style_emoticons/default/ph34r.gif)
wet skid pad

John

This post has been edited by Ojustracing: Aug 31 2006, 03:25 AM

[Crazy Canuck]

friction coefficient can be higher than 1.0
coefficient is based on the 2 types of surfaces getting in contact.

F = coeff x NormalForce
Normal-Force on the surface is the weight (not mass) of the vehicle, if measured in g's = 1g
F1's do ~4g's when cornering.
but then again, when sticky tires get hot, they get sticky, so it's some kind of adhesion by definition.

were talking of static friction, obviously... otherwise, the coefficient is was lower than static.
for all intents and purposes, static = not-sliding, ie still under grip conditions.

[z28tt]

You can get well over 1g without any type of aerodynamic downforce. That number isn't a magic wall... Eugenio posted the formula for the force of friction, and it all depends on the coef. of friction of the tire (which depends on the compound, temperature, slip angle, pressure, etc...). Most manufacturers don't even have the CoF curves unless they've done some very expensive tests (not on street tires or most racing tires we use). For some interesting reading, Racecar Engineering Magazine had an article a few months back about the Formula SAE teams chipping in to do the experiments and get tire data from a few different sizes. I believe the Millikens were involved w/ the test, and the tire research center in upstate NY.

Clear as mud, right? (IMG:http://www.frrax.com/rrforum/style_emoticons/default/smile.gif)

[DavidDymaxion]

Per g-tech, my 4th gen did 1.03 g (both left and right) on stock sized BFG KD street tires. The suspension was bone stock, including deCarbons with 140k miles. This was on Wendover brushed concrete, so the surface certainly helped. Even given some error, I was impressed both with the Camaro and the tires. Too bad the driver isn't a consistent edge of the traction circle driver!