Does weight affect cornering speed?

[Cedric]

I had a serious discussion with a friend over the following issue: if a car takes a corner on the limit, would a lighter car be faster? In other words, is centrifugal force greater if a heavier car describes the same constant radius curve? I always assumed a lighter car could bear higher speed through the corner, but I am not sure. I do know that lighter cars have superior acceleration and deceleration abilities, and they have less tendency to roll due to their lower inertia. But what about the speed in a constant radius bend?

[henk4]

largely depending on the medium of adhaesion to the road: The tires.

[Cedric]

I know that, but I am talking about two cars under similar conditions, adhesion is the same, power is the same, the only difference is the weight.

[twinspark]

The object (car in this case) tends to continue it's movement straight, and tires change the direction of the movement. So at the same speed, a heavier car has a larger kinetic energy making the car go straight instead of turning. Of course the friction between the heavier car's tires and the road is bigger than the lighter car's tires and the road, but it shouldn't affect as much as the amount of kinetic energy.

Tried to explain it as simply as I could but... well, my mothers tongue isn't english.

[Matra et Alpine]

it gets difficult comparing "adhesion" as the weight of a car increases it's contact patch so a heavier car has more rubber on the road for the same tyre width.

Generally the improvment in tyre grip throguh larger contact doesn't scale linearly with the weight and hence lighter is usually better.

Also suepsnion geometry and WHERE the weight centre of gravity is can alter the corner weights durign cornering and can push the outside tyre into the exteme where it's grip worsens. This clearly happens worse for heavier weight up higher.

[Wouter Melissen]

Tried to explain it as simply as I could but... well, my mothers tongue isn't english.

Newton would be proud of you.

[Cedric]

So, in a very simple car, let's say a go-kart, weight would not affect its ability to carry more speed through a constant radius corner?

[targa]

yes[]

[Matra et Alpine]

yes[]

mmmmmmmmmmmmmmmmmm

not quite because in the "simple" case you've given the Centre of Gravity is WAY above the centreline of the wheels and suspension and so quite often it's forced onto only 2 wheels and sometimes one brakign in a corner. The lack of rubber availabel at the tyres makes it unstable and the driver needs to go slower !!

Life is never simple until you're dead

[targa]

yes and no

[Matra et Alpine]

yes and no

I always find in these cases that "maybe" is a safer answer

[Cedric]

I wanted to get this discussion over with, cos me and my friend dont come to a conclusion. I consulted a very good book, P.Taruffi's Technique of Motor Racingand it doesnt mention weight related. Some people even claim heavier cars stick better to the road surface in corners, but I find this rather doubtful. This means that when car A (light) can take a constant radius curve at 40mph, car B (heavy one) can take it at, let's say 45mph. I do not believe this, and I would rather think it's the other way round, or I would even think that similar cars could take it at the same speed, regardless of their weight.

[Matra et Alpine]

I wanted to get this discussion over with, cos me and my friend dont come to a conclusion. I consulted a very good book, P.Taruffi's Technique of Motor Racingand it doesnt mention weight related. Some people even claim heavier cars stick better to the road surface in corners, but I find this rather doubtful. This means that when car A (light) can take a constant radius curve at 40mph, car B (heavy one) can take it at, let's say 45mph. I do not believe this, and I would rather think it's the other way round, or I would even think that similar cars could take it at the same speed, regardless of their weight.

it becomes complicated by the tyre contact patch.
First when cornering it is simultaneously slipping and this reduces the grip.
How that slip affects the tyre is complicated and dependant on suspension setup.
IF we were to assume a suspension design and a CoG on the wheel centres then the heavier car would have a large contact patch on the same tyres. That means more grip. This is true within limits though.
So in theory you could contemplate a design which may work as the theory suggests and more weight = more grip = more speed in turning.
Sadly the real world is NOT a simple mathematical equation of one or two variables.
The non-linear nature of tyre grip also comes to play at the extremities of grip and the heavier weight brings that limit on earlier, so usually the heavier car cannot corner as the lighter can with as many things equal as possible.
BUT the REAL world has heavy cars that corner well nd light cars that don't as the many other variables come in to play.
Sorry it's not a simple answer

[targa]

maybe

[Cedric]

Yes Matra, I know this is a rather complicated matter, and I guess that is why Taruffi never mentions it in a book that normally provides an answer to any of such weird slip angle and friction question. But let's take the go-karts as an example: who will be able to go faster through a constant radius curve: the lighter driver, or the heavier driver (and thus the heavier kart)? Or both equally fast?