Track width vs Wheelbase

[silente]

I write this post to ask your opinion about the ideal relationship between track width and wheelbase dimensions.

A long wheelbase car should have more stability during brakings and, if it's polar inertia is not so high, should produce more yaw moment in corner entry. On the other hand, in slow corners it should have a more "understeering tendency" asking for more steering angle and it should be less agile.

A wide track will produce less weigth transfer and so should give an higher cornering grip potential, but the car will tend to follow wider lines on the track and to have, for example, a bigger frontal area.

I read a lot of things on the relationship between these two parameters but i would like to read your ideas about which is, in your opinion, the best way to choose track width once you fixed wheelbase.

The wider is better? Or there are other things i am missing which could lead to choose a smaller track width if your wheelbase is not so big?

[mep]

I read a lot of things on the relationship between this two parameters but i would like to read your ideas about which is, in your opinion, the best way to choose track width once you fixed wheelbase.

What are you reading?

[silente]

For example there were some article on racecar engineering about one year ago of a man trying to build an hillclimb car.

It was claiming to use the so called "golden ratio" (which is around 1.7 i think) between wheelbase a track. But my question is why that ratio?

What i would like to discuss is what are the pros and cons of having a wider track also if your wheelbase is not so long.

[mx_tifoso]

I suggest taking a stroll through the threads in the "Similar Topics" list at the bottom of this page.

(Or doing a search the next time around.)


Welcome to F1T Silente, if you haven't been welcomed before.

[mep]

It was claiming to use the so called "golden ratio" (which is around 1.7 i think) between wheelbase a track. But my question is why that ratio?

Isn't that golden ratio/cut just some optical thing which looks pleasant to your eye?
There is no physical reason behind that.

http://en.wikipedia.org/wiki/Golden_ratio


What you have not mentioned yet is increased load transfer for a shorter car.
Let's say you have a rearward biased CoG. During acceleration load will shift to the rear wheels -> better acceleration.
During braking load will shift towards a more neutral position giving you better braking.,

[RH1300S]

For example there were some article on racecar engineering about one year ago of a man trying to build an hillclimb car.

It was claiming to use the so called "golden ratio" (which is around 1.7 i think) between wheelbase a track. But my question is why that ratio?

What i would like to discuss is what are the pros and cons of having a wider track also if your wheelbase is not so long.

The golden ratio is about 1.618 (or 0.618) - it would be fascinating to think that it applies to cars as well as other areas in life.

Perhaps someone should build a car with that ratio and let us know....

BTW - My beloved Alpine A110 has a wheelbase of 2100mm, rear track is 1290mm - damned near perfect!!! Perhaps it's true

[747heavy]

I think you would need to consider, what the intented purpose for your car (vehicle) is.
And perhaps the regulations which apply for this type/class of racing.

To give a rather extreme example: Top Fuel dragster vs. Kart

just some random thougths:

- car width (an thereby track width) is limited by the rules in most categories
- most categories demand that the drivers feet are behind the front axle line, so with some other given factors (engine length etc.) you will arrive at a minimum wheelbase fo pactical purpose
- a wider car, increases in most cases the frontal area (more drag), depending on your overall circuit characteristic (LeMans, Monza vs. Monaco etc.) this can have negative effects on your overall performance.
- you would need to consider things like minimum corner radius on the tracks you run (think Loewes hair pin in Monaco) and average speed etc. before you decide on a specific ratio - IMHO

So there is a difference designing a car to race on a varity of known tracks ( let´s say FIA GT championship) and a car for an FSAE autocross test (one specific event/track).

for the race cars I have seen/worked on ratio´s between 1.4-1.7 seem to be quite common. (but in most cases (in my field) regulatory constrains play a role)

Karts are close(r) to 1 while dragsters are the other extreme with a ratio of 2+