What do wheelbase and track do?

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Philly

Philly

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So this year, I have joined a first year Formula SAE team at my school. I have to do some of the looking into how we should go about setting our wheelbase and track, so I figured it would be a good idea to ask a bunch of car guys at the GTP.

So, what are the effects of having a wheelbase that is too short? Will the car be pretty unstable? How about having one too long? Will it lose agility?

And the same with track. Will a narrow car be prone to more than just excessive roll? Will a wider car get in it's own way?

I would like any suggestions I can get. Thanks.:)
 
You're pretty much on par with your thoughts there.

Shorter wheelbases will be great for low-speed turns, and overall turn radius, but at higher speeds they can get unstable on the straights and have a tendency to lose rear end stability on the corners. Too long of a wheelbase will be great for top speed runs, but are sluggish in the turns, and have a tendency to understeer.

Now, as far as the track width of a car, I would say most of the same effects are present. Too narrow, and the car will be very easy to roll on a corner. The center of gravity will have a huge impression on this as well. Too wide, and the car will cause more drag, and be sluggish on the straightaways and can easily oversteer if not being cautious with the steering angle.
 
Isn't the track the wider the better? Atleast to a certain extent.
Think of it using the rules of a lever. The wider between the wheels, the smaller momentum is forcing the tyre downward, which equals lesser stress on them. On the other hand, vertical pressure can be good for grip?

I might be way of the hook here, correct me if I'm wrong.
 
As toyomatt said, you've pretty much got the idea. With the wheelbase you want to balance agility and stability. With the track you want to balance roll and drag.

I would suggest looking at past Formula SAE entries to get an idea of where to start.

zoxxy
The wider between the wheels, the smaller momentum is forcing the tyre downward, which equals lesser stress on them. On the other hand, vertical pressure can be good for grip?
Click to expand...
The weight borne by the wheels never changes.
 
Wolfe
I would suggest looking at past Formula SAE entries to get an idea of where to start.
Click to expand...

This is what we are doing. That is really useful to find a sort of starting point, but I was pretty much just trying to figure out what would happen if we moved the dimensions around a little in that range.

And is anybody else here involved in FSAE?
 
I'm sure it will look great on a resume when applying to any engineering position, especially for a car manufacturer. But I'm sure it will be hard. Being a freshman, I don't really know what I am doing but I hope to learn so I can be better in the future:tup:.
 
Wolfe
I could be mistaken, but I do believe this thread is about track and wheelbase, not weight transfer while cornering.
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so what if it doesnt specifically relate to wheelbase and track. youre correct in the static form of car that it doesnt change, but a car thats being operated is not static. the weight shifts and changes. this is a formula sae car if im not wrong. its not going to be a museum piece.
 
I hate spending three (now four) posts on a point that only needed one.

Zoxxy suggested that a wider track would lead to less downward pressure (from gravity?) on the tires, affecting grip. I responded by saying that the weight borne by the tires would never change. I assumed it would be understood that I was strictly referring to changes in track, considering a quote of Zoxxy's post sat directly above my statement.

Whether or not he was specifically referring to weight transfer in a cornering situation is moot because he mentioned no such thing.

I'm not going to reiterate this again, because this thread is about philly cheese's FSAE car, not failed reading comprehension. I apologize to him for having drug his thread off-topic.
 
Wolfe
I'm not going to reiterate this again, because this thread is about philly cheese's FSAE car, not failed reading comprehension. I apologize to him for having drug his thread off-topic.
Click to expand...

it's all good. I got what I needed answered, and the thread seems a little dead now. Plus, what other threads stay on topic around here?:lol:
 
Wolfe
I hate spending three (now four) posts on a point that only needed one.

Zoxxy suggested that a wider track would lead to less downward pressure (from gravity?) on the tires, affecting grip. I responded by saying that the weight borne by the tires would never change. I assumed it would be understood that I was strictly referring to changes in track, considering a quote of Zoxxy's post sat directly above my statement.

Whether or not he was specifically referring to weight transfer in a cornering situation is moot because he mentioned no such thing.

I'm not going to reiterate this again, because this thread is about philly cheese's FSAE car, not failed reading comprehension. I apologize to him for having drug his thread off-topic.
Click to expand...


no failed reading comprehension there. i read your entire post and the only that stood out as "wrong" was your weight change statement. the weight does change in a dynamic application. i suppose in isolation its wrong but with a prefix or suffix its right, but i didnt see that prefix or suffix. and especially since the quote you quoted included the use of momentum, which by definition has to include movement.
 

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