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Why is 50:50 the ideal weight distribution?

The answer is actually that BMW advertise it as fact (and ensure their cars are close to that figure).

The reality is that it depends on the purpose and for our purpose the weight distribution of the Elise is actually perfect IMHO.
  • The centre of mass is close to the centre of the car giving low polar moment
  • The CofG is far enough back that under heavy braking there is still enough weight on the rear wheels to enable them to do useful work
  • The CofG is far enough forward so that under heavy acceleration there is significant mass on the rear wheels
  • The weight distribution is similar to that of a Formula 1 car
Looking for some truly tail happy cars - look no further than an unladen utility :)
With a forward weight bias and minimal weight in the rear they can be provoked into lift off oversteer with frightening ease!!!

:)

Lol. I agree, but I was addressing glb's concern of "abnormal" weight distribution.
Anyone else agree? :)


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My legs weigh a lot I wonder does that change weight distribution?
Only if the one is abnormally larger than the other :no:

all kidding aside, the bulk of ones legs is in the thigh area which is central to the car and the main weight is cradled through your seat. so I doubt it changes weight distribution significantly
 

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Why is 50:50 the ideal weight distribution?
...
While our cars are not F1 cars...
If an F1 has a 50/50 weight distribution then it is probably ideal.

And even though our cars are not f1 cars... What is an F1's weight distribution? (50/50?)
 

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I don't know about now, but I think the 2011 regs set a limit on weight distribution: front = 45.5-46.7, rear = 53.3-54.5. I'm not sure what the engineers would set if the distribution weren't limited. However, I imagine it would change from track to track.
 

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Pls see bold below:

According to Riley & Scott Racing, they don't care where the engine is, but want 56% of the weight on the rear tires.

I think we have about 61%......
Why is 50:50 the ideal weight distribution?

The answer is actually that BMW advertise it as fact (and ensure their cars are close to that figure).

The reality is that it depends on the purpose and for our purpose the weight distribution of the Elise is actually perfect IMHO.
  • The centre of mass is close to the centre of the car giving low polar moment
  • The CofG is far enough back that under heavy braking there is still enough weight on the rear wheels to enable them to do useful work
  • The CofG is far enough forward so that under heavy acceleration there is significant mass on the rear wheels
  • The weight distribution is similar to that of a Formula 1 car
Looking for some truly tail happy cars - look no further than an unladen utility :)
With a forward weight bias and minimal weight in the rear they can be provoked into lift off oversteer with frightening ease!!!

:)
 

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Gilbert,
I understand the weight distribution is not an ideal 50/50, but I think there is some serious hysteria surrounding the car. I'm only in the intermediate run group, however if you were to ask the expert track drivers (of whom some have commented on this thread) you would find that the weight distribution of our cars can be very helpful to rotate the car and accelerate out of corners. I was one of the people caught up in the spin hysteria. I was SO afraid of the car,that I was limiting my learning curve, until yesterday, and I think Bluesman is missing out on enjoying his car on the track due to the fear many of us have/had:(
I also think having your car properly set up for your objective is important. Bad tires/pressures, poor alignment, abrupt inputs to steering and throttle can certainly unsettle this car easier than say a Miata, but the car is one of the best track cars out there for a reason. It's not because it has a crazy propensity for spinning, which is what I think the OP and many others have embedded in the back of their brain. Is it more likely to spin than a Miata? Yes. Is it spin prone? I don't think so;) I think the car is predictable.
We should poll the top drivers on this forum.

Jack, Andy, Brent, Ross, John, Awesome Joe just to name a few, would you like to add your 2¢? I know some of you already have.

If I spin unexpectedly for no other reason than the car is spin prone, I promise I will come groveling back to this thread begging for forgiveness;)

OK? Lol.
OK.

I think we are now in the area of semantics...for which I have little taste.

The spin-prone question can be viewed more than one way.

1. Is the Elise more likely to spin than other, similar cars? Yes, it is. (As you show above...)

2. Does is spin for no reason? No. I'm not even sure anything happens for no reason.

3. Does a driver need a bit more skill with our cars vs. similar? Yes; see #1.

4. Would defeatable stability control have helped many of our members? Yes, but it would add ~ 35 lbs. (I got lambasted for bringing this up years ago...but the Evora has it and I think the V6 Exige does as well.)

5. I have nothing for this entry, but I'd already typed the 5. Only on one cup of coffee....

When I built the Elan, I moved the body back a bit on the Spyder chassis. (Also centered left to right so I'd have equal tire clearance in the rear for the very large tires I wanted to use.)

With me in it, 56% of the weight was on the rear. That (old) car was incredibly stable

One could all sorts of things with it and it just hung on. Very easy to track that car.

Some of those "tricks" would have spun my Elise.

(I often think the entire mid-engine thing - for street vehicles - is an affectation. While it certainly makes the car feel more "exotic", the packaging nightmare it presents is difficult. The Elan - a much smaller car - had a spare tire, larger trunk and a comfy interior. No cooling or oil lines running long lengths thru the car. No shifter cables either.)



I do agree with the setup having to be close to ideal...which means the car is finicky...which means it is what I contend.

You are right about not being daunted so much as to not take the car to the track. That is a mistake. The track is where we learn what the car does in so many circumstances.

I've already urged ppl here to go to a driving school and/or get a good instructor at a HPDE.

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This thread reminds me of when the Honda S2000 came out. Pretty much everyone was crashing them because the bulk of the demographic was accustomed to their old Civic [et al] and didn't know how to handle rear-drive, let alone one that had lively rear end movements.

The Elise isn't spin prone by itself, it's the nut behind the wheel not being used to relevant inputs.
 

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Thanks - I missed that post earlier.

My comment was mostly aimed at dispelling the 50:50 is perfect myth :)
My pleasure.
 

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I like to believe that yes, the Elise is spin prone...so much so that only a person with the finest cat-like reflexes can tame the Elise. Thus, to be able to drive one without crashing it elevates your status to "Car Ninja". It's a very exclusive status.
 

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[*]The centre of mass is close to the centre of the car giving low polar moment
IMHO, since the car rotates about a point between the rear wheels, having the center of mass further back would impede turning less.

I would be very much surprised if Formula 1 cars had a 50/50 mass distribution, what with their front tires being so much smaller than the rears.
 

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Ugh, this question annoys me. Sorry. With mild amounts of tuning using alignment, tires, swaybars, springs, and lastly shocks, almost any car can be made to be prone to oversteer or understeer.
 

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IMHO, since the car rotates about a point between the rear wheels, having the center of mass further back would impede turning less.

I would be very much surprised if Formula 1 cars had a 50/50 mass distribution, what with their front tires being so much smaller than the rears.
Should have responded to Steve, but the car says rotates about the center off mass.
The polar moment is not affected by the center off mass... But by the how far the individual masses are From The centre of mass.

That has nothing to do with steady state handling or ss oversteer .
 

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Should have responded to Steve, but the car says rotates about the center off mass.
The polar moment is not affected by the center off mass... But by the how far the individual masses are From The centre of mass.

That has nothing to do with steady state handling or ss oversteer .
A tracking car (sans rear-steer gear) rotates around the rear wheels.
 

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I like to believe that yes, the Elise is spin prone...so much so that only a person with the finest cat-like reflexes can tame the Elise. Thus, to be able to drive one without crashing it elevates your status to "Car Ninja". It's a very exclusive status.
This made me laugh.

Too long for a T-shirt however...
 

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A tracking car (sans rear-steer gear) rotates around the rear wheels.
When you doing a U-turn with little slippage then yes the car would rotation when the fronts are turned exactly at 90 degrees.
When the fronts are turned more than 90, I think it goes behind the axel.

If the rear wheel is toe'd in then where does the rotation point shift to?

When the rear has a slip angle, or all four are in a drift, then is there any rotation in the sense that you mean?

And even if there is a rotation point (?), then how does one go from rotation at the rear to a 50/50 distribution?
It makes no sense to me yet.
It should be 100% at the rear, or the weight should be entirely at the front for 90 degree wheel turning and moving forward as the turn radius increases.
But what happens in a drift, when there is no steering commanded other than in-line with the chassis?
 

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Revisiting this topic as an excuse to share my video.

Yes, Lotus's are very easy to oversteer if you have a supercharger and running on 9 year old OEM tires that are nearly bald in the rear.

https://www.youtube.com/watch?v=gwGAOlR2SVE

Great fun though!
nice vid :up:

pretty impressive control actually... that middle area between 'got it' & 'not having it' is small on our cars :shift:
 
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