Weight balance or weight reduction

My feeling is it's at it's worst in light front wheel drive cars, but a lighter tailgate could be offset with a lighter bonnet? Moving the battery back might help compensate for plastic windows (their weight saving would be at the back) and there's sometimes grp front wings about

Does surprise me when I see boot-mounted batteries that would be maybe a foot lower down if they were tucked behind the passenger seat

In my particular case, I'm more concerned with cornering, but I guess things are different for drag racers. It would be interesting to know peoples thoughts on both.

I think there are a couple of other factors involved.

The height of the centre of gravity being one of the most important (as mentioned with the battery above). Getting it as low as possible would be my starting point. I don't think a 50:50 weight distribution is ideal for all cars. Front wheel drive you probably want a bit more on the front for grip. And things like the 911, Imp, Davrian etc... have done very well with 40:60 weight distribution.

If it was a race car I'd go for getting as much weight out as possible and then look at the distribution and how it handles. Can possibly adjust the suspension to help with balance. Getting a car that is balanced and you trust in the corners is probably most important.

Ed

This! We can get a Beetle to wheelie with 120bhp, but its unlikely to go around a corner that well. Everything taken off the front should be balanced with weight out of the back if possible - that's why my drag bug ran a relatively heavy battery in front of the front axle instead of behind the drivers seat. It balanced out the lack of spare wheel well  and the tiny fuel tank.

Interesting, I recently had a chat to somebody who sets up cars from armoured Land Rovers to touring cars and he said the last thing he wanted was a 50/50 weight distribution. If you want a car than can change direction quickly then 50/50 probably isn't ideal.

Personally I'd prefer a well balanced and predictable car.

Don't forget polar inertia 50/50 with most weight near the middle will change direction (& be more 'unstable') than 50/50 with weights at each end.
Also removing weight is usually harder than moving it, but once removed more can always be added where you want/need it easily.

A racer I know used to do just that with his Porsche 996 cars when a driver of theirs lost alot of weight. Enough weight to now be under the mandatory weight limit.

However, he was also able to place the balast to make up the difference wherever he wanted .

Came here to mention polar moment of inertia as the third (or fourth with CoG height) piece of the puzzle.

From what I understand a 42-44% front produces the quickest car around a track as that's the ratio F1 cars hovered around before it was mandated. More traction coming out of corners, and more weight over the rear when you dive on the brakes and it all shifts forwards meaning they can split the braking F/R better.

As for what's more important weight vs distribution vs polar moment vs CoG height vs cross-weight I'm not sure. I expect it's a bit of a moving feast between all of them which isn't overly helpful.

One approach would be to pick an F/R percentage you want to aim for and then reduce weight staying within a percent or two of that goal, redistributing as much stuff as possible to be lower down, further inboard and evenly split left to right as possible.

Personally, I suspect polar moment of inertia and CoG height to have a greater impact on turn-in and twisty tight corners, and distribution to have more of an effect on sweepers (it affects which wheels will let go first, and how early they do compared to the other end).

CoG height also has an effect on springing as the higher it is the more a car dives and squats under braking and acceleration, meaning you need stiffer springs to control weight transfer which give less traction.

Overall weight will affect everything, but probably more as a scaling factor on how bad the other imbalances are. For instance if you have a 1000kg 60/40 car it's going to push in long sweepers, but if you have a 2000kg car it's going to push a lot more/sooner.

I expect someone fantastically clever could come up with a physics model for all of those variables and let you play around with what affects stuff more at different points, but that's not me!

If you are trying to corner faster, then would down force also be something to consider?
Extra spoilers might make you slower on the straights but could more than make up for it in bends.