Weight reduction, but retaining 50:50 balance

[TonyBlair]

Just pondering the idea of weight reduction and I thought I\'d ask the opinion of others...

Firstly, I think weight reduction is a good idea - I believe removing weight from the car will improve acceleration. However, is it possible that if you remove a lot of weight from the rear end of the car, it will be harder for the car to retain traction? By this I mean there is less force pushing the back wheels onto the ground. Also, could the same be said about removing weight from the front of the car. By this I mean with less weight on the front end, there is less force pushing the front wheels to the ground, and therefore the fronts wheels\' will have less traction - particularly going around corners?

With regards to the rear end, I *guess* a spoiler with a sharp angle on the fin (pardon my lack of technical terminology) would aid traction. But only when the car is moving - more so at higher speeds. I don\'t see spoiler can help you get off the line quickly, say for example if you were going for a good 0-60 or 1/4 mile time. I\'m guessing a light rear-end would mean you\'ll be spinning those wheels for a while before you actually get off of the line.

One final point about weight reduction. Mazda have obviously spent a lot of time and effort perfecting (not sure how perfect it actually is?) the 50:50 weight balance across the front and back wheels. I\'m guessing that this is one of the main attributes to the fact that the RX7 is one of the best handling, and quickest stopping production cars about. If I were to start taking bits and pieces off the car could I seriously screw up the handling of the car?

I\'ve been trying to think of a way to weight a car, but in a way that you could find out how much force/weight is being exerted on each wheel. The only thing I can come up with is to put a pair of scales under each wheel and see whether they all come up with the same reading - sounds crude I know, and besides that I don\'t think my bathroom scales are quite up to the task  

Thoughts and opinion...

Cheers
Jon

[ScuttleRX]

Regarding weighing the car, there is a place you can go which does what you suggested, gives you a weight on each wheel. See it used in jap performance all the time on there project cars, etc. Not sure where, maybe one of the places that do suspension alignment .

Interesting to hear the answers on this thread....

[TonyBlair]

Putting on a carbon fibre/fibbre glass bonnet seems like an obvious place to start... but I\'m thinking "should I putting in a carbon fibre boot lid at the same time to balance things out?".

Andy, you\'ve got a fibreglass bonnet haven\'t you? Did you notice any adverse effects on handling after fitting it?

Cheers
Jon

[ScuttleRX]

Nothing noticeable, although there is a weight difference the bonnet of the rex is quite light to begin with, not like say a supe one which gives you a workout when you lift it

Ive heard re-locating the battery can give an improvement in weight distrbution

[TonyBlair]

I agree the standard bonnet doesn\'t really weight that much.

I understand what you\'re saying about battery relocation, however if Mazda designed the car to a 50:50 balance, then wouldn\'t relocating the battery to the boot make it a bit more like 50.5:49.5? I suppose if I were to shift some weight from the rear-end, then I could relocate the battery to even things up.

If anyone has any information about these special places where you can weight your car from each wheel, please let us know.

[Donato]

Fibreglass bonnets will weigh as much or more than stock.

This all depends on your mods and what you are really looking for...

i have removed

air pump
air con system
and relocated battery to the boot
fitted carbon fibre seats
i have fitted a fibreglass scoot bonnet which weighs slightly more than the stock
fitted a aluminium race rad which is bigger than stock so will hold more water i.e more weight..

you can go crazy if you really want, no stereo, no door cards, no dash apart from the essentials, no spare wheel (great until you get a puncture!)

when i had my fd stock, i got faster quarter mile times with my boot full of tools (at least 150kg) than i did with an empty boot, so its not always good to shed off to many pounds, thats what i said to myself as i tucked into a bacon roll this morning too  :rollin

ideally i would like to replace as much of the body with carbon fibre as possible but only got one number in the lottery on wed so the order is still on hold..

cheers

Donato

[TonyBlair]

Thanks for your input mate   :cheers

Fibreglass bonnets will weigh as much or more than stock.

I had no idea fibreglass was as heavy as that, or is it the case that the stock bonnet really isn\'t as heavy as it seems?

when i had my fd stock, i got faster quarter mile times with my boot full of tools (at least 150kg) than i did with an empty boot

So now that your car isn\'t "stock" do you find that it is still better to put some balast in the boot for quicker 1/4 miles? I\'m guessing a full or full\'ish petrol tank will make a difference?

Cheers,
Jon

[Donato]

The stock one is aluminium and just very light.

To be honest i havent done a comparison, when i was stock my best time with the tools was 14 secs. now everything has been done its 12.9 secs with no tools, will need to try the tools soon!  :cool

[TonyBlair]

Didn\'t realise the stock bonnet was aluminium - I can now see why it\'s as light as it is.

Let us know the results of the with/without tools test mate. I can see it now... at Rotorstock III everyone will be turning up with there latest mod - a boot full of tools   :rollin

[Juriën]

Firstly, I think weight reduction is a good idea - I believe removing weight from the car will improve acceleration. However, is it possible that if you remove a lot of weight from the rear end of the car, it will be harder for the car to retain traction? By this I mean there is less force pushing the back wheels onto the ground. Also, could the same be said about removing weight from the front of the car. By this I mean with less weight on the front end, there is less force pushing the front wheels to the ground, and therefore the fronts wheels\' will have less traction - particularly going around corners?

With regards to the rear end, I *guess* a spoiler with a sharp angle on the fin (pardon my lack of technical terminology) would aid traction. But only when the car is moving - more so at higher speeds. I don\'t see spoiler can help you get off the line quickly, say for example if you were going for a good 0-60 or 1/4 mile time. I\'m guessing a light rear-end would mean you\'ll be spinning those wheels for a while before you actually get off of the line.

For a good acceleration off the line from a standing start, traction is improved with proper suspension settings. Usually tending to be a little softer, but still not too soft. Too hard will have the wheels spinning, too soft will result in loss of power transfer through the springs. Tyre pressure is also important. Less tyre pressure will get you a slightly bigger patch on the road, thus better grip.
The lighter the car is, the less power is needed to accelerate or stop.

 

One final point about weight reduction. Mazda have obviously spent a lot of time and effort perfecting (not sure how perfect it actually is?) the 50:50 weight balance across the front and back wheels. I\'m guessing that this is one of the main attributes to the fact that the RX7 is one of the best handling, and quickest stopping production cars about. If I were to start taking bits and pieces off the car could I seriously screw up the handling of the car?

Not if you remove bits thoughfully. It also depends on how far you\'re willing to go in stripping the car. In circuit racers they move bits around to keep the car as balanced as possible. For example, relocating the battery, moving the engine with transmisson backwards. In other cases they don\'t just remove bits, but they replace them for a carbon or FRP copy. Always keeping in mind that they still want to keep the 50:50 weight balance

[TonyBlair]

Thanks for the comments Juriën - it\'s appreciated   :cheers

[Juriën]

No worries, mate :guinness  

[barmar]

This is quite an interesting thread, I guess it would be quite easy to mess up the handling by removing the wrong parts and spoiling the weight distribution. We also need to remember that the lower the centre of gravity the better too.
On the carbon fibre issue I just weighed one of the front wings I have (only a bit more than 3kg) anyone know how much the standard ones weigh? Guess I\'ll find out when I swap them over if no-one does.

As Donato said you could strip out quite a lot of unnecessary stuff if you really wanted to, I guess it depends on what use the car for, things like carpets, headlining, trim even sound deadening could come out but it would make the car pretty uncomfy for everyday use.

Barry

[Freddy]

I\'ll show you my idea of weight reduction in around 1 week.  :evillaugh

[TonyBlair]

Sounds very sinister.... atkins perhaps?