Tuesday, November 15, 2005

Automotive Anorexia

Few more pics...

The wiring loom goes to a lunchbox, everything relay wise, fuse box wise and also EWP controller is in here, warm and dry and dust free.

The battery sits in the best location, over the rear axle and far lower than the original position! I am sure I could feel an improvement in balance mid corner when I went out to my favoured testing corners....The standard spit when fitted with fat tyres is very on the nose anyway, a bit too much... theres a cut off switch with cable to the dash as on the pics...

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If you have ever driven a decent mid engined car, or driven simulators such as Grand Prix Legends you will be steering the car with a combination of 3 things, steering, polar mass movement of the engine and rear end, throttle...... Also rapidly aware how well balanced they are - these cars have 50/50 weight or a front/rear bias such as 45/55 the car is so awesome mid corner and you can use the rearward bias to steer you round with correct throttle angle, driving that true 4wheel drift ---once turned in and settled you rotate the car past the apex using only the mid engined cars lower polar moment of interia.....

Spits never gonna be a mid engined car but we can certainly improve matters!

The spitifres too nosey -great responce at the nose to turn in but the ass is too light to follow often and floats about....leaving you countersteering at the point of greatest loading, usually mid corner.... to be great here needs a fundemental chance in weight dist......my reduction of mass at the nose (from windscreen frame forwards) must easily into 75kilos mark without even straining to remember what was removed!... Bonnet 27kilos, water pump and housing 6kilos, radiator and surround 2.5kilos, bellhousing 7kilos, engine side screens 3kilos, battery moved to boot 15kilo saving, bumpers 6kilos.....pipework, heater & valve 5kilos theres 65kilos...

I have removed from the boot end, bumpers + internal bracing 7kilos, bootlid 7kilo saving, perspex hardtop window 6kilos.....trim and boot carpet 2kilos, boot prop and frame 1.5kilos, + small savings, spare wheel must add up to 35kilos....

These sums are just quick jottings but you will see a change in my weight dist....

So I have placed the battery in the boot adding 15kilos....so say we are now only looking at a 20kilo saving over the stock rear end.... with the battery moved front to rear....

Standard car say 725kilos Dry

So if the car is 630kilos now....

We started with 60/40 Front - Rear Split and 725kilos.

...I'll not add anthing or worry about the mass removed the central floor pan area (carpets, seat, frames, dash, clocks, sound deadening, doors alone 25kilos!!! I havent accounted for....)

So assuming I have a 95 kilo loss in total mass from only the front and rear of the car (75 front, 20rear) remember the 15kilo shift in mass (the battery)....

So, 435kilos were on the front wheels and 290 on the back! @ 725kilos.

Remove the 75 kilos and we have 360 on the nose now....the back was 290 we add 15kilos for the battery, so 305...and subtract 35kilos for the savings in weight...rear is now 270....add the two together we have 630kilos....

The old split was F:435 R:290 60/40 145kilo difference

The estimated change is now F:360 R: 270 57/43 90kilo difference.....

But I don't account for any inner cockpit weight reduction and also I would think my roll cage is about 35kilos....which is mostly sat at the back half of the car....2/3rds of it atleast as a mass.... lets work it out!

Lets keep the weight at 635 as once my super light doors are taken into account the weight of the rollcage is barely anything additional...and there were atleast 20kilos of carpet and dash etc.

Lets call the cage 33kilos....of the overall mass....If we split it up into 11 kilos for the front and 22 for the back....

So it was 16.5 kilos on each end, now changed to -5.5kilos at the front now 353.5, rear is now 275.5 having gained 6.5kilos. 56/44 78 kilo difference.

Lets add 20litres of fuel the new mass is 650kilos the front is 353.5 the rear is 295.5 54.5/45.5 58kilo difference.....

Of course this very unscientific! but it gives an idea.......thats a big predicted shift. I'd need to move 58kilos rearward to get even weight on each axle...don't think thats gonna happen! maybe another 10! without adding ballast....

I was thinking of moving the engine back 6inches!



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