weight reduction

[spanner]

Many people it seems strip out the interior to save weight, but will this not be detrimental to the handling? OK overall reducing weight will help for acceleration and braking. But with the majority of the mass being removed from the rear ie spare wheel, rear seats, and being a front wheel drive car will this not mean it will understeer, and the rears likely to lock up?

[Adam43]

Generally I think the loss of weight far out weighs (sorry ) the change in handling.

However you could always add ballast to bring the c.o.g down, but not alter the weight distribution .

[graham bahr]

making a car lighter wil reduce its tendancy to understeer, as its the weight that stops the car trying to change direction, and if you manage to make the rear very light the rear will tend to grip less and therefore induce oversteer, dont forget that making the car lighter will not only help acceration but also braking, having less weight you'll be able to brake later, or at least give the brakes an easier time.

[tubthumped]

Removing your spare wheel and seat are only the start of the weight saving.
I remove thise for every track day anyway... if/when i can get my cage in that will go permanatly.

You will loose less than 20Kg from seat and wheel... you can probably loose double that just from carpet and sound proofing.. not to mention the thick bitumin you may have all over the floor pan.
Remove any unwanted bits of trim and then remove the brackets that once held these things on.
Get a decent FibreGlass/Barbon Fibre bucket seat and you loose another chunk of weight.

[HiRich]

Spanner,
You are quite correct. Removing weight can & should
- Improve acceleration and braking (with less mass to accelerate)
- Improve cornering (less mass to roll = less suspension movement = wheel closer to optimum position for more of the time)

However you do risk upsetting the balance of the car. If as you suggest you stripped 100kg, almost entirely off the rear axle, you would find:
- First, the back end will sit much higher (coz there's less weight on it). Suspension geometry has changed, roll centres are different, CoG is different, and there's a good chance your camber setting has changed.
- Second, your spring rates are too high (what matters is not the spring stiffness, but the natural frequency, which depends on the square root of spring stiffness/sprung mass).
- Damper and roll bar stiffness may also need reducing.

Then of course, you are assuming that the starting point was already optimum design. It's all a bit of a circular argument. Remember that the enginerrs built the original car to give the best compromise between one occupant on a perfectly smooth road through to 5 occupants on cobbles (and everything in between). Making a big change in weight could actually improve the handling, or make it more oversteery than a 911 on a diesel spill. If you make a permanent change to the weight, all you can do is accept that yu may have to make suspension changes, and they might range from fitting adjustable shocks to a full respec.

And as Adam says, the odds are that stripping weight will benefit overall, on a typical road car conversion.

[coln72]

If you remove weight from the rear of the car and you feel that it is detrimental, you can always shift what is left around if it is leagal. Tha battery is heavy and it is easily moved to the rear of the car, washer bottle (if full) can weigh a couple of kilos and are also easily shifted, etc. You can save a heap of weight by rewiring the car and removing all the unused wires from the loom. I know of a Corolla that has had around 200kg (owners claim) removed from it (original weight 800 - 850kg).

[spanner]

Thanks for the replys everyone, i'll certainly give it a go next time as long as it easy to do.