Do we really need all that safety stuff?

[oldtamiyaphile]

Originally Posted by RedDevil

The same goes for that, a heavier car can also provide more sidewards friction so it should - in theory - corner just as fast as a lighter car.

A smaller car would feel more nimble, as it has a smaller footprint so it reacts (rolls) more to changes in direction or speed than a big car would. But that's relative to its size, not absolute.

You're ignoring inertia and only thinking of steady state cornering on a skid pan. The heavier car is more likely to overheat it's tyres in an emergency manouver too.

[RedDevil]

Originally Posted by oldtamiyaphile

That's fine in theory, in the real world you could use softer tyre compounds with more grip and similar wear characteristics.

You'd have smaller and narrower wheels with the same compound, rather.
They'd be too heavy for that light car otherwise, too much unsprung weight for such a light car.

They'd be cheaper to buy, there you have a point.

[P-hack]

as well as extra weight is a handling liability in slippery conditions, so many corners in the leaf where I'm left wondering it is ever gonna stop sliding and start turning Where a tercel would have long since straightened out and been accelerating for a spell, even on cheap tires.

[oldtamiyaphile]

Originally Posted by RedDevil

You'd have smaller and narrower wheels with the same compound, rather.
They'd be too heavy for that light car otherwise, too much unsprung weight for such a light car.

By eliminating $2000+ worth of airbags etc (Renault still charge $500 for a passenger airbag), perhaps you could have light weight suspension, wheels, tyres and decent dampers instead?

[oldtamiyaphile]

Originally Posted by P-hack

as well as extra weight is a handling liability in slippery conditions, so many corners in the leaf where I'm left wondering it is ever gonna stop sliding and start turning Where a tercel would have long since straightened out and been accelerating for a spell, even on cheap tires.

It sounds like the Leaf has too much weight over the front end, not too much weight overall, as such.

My MB100 had this issue, it was front wheel drive and the front of the engine say a good three feet from the front axle centre line. Nothing but plow on understeer there. I did manage to get the back to step out a little once, by braking hard mid corner.

[RedDevil]

Originally Posted by P-hack

as well as extra weight is a handling liability in slippery conditions, so many corners in the leaf where I'm left wondering it is ever gonna stop sliding and start turning Where a tercel would have long since straightened out and been accelerating for a spell, even on cheap tires.

My Insight is heavier than any car I owned before and it has more grip than any car I've owned before.
Weight helps break the thin film of water on wet roads.

My '85 Civic forced me to slow down on rainy days, it would aquaplane at speeds as low as 50 mph.
My much heavier Nissan Almera never aquaplaned at all, nor did my Insight.

Friction increases with mass...

The force of friction is directly proportional to the applied load. (Amontons' 1st Law)

[oldtamiyaphile]

Originally Posted by RedDevil

My '85 Civic forced me to slow down on rainy days, it would aquaplane at speeds as low as 50 mph.

Nothing to do with 20 years of advances in tyre technology then? My 1400kg 1982 Ford would aquaplane where my 900kg Fiat does not, my 1600kg Jeep will aquaplane. My 2000kg Transporter handles in the wet as if it were dry. Aquaplaning isn't about weight, it's about contact pressure. My Ford aquaplaned because it was on 245 tyres, while my Transporter is only on 215's, with an extra 30 years tech behind them. The Jeep aquaplanes because it's on 275's.

At the end of the day all engineering is a compromise. In competent hands, a light car could be every bit as safe as a gimzo ladden pig.

[Rishar]

Originally Posted by RedDevil

My Insight is heavier than any car I owned before and it has more grip than any car I've owned before.
Weight helps break the thin film of water on wet roads.

My '85 Civic forced me to slow down on rainy days, it would aquaplane at speeds as low as 50 mph.
My much heavier Nissan Almera never aquaplaned at all, nor did my Insight.

Friction increases with mass...

That also has to do with the tires installed as they have been improved to handle water better. At the same time, I now drive a Prius which seems to handle water fine. But my last car was a 96 Sunfire, not a heavy car by any means and I used to wonder if aquaplaning was something that actually happened to people :P.

[RedDevil]

Tires are much better nowadays, definitely.
When I got Michelins on the old Civic much of the aquaplaning was gone (not all) and it did corner faster.
But the Civic was a very light car with relatively large wheels.
The Insight is over 50% heavier but its tires are just 2" taller and 2 cm wider, that is about 20% more thread on the road.
Tire pressure is higher too (even OEM)

[P-hack]

Strange, the only car I ever experienced hydroplaning on was a giant buick. I would guess wider tires are disproportionately more likely to hydroplane since any edge effects are minimized.