R&T: IS300 outbrakes everything!!!

Originally posted by S38:
This could be from pad material alone.... If you want short stopping on any car just throw some Perf. Friction Carbon Metallics on.

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Maybe Lamborghini needs you to slap 'um upside the head and get them to spec some "Perf. Friction Carbon Metallics" on their cost/maintenance-unlimited cars.

Originally posted by S38:
Stopping distance is just a result of the brake torque and bias.

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Thoroughly oversimplified. I can tell you that braking performance is determined by no less than these factors:

1. Tire and brake pad compound. The 225/45ZR-17 Dunlop SP Sport 2000E of the 328i are somewhat comparable to the 215/45ZR-17 Bridgestone Potenza RE040 of the IS300 in compound and size. The Michelin Pilot Sport that is supposedly going to come with the "graphite" wheel option should be in a higher performance/wear category. I have no real idea what the IS300 uses for its pads, but I seriously doubt that Lexus would compromise reasonable wear and completely overshoot the braking performance of it's intended rival, the 328i.

2. A much better indicator of braking performance than rotor size is swept area/ton: the more the better. The IS300 beats the 328i's 257 sq.in/ton with 270 sq.in/ton.

3. Load distribution between the front and rear axles during the weight transfer of deceleration: the more equal the better. This means that for a vehicle with a CG higher than the ground, maximal braking potential can only be approached with a rear weight bias (as in mid- and rear- engined cars.) This is actually a strike against the IS300 in its comparision versus the 328i.

4. Size of contact patch during the weight transfer of deceleration: the bigger and more even in pressure distribution, the better. Do remember that in order to maintain the outside front contact patch in a turn, the negative camber of the wheel is increased during compression of most suspension systems. But the increase in negative camber is compression dependent, not steering dependent (that would be caster, which is a whole other ball of yarn), which reduces both front contact patchs during braking compression with the absence of body roll. Together with the fact that the IS300 exhibits good turn-in but understeers at the limit, I suspect that the front suspension was not designed to significantly increase negative camber deep in its suspension travel, which also means that it does not lose much contact patch during braking compression.

Factors #3 and #4, in light of the degree of stability necessary for the target user, determines the front/rear brake bias. So it's not something out of the blue.

Wow, DtEW you sure have alot of info.

More random stuff:

Factory rep told me 33% Bridgestone Potenza RE040 tires and 66% Goodyear Eagle GS-D.

Whoever originally said that the graphite wheels have Michellin Pilot Sports may have been mistaken.

The new BMW 330i has 17" wheels standard since they enlarged the brake rotors (by a whole inch!) such that you couldn't even fit a 16" wheel around those brake rotors anymore. The IS300 can have 16" wheels so the rotors aren't as big as on the 330i...

Super long life brake pads can be prone to squealing... Toyota has a rep for using long life pads that may squeal a bit. Perhaps the IS300 is different. In my mind, Audi is a company that uses "dusty" brake pads...

Yeah - the tires are a huge factor in the braking. I am guessing that the tires and the EBD are the main things that contribute to the excellent braking.

And it is not just R&T - many articles have praised the braking on the IS300...