Lextasy89

anyone know how much rotation mass (weight) that could be lost on an is350 by changing to maybe a Light-weight 2-piece Cross-drilled Brake Rotor??

lobuxracer

iTrader: (2)

Unsprung weight will go down but rotational mass will be about the same. The disc has to have enough mass to store the heat from braking, so they can't lighten it much, if any, and get similar performance. The hat is lighter, but the hat is relatively close to the center of rotation, so its affect will be small compared to the mass of the braking surface.

al503

When I was looking at 2 piece slotted stoptech rotors for my G35, they were only 2-2.5 lbs lighter than the stock iron rotors and the bulk of the weight loss is from the aluminum hat. Their drilled rotors will weigh even less but it's probably no more than another lb or so. I eventually went with and Endless kit and their 14" two piece rotors were the same weight as the stock 13" rotors.

The best way to reduce unsprung rotational mass is to get smaller diameter, lighter wheels and lighter tires, which is usually not an option as they won't look as good.

lobuxracer

iTrader: (2)

But there are soooo many better affordable options for tires in smaller diameters.

carchitect

iTrader: (1)

Lobux is right on the money. Little can be gained as far as rotational mass goes with the 2-piece rotors. However, unsprung weight could be improved. But for the money spent, lighter weight wheels and tires would do so much more for you than this option.

R-compound road race tires could further be shaved to remove even more material but that is not the reason why they do that.