2004-2009 Rotora Circuit braker Brakes

You will want better tires too.

Tom

 

Since the Prius performs mild to moderate braking without the use of the mechanical brakes (it uses the drag of regenerating electrical energy back into the battery, thus regereative braking) and transitions to mechanical braking based on demand, I would be reluctant to add more braking force to the mechanical brakes. The computer would have no idea that the coeficient of friction was improved, so the transition might end up being a lot more abrupt than it is now. Yes, ultimate braking would be improved, but the balance as it transitions from regenerative braking to mechanical braking could be really screwed up.

 

Changing the friction brakes on a Prius is actively dangerous, in my view.

The fact is that while ceramic brakes resist high temperatures well, they don't work well at all when they're cold. Due to the regenerative braking on the Prius, the brakes normally are stone cold. I think this contributes to people's experience of problems transitioning from regen to friction braking (especially when going over bumps).

The stock discs and pads are well capable of handling one heavy braking event. While it's been criticised by some magazines (was it Edmunds?) for not being able to perform sequential emergency stops from high speed, I'm not sure anyone would really do that. (The organic brake material doesn't work so well when hot.) Drilled and slotted discs are more prone to breaking because the material has been weakened.

I'd say it was your life, but it's also everyone else's life too.

 

Could you repost this in English?

Tom

 

If you look how the brakes work on the Prius, once the car decides it needs friction braking, the solenoids switch and apply hydraulic pressure to the pads. At this point, they should behave just as in any other car. Press harder, you get more stopping force. The slotted & or cross drilled disks will help reduce fad, and cannot cause a problem. The brake pad material change can cause some change in the transition, and it may become more noticeable. Although they show the calipers in the picture, no price is given. I would check with Sigma on availability. I would also ask if they they have any guarantee that the transition is smooth using the ceramic material. It could work fine. If I needed new rotors, I would consider the slotted ones, otherwise, I don't think I would change anything, unless you find yourself making lots of short stops, or you make long runs down hill.

 

Unless the rotors are physically larger (and come with the necessary caliper upgrade), you will not see any significant difference in performance with aftermarket discs.

Slotted/drilled rotors may help keep the pad surface a bit "fresher", but don't increase brake fade resistance at all which is primarily a function of pad compound and brake fluid boiling resistance.

But hey - the rotors look nice.

Some good pads as well as a high quality fluid will make a difference, but keep in mind that you are only improving endurance under repeated hard braking events. You are still ultimately limited by the stickiness of your tires which the stock brakes are more than capable of overwhelming.

 

I think you're overlooking the weight reduction that may be possible with aftermarket rotors. It won't be a lot, but when it comes to rotating mass, every little bit helps.

And the calipers do look very nice.

 

If you get the cross drilled ones, inspect them frequently, cross drilling helps cracks start.
[ame="http://www.youtube.com/watch?v=xmW9c-7KCqA"]YouTube - overheated brake rotors[/ame]

 

You might be able to save a pound or so with aftermarket rotors, but unfortunately, you really want additional mass to absorb braking energy if you are aiming for fade resistance under multiple hard braking events.

2-piece rotors with aluminum hats would be significantly lighter in the same size, but you'd really want to upsize them in diameter if you're aiming for more fade resistance. Otherwise, you might even lose fade resistance unless they're able to shed heat significantly faster than a standard rotor.