Rotors smaller in rear...

[CaliGuy]

Does anyone know why the rotors are smaller in the rear? I have an Si..so I don't know if this is the case with the non-Si's

Thanks all!

[CivicWithNav]

USUALLY... most cars rear brake rotors are small

simple fact that when you brake, most of the weight goes forward, increasing load on the front brakes

some cars have bigger rear rotors, vented, non vented etc...

[skittleslegend]

You don't necessarily need them. They help slow the car, but your main brakes are forward, which is how you travel 95% of the time. You want the brakes stopping the drive wheels because those are the wheels being powered, and subsequently are the wheels that require the most power to stop. Larger calipers (more pistons) and larger rotors equals more area for the pistons to press against to use to stop the brake and shorter wear on the rotors. Therefore the rears don't technically NEED to be as large.

[NoBottleJustThrottle]

Like stated above, most of your braking power need to be in the front due to the load.

[CaliGuy]

Cool, thats what I figured...It just looks a bit funky to me...BTW Skittles...how is it that you know EVERYTHING about cars...at 21! Im jealous!

[skittleslegend]

Originally Posted by CaliGuy

Cool, thats what I figured...It just looks a bit funky to me...BTW Skittles...how is it that you know EVERYTHING about cars...at 21! Im jealous!

I wouldn't say I know EVERYTHING. I wouldn't even attempt to make a claim that bold. I just work on my cars myself cuz I'm too broke to pay somebody else to do it for me So I learn from experience, what works, what doesn't work and why it does or doesn't work. But I love cars. I've been into cars since the 5th grade. I'm still learning like everyone else though and I've made plenty of mistakes, especially on here :)

[NoBottleJustThrottle]

Reading, reading, and more reading.

[skittleslegend]

Originally Posted by NoBottleJustThrottle

Reading, reading, and more reading.

Ooooh, and that too

[NoBottleJustThrottle]

yea dude. You can become an expert on cars, and upstage just about everyone on this site if you spent the next 10 months doing nothing but reading on Honda-Tech.com, and other various Honda/Acura sites. That and like Skittles said, hands on. I learned so much just from taking my car apart, and doing a motor swap for the first time.

[Gone]

Originally Posted by skittleslegend

...You want the brakes stopping the drive wheels because those are the wheels being powered, and subsequently are the wheels that require the most power to stop...

Not true. Think about it, when you are braking when are the front wheels being driven (unless you are left-foot braking)? They aren't. But you did get the part about the front brakes doing most of the work right. It's all about weight transfer. Also, if your rear rotors were equal in size to the fronts, if you ever had to do a panic-type stop, with the front end diving and the rear end lifting, you'd lock up the rear wheels VERY easily. Then that means even less braking power you have available. Not good.

[rphinson]

Sorry, had to add my .02, for what its worth. If you want to argue semantics skittles was right. In a normal right foot break, with an assumed left foot clutch action, there continues to be power at the drive wheels, though it greatly reduces (without clutching the applied power would be greater, and you would stall of course.) It is inertia, and that power is only desiminated by friction, either through the weight of rotational parts and non-rotational, i.e. gravity and the friction of your rubber on the ground (you car would eventually roll to a stop on a flat plain even without breaking) or through braking (the energy spinning the parts is transfered to heat through friction.) Inertia only applies minimally to non-driven wheels which are being pulled (FWD.) So, remove the weight distribution of cars and directional momentum and driven wheels still need more breaking than non-driven wheels, hence skittles point. The majority of the need for better (bigger doesn't mean better in breaking) brakes up front is you are stopping forward momentum (usually) and the weight distribution of the vehicle (something like 60/40 on these Sis, isn't it?)

There is a great equasion for breaking I came across that I'll look up again if anyone is interested in not spending money that isn't doing something other than supporting brand names and aesthetics. The most interesting part is it had little to do with the size of the brake caliper and more to do with the circumference of the pistons.

In the end, the most cost efficient way to brake in shorter distance, and to launch better, is to spend the money on good rubber.

[Gone]

Originally Posted by rphinson

Sorry, had to add my .02, for what its worth. If you want to argue semantics skittles was right. In a normal right foot break, with an assumed left foot clutch action, there continues to be power at the drive wheels, though it greatly reduces (without clutching the applied power would be greater, and you would stall of course.) It is inertia, and that power is only desiminated by friction, either through the weight of rotational parts and non-rotational, i.e. gravity and the friction of your rubber on the ground (you car would eventually roll to a stop on a flat plain even without breaking) or through braking (the energy spinning the parts is transfered to heat through friction.) Inertia only applies minimally to non-driven wheels which are being pulled (FWD.) So, remove the weight distribution of cars and directional momentum and driven wheels still need more breaking than non-driven wheels, hence skittles point. The majority of the need for better (bigger doesn't mean better in breaking) brakes up front is you are stopping forward momentum (usually) and the weight distribution of the vehicle (something like 60/40 on these Sis, isn't it?)

There is a great equasion for breaking I came across that I'll look up again if anyone is interested in not spending money that isn't doing something other than supporting brand names and aesthetics. The most interesting part is it had little to do with the size of the brake caliper and more to do with the circumference of the pistons.

In the end, the most cost efficient way to brake in shorter distance, and to launch better, is to spend the money on good rubber.

The power being fed to the front drive wheels off throttle REALLY isn't significant enough to justify a larger rotor alone. If you look at it that way, then RWD cars would have larger rear rotors. The rear wheels have inertia as well, not only the fronts. The rotational inertia of the engine spinning alone isn't enought to justify larger front rotors either. If you think about it, a car left in gear slows down without braking faster than a car in neutral. Either way, like you said as well, its all about the weight transfer during braking.

But, nonetheless, I see what you mean. I dunno why I figured he was refferring to the front wheels still being driven while braking.

Yeah, bigger pistons are more effective at slowing a car because of the increased surface area the provide against the rotor during braking. Hence why supercars usually use multi-piston calipers (4, 6 and 8-piston ones)

Hell, at least I wasn't completely wrong.