davefzr

For those interested in Stop Tech's kits here is an email that I received back from Stop Tech about them developing a Rear BBK.

They also told me in another conversation that it would be available within a few months.

Thankx!

Kel Rx8

the stoptech is on my list for brakes
great info you got for us.

davefzr

Yup....

The lowest price I have seen for the front kit is here ==> AXR Online

332mm $1,669.35

355mm $2,413.35

and the best part.. Thats Shipped!

davefzr

Thats true.. but your paying 2400 for the price of the smallest Stop Tech kit.

Sputnik

Does this new ST22 caliper have the emergency parking brake integrated into the caliper itself, or will it be a separate itty bitty caliper like on the Acura kit?

---jps

davefzr

It remains in the unit like stock to retain full functionality.

shelleys_man_06

Why would you need a rear BBK? The rotors are big enough in the rear.

davefzr

Just to further assist in stopping power. It may only help a few feet.. if thats worth it to someone then go for it.. It would bring 60 to 0 to under 100 feet though..

That may sound enticing to some people... Vivid stopped the car from 60 in 102 feet without the rear kit using only the front Stop Tech kit. I bet they could get it under 100 with the rear.

PUR NRG

??? Call StopTech and ask why they sell a rear brake kit. Answer: because people want to buy it for looks. They will be the first to tell you it isn't necessary even on the track.
________
Paxil Classaction

davefzr

I dont know about that. Why would the rx8 race team even consider it if it didnt bring them results?

The only reason why is maybe because they are a sponsor and they want it on the rx8 race car.... Thats the only reason I can think of.. to bring stop tech more customers...

but still.. if they are not winning and just lugging around an extra component.. then why do R&D on the rear kit and waste everyones time?

Sputnik

Stoptech stresses tire grip and brake balance. Whether you need rear brakes or not depends on what you've done up front.

Some front brake kits only decrease unsprung weight and add thermal capacity, but adds little or no braking force. Adding such a front only kit will not upset the balance, and so a rear kit is not needed in that aspect. Even on a 50/50 weight distributed car, most braking is done with the front brakes, so the rears aren't going to be heat stressed as much as the front, and so a rear kit is not as needed in that aspect (although it might, depending on the car and how it is used). And don't forget, braking setups vary greatly between front heavy front engine cars, vs. 50/50, vs. rear-engine cars. The further back the center of gravity, the more rear braking you need for a good balance (a mid/rear engined car with rear weight bias is actually optimal for braking performance, but that's another thread). So what might work (or be advised) for one car, won't necessarilly work for another.

Some front brake kits do increase braking force in front, in addition to decreased weight and increased thermal capacity. In that case, you do throw off the braking balance, and you will decrease braking performance compared to stock. For performance reasons, you would then want to upgrade the rears to match.

Now, you also need to be careful of not getting too much braking in the rear. You want to err on too much up front. If you lock up the rears only, the back end will want to come around on you. If you lock up the fronts only, you lose steering, but the car doesn't want to swap ends. A good ABS will help with preventing the loss of control, but it is not an effective tuning tool, and it will not decrease the loss of performance due to poor balance. Which is why Stoptech doesn't suggest upgrading the rears in most cases, because it's not always needed or effective.

---jps

GeorgeH

iTrader: (2)

Won't ABS overcome the imbalance created by an overzealous front kit?

I suspect most, if not all, of the Vivid car's braking improvement came from uprated tires.

Seems to me the BBKs on the RX-8 are bling-bling, unless you are a track hound and need the thermal capacity. Although reducing unsprung weight is nice.

Sputnik

No. It will keep you from losing control by preventing the wheels from locking up completely, but it will NOT affect balance.

Remember, what ABS does is pulsate the brakes for you (once it detects lockup), which decreases braking force on that particular wheel. While ABS systems have become much better than those 10-15 years ago, they still are not optimized for performance, they are optimized for safety. When they activate, they will just start pulsating. They will not adjust themselves to get the optimum braking force to balance with the rear brakes, they will pull out much more braking effort than would be optimal, in order to ensure that the wheels keep from locking up. The result will be less braking force than if you had installed a proportioning valve and adjusted it well. Regardless of your setup, optimally, you want to press the brakes as hard as you can without causing the ABS to engage.

Also, ABS will not come into effect until the wheel locks up. With a front biased braking setup, the fronts will lockup sooner than with a balanced setup, and so it will activate the ABS at lower braking effort, and your car's absolute braking performance is decreased. And for track driving, when you are trying to drive at the limits of grip, this will affect your ability to approach the limits of grip in some cases.

A proportioning valve can adjust balance back to neutral, but a proportioning valve simply reduces braking effort to either the front or rear. If you install a front brake kit with more braking force, and you install a proportioning valve to balance things out again, you are simply decreasing the hydraulic effort to the front brakes, and effectively dialing out the performance increases you just spent money on. If you've adjusted the proportioning valve well, you will bring the car's braking performance back to stock levels (that is assuming that the car's brakes were well-balanced to begin with).
That could very well be, since tire grip is one of the most important aspects to braking performance. Not the only one, but one of the most important.

Reducing unsprung weight has alot of nice benefits in handling, ride, and steering feedback. And in some instances in traffic and spirited canyon carving, an increase in thermal capacity can be beneficial too.

---jps

GeorgeH

iTrader: (2)

Ah, I guess I am still seeking that canyon drive that causes my brakes to fade. I am envious of all who have found such a road.

And yes, I am quite familiar with the effects of unsprung mass, as well as an adjustable bias valve. I am installing one of those in my '94 Miata as we speak, a car that came from the factory with terrilbly front-biased brakes. I guess that's why I shrug off BBKs for the RX-8 - the braking is SO much better than what I came from, I just don't feel the need to improve it. But to each his own...

shelleys_man_06

What difference does two feet for $1300 make?

davefzr

Not too much to the occasional track racer.... Just saying thats freaking good.. if you are in the position to want those extra feet then go for it. I personally think that having all the stopping power possible is awesome...

Not only the performance aspect but having a BBK all the way around sounds and looks attractive as well.

shelleys_man_06

But, what about for the street? In some instances, a rear BBK can actually increase your stopping distance. I don't plan on taking my car out on the track, so I guess this wouldn't be for me. Perhaps Stoptech's rear BBK is not meant for 60-0, but rather average braking distances between speeds, like on the track .

davefzr

some more info I got from Stop Tech...

shelleys_man_06

Sweet. Thanks for the update davefzr.

ScudRunner

Those prices sound like the Rotora rotors

mdawgx24

I think they're a little bit cheaper. I want them.

davefzr

Some more useful information....

Stock Brakes:
322 mm = 12.7"

Stop Tech BBK:
Kit 1: 332mm = 13.07" @ $1,669.35
Kit 2: 355mm = 13.97" @ $2,413.35

Brembo BBK:
Kit 1: 328mm = 12.91" @ $2,512.52

sup3rbad

thanks for the useful info Sputnik