AH HAH! See, I told you all that stickier tires shorten stopping distances NOT bigger brakes! Bigger brakes increase, broaden, or shift the brakes optimum operating range according to the expected driving conditions. Bigger brakes will also increase the clamping force on the the wheels/tires for a given pedal input force. But bigger brakes won't help your car stop faster!

Take home message--get the best road or track tires you can afford!

This is the next to the last paragrapth from the GRM article:
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From this example, it would appear that in order to make the car stop in a shorter distance, there are two options:

1) Change the brake system to increase the force between the tire and the road for a given pedal input force.

2) Press on the brake pedal harder.

This theory holds true, but only up to a point. Anyone who has even driven on an icy road will get this right away. As the brake pedal force is gradually increased, the deceleration rate will also increase until the point at which the tires lock. Beyond this point, additional force applied to the brake pedal does nothing more than make the driver’s leg sore. The vehicle will continue to decelerate at the rate governed by the coefficient of friction between the tires and the road. As you can imagine, the coefficient of a given tire on ice is much lower than the coefficientof that same tire on dry pavement, hence the increased deceleration possible on the dry, paved surface. You can take this one to the bank. Regardless of your huge rotor diameter, brake pedal ratio, magic brake pad material, or number of pistons in your calipers, your maximum deceleration is limited every time by the tire to road interface.

That is the point of this whole article. Your brakes do not stop your car. Your tires stop the car. So while changes to different parts of the brake system may affect certain characteristics or traits of the system’s behavior, using stickier tires is ultimately the only sure-fire method of decreasing stopping distances.
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So go out and buy those Hoosier R3S03s for the track or Bridgestone Potenza S-03s for the road!

Manny Lozano
Motorsports Driving Club
www.autosportoutfitters.com/mdc/

is the Mov'it kit for FDs only the 322mm (12.677 inches), or do they offer a larger kit for the FD also??

I like the new M2 kit (front and rear) and the Valspeed (sp) one that Crooked Willow carries.

Ever seen Mark V's FD with the BIG ASS AP's???&nbsp I think they were *8*-pots!



-Ted

Yep, those are the ones that I was talking about. HOT!!!

is this the guy with the CYM FD?? if not, where can i find pics of this??

TIA

Mark's biggest 8-piston setup was all Brembo. You can get more info on the Valspeed kits at these URLs:
http://www.geocities.com/valspeed/
http://www.crookedwillow.com/brakes.htm

-Max

Hmmmm...those URL's don't really show the CRAZY set-up he used to have...

It sorta looked like this. :)

http://n-xsi.com/images/brembofd.jpg




-Ted

:mspank:

I want those, NOW
Nick.

Manny,

I'm glad someone is on here preaching about getting good tires! I can't believe that people would put poor quality tires on their car, especially when they have sunk hundreds or thousands into mods.

Reeves Callaway said (although he was probably repeating someone else) once that "everything on the car is designed to make the tires work better." This is a great statement. You do NOTHING without good tires. The horsepower, sophisticated suspension, monster brakes all have to work through the tires.

Yep! It's sad to see so many Rx7 enthusiasts running around on Kumho Ecsta Supra 712s shod on high-dollar forged aluminum Volks, Fikses, or Kinesis:(

Are the Kumho's really that bad for street driving? If I'm driving 8/10ths on the street, is there such a world of difference between S03s and 712s?

My AVS Sports are almost completely worn out, and I was contemplating replacing them with low buck Sumitomo HTR Z IIs for the street. I have a set of Victoracers on stock wheels for the track.

waltk88,

There's never a "free lunch". You get what you pay for.

If you're going inexpensive, why not try the "old guard" performance tires, like Pirelli P-Zero Asimmetrics? If you're really on a budget the Yokohama AVS Intermediates are excellent for the money (in limited sizes).

I dunno about the Korean Kumhos. I've had the V700s Victors. They're ok as track tires go. I've had their previous road tire, the Ecsta 711s. They were the absolute worst tires I've ever had on my R1. About the only thing the 711s were good for was "drifting".

Michelin, Pirelli, Bridgestone, and Yokohama all excel in high end motorsports (and I ain't talkin about NASCAR). The technology these tire makers use to win races, trickles down to their road tires.

IMO, you drive on the road more than you drive on track. Since you spend 90% of your time on public roads, why NOT put decent tires on the Rx7?

ML
MDC
www.autosportoutfitters.com/mdc/

I ahve Kumho Ecsta 712's on my car and hate them. I have hated them since the day I bought them. They do have stiff sidewalls and give good feedback, but their grip is not much. I have finally nearly worn them down and will be happy to spend the extra money to be rid of them.

Going to Yokohama AVS or perhaps Bridgestone Sport Contacts.

DamonB,

With your Kumho Ecsta 712s, you can practice your drifting technique! Enter a contest! You might win for the longest, sweetest power slide:) That oughta take care of the last bit of tread depth:)

Yeah, I love the new Bridestone S-03s. The Yokohama AVS Sports would be a great choice as well!

ML
MDC
www.autosportoutfitters.com/mdc/

The Kumhos are easy to drive sideways; like I said the quality of the feedback is good which makes them easy to drive. They just give up way too quickly.

I ran an autox with the Porsche club in Dallas on a tight 35 second course with my street tires. I was good on the circle and tried to keep the rear behind me but everywhere else I let it run wide to keep the revs up; the course was so slow I couldn't keep it in the power driving "neatly". I like to think I am a clean driver, but it was fun spending an afternoon sideways:D

rx7gslse was there that day too; most of the Porsche guys sucked.

Any news Manny?

I'd love to get a set of old guard tires, but the AVS Intermediates don't come in 235/40-18 and 265/35-18, and 18" P-Zeros are not cheap.

Kumho has a new tire, the MX. I might give it a try. It's Max performance and targeting BFG KD and Goodyear Supercar. Suggested applications are BMW M Cars, Corvette, Porsche.

Then again, I might not risk it and go with S03 instead.

Yeah, I noticed the new Kumho MX in Tire Rack's (made-up category) "maximum performance" category.

I'm always afraid to try a new tire...

I'd say you wouldn't go wrong with S-03s, especially in wet-braking performance!


Good luck!

Only bad news:( I'm still waiting on the backing plates and hard lines from Japan. Sadly they'll arrive AFTER my March 23 Putnam Park track event, which means I'll need to make do with the US spec brakes (which I've used all along with good results). It's too bad really, since the type RS calipers and rotors are ready to go (still awaiting the silver paint).

My next track event won't be until April or May, so I won't have any hard track use experiences to share until then:(

ML
MDC
www.autosportoufitters.com/mdc/

I am currently working on a 13" brake kit using monobloc (one piece) calipers which feature a larger pad than the "big red" kit by Mov-it yet uses a much lighter, and newer, caliper, aluminum hats, and off the shelf OEM rotors.

The main philosophy behind this brake kit (besides the stopping power) is that the items which wear (rotors/calipers) can be ordered overnight if necessary, ie. they're in wide supply from lots of different vendors if need be.
And this would apply even 10 years down the road. With the M2 (and other) big brake kits, there more than likely will be a substantial wait (and cost) to replace rotors/calipers in the future. Rotor costs for my kit (vented 13"+, cross drilled) will be about the same as high quality RX7 rotors (say Powerslots) and will offer a wide range of pads to choose from. This eliminates the $400/rotor syndrome most other kits suffer from.

I'm still in the early stages due to other commitments, but I'll be test fitting various wheels shortly to determine what size will be necessary to run this setup. I'm assuming 17's at the minimum, but I'll try the stockers just to double check. The brakes will offer probably the largest swept area short of a 6-piston 14" rotor configuration and will supply more than enough fade-free stopping power for any RX7, even serious track cars. The stock master cylinder will work fine, although it wouldn't be a bad idea to install a 929 master if the rears are upgraded using say the 99-spec RS brakes. And get this...price should be around $1700. Same as the crappo wilwood setups.

More pistons or lighter wieght?
 

Stillen has a set but it's four piston (stock is 4 piston's also)? I can only assume it's lighter wieght. The bigger size rotors add more wieght, so I don't understand any advantage to that. I can't figure out the advantage vs cost unless you get both more pistons and lighter unsprung wieght?
I'm still confused.

More pistons aren't going to give you more braking power, just better pad wear and feedback. What is important is swept area, rotor size (related to swept area) and caliper stability. Two piece calipers are not as ridged as monobloc calipers. Just ask anyone who has sampled Yamaha R1 brakes which are 4 piston (or Porsche4-piston monoblocs for that matter). Just because it has more pistons doesn't mean that the caliper has superior stopping power. Usually it's to increase pad size. Stillen's kit uses the off the shelf brembo F50 calipers, same calipers they use for the C5 and the civic kit, every kit for that matter and is actually the Brembo kit offered for the FD by Brembo USA. The other issue for me was the extraordinary cost and cost of replacement parts. All of this led me to the decision to create my own kit using off the shelf parts and OEM manufacturers. My car will stop just as hard, just as many times, without fade, as any of the other kits offered yet cost on average $1000 less. And the (344mm?) won't cost a small fortune to replace. As for the bigger rotors adding weight and not seeing the advantage, it comes in the form of being able to dissipate more energy repeatedly before the heat saturation point is reached. More mass= more heat absorption. The trade off in weight comes with lighter weight calipers and the aluminum hats which cause the hat/rotor setup to come in about the same weight as the stock OEM disks. Add to that the lighter calipers/brackets, and you'll end up saving a pound of two per corner. Pretty significant.
Michel

Michael: What's your ETA? Heh, and are you ready for the heaps of crap you'll take on the List :) Remember Dale Black (or was it the other Dale-- I get them mixed-up)...

swept area?
 

= more rotor area covered by the brake pad?

What about cross drilled rotors being better in the rain?

So which set is better? The Brembo F40 or M2?