ss lines help pedal feel, which in some cases can help your threshold braking and helps your foot become more one with the car, i didnt mean to say its a performance enhancement but certinally helps and hey its another thing you wont have to worry about on the track...worn rubber lines spliting open during a session would not be fun to deal with.

 

if you have ever upgraded to d&S rotors, you know the difference. they might not make a huge difference, but its enough that they have been one of the first upgrades of my cars i've had. those will be on my next FC as soon as its kinks and flaws are worked out for daily driving. brakes will probably need to be changed on mine anyways so, that'll prolly be one of the first upgrades. the SS lines are basicly for longevity, looks and strength. they dont make a difference in braking. also, bigger rotors probably arent gonna do anything to our cars. most big brake kits come with different calipers which make most of the difference.

 

yeah i have to agree w/ you of the feeling of the fc's brakes. at first i didn't like them but now i prefer them over the more "sensitive" or "touchy" brakes. also its good to see that you are another SCC reader. that quote you wrote was on the 6(?) things you need to know about brakes in technobabble.

any wasy i need to know how to find out what kind of brake calipers are on my car. what came stock on 91 na's?

 

.

 

the reason i want to run bigger rotors is because of heat. i race at a 2km track for up to 40 laps. after a few laps the brakes are close to dead. the more material in the rotors i can get the better, but i want to keep my light weight 16's (and slicks are easier to come by too)....so 304mm are it really.

in reality the rx7 brakes are too small for a racing car. they are fine on the street, but once you get to a track their weakness become apparent

 

Seriously, you don't need to upgrade the brakes man.. I race mine on stock brakes, no fancy slotted/drilled crap (which will end up cracking under high heat anyway), with a good set of race pads. I don't even use ducts. The last thing I'd mess with on an FC is the brakes.

PaulC

 

91FC, depends on if you've got a GTU or GXL. GXL and T2 came with the 4 piston calipers, the GTU came with singles up front. Rotor size is same diameter IIRC, but the 4 piston rotors are thicker.

Pitchblack..

Ok, what pads are you running?

 

depends what version you have. i have 4 pistons in the front (which are fixed calipers, not sliding), with vented disc. thats factory front. the rear people say is a 1 piston, but i'm confused why Mazda would put 4 piston fixed in the front, and 1 piston sliding in the rear. which leads me to believe it must be 2-piston on the rear (i'm not gonna go take my wheel off to look). the rear disc, again, on my car, is also vented. some came with solid rotors in the rear which also most likely had the 2 piston in the front.
if someone can prove me wrong and provide evidence it is, indeed, a one piston, i'll be both thankful and surprised.
also, sorry, i dont know the diameter nor width of new factory-size rotors.

 

awww dam. that sucks. i have rear solid disks. im guessing that the calipers are not 4 pot up front. i know this may be a stupid question but can you tell just by looking at them?

 

bigger rotors have more swept area which is that much more time until the pad hits the same spot again. the more metal, the more heat it can absorb (i dont understand why some people run as big of FMICs as they do, and i doubt they do either). also, the wider around it is, the more torque is available.
i read on the brake site the poster linked that difference in stopping distance doesn't change (at least not much) until the previous brakes threshhold reaches its max.
as for taking 50 pounds out, thats simply a guess. not to mention that some racing (or, all?) has a weight limit. its really easy to spit out a number, but how can you actualy relate the 50 pounds to stopping? its just a guess. every pound helps, i agree, but youre more than likely going to have trouble proving your number.

 

You sure you know what he means when he says vented disks? it's hard to tell unless you pull the wheel off. Vented disks are two disks with veins inbetween..
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That's what the rotor from the edge will look like. If it's solid, you won't see the veins inbetween the disks, it'll just be one solid piece.

PaulC

 

yea, its easy. you'll see a sort of sideways 8 on the caliper. its 2 circles that overlap in a sense. the rears are one bigger circle. its a shape that houses the pistons. also, i dont know if the 2 piston fixed (or 1 sliding, still undecided) calipers say "mazda" on them or not. the 4 piston ones do.
here's a question i dont know the answer to, what does "pot" refer to... *cough* in _this_ situation. i say 'piston' because i dont know the relevance of 'pot.'

 

silkworm - at the moment i have hawk hp plus for the street, change out to hawk black a on the track

 

You got an estimate on the power your car is putting out?
As the power output increased, an increase in braking performance is required.

The CHEAP way is to add more ducting.
It's all about the heat.
Ducting helps get rid of the heat.

ANY big brake kit is going to cost serious money.
If you're racing, I'd look for a RACE kit, which means even more money.
Are you willing to spend upwards to $2,000USD on this???


-Ted

 

the car will be putting out around 250-300whp. nothing huge, but plenty of fun.

i didnt want to spend $2k + , that's why i'm looking at the idea of just upgrading what i already have by just getting larger rotors

 

here is something to think about: a larger diameter rotor will reduce your horsepower at the wheels, even if the rotors are slightly lighter in MASS, since rotional inertia increases. it will also take slightly more force to stop this, but this factor is less pronounced. therefore, when you are considering this particular upgrade, make sure that you are gaining considerable braking performance to offset this loss of power...of course this is advantage is only applicable on a road course, where braking is a large part of lap times...

as for getting thicker rotors, i don't really know why you want to do that. it creates more mass and is harder to dissapate heat. the only reason i see is if you are looking at aftermarket vented rotors that are that width, and you want to stick to the stock calipers...

also consider getting a really good brake pad, it will definetly improve brake response and fade. i recommend Hawk HP Plus Race brake pads, they sell them for the stock RX-7 calipers.

 

the reason i want thicker rotors is 2 fold.

1 is that 28mm thick rotors are much more common and cheaper to buy

and 2, you're only half correct with the heat thing. thicker rotors take longer to heat up than do thinner rotors, yes they do make it harder to dispurse heat, but much more braking for is required to heat them up, also, usually with thicker rotors, all that changes is the vent gap - so infact even more surface area is available for cooling and the cooling is more effective (more air can get deep into the rotors).

 

Ok, well, first things, you need to dump those Hawk Blacks in favor of Hawk Blues or Carbotech XP1109s.

Add some ducting for cooling

Then see what you get before you start messing around with new brake caliper brackets and rotors.

PaulC

 

alright, i did not realize that 28mm rotors are more common and cheaper..?

and also back to the heat, i was thinking you might say this. the thing is, you want to look at how quickly the max heat after breaking goes away, and you should be less worried about slowly it heats up. in fact, your brakes will work better with a certain amount of heat in them, especially if you are using high performance brake pads.

but by all means, i am sure they would fit. the calipers should expand far enough, since it is only a 7mm increase, stock is 21mm i think. remember that you probably get that much wear (7mm) out of your brake pads. i would be interested to see how a thicker rotor changes pedal feel...

also, another thing i forgot to mention is that RX-7 heat dissapation is fairly good in its stock form. remember, the CAR COMES STOCK WITH BRAKE DUCTS that work fairly well, at least my S5 does. so honestly, i would start with brake pads, and then your calipers. if you don't have the 4-piston system, you could try even switching to those, and getting good vented rotors all around. i think Brembo makes OEM replacements. yes, you could go with a race kit, but you said yourself you are not willing to spend that much.

overall, the best thing is to the have a good working, efficient brake system: get a new brake cylinder, stainless steel lines (more for replacment and prevention of worn/leaking rubber lines), some clean or refurbished factory 4-pistons, those new OEM rotors from Brembo, some real good brake pads (those Hawk Race ones are good), and top it off with a good bleed and brake fluid. oh, and make sure those brake ducts are clear and do some weight reduction when you go racing. this whole setup won't cost much at all (under $600 US), and i guarantee it will be a track-worthy setup.

 

The stock brakes are quite good, they are basically identical to the brakes on the 3rd gen. I just got back from VIR, my instructor was driving a GT1 prepped viper with hoosier tires on it and huge stoptech brakes, and after about three hard drags on the brakes he was raving about how good they are. (this is with carbotech panther plus pads) They haul the car down nicely and fade wasn't an issue with 25 minute run groups.

Going to slightly rotors can'r hurt though, since you are increasing leverage.

SS lines do make a big difference, pedal feel is greatly improved. They are also less likely to be damaged if you go off course and pick up debris.

 

so nobody has widened their stock 4 pot calipers using the mandeville auto tech option?

i know you are all giving a great recommendation for the stock brake setup, but even good things can get better.

ps - great conversation too

 

I'm 1,000% positive that it is a single piston on the rear. I just bled the rear calipers today and they are definately single piston. No doubt about it.

 

you could be right, like i said, i wasn't sure. still, doesn't it seem weird that the fronts would be fixed calipers (which i believe to be older, or perhaps cheaper, technology) and the rear would be sliding (like newer cars (ie WRX) have ?? seems odd to me. maybe there's some obvious reason i'm missing. heh.

you bled them, which means you didn't look at both sides? i cant remember from memory, but it seems as though it would be hard to tell if the caliper was 1 or 2 piston, sliding or fixed from just bleeding the brakes and not dealing with the caliper itself or brake pads.

okay, i found this:
Four wheel disc brakes were fitted, base models getting vented 9.8 inch dics with single piston floating iron calipers at the front and solid 10.3 inch discs also worked by single piston calipers at the rear. The Turbo and upgrade models were fitted with vented 10.9 inch dics with 4 piston lightweight aluminium floating calipers up front and vented 10.7 inch discs with single piston calipers. Anti-lock braking was not available at introduction of the car but a system based on Bosch ABS with Mazda improvements was added to the all models except the Cabriolet.
-- http://www.rx7uknet.dircon.co.uk/rx7_fc3s.html

now i'm getting my terms confused because it calls both floating...

 

okay, this from "Six Things To Remember About Brakes":

"The pistons can be arranged in several different ways, depending on the caliper design. Fixed caliper will have pistons on both sides of the rotor. A two-piston fixed caliper will have one on each side, while a four-piston caliper will have two on each side (ie rx7 front brakes)...
A sliding caliper only has pistons on the inboard side. The piston pusges on the inboard pad and the cylinder itself gets pushed away from the pad. That's the sliding part. When the cylinder slides backward, it pulls on the outboard pad, since it conveniently happens to be cast into a big fork that reaches over the rotor."

the site refers to the 4-piston as floating (or sliding)where i believe it should say "fixed."

 

The 4 pot fronts are not floating, they are solidly bolted to the suspension upright. You don't need to float calipers that have the pistons on both sides of the rotor.