4 piston brakes?
 

today i got 88 rx7 front end wit 4 piston brakes they are 5 lug i own a 88 rx7 se with singal piston what all do i need for the change over im goin to run in IT class will this be legal and who makes the best SS brake lines that can handle racing temps? also will the rear brakes from that can help out or should i keep what i have my wheels now are 4 lug so i would have to run 2 diff wheels but will they really help me out for IT racing?

Jeez man, use a period and comma once in a while..

Ok ok, let's see if I can deciper this.

Yes, you can use the 4 piston brakes.

However, it means transferring rotors, calipers, and HUBS from the other car. The rear is kind of a pain to swap, but you have to swap them all if you swap the front. Can't create a model of car, and no RX-7 came with 5 front and 4 rear :) IT won't let you do that.

The SS lines, no biggie, new rubber lines are ok too. I run MazdaComp's (now Mazdaspeed) SS lines, the ones from Mazdatrix will work fine too.

PaulC

ok cool, what kind of pads do you run?

Carbotech Panther Plus.. Those are track only pads, if you're going to run the street at all, don't use them.

PaulC

Hawk Blue. Some say they're rough on rotors but I haven't had a problem. Ran 6 weekends, two schools, and two track days on my first set of fronts. Had some pad left but I replaced them to restore balance with the rear. As the pads wear thinner you'll get less pressure at wheel. After those six weekends there was a slight pad groove. Since the rotors were true and bedded for the same compound I didn't bother to turn them just replaced the pads. Mazdaspeed has the best prices.

Chris

This is entirely untrue. Brake pads will work the same right down until you get to the backing plate, at which point you get a bit too mucb braking :)

Uhh, no....

Chris

Wanna bet? ;)

Mazdaspeed currently sells the Blues for $125. I beat that all day long. PM or email me for details.

I got the whole rear end and subframe today. It was only $40 so in all i got a whole 5 lug for $60. I plan on gettin all new calipers and rotors along with new bushings ect... Who did u guys get your bushing kits from i see mazdatrix sells them. Do you know of any others? Thanks...

Cool! I gotta deal with ya more often! Chris is a good guy to deal with if you guys haven't.

Chris

theres an entire topic on converting to 4 piston brakes in the first gen section right now. the post is titled "front brake upgrades" or something like that. theres a site that explains how to do it with pictures.

--eric

Cool, I just got a whole subframe as well last Friday. A friend who owns a towing co. had a '86 GXL heading to the crusher. He let me take whatever I wanted before he sent it out. Spare oil cooler, 5 lug frt and rear suspension, 3 stock wheels, LH door, hatch glass, all for free!

I used Energy Suspension bushings in front and installed the ISC Racing trailing arms in the rear. I will use the spare set of fronts I just got to convert to Delrin from Mazdaspeed. They seem to have less bind than the Energy Suspension pieces. The ISC arms are sold on an exchange basis and incorporate spherical bearings. When installed, they have virtually no bind at all! ISC and Mazdaspeed also sell the Delrin toe eliminator bushings and subframe bushings.

Care to explain your reasoning, b/c it doesn't follow suit with what I know, and with the theories behind the deisgn of a hydraulic system.

Ever run a car with pressure gauges on the front and rear circuits? As the pads wear the balance changes. Since the fronts wear a bit more quickly than the rears I've needed to dial a bit more bias toward the front to maintain balance. There is a slight pressure difference with the thinner pads. Have no idea why but have heard and seen others with the same senario. The difference would be undetectable on a street car and only noticeable in braking balance at the limit and not really overall braking potential.

The only theory I could come up with and this is really just a WAG is that as the pad wears the volume of the caliper increases. And as such it will take a longer pedal stroke to create the same amount of pressure as you would get with a fresh pad. You may still have the capability to produce the same ultimate pressure but you will receive different pressures at the front and rear for a given amount of pedal travel as the pads wear at uneven rates. Same idea behind the need to change pads on both sides when doing a brake job. Don't want one wheel out braking the other.

Chris

I have done the same swap. In my case I drilled the front rotors to accept the 4 bolt pattern. I left the rears as is mainly to lessen rear bias. This works better in auto-x in my experience.

The amount of pedal stroke never changes. The pistons self-adjust; this is the beauty of disc brakes. Anyways, pressure is not created by volume, they're two different phenomena that only slightly relate to each other in a hydraulic system. Pressure in the hydraulic system is a function of the pressure on the brake pedal multiplied by lever length and master cylinder area, plain and simple, no matter how much travel there is. (Until the point where the pedal bottoms out before there's enough resistance on the caliper to create pressure, but I hope at that point you're headed for the pits!)

I do appreciate that you're reporting something that you have observed, though. Perhaps there is another phenomenon at work here?

I expect that, with less pad material, more heat would be imparted to the fluid because there is less pad material to absorb the heat and because the pistons are closer to the source.

Just a thought, I don't have any data to suggest that this would be significant enough to explain the phenomenon.

Peejay your description sounds good to me.:) I can assure you that it's not a heat or air in the sytem issue. It's a consistent balance issue with a slight pressure drop noted as the pads wear.

Chris

Great thread, anyone have a contact/url for ISC. I could be interested in those arms mentioned above... Thanks in advance

Ludwig my friend

I think you are totally wrong.

It sounds like the thin pads are transfering more heat into your brakefluid and boiling it.

ISC Racing - 1-863-324-4539 ask to speak to Mike Van Steenburg, he's the owner.

You will either have to send him your arms for exchange, or see if he has a core charge you can pay to save the time/effort/cost of shipping your arms to Florida. I was lucky, I just called him before a race weekend and picked them up at the track.

Well if the balance was there with cold brakes or I got a soft pedal to go with it I'd believe ya.

Chris

It could simply be that the friction of the pads goes down as you approach the backing plate, causing the bias change. The pressures should be the same no matter how thick the pads are. You will get more heat transfer to the fluid as the pads get thinner.

-Max

Thanks Chris! I'll be at the 12 hours of Sebring by the looks of things so perhaps I'll try and exchange them then. Cheers