BlaCkPlaGUE

Just curious, but whats the deal here? Is it that there are 4 pistons that provide more friction over the pad surface area? What are the differences in brake lines that lead to the master cylinder if any?

Just wanted to know thats all. thanks for any help.

SureShot

More pistons = more friction with the same hydraulic pressure.

Same lines.

kontakt

isn't it something more like: more pistons = more area for the pressure to build on (more square inches = more pounds of pressure per PSI)

Edit: I re-read that rat, and I am in fact just nit picking

SureShot

Middle school science: pressure X area = FORCE

Icemark

pads are also less likely to deform with multiple points pressing on the back

Team_Mclaren

hey im new here, but where can you find the 4 piston calipers? all s4/s5 GXL and Turbo? what about the sport edition?

Icemark

Sports, GXL, 88 GTU, Turbo, Verts, 89-90 GTUs (note the small S), and 91 coupes with A packages.

Snrub

iTrader: (1)

Another big difference is that you've got big aluminum blocks that absorb/disipate heat. The main advantage with the 4 piston calipers is their resistance to brake fade.

RXgirl7

i upgraded the brakes on my '89 GTU to the 4pots with stainless lines. im using stock pads for now, and even with those i noticed ALOT less fade at the track. the initial bite improved as well..i would definatly reccomend it

RETed

All things being equal, going with a multi-piston brake caliper just gives you more even brake pad wear, as Icemark has already mentioned.
Counter to what all the big brake vendors want you to think, it does not necessarily give you automatic better braking performance.

1) The stock brakes will easily lock your tires up; the weak link is the *tires*, not the brakes.

2) In reality, the 4-pot (front) brakes are larger in mass - as Snrub has already mentioned, this goes into heat dissipation. Unless you're braking hard enough to heat soak all the surrounding metal, this should not be an issue.

3) As with the brake rotors, the 4-pot (front) brakes have more (metal) mass in the rotors - it's almost the same as #2 above.

I don't know the full specs on the 4-pot versus the single pot brakes in terms of brake disc diameters and such, but that all only goes into "brake feel" - be careful what you call "brake performance", because what you're really describing is "brake feel".

Slam on the single piston (front) brakes hard enough, and it'll lock up the tires.
I pretty much guarantee it.

Please read that Grassroots Motorsports magazine article on (big) brakes - the writer is an engineer for one of the big brake companies, and everything is covered very well in there.


-Ted

jhammons01

The single piston calipers have one piston................

The four piston calipers have four pistons..............

djpacman

I'm wondring what the compatability is with the 1 piston - 4 piston conversion? can i just buy 4 piston calipers and put them in the 2 piston car without changing anything or what do i have to get?

Chief

4 piston setups had bigger rotors.
single piston 9.8" rotor.
4 piston 10.9" rotor

Go48

iTrader: (7)

There are many excellent threads on this topic, one that comes to mind has ALL the details. Do a search for "4-pot calipers".

Edit: Here are links to just 2 of them:
https://www.rx7club.com/showthread.p...4-pot+calipers
https://www.rx7club.com/showthread.p...4-pot+calipers

Go48

iTrader: (7)

I believe the front rotor is the same for the 1-pot or 4-pot caliper. The rear rotor is different.

Chief

nope. theyre both different, but the back by only .4" and the rears are vented on anything other than 4 lug.

speed_monkey

I just did the 5 lug conversion with 4 piston brakes. You need the calipers, rotors, lines, proportioning valves, brake booster. I am very pleased with the new setup.

digitalsolo

iTrader: (2)

The 4 piston calipers also run a larger brake pad then the single piston units. More pad = more braking capability, all things being equal. This becomes more of an issue if you have enough tire to stress the front brakes.

ZeroDrift

iTrader: (1)

From what I have learned about brakes is that if you can lock the tires, thats the max, every thing extra is to add control and feel to your brakes, not to make you stop faster (unless its the pads themselves)- you have the best brakes for the application. This is because if you can lock your tires, you are loosing traction at the tires, not your brakes- at this point your tires are the weakest link in the system. Here are my observations:

Single piston (sliding) VS multi pot calipers (floating):
Imagine if you will: you have a brake pad- and its slightly flexible under load. the more pistons you have the force is distributed evenly thru the brake pad. ie: 1 point of contact per pad- as opposed to multi pot brakes which have 2 or more points of contact on the same pad- the force is distributed in more places, making the brake pad work evenly.
(see figure 1)



Difference between floating and sliding systems:
- you have 1 big piston on one side and it forced the closest brake pad to the rotor- therefor pushing back on the caliper, and the other pad will follow afterwards because the piston is 'pulling' the pads together. Mind you the calipers will flex under load and therefore making the pad move as well.


All in all brakes will resist fade if the force is distributed evenly and if the calipers dont flex, making the pad wear unevenly.

I hope this helps!


(single piston see figure 2, floating see figure 3)

ZeroDrift

iTrader: (1)

As far as the rotor size: larger brake rotors will allow the rotor to cool more for each revolution, therefore keeping the brake pads within their operating temps for longer periods of time (resting brake fade). I upgraded my civic's brakes from the stock 9" rotors to slotted 11"ers.. it made a HUGE difference with the upgraded pads. (braking confidence goes up alot!)

Go48

iTrader: (7)

Hmmmm, I'm confused. Are you saying that the front rotors for the 4-piston calipers are different than the rotors for the single-piston calipers? If so, my interpretation of the parts manual for the S5 does not support that statement. See the attached image and the following comment.

The rear axle page in the parts manual shows a difference between the rear rotors. I'm aware of that difference. But, only one rotor is shown for the front axle. I'm in the middle of a 4-pot upgrade and everything I have heard, read or been told by people who have done the 4-pot upgrade indicates that the front rotors are the same for the single piston and 4-piston calipers. I guess I'll have to talk with a knowledgable parts guy to find out. Assuming I can find one.

ZeroDrift

iTrader: (1)

I'm not too framiliar with the rx7, but i'm guessing that all stock rear discs are single piston brakes, and the fronts either had, single pot, or 4 pot brakes- pending on the model of your car.

ZeroDrift

iTrader: (1)

haha- just noticed that my 4 pot brakes are missing some brake pads..