Brake calipers

[Hullabaloo]

When the Australian DC5R and S15 came out they seemed to both be slightly detuned from their Japanese counter parts. On paper they (Aus spec ones) both seemed very similar with 147kw, 16inch wheels, etc. Yet I believe DC5R's come with single piston floating calipers up front yet the s15 came with 4 piston fixed calipers on the fronts.

Correct me if I'm wrong but from what I've read it seems that fixed calipers (2, 4, 6 piston) are more expensive to make/repair/service but give better braking capability. Floating calipers (generally single piston?) are cheaper to make/service/repair. I assume that is why floating is used on most vehicles?

I'm guessing the single piston diameter in the floating design on the DC5R is large enough to apply ample equal spread force on the brake pad which is comparable to the (smaller?) pistons in the fixed 4 piston design.

The question is, how much less effective is a single piston floating caliper design over a fixed 4 piston? I understand things like caliper size and rotor size will play a factor, so let’s assume same brake pad contact area and rotor size for the purpose of this example. Will a fixed 4 piston design be less prone to fade?

[dsp26]

depends on the size of the piston...

naturally multi piston designs are more efficient in that pad pressure on the rotor would be generally equal or spread...

i have seen custom made ferrodo ds2500s on gtir calipers (single 54mm piston) bend inwards from the centre where the piston contacts including the backing plate due to severe heat... this killed the rotors also....

but this is an extreme case and was used for a high speed track... how often do you plan on that?

***EDIT***

even a 2 piston design where there is one on each side would be more efficient in that there is even pressure instead of a a single piston design pushing the pad and rotor outwards towards the front of the caliper...

[Hullabaloo]

Not planning on tracking the car so I'm sure single piston floating is fine for street.

Is the cost of fixed caliper design that much more expensive? (compared to the gains in braking performance?)

I thought that single piston caliper design mean that the front of the caliper was pulled in towards the disc? (as well as the piston pushing the pad towards the otherside of the disc)

[dsp26]

Not planning on tracking the car so I'm sure single piston floating is fine for street.

Is the cost of fixed caliper design that much more expensive? (compared to the gains in braking performance?)

I thought that single piston caliper design mean that the front of the caliper was pulled in towards the disc? (as well as the piston pushing the pad towards the otherside of the disc)

well speaking of factory single pistons, the pistons are on the inside (strut side) and push outward so...
- Piston pushes inner pad
- inner pad pushes against rotor
- rotor pushes against outer pad
- outer pad pushes against the caliper claws (opposite end of the piston).

for street/non high speed track car a good small upgrade are as follows:
- slotted rotors (don't get crossdrilled as they are prone to crack especially from single piston pressure unless the drills were strategicaly placed and balanced from cad design). the slots will always scrape off any glaze/dirt off a good set of pads.
- good fluids especially multi temp range (i recommend NEO)
- good pads along the lines of Ferodo DS2500/3000
- Braided lines all round + brake master cylinder stopper (now this combo will prevent any hydraulic flex in the brake system and provided awesome response, grip and pressure to the entire brake system. a common error that some racers do is only put braided hoses ont he fronts in turn increasing hydraulic pressure to the rears where it is still oem rubber, especially when the fluids get hot!)

***EDIT***
sorry to address your question, it is fine for your use. I wouldn't be able to justify the expense in your case... less than $1k can get you all the above upgrades mentioned

[dsp26]

just remember that the case i provided above with the gtir is a worse case scenario where the DS2500 pads heated well above the peak temp range of ~800*C from VERY prolonged used at wakefield... keep in mind also that the pad/piston size ratio is also smaller than a DC5 (they are 256mm rotor with 54mm pistons and the pad extended pretty wide beyond the piston area)

i can provide pics of what happened if you'd like...