Why are 4 piston calipers better than 2?

[ScotWithOne_t]

This may sound like a dumb quesiton, but why are 4 piston calipers (such as are found on the 2000 Cobra R) preferred to two piston calipers such as the PBR calipers found on Cobras and Vettes? (This came up in the BIR thred, so I thought I'd start a new thread instead of whoring that one.)

Theoretically, if the pistons are the same diameter, then the two and four piston calipers should both provide equivalent clamping force. This is slightly counterintuitive, since one would think that the 4 piston caliper should have twice the clamping force, but it doesn't. The key is the placement of the pistons. Since a 4-pot caliper has 2 on each side opposing the two on the other side, this is no different that the 2 pots on a PBR caliper opposing the casting of the caliper on the other side. I have attempted to illustrate this with the picture below. Of course, it may very well be that the diamters are bigger on a '00R caliper, but for the sake of argument, let's say they are the same as the standard Cobra PBR pistons.



If we do get equal clamping force from a 2 piston caliper, then why would they even bother to make a 4 piston? Isn't it just more complex, with more parts. And futhermore, doesn't the 4 piston caliper transfer more heat into the brake fluid, since there is more surface area in contact with the hot caliper?

[sport the war]

you dont have the kind of car that would require that kind of braking system, they use them for supercars because of the 200+ mph speeds, if you were to try to hit the brakes without a quad it would more then likely shatter the rotor from the heat.

[StangerJon]

because when you have 4 or 6 pot calipers they come with cool words on them like wilwood or brembo. where your 2 pot calipers only say PBR.


DUH!!!!

[bad-speller]

you dont have the kind of car that would require that kind of braking system, they use them for supercars because of the 200+ mph speeds, if you were to try to hit the brakes without a quad it would more then likely shatter the rotor from the heat.

Sorry man, but that is bogus info. Piston quantity as in Scotts example above would make no difference in rotor heat.

Scott,

Your logic is very sound, I have mentioned that before, but in here people seem to correlate piston # to performance which isn't necesarily correct.

Given the same total piston area, whether it be a two piston or a four piston caliper, the clamping force will be essentially the same. Where a four piston caliper will have the advantage is distributing the load more equally to the pad and thus to the rotor. This becomes more and more important the larger the brake pads get.

Brakes are so much more complicated than how many pistons a caliper has. Master cylinder piston size is just as important, as well as front to rear balance(front caliper size in relation to the rear), ect ect.

Brian

[StangerJon]

but I am also an idiot.

and I stand by it.

[RayK]

So if I have 4 brake hoses instead of 2 on the front, my brakes will be better?

[worduphomefry]

because when you have 4 or 6 pot calipers they come with cool words on them like wilwood or brembo. where your 2 pot calipers only say PBR.


DUH!!!!

whoa there, don't hate on PBR

PBR > uncommonly smooth red dog

[OrangeCrush 86]

How many pistons do you need to slow down the dub dueces? 10 piston?

[ScotWithOne_t]

Sorry man, but that is bogus info. Piston quantity as in Scotts example above would make no difference in rotor heat.

Scott,

Your logic is very sound, I have mentioned that before, but in here people seem to correlate piston # to performance which isn't necesarily correct.

Given the same total piston area, whether it be a two piston or a four piston caliper, the clamping force will be essentially the same. Where a four piston caliper will have the advantage is distributing the load more equally to the pad and thus to the rotor. This becomes more and more important the larger the brake pads get.

Brakes are so much more complicated than how many pistons a caliper has. Master cylinder piston size is just as important, as well as front to rear balance(front caliper size in relation to the rear), ect ect.

Brian

If the idea is to get an evenly distrubuted load on the pad, then wouldn't a cast peice of aluminum provide a more rigid and even surface pressing against the pad than 2 or 3 pistons that can move independently?

[Osiris22]

you dont have the kind of car that would require that kind of braking system, they use them for supercars because of the 200+ mph speeds, if you were to try to hit the brakes without a quad it would more then likely shatter the rotor from the heat.

Y would U post that. most peeps on here R nice. I am not. U R a stupid idiot.

with a floating caliper design, it's mostly the same force on both sides.

[KickAssFlash]

whoa there, don't hate on PBR

PBR > uncommonly smooth red dog

as the only one that got this subtle joke, im going to go ahead and give this an

[Outrun]

as the only one that got this subtle joke, im going to go ahead and give this an

I got that joke. PBR tastes like piss. Never tried Red Dog though. I assume it tastes worse than PBR.

[Osiris22]

Correct, sirs.

my g/f piss>PBR. This I know for sure. I am not sure about all piss tasting better than PBR though.

[OrangeCrush 86]

I have seen more calipers stuck on the sliding pins (for lack of a better term?) then pistons siezed in the caliper bore in most cases. Thus, remove the pins and replace with pistons.

[sport the war]

i've heard of rotor's shattering because of floating design's cause the rotor to shimmy at speed and with the heat i heard it shatters, i was going off what i've heard as to why going to a 2-4 piston calipers, that's why they give you a larger contact area to prevent shudder.

testing of a supercar breaking system, not fully at speed either. you tell me nooblets, is that hot enough to break a rotor? geee...