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Random Brake Question

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#1 FLD


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Posted 18 March 2019 - 10:40 AM

My mind just randomly wandered off on brakes. Given this isn't VX specific I posted it here rather than in tuning and mods. Anyways, my random thought is:

If pad area is identical and piston area is identical is there any difference between 2,4,6, etc piston calipers? Is there some other benefit I don't know about? Heat transfer perhaps? Lead in pressure on the pad? Other?

I'm not doing anything, it's just a question that floated through my head as these things often do.

#2 Madmitch


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Posted 18 March 2019 - 06:15 PM

Is it not more to do with how to get powerful brakes into a given wheel size.  Suppose you wanted a lot of friction area but wanted to get it all inside a normal size wheel then it makes sense to spread that around the disc using a long pad and two or three pistons to keep everything flat and the rubbing pressures equal.  If you only had a single pot caliper then the diameter of the piston would be much greater and the pad therefore less long but more equally dimensioned.  The disc would therefore have a much wider friction area making the whole disc much bigger, heavier and more expensive.  Am I making sense...………….

#3 Ormes


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Posted 18 March 2019 - 06:25 PM

My understanding, which could be wrong I add, is that area of piston will dictate the distribution of total force applied between front and rear, and area of pad will dictate friction per unit of force applied.  Exception being 1 vs. 2 which would ditate sliding vs. fixed.


Guessing that larger overall surface area means better heat management, and as pistons are cylindrical, packaging the force into multiple pistons is preferable to using just 2 massive pistons.


That is my logic anyway... happy to be corrected :) thumbsup

#4 Chris P Duck

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Posted 19 March 2019 - 02:30 AM

My understanding was (assuming equal pad and piston area) the key benefit is the modulation.
Personally I’m too sh*t to take advantage of an improvement here!

#5 FLD


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Posted 19 March 2019 - 08:36 AM

All interesting stuff, thanks guys.

@madmitch : made perfect sense

#6 Nev


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Posted 19 March 2019 - 09:12 AM

More pistons = more control of pressure distribution. Incidentally pressure distribution is often not meant to even, there can be a deliberate leading/trailing edge bias.


If I remember correctly my 4 pot Brembos (off a 2.8 ton GVW Porsche Cayenne) have one small and one large slave cylinder.

Edited by Nev, 19 March 2019 - 09:19 AM.

#7 siztenboots



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Posted 19 March 2019 - 12:22 PM

if the piston area is same , but divided by more pistons , then each piston will be displaced less , if I understand your scenario


the main reason to have more calipers , is for a bigger pad for extra duty

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