Subaru 4 pots!

[Scooby South]

Originally Posted by Admiral Ballsy

Yep. Neither is number of pistons. Again, look at an M3's brakes sometime.

Bottom line is, the 4/2 setup from the earlier WRX isn't any improvement over the stock. Neither is it significantly worse. Since most people doing it are likely driven by aesthetics (NTTAWRT), no harm no foul.

I will contribute this to the argument. First is aesthetics.. next is a weight reduction..going to the Stop-Tech BBK and Subaru 2pot rear. I have lost about 25lbs total over the stock Brakes... Plus I feel it does stop better. Plus...it just looks BADASS..

[Wonderbar]

Originally Posted by Admiral Ballsy

Yep. Neither is number of pistons. Again, look at an M3's brakes sometime.

Bottom line is, the 4/2 setup from the earlier WRX isn't any improvement over the stock. Neither is it significantly worse. Since most people doing it are likely driven by aesthetics (NTTAWRT), no harm no foul.

For me personally, without testing if say there is improvement but I also did pads and rotors at the same time.

The weight savings of these over stock makes it worth the money by itself in my opinion, the lower unsprung lbs will indeed improve braking performance as well as aid every other category of auto performance.

I do prefer the visual appeal.

[wheelhaus]

Originally Posted by Admiral Ballsy

Again, that's not how it works. It's not "50 units per pad". If the piston pushes with 100 units, the other side of the bracket pushes back with 100 units. If it didn't, the thing would fall off the car.

Opposed pistons are used for several reasons, but force applied isn't one of them (BMW uses only single-piston calipers, BTW), even on M-cars).

You don't have to take my word for it. Google around.

I have a good understanding of hydraulic fundamentals, but for some reason this concept of opposed pistons completely escaped me. Makes sense that it's the same body of pressure surrounding the entire assembly, and so long as force A is matched by Force B, it's no different than a single-sided floating caliper that's doing the same thing mechanically.

[Flat Black VW]

So I just got my 4-pot calipers installed upfront and the pedal is definitely a bit lower know. I knew this would happen due to pushing more fluid through the pistons, but my question is does any one have a solution for this yet? Im assuming the best solution would be a master cylinder upgrade but I have not seen anything around. Anything we can steal from the Subaru parts bin that would work?

[Admiral Ballsy]

Originally Posted by Flat Black VW

I knew this would happen due to pushing more fluid through the pistons

Something else is wrong; you're pushing less fluid, since the pistons are smaller.

Assuming you filled the MC properly, something else is wrong.

[Flat Black VW]

Originally Posted by Admiral Ballsy

Something else is wrong; you're pushing less fluid, since the pistons are smaller.

Assuming you filled the MC properly, something else is wrong.

Pistons may be smaller but there is 8 of them as opposed to 4 of them.

Everything else in the system is fine.

[Admiral Ballsy]

....and they only move half as far, so use half the fluid.

[Flat Black VW]

Originally Posted by Admiral Ballsy

....and they only move half as far, so use half the fluid.

Makes sense. Guess ill have to go over everything again.

[Admiral Ballsy]

There really shouldn't be any fluid effects - the pads sit pretty much touching the discs all the time, and applying the brakes just applies force; the actual movement is negligible. Opposed-piston calipers require more fluid in the system (more space to fill), but it sounds like you have that covered.

If all else were equal, your setup would require a little more force on the pedal to generate the same force at the discs, since the pistons are a little smaller, but I suspect you've got grippier pads than stock - so that's probably a tossup.

About the only thing I can think is that you've still got some air in the system. Multipiston calipers can be a pain to bleed, that's for sure.

[Racecomp Engineering]

The total change in piston area is fairly small, and Admiral Ballsy is correct that there is less functional piston area with the 4 pots. So yeah, something else is probably wrong here. Try bleeding again.

Did you switch to Hawk HPS pads by any chance?

- Andy

[Wonderbar]

My pedal is identical to stock as much as I can tell.

[OrbitalEllipses]

Originally Posted by Racecomp Engineering

Did you switch to Hawk HPS pads by any chance?

Garbage pad.

[Racecomp Engineering]

Originally Posted by OrbitalEllipses

Garbage pad.

Michael: It's like we finish each other's...

Lindsay: Sandwiches?

Michael: Sentences. Why would I say...

Lindsay: Sandwiches?


- andy

[Scooby South]

Finally got my stuff done for Toledo. Looking Forward to it..
Got my Rear Brakes on Finally... HUGE THANKS to Ken at KNS Brakes.. Once I Got it all sorted.. They Went on without issue.. ...

Also taped up the front end for my bug infested Drive. Got my trailer ready to go also



OEM Rear 2pot..Getting some Refurbishment.



Installation was a snap with KNS Brakes Adapter Bracket.. Make sure if you get this to read the installation guide on Kens Website. http://www.knsbrakes.com





Looks and Performs AWESOME.. Definitely a HUGE upgrade over the Stockers.. plus I lost some rotational weight..

And With the wheel on ..



Overall