Thank you Golgo!

250miles on the new setup and have found no problems. My only note is that I plan very soon to switch to ss lines and speed bleeders so that I can get rid of some of the pedal travel but I know ultimately it could be because of the master cylinder difference ours being 22mm and the cayenne/touareg being 27mm. I plan on taking care of that soon. Some may not have this issue and it may not be an issue at all since I have only done one full circuit bleed and got a bunch of bubbles from the outside pistons on all four corners. I didn't get that result during the initial bleed because I needed to start the car, get some vacuum on the brake booster and do it over but didn't have the time. Ultimately though the pedal travel is minimal. I'd say about an inch and even still they slow the car during that inch but after that inch boy hold on!

 

post a video if stop from 60 - 0 and tell us how long it takes and how big the improvement over stock is, also are you changing out the back brembo also?

 

I will get a video up this weekend of the 60-0 between my car and my friend's evo 9 with stock brakes. I plan on doing the rears as well but just trying to find the time right now for the mods along with some proper measurements for a viable 4pot rear swap without any mods or very little mods.

I did some digging and have been talking to a bunch of guys that have done brake swaps before or have gone to calipers that have a larger piston surface area than stock and the altered or rather lengthened pedal travel is normal seeing as the master cylinder has to technically work a bit more to create the pressure to push two more sets of pistons over stock. No amount of bleeding can over come pressure differential and requirements.

That being said, the pedal travel I experience isn't one that would scare me or cause me to drive cautiously because the amount of braking pressure applied to the piston surface area during that travel is enough to notice a decrease in speed just as the stockers offer. Again, a video will illustrate this better and is soon to come.

 

There are aftermarket six piston kits for the evo that do not require any additional changes, so I think this would be no different.

 

34mm piston diameter = 1.33858 radius of which is .66929
36mm piston diameter = 1.41732 radius of which is .70866
38mm piston diameter = 1.49606 radius of which is .74803

pi=3.1417 x (.669x.669) x 2 = 2.81220478 or just 2.812 sq/in of piston area if there were 4 34mm pistons

doing some math

 

So the evo caliper pistons are 46mm and 40mm. Using the equation above the evo calipers have
46mm piston diameter = 1.81102 radius of which is .90551
40mm piston diameter = 1.5748 radius of which is .7874

since we are only accounting for the number of these pistons on the car totally one can say that the evo has
(46mm piston) + (40mm piston)
1660+1254.8=2914.8mm/sq piston area for the evo caliper by calculation

and

(34mm piston)+(36mm piston)+(38mm piston)
907.09+1015.5+1133.5=3056.09 mm/sq piston area for the 17z caliper by calculation

 

So not insanely bigger surface area.

Still an upgrade, but I wonder if it's worth it for such a nominal incremental increase?

 

Yea so here's the thing. It's a small upgrade, about a 10% increase in piston surface area, but the piston surface area lends the ability to press upon a much bigger pad and thus be more effective over a much wider surface area on the rotor. The 17z calipers being used on the evo 328mm rotors allow them to utilize 100% of the rotor swept area. Too much bigger and the master cylinder ends up having to work too much to provide the amount of braking being requested. Which would, in turn, end up resulting in more pedal travel which some people would translate as spongy brakes.

 

Great info in this thread. I am going to have to do some reading about how to setup the six piston rotors to my needs but I am glad that you did the majority of the legwork on this.

Thanks for the contribution.

I have a simple idea to make the mounting of the six piston caliper just a little safer. Since the mounting points on the hub are slightly off the mounting points of the caliper then one could drill/mill the holes in the hub bigger like previously shown. Then one can mill or more likely machine a sleeve. The sleeve would have the outer diameter of the hub mounting hole. Once the sleeve is inserted its flush with the hub. The inner diameter will match the hardware previously mentioned. However the position of the inner diameter hole would not be in the center of the sleeve. It would be off center to match the mounting point on the caliper.

I am curious to hear your input on my idea. Thanks again.

Picture of my concept

 

Been thinking about this idea too except the holes don't seem to line up at all.

What I've been thinking about is relocating the whole caliper upwards or downwards and making a bracket. That way, you don't need to mill/cut/machine out anything except maybe for the heat shield. Of course, my car still isn't running so it'll take a while until I get to that point of even trying to get these on.

As for the rears, it looks like the right caliper has to go on the left and vice versa since the calipers are towards the front of an actual Cayenne while our cars are towards the rear. Of course, you might be able to swap the brake line to where the bleeder and bleeder to where the line was so you wouldn't have to mess with the brake bias on the rear (yeah, pistons are different sizes on the rears too). Also, Evo X rear rotors won't fit our cars so you would have to find someone that makes 330mm rotors with our drum size and everything. Unless you get the black Cayenne rotors, which I think are 300mm? I'm not 100% sure. I just know the silvers and reds are 330mm.

 

Wow this is really innovative... i might have to try it and the srt8 rears.

Thank you all for sharing this information

 

I did some more reserch on this option and found a thread somewhere on the great google and there is a fella that did the conversion on his 91 NSX with the same concept but pressed the machined spacer into the caliper ear versus messing with the already thin hub. He pressed them in and offset the hole to match.... just an idea guys that may cost less than destroying your caliper mounting bracket on the car.

 

Care to share the link to the thread you are mentioning?

 

I am trying to find it... I was searching google it was on a thread on nsxprime.

 

I am definatley on oa mission from this thread to get a BBK completed at a reasonable and practical price. I have been looking at the bigger 18Z and some other 6 piston options out there but man its tough to get these things to fit without a bracket.

The ralliart guys seem to have an easy boltup solution but not so much for me.