2001CamaroGuy

iTrader: (6)

After working out all the numbers, it looks like one can actually get more clamping force out of most 4 piston calipers than one could out of 6 piston versions.

The reason being that (use Wilwood calipers for example) the effective piston area of a 6 piston is limited by it's staggered bore vs. a standard 4 piston having symmetrical bore.

ex:

Wilwood SL6R bores are 1.62"/1.12"/1.12" which gives an effective area of 4.03"

vs.

Wilwood SL4R bores are 1.75"/1.75" which gives an effective area of 4.81"


Now when one runs the numbers of line pressure, rotor size, pad compound, etc., the differences are quite a bit.


As I understand it, the entire idea behind having the staggered bore of the 6 piston is to help with pad wear under extreme conditions but how serious is this? At what point does the 6 piston actually become better than the 4 because based on numbers only, the 4 would result in a much higher clamp load at the same pedal pressure.

SouthFL.02.SS

Many times, a 2 piston, non fixed caliper (common OEM design from many manufacturers) will offer more clamping force (as you've stated) than a 4 piston fixed caliper. When dealing with fixed caliper brakes, 4 piston vs. 6 piston, we're talking about brake modulation and design for heat dissapation and distribution of force needed for pad clamping (as you've mentioned already). 2 pots can make a tire lock up, but 6 pots will help you modulate that threshold to lockup much better.

2001CamaroGuy

iTrader: (6)

so at what point is it better to "give up" a bit of clamping force?

Castrellon

You can lock up the tires easily with six as with a two pot. Clamping is not the issue, modulating the clamping load just above impending lock up is.

Two pots, four pots, six pots. Either one of these will lock up the disc. Which keeps you out of lock up longest is what you're after with more pots.

Hope that helps clarify.

2001CamaroGuy

iTrader: (6)

yeah....that seems to be what I was missing. I can "clamp" the stock brakes on my Silverado but can't feel them at all (they just LOCK and then kick in the ABS).

Castrellon

That's it in a nut shell. Hovering longer over impending lock up is what it's all about with more pistons.

2001CamaroGuy

iTrader: (6)

I'll take the 20pot version...lol


Now I get to look at who I go with for calipers. I like Wilwood (don't cost HUGE $$$) but everyone seems to feel they won't hold up to any real dedicated track use.

Castrellon

Don't know what to tell you. I read on an SCCA site that this dude bought some cheapo discs, sent them out to get sonic tuned or some thing and then cryo'd. Said they've lasted like four years in competition. But I've also read that rotors are cheap and just stick with stockers if your not super concerned about the weight.
I had a friend who had bronze coat or what ever wash, he loved his, but I don't think it's worth it. Project Mu's on a Skyline. Then he got a Fairlady Z. Now he's got a crotch rocket. Just can't make up his mind.

2001CamaroGuy

iTrader: (6)

Wow!!!

Castrellon

http://sccaforums.com/forums/thread/22968.aspx

Castrellon

I remember now, the rotors were Zinc washed.

2001CamaroGuy

iTrader: (6)

just Zinc washed? isn't that just for "anti-rust"?

roadracetransam

iTrader: (14)

After looking at how my disks look after 2 hours of track use, I have a hard time beliveing that disks might last 4 years, no matter how they been sonic tuned?, cryo'd, and or any other woodoo magic performed on them.
IMO disks, like pads are wear items.

Castrellon

Don't know, you're to have to research it like me and find out.
I've tried emailing my friend in Japan, but he's hardly ever online and I don't know how to dial to Japan.

Castrellon

Check the link I posted up. Scroll thru it until you see stuff about the sonic tuning and what not. I've seen lots of others with your mindset saying it just isn't going to help any.
Only way to know is to try it, hope you don't get busted, and then keep a log on how many runs you get with modded and unmodded parts.