RACER

More flow, less pressure. Less flow, more pressure. Example, place your thumb over a garden hose. The flow is reduced but the pressure is increased. Now remove your thumb from the hose. The flow is increased, but the pressure is reduced.

As long as the piston inside the master cylinder remains the same, a smaller caliper piston will create more pressure, hence more feel for the driver. This is also true of various diameter brake lines.

alexf20c

You guys think too hard.

jbot, what size tires are you running on your S2000?

RACER

Nobody

I don't care what calipers you're running--if they don't have a significant increase in mass (the Pinnacle system does not) they're not going to have a significant increase in thermal capacity. Additionally, if you can hit ABS with the stock calipers (whatever tires you're running), you're not going to reduce braking distances by any significant amount with a different caliper. Tires are another matter. I run RA-1s, which are surely stickier than the Goodyear tires you're running and I've not come anywhere near reducing braking distances by 25%.

And removing the inner shields definitely helps dissipate a small amount of heat (which will radiate into your suspension components), but it's no where near the heat dissipation you'd get from running 3" ducting.

But with all that aside, would you care to comment on the electronic equipment you're using to gather your data?

slipstream444

Your garden hose theory is really a very poor example. While it shows you're trying to reason through the problem, it lacks any practical application to the argument at hand and shows you do not have a solid grasp on fluid dynamics.
Now there's nothing wrong with that as long as you're willing to learn.

I don't have the time to explain the principles at hand here in great detail, but here's a basic run down why your theory is wrong, and what forces are really at play. This is only a very basic explanation though.

A garden hose running water past your thumb is considered an open system. A braking system is a non-compressable closed hydraulic system ... two very, very different principles at play.
This is a very simplistic, but effective example:
Consider a closed hydraulic system to be a solid mechanical link in the lines - and the size ratio between the input and output piston (force) areas in the system to be force multipliers. There is no flow return. Any circulation is minimal and due to heat differences in a braking system. Think of a hydraulic system as a force multiplier, as a gear reduction system is in your transmission (not in the literal sense). Gear reduction systems turn high speed low force motion into low speed high force motion.

If you own a hydraulic jack, take a look at the difference in size between the input (hand pump) and output sides (the cylinder that moves your car). You move a small piston using a leverage arm several times to move a large piston with several times the force you alone can produce. The large piston moves a proportionally smaller distance, but with much greater force. It's a tradeoff of volumetric displacement to amplify force in a closed system.

The only difference in your braking system is that you have a booster (and proportioning valve) that distribute your ~200 lbs of force over four brakes (and lots of pistons) providing thousands of pounds of clamping force. The amount of feedback or feel in the system is a function of the amount of flex inherent in the system (caliper material, machining tolerances, hose flex), and other damping forces created either deliberately or through design flaws.

slipstream444

[QUOTE=Nobody,Oct 6 2004, 10:00 PM] I don't care what calipers you're running--if they don't have a significant increase in mass (the Pinnacle system does not) they're not going to have a significant increase in thermal capacity.

slipstream444

[QUOTE=Nobody,Oct 6 2004, 10:00 PM] bla bla bla ...
Tires are another matter.

slipstream444

The stops from ~120MPH were not as well documented because my stock system tolerated only one stop. The two stops I made from (118 & 116 MPH) with the Pinnacle system were consistent, and a solid 35% shorter than the stock brakes. I didn't feel comfortable attempting a second stop from near the 120MPH mark with the stock brakes. It took forever for the stock brakes to cool down after the one stop ... and the smell was horrible.
Is this a scientific experiment? No. But a good demonstration of the difference. I felt I could have made several more 120+ stops with the Pinnacle system. I'm that confident in them.

jbotstein1

I have stock wheels and stock potenzas. S-02s

slipstream444

The stock wheels are just fine and SO2s are one of the best tires out there.

How many miles are on the SO2s and what condition are they in?
The reason I ask is SO2s can get pretty unstable once you get below the wear indicators ... pretty much on any surface. I got 12,500 miles out of mine, and that was pushing it longer than I should have.

While your Willwoods may not provide a difference in clamping force, they should not cause your ABS to cycle unless something is not right. It very well may be the condition of your tires. I talked to a couple of brake gurus and the consensus was the caliper flex in the Willwoods shouldn't be great enough to cause your ABS to cycle.
Additionally, I would pull your wheels and check the torque on your caliper's mounting hardware. Loose hardware would be a very bad thing and could cause your ABS to cycle.
If you have any distortion in your rotors, they may cause your ABS to cycle as well. Have your rotors checked for runout.
I would consider bleeding your brakes ... this should be done once a year anyway.

What kind of pads are you using? If you're using a pad that's too aggressive, you'll get inconsistent braking because your brakes will never be able to maintain the proper temp for a racing brake compound and your friction coefficient will constantly vary - resulting in possible ABS cycling. If you're using a racing pad on the street, I'd switch to a more street oriented pad.