[Ron Sutton]

Originally Posted by carbuff

Ron,

A couple of questions:

What is the * asterisk for? I didn't catch it in the follow on. And how is this test/proven? I'm sure you've told me before, but I don't recall...


In looking at my rotors/hats, I don't see how the rotors 'float'. In reading StopTech's website, it seems they have a version of the Trophy kit which comes with the floating rotors, but that version doesn't have the piston dust seals. The kit with the seals doesn't have the floating rotors.

Obviously you can assemble these kits however you want I assume. But I cannot tell if/how to identify whether my rotors float? This would be a great feature to help stave off the purchase of a full floater on the rear of my car, although admittedly I haven't yet experienced a real problem with knock back that I'm aware of...

Thanx!

Hey Bryan!

It's hard to believe as long as my detailed answer was that I left something out, but I did. I meant to add some text that explained the * asterisk, but forgot. Here goes ...

When I first came into the Pro-Touring world in late 2012, I was surprised at the brake problems that existed. People were buying & installing big brake kits on their Pro-Touring cars ... driving them on the street ... and running them in autocross & track day events ... with complaints of low braking force.

The people "solving" their low braking force problem were switching from street performance pads to full on race pads. I have seen a ton of them utilizing Hawk DTC-60 & DTC-70 racing pads. That's about as aggressive a race pad as you can run. There are better race pads, but not much higher CoF than a Hawk DTC-70 race pad.

But these high CoF race pads are horrible for street driven Pro-Touring cars.
* Race Pads cost 3 to 4 times as much
* Race Pads wear out 2 to 4 times quicker
* Race Pads dust up like mad
* Race Pads squeal like crazy
* A friend of mine says they couldn't sneak up on a Rock Concert. LOL
* And as a bonus, Race Pads eat up your rotors

As I looked at the challenge of a brake system to do all three, the problem with the brake packages on the market were obvious to me. None of the current systems had enough clamping force from caliper. The piston area in the caliper was too small. So their only solution was high CoF race pads.

While brake technology is complex, the concepts are simple. There are four things that make braking force.
1. Hydraulic pressure from the pedal & M/C (and booster if utilized)
2. Clamping force of the caliper from that pressure x piston area
3. Rotor size (Leverage)
4. Pad CoF (Coefficient of Friction of the pad material)

In 2012, the pro-Touring brake systems all came with small piston area. When I studied the calipers, it was clear we couldn't simply increase piston sizes, as the calipers offered were too small, too thin & too weak. What I'm saying is they lacked the structure integrity & rigidity to handle more clamping force without flexing. If you increase the hydraulic pressure to a caliper like this ... through higher pedal ratio or smaller master cylinder ... all it does is flex the caliper more. The same thing happens if we increase the piston sizes (piston area) in a weak caliper. It just flexes more, in a clam shell sort of way. When you do this, calculations on paper may show the braking force going up 20%, but the real world "measured" braking force increase may only be 2-5%. That loss is from the caliper flexing. Caliper rigidity is a big deal in a performance or racing brake system. That much caliper flex is dangerous & annoying. The pedal feels like mush. There are videos out there showing these calipers flexing like crazy when people increased the hydraulic pressure or piston area in weak calipers.

The solution sounds simple. We need calipers with larger piston area so we don't have to run high CoF race pads. But this would require a much stiffer front caliper to handle this larger piston area ... and not flex. I was excited when Wilwood introduced the Aerolite calipers. They were significantly more rigid than anything being offered at the time in 2014. I probably have 100 customers running that caliper with the increased piston area from 4.04" to 5.40". They work a lot better.

I still like that system today, but frankly I wanted something even better than that. So I set out to find the stiffest caliper I could ... to build my new brake systems around. I went to a private company with a brake dyno and did back-to-back tests of 5 brands of calipers, all with the same piston area, same pad compound, same rotor size & same hydraulic pressure.

The Test Results:
StopTech ST 60 Caliper / .010" Caliper Flex / 984# Braking Force
Brand X 6 Piston Caliper / .013" Caliper Flex / 972# Braking Force
Brand Y 6 Piston Caliper / .016" Caliper Flex / 965# Braking Force
Brand Y 6 Piston Caliper / .070" Caliper Flex / 922# Braking Force
Brand A 6 Piston Caliper / .105" Caliper Flex / 886# Braking Force

So I made a deal with Stoptech to co-design & manufacture a new line of cutting edge brake systems, specifically for Pro-Touring Muscle cars doing triple duty on the street, autocross & track days. The new systems did everything I wanted ... because we designed them to ... with one BIG bonus. Never in my wildest dreams did I think we could do all 3 with one pad. But the StopTech 309 performance pad ... which is only .40-.45 CoF ... had excellent cold bite for autocross (and street) and had zero brake fade up to 1200°. Frankly it has only a small brake fade at that point up to 1400°. It is an amazing pad. By itself, it doesn't have a high enough CoF for the small piston brake systems out there. But combined with the rigid ST60 front & ST40 rear calipers ... the braking force of 3460# is higher than Zr1 or C7 Corvette. Giddy Up !

This video is NOT my test. But this video shows a caliper flex test of the StopTech St60 versus a Brembo monoblock caliper.
Go here:


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Floating rotors?
The StopTech rotor mounting hardware is engineered with a conical washer made out of inconel ... the same material in high end exhaust valves. This inconel conical shaped washer acts like a temperature controlled spring. At low temps, driving around town or on the freeway, the washer is in its conical shape ... holding the rotor to the hat rigid. It's the same way at room temp when you're checking it in your garage. This is so the rotors do not rattle and make a lot of noise during street/freeway driving.

As the brakes get warmer, from usage on track, the washers actually flatten out ... allowing the rotor to float on the hat.
Road racers actually change the conical washers to flat washers, so they float all the time. But they don't care about the rattling noises the driver hears at low speeds.