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[FMTRVT]

Figured you’d be back with another receipt. 01, you’ve got a good feel for friction materials.

The 1C3Z-2001-BA were the late 2001 (year) revision of the pads, 2001 (part number) being the base number for front pads. The original pads for the platform in ’99 I believe carried an F8 (1998) prefix. This was another change for brake noise, going to double stick insulators from MSC. With these pads the stainless steel heat shield is no longer used, and the MSC insulator has what I refer to as “Mickey Mouse” ears, little projections on the top of the pads that protect the piston caliper boots from rotor heat like the stainless shims were utilized for.

When these pads are utilized it’s important to serious clean the caliper piston and caliper finger surfaces so the double stick insulator will adhere to those surfaces like they would on the assembly line. I know you’re done with them, but just a public service announcement.

Friction material whether sold OE or aftermarket are required to have the edge code per several states laws. There is no federal requirement. The edge code is generated on what is known as a Chase machine (developed by Dr Chase when he was at GM) and performed under SAE J661. Geoff Nicholson was an engineer at my old company when I first started and his son has a good website that discusses the test, and why it’s not great.

Technical Reports

If you wander around the site, check out Arne Anderson’s article about rotor pulsation. Arne was the head of Ford’s Scientific Research until the latter 90’s.

And an example of the Chase test……

http://www.stopcobrake.com/en/file/en.pdf

From those tests an average cold and hot rating is determined for 250 and 650F. The alphanumeric codes equate to a friction range, i.e. E = .25 to .35, F = .35 to .45, G = .45 to .55. In some ways it can be confusing as a high EE rating is really equal to a low FF rating.

But it gets worse as Geoff alludes to. What a 1” square piece of friction material does in a drum dose not equate to what happens on a vehicle, especially with a disc brake. And it’s all about in-stop friction.

The OE pads you noted are rated an EE, and are a high EE, about .34. But a stable in-stop .34.

By law, somewhere on the pads EBC should have the two-letter friction code. So they are supplying a lower friction rear and higher friction set of front pads. But since they state an average rating, you can’t see if there is a good spread between cold and hot friction. But you’ve already stated there is, as the pads are not as effective until they see some heat. But many semi-mets do this to ‘some’ extent, even the OE material on this vehicle.

And that’s somewhat the kicker. As we get into the more “high performance” types of pads no matter what the friction range, there is a bell curve in the friction level. The bell curve is steeper with really high friction materials, and if compounded for really high temps, the cold ramp-up extends for a longer period of time. The anti-thesis for what OE brake engineers really want in their system, not only for consistent feel, but shorter stopping distance (when cold) and predictable ABS actuation.

I’m gong to go off on a tangent here, so this is not directed towards you. (Here’s where I start loosing audiences).

In-stop friction is the key to short distances. Many people rave about a friction material that really comes in at the end of the stop. The deceleration builds and you get pulled more towards the steering wheel. But if you’re making a stop from 60 mph, you’re traveling at 88 feet per second. If your pulling 15 fpsps (feet per second per second) at the start of the stop and 25 fpsps at 20 mph (~30 fps), it “really comes in”, but your distance isn’t anything special because at the beginning of the stop you’ve “left at lot on the table”. More then the width of the car you just T-boned.

88-15=73 73-17=56 56-22=34 34-25=9 9-25=0 About 4.3 seconds to stop.

With a more stable but slightly lower friction ….

88-18=70 70-20=50 50-22=28 28-24=4 4-24=0 About 4.1 seconds to stop.

But look at the speed differential at each second and think of it as energy. If the hit occurs at the start of the fourth second, the speed differential is 34 fps vs 28 fps, 23mph vs 19 mph.

A driver in a T-boned car usually dies from head trauma when hitting the door at the threshold of 25 mph from my memory.

And the total stopping distance as SWAG of the above values are 208 ft vs 186 ft. for the lower stable friction, way more then a car length although the decel rates are not that different and lower in example number 2. It’s at the start of the stop that counts. Typically the SDs with stock tires are tire skid limited at about 25 fpsps.

And for reference, the 99-04 SD’s with OE materials at 60mph generate about 170 ft stopping distance two passenger and 190 ft at GVW. The GVW tire skid threshold occurs at 55lbs Pedal Effort if the brakes are at 200°F. FM6091EE

The ‘05+ SD’s with OE materials at 60mph generate about 160 ft stopping distance two passenger and 165 ft at GVW. The GVW tire skid threshold occurs at 35lbs Pedal Effort if the brakes are at 200°F. Slightly larger rotors, larger caliper pistons, and the friction material is higher in mu (coefficient in friction) in the cold range. FM2160FE.

That is if you believe the Chase machine ……

By now someone is thinking about going back to the OE material. Not if you have experienced pulsation, and not if you have larger then OE tires on this vehicle and the brake size is easily overwhelmed with oversize wheels and tires.

I’ll throw out one more thing that is important to us that (or used to) develop brakes for vehicles. In Geoff’s Chase test information he states something that to many people defy common sense. After all, you want the most stable brakes on the planet.

“A material that does not fade when temperatures get high can be dangerous. A driver is not aware the brakes are hotter and does not adjust his driving to compensate. Brakes can get hotter and hotter until the tires burst, or the brake lining catches fire.” Or the brake fluid starts to boil.

But that’s for another tirade of mine………

An image of our caliper piston boots that burned during a brake fluid boil test. And why those heat shields or “Mickey Mouse” ears are important for those rare extreme heat conditions, like Townes Pass.