Brake kits...how to navigate it all..

[spanky55amg]

Thanks all. I'm going to do the stock stuff... this is my Home Depot run truck.... sometimes burnout truck.... I have my BMW for my performance urges! Yes my BMW is 580hp!

And the Mercedes Benz tech says, "What, you couldnt afford the Benz?"

 

[krautmeister]

And the Mercedes Benz tech says, "What, you couldnt afford the Benz?"

Oh I'm going over to that side soon... E63 wagon... I would do CTSV wagon but the wife likes benz better. It's that or the new GLE63... having a kid changes my requirements!

 

[Affende]

^^^ This, unless you want/need performance... from pads or calipers. But either way, a good blank rotor is the best way to go. You dont need these slotted or drilled rotors. They actually cause you to loose stopping power as it is less friction material.

First, i will preface my dissertation by saying i agree with most of your statement. For 90% of braking application, i believe you are truly correct. Barring special applications (and likely all of us, including me) a blank rotor is the best way to go for many reasons.

Whether or not they add or subtract stopping power depends on how they are used. Brakes work off of surface friction and and their ability to control heat input. When we brake, we are transferring friction material from the pad to the rotor which aids us in gripping the rotor with the pad ( "warped rotors" are very uncommon .... however, hard stops and transferring uneven amount of friction material to the rotor, thus causing a pulsating feeling in the brake pedal, is much more common).

Higher mass in the rotor can hold more heat. Hence the reasoning behind 1.25" rotors being heavier duty than 1" rotors. Same goes for diameter. Larger diameters for a given thickness increase mass. (Side note, larger diameters also move the caliper further away from center line which increases its ability to stop the rotating mass ... think 6" pry bar vs a 12" bry bar). Speaking of heat input, we also need to control the temperature at which our brakes are operating ... so we start adding vents to further dissipate head by adding surface area and giving cooling passages for air to draw heat away.

Now we start drilling holes and machining slots. These do two things: they add (marginally) more surface area which allows us to dissipate more heat, but they also decrease our mass slightly. So, in these regards, its a balancing act. Are we adding enough surface area and cooling capacity to offset the loss in mass (Thermal absorption)?

Now we get to mention the REAL reason we add slots and drilled holes .... gasification! Our brake pads are made up of friction material (semi-metallic, ceramic, carbon, etc) held together with bonding agents. As we use our brakes we generate a LOT of heat. We try to transfer most of the heat to the rotor where it can be absorbed and dissipated. Unfortunately, some of the heat stays in the brake pads. As the pads heat up, the friction material and especially the bonding agents heat up, too. As they do, they gassify (This is the tale-tell "burnt brake" smell) .... just like boiling water turning into steam (Vaproization) or dry ice turning into gaseous CO2 (Sublimation). This gas as it works through our pads and out to the surface gets trapped between the brake pad and the rotor forcing the pad off the rotor where it floats like a puck on an air hockey table. Brake fade (or "oh ****" as its usually referred to in most instances) is a combination of gasification (pad floating on a thin layer of gas above the rotor), hot rotors (not enough mass to dissipate the heat .... pads cant grip a soft hot rotor), and possibly hot or boiling brake fluid (gases compress more easily than liquids or solids).

So one of the uses of drilled and slotted rotors can be to give an escape route to the gases we create by heating up our pads. If that gas has an escape route (through a slot or hole) it cant build up between the pad and rotor. Thus, our pads stay in contact with our rotors.

Now, if you go through a 'proper' bedding in procedure with new brake rotors and pads, you do decrease the amount of gasification that occurs during heavy use by essentially forcing the agents to gasify under a more controlled situation, prior to your aforementioned "oh ****" moment.

I personally, always bed my new pads and rotors (and new rotors ALWAYS get new pads, never used IMHO). I cant say i have noticed a difference but i also dont race or use my breaks heavily.

Aside: slots have also been said to help clean old material off the face of the pad, decreasing pad life, but insuring good bite from a clean and fresh surface. I have not been able to confirm or deny that claim in my research.

 

[Affende]

For me, the next step up would be Wilwood D52 calipers and their pads with BP10 compound on stock rotors.
http://www.wilwood.com/BrakeKits/BrakeKitsProdFront.aspx?itemno=140-11290-R&year=1982&make=Chevrolet&model=C10&option=With+1.25"+Wide+Front+Rotor

I think this is the route im going with my C15 ... i really like the wilwood D52 calipers, but with the Poly E compound as it has a wider temperature range and higher coefficient of friction across the entire range than the BP10.

 

[spanky55amg]

[QUOTE="Affende, post: 378840, member: 5723"Stuff about brakes...[/QUOTE]

Yep, which is why Im guess that most of us do not need these features. There is a reason that engineers build brakes the way they do. So unless you are racing your truck, you dont need them. I had them on my Trans Am and I'll tell you that it didnt help me one bit. You dont get your brakes hot enough to take advantage of them.

That said.... NEW rotors ALWAYS get NEW pads. End of story. We super agree on that. But Im from the school that you do an alignment on new tires only also. (getting ready for a fight )

 

[Honky Kong jr]

I made my own disk brake kit lol cheaper that way. And all GM stuff just Crome a few different source vehicles.

 

[Affende]

Stuff about brakes...

Yep, which is why Im guess that most of us do not need these features. There is a reason that engineers build brakes the way they do. So unless you are racing your truck, you dont need them. I had them on my Trans Am and I'll tell you that it didnt help me one bit. You dont get your brakes hot enough to take advantage of them.

That said.... NEW rotors ALWAYS get NEW pads. End of story. We super agree on that. But Im from the school that you do an alignment on new tires only also. (getting ready for a fight )

I would not argue about the alignment with new tires. At worst, you are ensuring your alignment is in check to guarantee maximum life out of your new shoes .... nothing wrong with that every 50-80,000 miles.

About the brakes, they only thing i didnt factor in was personal preference. I will be going with drilled and slotted rotors (hopefully in the 12.5" range) just for the sake of doing it. I dont need them, i wont use them to their full potential, but they sure do look great, IMHO.

 

[Affende]

I made my own disk brake kit lol cheaper that way. And all GM stuff just Crome a few different source vehicles.

Details?

 

[krautmeister]

I ended up with the AC delco caliper & pads kit with upper control arm replacement... easy peasy!

Replaced flex lines too...easy enough.

Stops like a champ and panic stops are straight. Gotta do the drums soon.

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[Honky Kong jr]

Details?

92 ish Blazer rotors with the centers machined to fit over the lip of the axle, caliper brackets from a K10 front axle with the centers machined out to fit ones the axle snout. 76 Vette wheel studs, K 10 calipers and lads but had to modify the pad a little.

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[MikeB]

Anyone who uses drilled rotors should check them periodically for cracks around the trendy holes. Very common, especially with Chinese rotors. IMO, slots and holes are nothing more than fashion statements on the typical street-driven vehicle. And I doubt most of use will ever heat up our pads enough to cause them to float on a layer of gas! Heck, I have driven several vehicles from Jeep Grand Cherokee to Chevy pickup to Eagle Talon in the Colorado and Utah mountains, and have never experienced fade with OE-type rotors and premium pads like Raybestos EHT, Wagner ThermoQuiet and others.