Johnny C is the majority of my real name. I'm a "brake guy" by profession and by hobby. I have an obnoxious amount of brake tech swirling around my noodle. If I crammed that info into a Book, nobody would read it. It's some of the driest information anyone could imagine. If and only if you have an issue with your brakes would you pay attention.

About me: I'm a former PFC factory Rep. I've worked with top racing teams like Joe gibbs racing, Ganassi, Rum bum, Irish mikes, so on, and so on. I've been in the motorsports world professionally starting in 2006. I've worked hand and had with teams and engineers to build braking systems and to fix issues with braking systems.

If you having an issue with your brakes, please ask. Or if you are looking to upgrade your brakes, please ask. The majority of club racing related braking issues I come across, are from individuals who tried to upgrade their system.

 

Here's a question for you:

How do teams like Joe Gibbs and Ganassi predict pad life? How do they calculate when to change pads in a 24 hour race?

 

Brands like PFC, AP, ENDLESS, Brembo, and so on do testing on brake dynos. they will take telemetry and make protocols to run in computer simulations and on a dyno. for example on a short track (nascar), one car will brake from 170-60, 300 times, at a force of 1.6g. They will build a pad in the computer then test it on the dyno with a simulated race. Back when Ganassi was running a DP on iron rotors we told them that at hour XX you will need to do a brake swap.. It's crunch time for brake engineers during an endurance race. there are so many factors that can throw their calculations into the weeds.


For nascar we made a Huge pad. normal pads are 16-25mm thick, nascar pads can get close to 38mm. they need to be that thick In order to stop a huge car(3400LBS), with tiny brake rotors, 900hp and do that for 3 hours.

 

I run Sports Brakes all around on my turbo'd 1990. I decided to go with regular/jobber rotor with my HP+ since a lot of people told me that expensive rotor was money thrown out of the window... Knowing that the car don't do more than 30min session, I'm daily driving it and I get no brake overheat.. Are these people right? Would it be beneficial to get proper rotor performance wise?

I'm on my second year with HP+ and I'm curious about trying something else, what pads/rotor combo would you suggest for my current setup?

Thank you for your time, this thread will be interesting.

 

there are allot of different aspects when it comes to a rotor.
What is it made from (Iron, Steel, Aluminum, Carbon ceramic, Carbon Carbon)
Where is it made
Is it 2 piece (hat made from aluminum, Rotor ring made from iron)
if it is 2 piece does it float?

Not wanting to spend all day i'll try to keep the answer short. and focus on the standard parts store rotor.
Standard rotors that you find on Rockauto, Autozone, and so on come from china. They are covered and machined with oil, the material to make them is not as pure as it should be, and are never made engineered for racing. allow me to explain.

The machining process for Chinese rotors involves blasting the machining surface and tools with a oil to keep them cool, this lowers maintenance costs on machines. Then factory workers will warp the rotors with an oil impregnated paper. This oil is in an attempt to prevent rust, at that it works well. The problem with using so much oil is that, it will impregnate itself into the iron. once that iron is impregnated the oils will come out under extreme braking. Most of the time when you see issues creating and keeping a transfer layer, the oil inside the iron is causing that issue. It impurities in the rotor are kicking the transfer layer off. Racing companies like PFC, Brembo, AP, will cut the rotors "dry". Dry means to machine the parts without any oil. it is more expensive to do this but will increase the rotors ability to obtain and keep a transfer layer.

Next is what it's made from. Iron is easily one of the best materials used for rotors. Size for size an iron rotor will outperform a carbon ceramic rotor. if you have 14" rotors one in carbon ceramic and one in iron, the iron one will generate a more consistent and higher TQ output. Not to go too off track but that is why you see 15-16" carbon ceramic rotors on oem vehicles. The oem manufacturers need the increased size to get the performance. but Carbon ceramics will outlast a iron rotor. ...sorry back on topic, right iron.. Iron is one of the densest materials in the universe. also how pure it is in the casting for a rotor makes a considerable margin in braking performance. rotors that are casted in china are known to have quite a few impurities, and are labeled incorrectly. anyone that has dealt with 304 *chinese* stainless will know what i'm talking about. these impurities will have a decreased effect on braking performance. I like to find Rotors manufactured and casted in the usa. the us has a higher standard of casting. again PFC, AP, and brembo all are manufactured in the USA, GB, or Italy.

finally the engineering in the rotors could take year to explain, so i'll focus on balancing only. when a rotor gets hot it cones, it beds, and it looks like a wave. it's never still. The material is constantly flexing. think about a top fuel dragster tire in slow motion.. it's not 100% the same but it is close. that rotor is constantly trying to keep itself together and not explode. in order to stop a rotor from shaking the wheel all manufacturers will balance them. Top Motorsports brake manufacturers will balance the rotor by cutting the entire outer perimeter of the rotor on a lathe. this ensures that when a rotor is at thermal capacity, there will be no places of excess or minimal material. it makes the rotor stronger, and more resistant to cracking. part store rotors balance the rotors by finding the heavy spot on the rotor and cutting that off.

what not to do.


In motorsports this is a huge no-no. the hard edges give a place for cracks to start, the material has a thin spot on the rotor, and it means that the material that is spinning is not balanced through the assembly. it can lead to a cracked rotor and can lead to problems with a long pedal.

In conclusion, :P. is high quality rotors a waist? Like tools good quality parts are never a waste. On average a motorsports rotor will outlast a parts store rotor long enough to justify the price. Parts store rotors can work, they also let allot of people down. If it was my money, paying for my track day, i'm putting the parts on my car that will insure that i have a fun weekend. i'm not looking not fight the $30 rotor that costed me $800 of track time. Allot of people might say "they worked fine for me". Truth of the matter is 80% of the motorsports population knows how to build a motor, 10% know how to build a braking system. when the brakes that they said "worked fine" didn't work "fine", and that person has no idea what the problem actually is.


For the street/race duty pad you got it. The hp+ pad was the only compound from hawk that i like. They have a new pad compound out now called the "5.0". I have a set in my garage right now and i'll let you know how they work.
Rotors, Find something with a curved vein, manufactured in the USA,GB,Italy or australia... if you can.

 

A few folks have poo-poo'd the wildwood calipers that comprise a lot of miata BBKs due to the caliper itself supposedly flexing. Any experience with this? Is this a legitimate issue for the 99.9% of cars that aren't built to win a world championship?

 

Red car has a Goodwin V1 BBK on the front (Wilwood Dynalites). Purchased and installed by PO.

I just changed a set of XP10s last night after 4 months of almost-every-week track use. Compared to OEM brakes with similar pads, that was excellent life. There was pad taper, but it was easily only 25% of the taper I used to get with OEM floating calipers and I was able to run the pads thinner.

So, do the Dynalites flex? Yes. Does the BBK with Dynalites still deliver less taper and better life than OEM? Yes . . . by a 2X margin on my car.

 

I really want to make these posts about education of the community and not just "well it works well for me". to do that i'm going to need to be quite dry and i apologize for that .

I know all about it.. i have them, hate them, but you don't see me removing them. not yet anyway. The Dynalights are Flexy little calipers. wilwood will admit it too. they will also admit that they are originally designed for the rear of a car, and the cheapest calipers they have in production. When you have a 4 piston caliper like the dynalight you can expect a lot of drag. but hope is not lost. A motorsport caliper is only as good as how strong it is. after that we look at how well it keeps heat out of the fluid, and piston size.

A Caliper that creates a pad taper is a caliper that flexes, that flex creates drag. 370z sport brakes are notorious for doing this. the 370-sport brakes are complete garbage and they heat up brake fluid very quickly. People that Don't know braking systems like to blame the fluid, as that is the component that failed. When in actuality it's the caliper storing the heat like an oven and inserting it into the fluid. some people might remember the 370 that a journalist drove into a wall during the z's release. I think the journalist blamed the brake pads. shows you how much an auto journalists know about brakes. Anyway i digress... A flexy caliper. the wilwoods dynalights are very inexpensive calipers and the good news is that there are many companies out that that make their own version of the dynalight. Stoptech and bear are the ones the pop to mind.



Keeping heat out of the caliper is another aspect of a good caliper. the dynalight has what is called an "internal" crossover line. that means that the fluid travels inside the caliper. this is generally considered a bad thing when it come to performance. as the calipers temperature rises the heat of the caliper enters the fluid. also causing fluid failure.
PISTONS. omg pistons drive me mad. I get asked all the time "should replace my piston with stainless pistons"... STOP!! the pistons need to be made out of the same material as the caliper is made from. I have no idea who invented the stainless piston but that guy needs to kicked in the *****. I've had to fight this topic for a while. If your caliper expands at a different rate than your piston then you have a higher chance for those pistons get locked in the bore. this is especially true if you're near the end of pad life and the pistons are hanging out. the excessive tolerance causes caliper failure and leaks. yes stainless does transfer heat less than aluminum but replacing the piston with stainless is not a good idea. instead if you are having heat issues try an insulator. plenty Of circle track shops carry insulators for dynalights and super lights.

to answer the question "Is this a legitimate issue for the 99.9% of cars that aren't built to win a world championship?" it depends on what you find important. none of us are out to win a world championship, not on dynalights anyway. the Dinallight is a flexy little caliper that is cheap. it will help you burn threw rotors and pads fast but... Very high end pads are very cheap in the dynalight size. so if you don't mind burning threw them then keep on rocking. keep in mind that if the caliper flexes a lot that means it wont last very long and replacement on a very heavily tracked car should be every 3-4 years.

 

Then the question is, is the extra few ounces and dollars of the dynapro worth its increase in stiffness over the dynalite and can it be used interchangeably? I'd just look that last part up myself but my work seems to alternate weeks where wilwood's website is blocked by the firewall and this is one of the blackout weeks. Or is there another better caliper that drops in place of the dynalite thats better and isnt like $400 or anything silly.

 

Calipers are wear items? The ****....

 

A couple of observations-
More aggressive pad compounds require less pedal effort and therefore cause less flex.

Some of the pad taper I encountered back when I was using stock calipers was attributable to play in the slider pin to slider pin hole interface. When worn it would tilt a little under pressure, generating some taper. Caliper flex added to it made pads go bad quickly. Things improved with new slider hardware.

 

the older calipers get the more they will drag. we'll walk around in the hot pits of practice and test days with a proble. we'll hit the rotor and record the temperatures. You can tell if a caliper is dragging by an unusual temperature, at that point it's time to replace it. sometimes the driver notices it, sometimes they don't.

Yes on a sliding caliper that can be the issue. My post was focused on a fixed motorsports caliper. that being said a OEM caliper has it's own disadvantages. and upgrading to a fixed caliper is recommended.

One other thing that allot of people don't know. Braking components absorb less heat with a higher friction pad. it's sounds backwards that a higher tq pad with create less heat. it takes X amount of energy to slow a W weighted vehicle to Z speed. Brakes turn rotational energy into heat. everyone know that, correction... everyone should know that. if variables W and Z stay the same that means X stays the same too? the answer to that is yes. So you're going form a (for example) low TQ pad like a PFC 97 to a med TQ pad like a PFC 01. If the vehicle's weight remains constant and the amount of speed needed to decelerate remains constant, then both the 97 and 01 will produce the same amount of energy (heat). the Med Tq pad will create that energy faster and more intensely. With that you might ask yourself "how can braking components absorb less heat with more intense heat being produced?" The thing with a higher tq pad is that you're using it for a shorter amount of time. This give the heat less time to leach itself into other braking components.
I had a problem with a team running a caymen. They were bending the backing pads on a set of 97 compound. They could not figure out why they were doing this. After some investigation I discovered they were using a OEM abs system and refused to turn it off. I upgraded their whole system to pfc 01, and the problem went away. the backing pads on the 97's where getting so hot the abs could hammer the backing plates like a blacksmith and bend them.

the dyna pro's are not a direct bolt in. they are .07" taller than the dynalights. Baer does make a caliper that is a direct bolt in. it's almost identical to the dynalight except that it's a 2 piece caliper, Vs the dynalight 3 piece construction. it retails for 200 something and will be giving them a try. they seem to be taller than the dynalight. I hope they clear a 6ul.

 

Are you familiar with Coleman Racing Products, and how would you rate their rotors?

 

Great thread - thanks. Although my season is over (winter's coming), I will watch this thread with great interest. I currently go through XP12 front pads like they're going out of fashion with my Goodwin BBK with DBA friction rings. I had just installed higher-torque XP24s, in the hopes of getting better life, but then my transmission gave up the ghost and ended the test. I've experienced pretty much all the symptoms you list (pad taper, heavy wear, boiled fluid) and would seriously consider a better caliper.

 

Recommendation for stock rotors for a '94?
Ones that aren't made in China/etc?

 

This doesn't make sense to me.

The amount of braking force you can put to the ground is largely dependent on the tires being used.

To me that implies the lower tq pads didn't have enough power to lock the brakes..........which seems strange even for a low end track pad on Hoosiers.

 

Honestly, with the HP you're sporting, you need to go to the 11.75" brakes. A better caliper by itself won't get you there.

 

If it was a track-only car, I would be all over that. Given that it serves a dual purpose, I need to keep brakes that allow for reasonable street wheels.

That being said, I had a discussion with Emilio at 949 Racing on the subject and he recommended that I try the XP24s first, along with 3" ducting (currently installed, but needing fine tuning on the inlet side). I'll see where temps are once track season starts again next year. If things aren't appreciably better, I'll likely break down and spring for the bigger kit. Regardless, though, wouldn't a better caliper help the 11.75" system just as much?

 

14's are reasonable street wheels to you? 11.75" brakes fit under a wide selection of 15s.

 

Nah, I run the 15x6 BBS rims (+1 to what came with the car). I run 15x9 6ULs on the track and am considering 15x8 for the street. However, as far as I can tell, spacers are required for both of these wheels, which means running extended studs. From another thread here, it seems that installation of longer wheel studs can create stress risers that promote early hub failure. I dunno...