johnny c

adjusting brake torq by using pad compounds is the last step in balancing a system. we want to start with a square set of compounds because with a well balanced system the rears and the fronts will run within +- 200* of each other. when i'm building a system i know the rears will have less of a duty cycle on them so i will install a smaller rotor, and smaller piston. if i get it right the temps should match.




I say that mixing compounds is a last hope Idea because doing so is easy and can be done at the track. The reason why I don’t want to mix and match pads is proven by the hawk chart. Let’s look at the dtc 60 vs dtc 70 as an example. at the 0-400* range the DTC60 has a higher mu rating than the 70’s. after 400* the DTC 70 bolts 12% higher than the 60’s.

Let’s take what we know and apply it to Daytona and specifically turn 1. Turn 1 at Daytona is a 150-170mph braking zone that is not straight. it has a slight arch. It’s also after a very large straightaway that will cool the brakes significantly. Going into turn it the brakes could very well be under 400* the rears will start slowing the car before the fronts will. This will cause the car to weave around and become unstable. Once you pass the 400* mark the fronts will ramp up torque 12%! So in less than a second your car goes from sketching around to locking the front , and using more the front tires grip. Mind you this extra front grip is being taken away by the brakes, is the same front grip you need to turn the car.

I use the hawk graph because it’s a cartoon. I do not think it’s accurate in any way. The fact that the dtc70 is over .9Mu is ludicrous. If that was true there would be no way you could put it on a street car without constantly smoking tires. But it does highlight my point of why you want to build a system and adjust it with rotor sizes and hydraulic advantage first. adjustments with pad compounds should be a “at the track” option.




What I do think is accurate is the padgid chart. It shows a very low but existent TQ levels at low temperatures. Rarely do you see lines cross each other and the friction levels stay consistent. This is the difference between a high quality pad and the cheap pads that are available. The only compound that crosses is the rs4, it has a very large amount of tq rise with heat, but it is considered an endurance pad and some considerations had to be made to make it last so long.

johnny c

fixed rotors Vs floating rotors.

Chinese iron Vs american iron.

the metal make up makes all the difference in the world

truth.b

Bert,

Are you using AP Racing rotors @ Z06 sizes or actually going with a Z06 styled big brake kit? (i.e Brembo, Willwood, etc)

TrackAire

Johnny,

Do you have a list of where the major players in the rotor game make their rotors (Stoptech, AP, Racing Brake, Wilwood, DBA, PFC, Centric, and anybody else I'm missing). I would assume most are made in the USA, China, UK or Europe.

Also, where are most of the calipers of the major brands made? I'm thinking a lot of the big names are made in China. I've noticed at this years SEMA that there are a lot of people getting into the brake game with big brake kits with huge beautiful uber pistoned calipers that are private labeled and made in China....but it isn't obvious in the marketing.

This thread is one of the best I've seen with technical info and real world advice.

johnny c

All of Wilwood’s iron comes from Taiwan. The final machining happens in California so they can say it’s “Made in the USA”

Stoptech I really don’t know. No idea where it comes from or if they even make it themselves. I know Frozenrotors.com was supplying stoptechs rotors for a long time. But that program was ended around the 2008 time frame. Don’t know if stoptech found a new supplier or took it in house.

AP is a “Made in England” company. Jeff would know where the iron mills are.

I have no clue of where DBA gets it’s iron from but it’s satisfactory. I’ve had good life from them personally. I really hope it’s from some New Zealand mill and they do the huka for every batch of rotors they make. I really really hope that’s true. It’s strange to see DBA’s last so long because the engineering is not so great. The kangaroo paw is a mess and should let the rotor distort like mad (distortion=drag) , ideally we want to see curved veins so it adds strength to the design. The paw pattern just allows them to make one rotor, and not a left and right. (Saves $$ on tooling).

Everyone else you can just assume the mills are in china.

PFC’s iron mill is in South Carolina. Only the purest iron is sourced. The rotors are quality checked 60 times and has a +20% rejection rate. They have rejected iron rotors stacked to the rafters in the warehouse. The rotors are engineered, cut, heat treated, and assembled in Clover, South Carolina.

The key to rotor life is the iron and engineering.

My pfc rotors won’t rust. If you leave water on them over night they kind of turn brown a little. It’s very odd because iron rusts naturally. My oem z51 c6 rotors see water and completely rust before I’m done washing the car. I’m not sure what causes a rotor to do that. when you see it, you’ll know they are different then everything else on the market.

TrackAire

Thanks for the answers Johnny. I've used two sets of the DBA 4000's on the front of my track Mustang and flipped the rotors side to side to even out the wear a bit when doing consecutive track events at the same track that was hard on the right front brakes. Since the DBA's are not directional, is there any detrimental issues with swapping the rotors side to side? I can usually get around 9 track days on one set of DBA 4000's before a radial crack would occur (stock size 13" Cobra front brakes and calipers).

naschmitz

I just installed the AP kits front and rear with AP rotors in C6Z06 sizes. I've got two track days on those and so far it looks promising.

KNSBrakes

I am pretty sure PFC rotors are cast by Waupaka - likely in TN. PFC is extremely particular and maintains all of the specs for materials and casting design etc. and I think they do the finish machining themself.

As good as it gets.

I would expect for 2 piece rotors AP and Brembo have a similar process but in the UK/Italy.

Here is a nice place for a rotorhead. Waupaka makes probably every rotor for cars assembled in the US. The quality and JIT delivery to the US assembly plants is likely unrivaled. They are slammed and have been for years.




Stoptech regular rotors are Centric's - and most are China with a few still coming form Taiwan. (The 'high carbon's etc).

Stoptech 2 piece rotors are now USA and there are only a small handful of West Coast foundries that they could possibly come from. I think I google found it in the LA area a couple years ago.

My guess is that they started out getting them in IT - then switched to Taiwan/China and then brought it back here as price, timing and quality levels changed.

Parts store rotors are china aside from some random lower volume stuff from Germany etc.

DBA uses an Australia foundry and does the finish machining. They are certainly an oddity as there are very few 'boutique' rotor producers left. As far as the pillar vane design - it may not be perfect but many Brembo rotors for OEM are designed in a similar way. A well designed curved vane is probably the best but pillar vane rotors are proven to work.

I would have really liked to bring replacement OEM rotor production back to the US from Waupaka but the volume requirements are still outside my tax bracket. DBA does quite well though and we will make more applications going forward.

KNSBrakes

I have defended Hawk often. They are not nearly as bad as the idiots in their marketing department who approved this

When they added the newer street compounds.....they just swapped the names onto this same chart.

That's when I gave up.

0Todd TCE

I have a copy of the Hawk chart somewhere and refer to it when a customer mentions a compound for reference. I wouldn't stake my life on that data by any means. Probably representative of the entire lot but manipulated for impact reasons.

Reminds me of another companies old caliper flex chart, once you truly scale the x-y values and look at the info it wasn't quite as impressive.

0Todd TCE

Johnny might be able to make some coin off me here in fact.

I've had an open bounty of $500 for anyone with proof of iron rotors with holes CAST into them. Not carbon, not one offs from a 917 or something.....just the good old ones everyone talks about but has never seen.

For the record I spoke with many engineers and casting people. We even got images of some tooling reported to produce such parts. When pushed they fessed up that while supports were cast for the holes...the hole was actually drilled. Some in the casting biz suggested it would be a outrageous mold design.

I've always held that if one really produces such a beast they'd market the crap out of it and be more than happy to prove their validity.

johnny c

if your seeing uneven ware from one side to another you have a problem. you should be mostly off the brakes when your starting tun in so left/right should be even. I would look into it, as one side must be dragging. you could have sticking guide pins,a worn hub, or a stuck caliper piston. I've been chasing a soft pedal, heavy left side wear (and locking tire) issue. I found one of my bleeders was lose. just enough to have a tiny amount of moisture around the nipple, but that caused my issue.
again i don't like flipping rotors because it can reduce the life of the pads/rotors. and DBA's are non directional so you can run them on any side.

there is a disconnect between hawks engineers and marketing people. i can say that hawks marketing people are some of the best in the industry. they really get a name out there, the pads are easily distinguished, and they are inexpensive. but .9 mu is stupid. that's more than i would put on a F1 car (if they still ran iron)

johnny c

i know it's getting late in the season and nobody is hitting the track but does anyone have any more questions.

garrun

I don't have any more questions right now, but just wanted to say that I've learned a lot reading this thread and have it bookmarked. It convinced me to give up on finding dual track/street pads, and to get a set for each and change them myself.

For any other noobs out there that have never worked on a car, I found this Youtube video that shows how to change a pad on a C7 pretty clearly.

Thanks!

Poor-sha

Does anyone make a pad spreader that will actually fully compress the pistons on those massive AP endurance calipers? I have the Girodisc tool and a bunch of cheaper pad spreaders but nothing seems to spread large enough to stick in a new set of those 25mm pads - even with a used set of pads in place.

johnny c

when i change pads i change it one pad at a time. i pull the pad 1/2 way out, so the bottom of the pad is sitting on the piston. with he bit of the pad that's sticking out i pull it over the rotor. using the pad as a lever on the pistons, i apply very slight but firm pressure until the pistons are all the way back in the caliper. then i pull the pad and slide in the new one. do one pad at a time.

Poor-sha

Thanks Johnny - that's actually what I've been doing as well. Although I usually put the pads in at 90 degrees to get a bit more leverage. I do wonder now though if the Girodisc tool would work if I just did one pad at a time and place the one side up against the rotor face and other against a pad on the same side.

johnny c

just weld 3 prybars together lol

back when i was working Grand am, and The DP cars had iron rotors. the teams would all stop at the 12 hour mark of the 24 hours of Daytona. they would all bust out the caliper expanding tools and swap pads. Ganassi Bought an extra car set of calipers, rotors and pads. they came into the pits, pulled the tires, un-bolted the calipers and swapped everything. the lines where on a quick disconnect. they where easily 10 seconds faster in the pits then everyone else.

TrackAire

Johnny,

Regarding swapping the rotors side to side, I was doing this because my right front rotor was heat checking much faster than the left front rotor. I figured it was because I was doing continuous track days at Thunderhill and it is a counter clockwise track. I had this happen to the Brembo rotors that came on the car and two sets of DBA 4000's. Since the DBA's were non directional, I started swapping them side to side after every track weekend and it did seem to help, otherwise the right front would get a complete crack to the radial edge and the left front rotor looked great.

I never wore out a set of rotors, the would usually crack before I ever got that much wear on them (about 9 track days). In the fronts, I had used both CarboTech XP10's and Hawk DTC-70's. The car had ducted brake cooling with a spindle mount duct pointed to the inside of the rotor hat.

Regarding heat checking, what is normal, how fast should it occur, is it normal or a sign of inferior metal?

Again, great thread and info.

johnny c

Cracking can be a sign of many things. That fact that it’s normal on c5/c6 cars tells me it’s from the engineering in the rotor. The lower quality iron doesn’t help. The fact it’s happening on only the right side of your car is alarming. Like I said before the majority of braking happens in a straight line. So it shouldn’t happen to one side or the other. It especially shouldn’t happen more often on the side of the car with less weight. I would check out the caliper. It might be dragging. Or your hub might have excessive run out, and that causes drag. Throw some temp stickers on the calipers. I bet the right side come out higher.

As far as rotors go, to fix the engineering we need to find a better engineered rotor. The PFC’s are just that. It’s a floating rotor so it will allow the rotor to grow with heat. 99% of all rotors on the market are fixed and that doesn’t do much for performance, just reduces weight. The veins are directional, that helps cooling but more importantly strengthens the rotor. They are heat treated before final machining to remove all of the casting stress in the metal. As far as I know PFC is the only place that does that, and it’s proven to increase life. Finally to balance the casting, every edge of the rotor is machined. This makes for a perfectly balanced rotor. The lathes used to balance them cost over $2,000,000. They have an insane low tolerance. Give them a try I guarantee they will last longer. http://www.ogracing.com/performance-...corvette-c5-c6