Brakes and the track...

[titaniumdave]

Sorry Dave, my bad. Here you go......


larger caliper made out of thin aluminum = lower metal temp, thus lower fluid temp.

larger caliper = more piston room (wider, and also on BOTH sides 'very important')

larger caliper = room for a larger pads thus more surface area and also variable piston diameters (small on leading, and big on trailing edges for even and consistent wear)

wider caliper = ability for a wider rotor

wider rotor = less warpage, and cracking

wider rotor = wider vanes, thus drawing in more cooling air

taller rotor = more area to draw in fresh cooling air.

2 pc rotor with alum hat = less weight, and lower hat metal temp

BBK = slotted rotors (keeps pads clean, extra force in the wet, and helps cooling.

BBK = s.s. lines to eliminate spongey pedal feel

All the BBK I have seen assembled for sale as a set use the same width front rotors as stock, 28 mm(as you said, fronts are the most important). Limiting factor is clearance behind the rotor with the knuckle. So the big advantage of the aftermarket caliper is bigger pad, aluminum body, and piston size, number and quantity.

It seems like many of the benefits you have laid out can be achieved with the stock calipers.

Any racers out there who have been required to use the stock set of calipers to stay in a class care to chime in?

 

[nsxtasy]

As you properly note, Dave, no one doubts that most of the aftermarket big brake kits are better in various ways than the stock setup. But whether the stock brake calipers and stock-sized rotors are "adequate" or "weak" - I think that's your question - is strictly a matter of (a) semantics, and (b) opinion.

Even in a matter of semantics/opinion like this, there are a couple of problems in coming to any conclusions. One problem is that it's not clear whether the cause of any braking problems lies in the design of the brake system, or in the way it is used by the driver/owner. For example, if someone reports that his brakes are fading, does that mean that (a) his particular aftermarket brake pad is "weak"; (b) the brake pads are just getting broken in for the first time, and are experiencing "green pad syndrome"; (c) he is overusing his brakes; (d) the track he drives at is particularly hard on brakes; or (e) the stock calipers/rotors are inadequate? Any combination of these could be the cause, and you won't know for sure until you eliminate all the variables, one by one. The same thing is true for other braking problems, such as shudder, rotor cracking, etc.

The other problem is that there is rarely an opportunity to quantify braking problems or brake effectiveness. For example, just making up some numbers, theoretically, with the exact same usage and driver and everything else, let's say that a brake setup with the stock rotors/calipers would experience cracked rotors every 6-8 track events (figuring 200 track miles per event), whereas a big brake kit might experience cracked rotors every 10-12 track events. Some might say that those numbers make the stock setup "weak" while others might say that the difference is "insignificant"; again, this is a matter of opinions (value judgments) based on semantics. The other problem with this kind of theoretical analysis is that you never have the opportunity to gain practical experience with all the other variables held constant to determine numbers like in this example. People use different brake pads, different drivers have different experience and techniques, and on and on. So there is no way to know what those exact numbers are (e.g. 6-8 vs 10-12 in the above example), and even if you knew what they were, opinions on "adequate" vs "weak" could still differ.

What I can tell you is my own experience, as one data point. I've driven roughly 200 track events, over half as an instructor, with over 10K actual track miles in my NSX and about the same number in various other cars. I'm not even close to being the fastest driver in the instructor group, but I'm not close to the slowest, either. I am still using the stock calipers and stock-sized rotors on my NSX. I use street-track pads (currently the Cobalt Friction GT Sport; have also used Hawk HP Plus, Carbotech Panther Plus, Porterfield R4S, stock pads, and a few others, all with similar results). I use Stoptech two-piece rotors and Motul RBF 600 fluid. I have the original, stock brake lines. I have cooling ducts installed to direct air from the front air dam onto the front rotors. I had previously experienced problems with brake shudder, but have since found that bedding the pads any time the pads or rotors are changed eliminates this problem. My front rotors develop cracks and need replacing every 8-12 track events (when I was using one-piece rotors, it was more like every 5-8 events). My front piston boots periodically melt and get replaced, but less often than the front rotors get replaced. I have never had any problems with fade (other than when breaking in a set of front pads for the first time) and have never boiled my brake fluid. I have never experienced problems with the rear brakes other than replacing pads; no shudder, no replaced rotors (yes I've checked the thickness in the rear rotors I've been using for years, still fine), no piston boot problems, etc. Those are facts and actual experience. Based on those facts, it is my opinion that my brake setup, using the stock calipers and stock-sized rotors, is "adequate" and not at all "weak".

 

[Andrie Hartanto]

Dave,

I don't think the stock caliper is weak. But because of the slider design it will have more flex. This will contribute to less pedal feel and worse modulation than fixed caliper.

 

[ncdogdoc]

Dave,

I don't think the stock caliper is weak. But because of the slider design it will have more flex. This will contribute to less pedal feel and worse modulation than fixed caliper.

That is it in a nutshell. I had typed a very, very long diatribe (as long as Ken's ) and lost it all when my connection timed out!!! But to make a long story short, with proper rotors, i.e. floating hat two piece with appropriate vanes (the latest Brembo's are just fabulous, very light weight and excellent construction, and God awful expensive), you will have a lot of fun with stock calipers in your proposed setup.

 

[mikeh]

Interesting datapoints nsxtasy, thanks! I've deceided to see how well I can get the stock brakes to work on my current nsx, instead of upgrading to a BBK rite away as I did on my old nsx (and this one has 125-150 more hp at the wheels). I have Andrie's old BBK sitting on my shop bench if my plan fails miserably in the first couple track days.

nsxtasy, a couple things you didn't mention below and I was curious about:

what tires do you usually run at the track?
what non-stock aero aids, if any, do you typically run?
what's your basic suspension changes from stock?

-mike

What I can tell you is my own experience, as one data point. I've driven roughly 200 track events, over half as an instructor, with over 10K actual track miles in my NSX and about the same number in various other cars. I'm not even close to being the fastest driver in the instructor group, but I'm not close to the slowest, either. I am still using the stock calipers and stock-sized rotors on my NSX. I use street-track pads (currently the Cobalt Friction GT Sport; have also used Hawk HP Plus, Carbotech Panther Plus, Porterfield R4S, stock pads, and a few others, all with similar results). I use Stoptech two-piece rotors and Motul RBF 600 fluid. I have the original, stock brake lines. I have cooling ducts installed to direct air from the front air dam onto the front rotors. I had previously experienced problems with brake shudder, but have since found that bedding the pads any time the pads or rotors are changed eliminates this problem. My front rotors develop cracks and need replacing every 8-12 track events (when I was using one-piece rotors, it was more like every 5-8 events). My front piston boots periodically melt and get replaced, but less often than the front rotors get replaced. I have never had any problems with fade (other than when breaking in a set of front pads for the first time) and have never boiled my brake fluid. I have never experienced problems with the rear brakes other than replacing pads; no shudder, no replaced rotors (yes I've checked the thickness in the rear rotors I've been using for years, still fine), no piston boot problems, etc. Those are facts and actual experience. Based on those facts, it is my opinion that my brake setup, using the stock calipers and stock-sized rotors, is "adequate" and not at all "weak".

 

[nsxtasy]

nsxtasy, a couple things you didn't mention below and I was curious about:

what tires do you usually run at the track?
what non-stock aero aids, if any, do you typically run?
what's your basic suspension changes from stock?

Oops! Sorry about the omissions.

For the past five years (~2500 track miles) I have been using R compound track tires, first the Yokohama A032R, and more recently the Toyo RA-1 (although I also still have a pair of A032R rears that I haven't worn out, and sometimes use with the RA-1 fronts). Before that, I was using the stock street tires, Yokohama A022H.

No aero aids.

Four years ago I replaced my original stock shocks with Bilsteins. No other changes to the stock suspension.

 

[DanO]

I think the incremental approach that you chose is the best. Max out the OEM setup and if that works for you and your driving style then great! Someday down the road there might come a time when you experience fade even with a maxed-out OEM package. Then you’ll have to learn to take the corners faster or upgrade the brakes.

.02

DanO

 

[OLDE GUY]

...look at the NSX type R calipers!!!!.....

The NSX type R calipers are identical to the 1997 or later NSX calipers. The type R utilizes slotted rotors and more aggressive pads.

Rotors:
NSX Front: 282 x 28 mm
NSX-R and 97+ Front: 298 x 28 mm

NSX Rear: 282 x 23 mm
NSX-R and 97+ Rear: 303 x 23 mm


I added the 1997+ calipers with larger slotted rotors, Dali air deflector, Carbotech Panther Plus pads, Motul 600 and removed the dust shields on my 1994. I am very pleased on the track and also the street. The brake bias is spot on and therefore the balance is incredible which is a very important point on the track for stable straight line braking, transition from braking to turn-in, trail braking, etc. You can find a complete set of front and rear 1997+ brakes on NSXPrime from time to time for $600 to 1,000. For me, this is the most bang for the buck and it has the hugh advantage of preserving the balance of the NSX, unlike front only BBKs and some poorly engineered BBKs. You could add two piece rotors and more aggressive pads if you need. Unless you have greatly increased horsepower, I don't think that you need more.

PS: My NSX has the type R suspension and runs 225 and 255mm SO3s - obviously, not all-out-race.

 

[SMGNSX]

$3,000.00 later the wilwood calipers were removed from the track car and replaced with the Comptech powertech 13.4 brake kit.
Yes they were alot of $$$$ but the car stops on a dime an the brakes never fade or have any problems these are well worth the $$$$.
So don't take any short cuts and install the right kit the First time and you will save $$$$ in the long run

Steve

http://www.comptechusa.com/store/420110.html

 

[Andrie Hartanto]

Steve,

lots of people don't understand when I tried to explain about the feel and what makes this Comptech powertec kit better than other brake kit. Me personally don't understand why they do not understand that driving race car is all about feel

Maybe you can shed light in first hand experience after experiencing both kits.

 

[AU_NSX]

I have some track experience with brakes in my NSX's...

One track in particular was murder on brakes. 200kph in my NA NSX (and now 240kph in my TT NSX) down the back straight before a 1st gear hairpin.

I destroyed a set of rotors front and rear with OEM pads the first day on that track.

Next I upgraded to the Stoptech 2 piece (282mm) slotted rotors and performance pads up front and another set of OEM rotors that I had slotted with performance pads on the rear. I also took off the front and rear splash guards and added Dali deflectors up front. The next track day I chewed through another set of pads and was getting a vibration through the brake pedal when they heated up.

I then changed brake fluid with a competition fluid, installed braided lines together with competition/race pads which were high temp and only just streetable. The brakes were getting very hot but I wouldn't say they were overheating. However, I was still getting the vibration which got worse the hotter the rotors got. The pads lasted the whole day and quite a few more track days.

However, I was just a little uncomfortable with the amount of vibration from the brakes at temperature.

So now on my twin turbo NSX, I have the Comptech powertech 13.4 brake kit (front and rear) complete with the Dali CF brake ducts up front. No more brake vibration and the brakes are fabulous both on the street and the track.

I agree that they are LOTS of $$$$. But I have no more vibration issues, I don't have to run such an aggressive pad, the balance is perfect with no need for a BBK proportioning valve.

I am very happy!

 

[SMGNSX]

I have some track experience with brakes in my NSX's...

One track in particular was murder on brakes. 200kph in my NA NSX (and now 240kph in my TT NSX) down the back straight before a 1st gear hairpin.

I destroyed a set of rotors front and rear with OEM pads the first day on that track.

Next I upgraded to the Stoptech 2 piece (282mm) slotted rotors and performance pads up front and another set of OEM rotors that I had slotted with performance pads on the rear. I also took off the front and rear splash guards and added Dali deflectors up front. The next track day I chewed through another set of pads and was getting a vibration through the brake pedal when they heated up.

I then changed brake fluid with a competition fluid, installed braided lines together with competition/race pads which were high temp and only just streetable. The brakes were getting very hot but I wouldn't say they were overheating. However, I was still getting the vibration which got worse the hotter the rotors got. The pads lasted the whole day and quite a few more track days.

However, I was just a little uncomfortable with the amount of vibration from the brakes at temperature.

So now on my twin turbo NSX, I have the Comptech powertech 13.4 brake kit (front and rear) complete with the Dali CF brake ducts up front. No more brake vibration and the brakes are fabulous both on the street and the track.

I agree that they are LOTS of $$$$. But I have no more vibration issues, I don't have to run such an aggressive pad, the balance is perfect with no need for a BBK proportioning valve.

I am very happy!

See after it was all said and done the Comptech brakes came through with flying colors as I said they are big $$$$ but it will be the last time you ever have a brake problem.

Steve

 

[SMGNSX]

Steve,

lots of people don't understand when I tried to explain about the feel and what makes this Comptech powertec kit better than other brake kit. Me personally don't understand why they do not understand that driving race car is all about feel

Maybe you can shed light in first hand experience after experiencing both kits.

Andrie,

You hit the nail on the head you know with the Comptech brakes they will always work and never let you down and they work so smooth and the feel is perfect
The wilwood 13" kit with the superlite ultra thin 6 piston calipers wer good up to about 100 mph max with hard braking and then shake and fade real bad, (they are ok for a street car but noe a race car like ours)
The Competchs stop on a dime and when you set the car it is with little effort even @ 125 mph up. Well worth every cent,You, Kip and mysels know this first hand.
Car is almost finished I will keep you posted as I did not make Laguna Seca

Steve

 

[nsxnut]

I went with the tarox route. In hind site the comptech may be easer.

After all US sources for replacement pads dryed up I contacted
Tarox directly.

After 3 years, 50 track days and 30k miles my rotors were getting a little tired as well

Since I had my wallet open. I went for tarox calipers on all four corners, new rotors and 8 axil sets of pads. who needs an ebreak anyway.

After a day at laguna and the weekend at Sears Point I am pleased. I'll have to re-learn my break points

The advantage of this setup is that it fits under stock 16/17 rims.
Once I orderd the stuff from tarox it came via fedx in 4 days. They were easey to deal with.

maybe some day I'll let kip drive my car to get his opinion?

Later,
Don

 

[2slow2speed]

Any racers out there who have been required to use the stock set of calipers to stay in a class care to chime in?

Dave,

FYI: I posted a similar question on a somewhat related topic before and I got the following reply:

The DAL Motorsports NSX runs the stock brakes per the rules for the Grand-Am Cup series and we have had little to no fading problems. The biggest problem we have is premature ABS activation and thats more a programming problem than anything else, and it would be encountered with almost any street ABS set-up.

We run stock 91 brakes with Cobalt pads and 3 inch ducts on each side. Brake Fluid is ATE Super Blue. Engine is has completely stock from the throttle body to the end of the exhaust manifold.

For reference we've run low 1:30's in the car at Texas Motor Speedway. Mid 1:50's at Texas World Speedway the only time we've been down there. We were in the 2:10's at VIR and ran 2:11's at Daytona with handling problems that we never really got sorted out. All this and we are still sorting the suspension set-up on the car.

http://www.nsxprime.com/forums/showthread.php?t=27042

Ken

 

[titaniumdave]

Thanks Ken,
I have decided to re-invent the wheel with my brakes...I am putting 2006 Porsche 997 Carrera S calipers all around with 33 x 330 mm front, 28 x 330 rear rotors, custom hats which will allow no spacers with Tecnomagnesio wheels. I am working on a floating hat design similar to Performance Friction Brakes Direct Drive Attachment system.

I will post pics when it is all done. Hopefully by then there will be more manufacturers supporting the pad backing plate.

Should have front and rear mono-ball, sealed, camber adding or subtracting suspension pivots by the end of March too.

I am a sick man...

 

[ak]

Let me pose a question with all these BBK talk. Is there a need for a bigger brake master cylinder with these BBK upgrades? I'm somewhat surprised that there has not been any need for this with the existing kits.

 

[titaniumdave]

Sometimes there is a need to change. Depends on the size(area) of the pistons on the calipers. The stock is surprisingly capable.

 

[nsxnut]

I have to agree. The stock master dose seem to have some reserve.

It is not the number of pistons but the area they displace that is important.

My front calipers are 10 pistons. Sounds like allot but the pistons are very small. They distribute the force along the pad.

I believe there are other factors involved as well. The compressibility of the pads and the lines.

Later,
Don