Help. I need brake upgrade advice for the track.

[ryneen]

I just finished my 10th track event last weekend with Speedventures at California Speedway. I'm driving the car far quicker and braking harder than in the past. I'm probably driving about 9/10th's. I have a '91 with R compounds, Type R suspension, full non compliance rear end, Type R chassis bars, stock anti sway bars, moderately aggressive alignment, stock motor and transmission.

I'm running the stock brakes with drilled rotors, stainless brake lines, high temp fluid, Dali air ducting on front brakes, Brembo pads (not sure the model #, but they are superior to Carbotech Panther Plus that I used to run. I get them through Autowave). I always bed my new brakes properly and never experience shudder.

The brakes have always worked excellent for my needs. I drive fairly hard and I've never had them fade. I was running hard at Cal Speedway and they performed perfectly every session. However, I noticed on the drive home that they do not grip as well as before the event. They require much more pedal pressure and don't bite nearly as well. The pads were new before the event. Does anyone know why they don't work as well after the event? Do the pads or rotors get scorched or something making them useless? In addition to the decreased braking ability after the event, I noticed some substantial cracks in the rotors. One crack goes through the entire 1/4" thick edge and is about 3/4" long. I will be replacing the rotors. However, I may end up going to a big brake kit. Does anyone know of any moderately cost effective brake upgrades so I won't have to worry about tracking my car?

Thanks,
Ryan Rush

 

[mikeh]

Try a few events (at your current speed/level) with a new set of oem rotors (non drilled/slotted). The bling-bling (cheap) drilled rotors are not your friend for track days.

Depending on the type of pad it is, sounds like you either had some build-up on the rotors/pads which caused the increased pedal pressure to slow down after the event, or you might have slightly boiled the fluid and didn't notice.

Did the braking performance get better by the time you got home (and maybe removed whatever was built up on the rotor/pad faces) or did they still suck? Try bleeding them yet?

Also if they are a new pad combination (ie; agressive/track pads) then you would need to put some heat in them before they work decently on the street...

-mike

 

[Hrant]

You most likely boiled your fluid and wore off a good chunk of your pad material if you were breaking hard. The drilled rotors are for looks and not for track, so having craked one is expected.

 

[VBNSX]

I'd vote to bleed your brake lines... then check to see if it feels better.... i sometimes bleed my brake in the morning of the second day of an event.. just to have some sort of consistancy from the first day...

hth,
x

 

[RP-Motorsports]

I can get you a deal on a BBK. Check my site. I boiled my OEM brakes after 10 min. I bled them, and ran som ATE Blue, and boiled them again, but it took longer. I need some ducting big time! I will end up installing the Greddy/alcon, or the Brembo's soon. You will NEVER learn how to drive your car at its peak, if the brakes are not at 110% all of the time.

 

[nsxtasy]

Ryan, you're doing a lot of things right. Let's talk about the few areas where you might get an improvement without spending a fortune. Now, on to your questions...

Does anyone know why they don't work as well after the event?

Probably just because the rotors were cracked, and also because they were probably not totally true (flat) as a result of the cracking.

Does anyone know of any moderately cost effective brake upgrades so I won't have to worry about tracking my car?

A couple of things.

One is brake ducts. Not the Dali deflectors, but real ducting hose. You can get NACA intake ducts for the front air dam, then run 2.5-inch silicone air ducts from there, past the lower corners of the radiator (above the core support), zip-tied to the suspension arms, and blowing directly on the rotors. (On mine, we cut a hole in the splash guards and welded a flange to it, to which we attached the duct hose.) You can get ducting hose from a race prep shop like Pegasus. You'll need about four feet for each side.

The other is brake fluid. You didn't mention which one you're using; is it one with a dry boiling point of 590 or higher? You can check the boiling points for the most popular fluids in this post. Make sure you're using one with a dry boiling point of 590 or higher. And make sure your fluid has been completely flushed within the previous six months of going on the track.

A good shop can test the actual boiling point of your fluid. It will go down a bit over time, and it's not always as high as claimed on the label... in any case, if you're not satisfied with the actual boiling point as tested, then flush it.

Try a few events (at your current speed/level) with a new set of oem rotors (non drilled/slotted). The bling-bling (cheap) drilled rotors are not your friend for track days.

In my experience, all rotors crack. Drilled rotors crack, slotted rotors crack, and solid-faced rotors (including OEM rotors) crack. I've cracked all of them. I've kept track of my total and track mileage, and found that they all last about the same amount of time and track use. The only ones that last longer are two-piece rotors, which still crack, but take longer to do so. I know folks who have the expensive big brake kits and their rotors crack with track use, too.

So, get new rotors, get some real brake ducts, flush your fluid, and try again. That will probably be all you need. (But if that doesn't work, the next step is to get a big brake kit, where you're looking at at least a few grand for the kit, and maybe a few more for new wheels and tires to fit over the bigger calipers.)

 

[VBNSX]

Just to give you a possible 'pictoral' of what Ken is talking about... (Ken I hope you don't mind me using your car)..

These pics were taken at NSXPO 2004 - it's a visual of what Ken was talking about in the previous post (considering it's his car)... good luck.

x

 

[ryneen]

Thanks everyone for your info. Below are answers and questions to your comments:

These are my second set of Brembo pads. I'm familiar with how they work on the street and track. They are not race pads, therefore they still normally work well on the street with no heat. However, the brakes still do not work well after a few hundred "after event" miles. Could there possibly be some build-up or hazing left on either the pads or rotors? Could I have cooked my pads too hot and now they are useless? Does this happen with pads? If so, how would I know? Is an overheated pad obvious to the eye?

I will take your advice and replace the drilled rotors with stock smooth face ones. I will then bleed my brakes. Is it easy to bleed my own brakes? Does anyone suggest installing Speed Bleeders to make bleeding quicker/easier? Do I need to get new pads when replacing the rotors? I'm assuming I will, but since my pads are nearly new, I would like to keep them if possible. How often should I replace my brake fluid? Should I base the time on a certain amount of track days or a certain amount of months?

Thanks for the brake ducting info and pictures. I will look into this and try to implement it before my next event.

I'm pretty impressed with the braking power of my stock brakes. I'm curious, if anyone can comment on how much better (if any) do Big Brake Kits stop?

Thanks again,
Ryan

PS NSXtasy, how do you inject other people quotes into your comments? It would be easier for me to reply if I could do this.

 

[NSX-Racer]

I'm pretty impressed with the braking power of my stock brakes. I'm curious, if anyone can comment on how much better (if any) do Big Brake Kits stop?

I have the P-car Brembos and can tell you that they don't stop better than OEM brakes (when they are not worn) but they do it more consistently - especialy with race slicks. Reason: Braking distances are usualy affected by the tires not by the brakes.

You didn't mention the brake fluid topic nsxtasy brought up - a main question IMO.

 

[MarkB]

...Could I have cooked my pads too hot and now they are useless? Does this happen with pads? If so, how would I know? Is an overheated pad obvious to the eye?...

I realize that Porterfield pads are not the same as Brembo pads, but if you overheat Porterfield pads, they will carbonize and lose braking efficiency. If this is the case, the pads will look flaky and or powdery or will, when scratched gently with a screwdriver, gouge quite easily.

...Does anyone suggest installing Speed Bleeders to make bleeding quicker/easier?...

I, personally, use speed bleeders. They make the job much easier. My habit is to bleed all the way around (a small amount) before each track event.

...How often should I replace my brake fluid?...

If you make a habit of bleeding a small amount from all 4 corners prior to each track event, you won't need to worry as much about flushing your system or the possibility of losing brakes because of boiled fluid.

...Thanks for the brake ducting info and pictures....

I have a pair of very large brake cooling deflectors on my car and find that my post-session brake temps are about 120°F cooler. If you or anyone else wants, I will post a template and pictures.

...I'm curious, if anyone can comment on how much better (if any) do Big Brake Kits stop?...

I will have to agree with Wolfgang that BB's will be more consistant than OEM where high temperatures are concerned.

...how do you inject other people quotes into your comments?...

 

[VBNSX]

speedbleeders are a definite plus... i'd strongly recommend them.... also please don't forget the proper bleeding procedure for the nsx.. it IS different from standard cars.

x

 

[nsxhk]

I've heard good things about speed bleeder, but how about durability and reliability?

Henry.

 

[docjohn]

Ryneen,as you can sense the stock calliper/rotors can take you far if you have good track pads,cooling ducts and use high temp fluid,and you change fluid every 3-4 events.I think your ? about sloppy pedal feel after an event is valid,I get that even with my bbk brembos.Imo part of this feeling is due to the nature of your braking on the street,which is 5/10 ths compared to the 9-10/10 ths when on track.If you braked excessivly on the street as if you were back at the track then your feeling of diminished braking would be less.In a way though you cant' and won't find a perfect one combo street -track combo, there will be compromises.

 

[VBNSX]

I've heard good things about speed bleeder, but how about durability and reliability?

Henry.

Well I'm rather excessive when it comes to bleeding my brakes. I change my oil and bleed my brakes before EVERY event.. I know it's not necessary but I would rather err on the side of caution when it comes to that stuff. With that said.. I have run speedbleeders ever since I have had the car (one of the first things I purchased) and have had no problems w/ reliability.

However I would like to note that the metal made for them is rather soft.. so when bleeding use a good wrench.. snap-on.. etc.. i use craftsman and I rounded it out... (3/8 is what you'll need).

x

 

[Hrant]

Concur with most of the posts. Below are my recommendations from what I have experienced and noticed on fellow NSXers who have for the most part street friendly cars but also track their cars. If your priority is first a more track ready car, then the following may not apply.

Speedbleeders: Yes, I have them and they work great. They are easy to use. As VBNSX noted, it is not metric.

Brake Fluid: Try Motul 600. It is reasonably priced at about $12.00 max for a bottle though you might find it cheaper - check local Motorcycle shops they tend to carry them. Make sure you bleed correctly and don't press the brake pedal all the way down - put a piece of 2x4 under the brake pedal ....... MarkB's suggestion re bleeding is a good one; alternatively, you can bleed after 3-4 track events as Docjohn suggested - at that time try to check/bleed if necessary your clutch fluid too; many forget this step and that fluid gets dirty as well.

Brake Pads: This really depends on what your preference is. If you want street/track with great bite and high temp (up to 1200F) but you are not too concerned with possible squealing noise, there is no substitute to the Carbotech Panther Plus. If you want good bite but at the price of lower temp performance (often in the range of no higher than 950F), you have several options from Carbotech Bobcats, Cobalt Friction and Hawk. As far as I know, no one thus far offers the performance/combo of Panther Plus unless you start mixing different front/rear pads ............ as Docjohn noted, this is a balancing act in compromise unless you want to have dedicated pads for each application.

One application that might reduce some of the squealing noise is to lubricate the caliper bolts at every major brake inspection and of course pad change.

Brake Cooling: For the most part, for your needs, the DaliRacing air deflectors should suffice especially if you remove the dust shield. Dali has two versions, I use the smaller version and have had temp reading on the rotors as high as 600F in the paddock (so track most likely will hit 900F) and no problems with brakes or braking - but then I don't stomp on the brakes.

Rotors: It seems to me your limitation is that you have a 91 (or pre 97) rotors. Size (ie mass) does matter in OEM rotors. You can either upgrade to BBK at which time you have to get new wheels, assess brake bias between front/rear with some pad adjustments. NSX-Racer is correct, BBK give you more "consistent" braking not necessarily better braking. And with big brakes you have to consider the possible added weight of bigger wheels and tires. Or, you may opt to (a) Stoptech's slotted floating rotors or Science of Speed's Project U in OEM size for pre 97 - you will get better cooling than OEM with less weight and thus better performance, or (b) if you can find 97+ brackets for the brake calipers, upgrade to DaliRacing new slotted two piece floating rotors for 97+ and keep 16" wheels in the fronts. Dali's new rotors are "racing rotors" and they perform absolutely great with the Panther Plus pads; they look great too. Cryo treatment of the rotors may give you some additional benefit and again, DaliRacing's price is very attractive.

As it was noted, with street tires, the limiting factor is the tires and not the brakes. With DaliRacing 97+ rotors, I now have more braking than my tires can handle. You can improve on this a little by using Comptech's front non-compliance clamps.

And to keep your references and benchmarks predictable, it is best to put new pads when you replace your rotors. And with performance pads, embedding them is critical in making sure they perform as advertised.

HTH

 

[nsxtasy]

These are my second set of Brembo pads. I'm familiar with how they work on the street and track. They are not race pads, therefore they still normally work well on the street with no heat. However, the brakes still do not work well after a few hundred "after event" miles. Could there possibly be some build-up or hazing left on either the pads or rotors? Could I have cooked my pads too hot and now they are useless? Does this happen with pads? If so, how would I know? Is an overheated pad obvious to the eye?

I'm not sure of the answers to your questions here. However, my suggestion would be to call Andie Lin at Cobalt Friction to discuss it. Cobalt is a leading supplier of brake products, including brake pads, rotors, fluid, and big brake kits. Andie, the owner, knows more about brakes than just about anyone around. And he tracks his NSX, so he's familiar with our cars.

You're going to want to call him anyway, since it sounds like one of the things you might try are different brake pads. Cobalt carries their own brand of performance brake pads, which are simply outstanding, as well as most of the other major brands. They can help you select the pads (and rotors) that will work best for your needs. I have been using Cobalt's GT Sport street pad for street and track use on both my cars, and I have been very happy with it. It's a street/track pad, meaning that it almost never squeals, and still has decent performance on the track. (In the past, I have tried other pads, including OEM, Hawk HP Plus, Endless CC-X, and Carbotech Panther Plus, among others, and decided that none of these was really great for my needs.) A lot of people I know are using Cobalt's Spec VR pad, which is a track-only pad, offering great performance on the track, albeit with the squealing and need for warmup that makes them less suitable for street use. (These are people who don't drive their cars on the street or switch pads before and after each event). I am considering trying out Cobalt's Spec B pad, which is somewhere in between these two in characteristics.

Most brands of performance pads sell more than one pad composition, and which one you choose depends on your needs. I suggest you keep a record of which kind of pads you are using and what kind of results you get. It will help you understand how those results may be related to the type of pad you're using, and when you need to change to a different pad.

There's a benefit to the fact that you need to change brake pads every few track events - you can try out different kinds of pads, and use each set as a "controlled experiment" to decide which one works best for your needs. Once you're happy with a particular pad, you can change other variables (e.g. tires) to do the same thing.

My NSX has 57K total miles including 10K actual track miles. I am on my 21st set of front brake pads and my 12th set of rear brake pads.

Do I need to get new pads when replacing the rotors?

The basic answer to you question is "No, but..." You don't automatically have to get new pads when you replace the rotors, as long as your pads are working okay, and as long as you go through the standard bedding procedure again with the new rotors. (Again, I would be interested in hearing what Andie says regarding your problems on the street.) If the pads are cracked or crumbling (or, of course, if the pad material is fairly thin), then you will want to replace them. Or, if you just want to change to a different type of pad.

How often should I replace my brake fluid? Should I base the time on a certain amount of track days or a certain amount of months?

My standard rule of thumb is that any time I go on the track, I want to make sure my brake fluid has been changed in the previous six months, regardless of the number of track events. Here up north, I have my fluid replaced in April, at the start of the track season, and I'm good for the entire season, which runs through October, as well as street driving until the following spring. In the absence of problems, I don't bother bleeding the fluid at all. (However, any time you think your brake fluid might have boiled, you want to replace it before your next event.)

I realize that there are people who bleed or replace brake fluid and oil more often than that, some before every track event. As long as I am not having any problems, I don't.

I'm curious, if anyone can comment on how much better (if any) do Big Brake Kits stop?

As noted by others, big brake kits don't shorten your stopping distances, since those are usually limited by your tires, not your brakes. Their primary advantage is in standing up to the effects of heat buildup.

One final word - tires. They haven't really been part of this discussion, but, along with brakes, they are one of the two most important factors in track driving. I'm not trying to start a long discussion about the selection of specific tires, or the advantages and disadvantages of street tires vs R compound track tires; that's been discussed plenty elsewhere. But tires are something you will want to keep in mind regarding the possibility of getting a big brake kit. I say this for a couple of reasons - for fit, as well as for the cost-effectiveness of the mods.

In terms of fit, you will need to look at any kit you are considering, in terms of which wheels fit over it. (Some require 16" front wheels, some 17", and some will work with some wheels of a given size, and not others.) Maybe you are currently using 17" front wheels that will fit a big brake kit as is. If not, though, then you must consider the cost of another set of wheels and tires as part of your investment in the kit.

From the standpoint of cost-effectiveness, I think it makes more sense to upgrade to dedicated track tires (and wheels) before or during the implementation of a big brake kit; IOW, I wouldn't go out and buy a big brake kit with plans to keep using street tires with it. FWIW, as noted above, I am still using the stock calipers on my '91 NSX. In addition to the performance, which I find to be everything I need, there are three benefits that I really like about this approach, features that will be tough to take advantage of once you install a big brake kit: (1) I can use extra sets of '91-93 stock wheels for the track tires. It's pretty easy to find used sets going for $200 or less for the set of four. (2) Most of the R compound tires on the market come in the '91-93 stock sizes, including my current track tire of choice, the Toyo RA-1. (3) I can fit the set of track tires inside the car, and drive to the track on my street tires.

 

[Andrie Hartanto]

My take on speed bleeder is I didn't like them. I never get as good pedal feel when I use them. Revert back to stock and everything is great.

The NSX braking power is pretty good. Put a good track pads (Carbotech XP) and you're good for any HPDE. BBK do has advantageous. The biggest advantage to me is the consisteny and much easier to modulate. Thus more confident in braking and lower lap times. In addition, I get to run lots more available pad compound as they are more widely available. With BBK, I don't have to swap pads and/or rotors as often as when I use stock brakes.

 

[VBNSX]

My take on speed bleeder is I didn't like them. I never get as good pedal feel when I use them. Revert back to stock and everything is great.

The NSX braking power is pretty good. Put a good track pads (Carbotech XP) and you're good for any HPDE. BBK do has advantageous. The biggest advantage to me is the consisteny and much easier to modulate. Thus more confident in braking and lower lap times. In addition, I get to run lots more available pad compound as they are more widely available. With BBK, I don't have to swap pads and/or rotors as often as when I use stock brakes.

Hey Andrie.. some people comment about carbotech's pads as very inconsistent from one pad to another.. (i.e. now that I've worn through my set... my next set may feel rather different).. what is your take on it? I imagine you've probably gone through tons of pads....

x

 

[Andrie Hartanto]

Xavier,

I've been very happy with all Carbotech products, and my favourite is their XP9 for track use. Even for the street they are not bad. I've never experienced the inconsistencies you mentioned. And I've used them a lot.

If you want, the Hawk HT10 is very good as well. Although I'm not sure if they make application for NSX.

 

[Andrie Hartanto]

As noted by others, big brake kits don't shorten your stopping distances, since those are usually limited by your tires, not your brakes. Their primary advantage is in standing up to the effects of heat buildup.

Often time at the street or track, big brake kit does shorten your stopping distance. How? Trough modulation. Better modulation mean you can hold the brake at the treshold better, thus resulting shorter braking distance.

Sure you can lock up your tires easily with stock brakes. But does that mean it is the most effective way in braking thus shortest braking distance? Maybe with car with modern ABS, but NSX ABS system sucks.

 

[nsxtasy]

Often time at the street or track, big brake kit does shorten your stopping distance. How? Trough modulation. Better modulation mean you can hold the brake at the treshold better, thus resulting shorter braking distance.

I disagree. Modulation is a function of the driver.

Sure you can lock up your tires easily with stock brakes. But does that mean it is the most effective way in braking thus shortest braking distance? Maybe with car with modern ABS, but NSX ABS system sucks.

I disagree with that, too. The ABS on the NSX is just fine. However, maximum braking on dry pavement is achieved through threshold braking, holding the brakes on the threshold of locking up without doing so, and you never activate the ABS.

 

[NSX-Racer]

But does that mean it is the most effective way in braking thus shortest braking distance? Maybe with car with modern ABS, but NSX ABS system sucks.

That's not my experience (at least with the system in my '98 cp., former and later ABS tunings may be different). Stock ABS works fine with big brakes front/rear together with race slicks meaning it allows a bit of "overbraking" to the point where you have the maximum grip (about 10% slippage I guess).

That's a bit astonishing because I always heard that you need special race ABS with other cars (Porsche GT 3 Cup) which seems to be not necessary at the NSX.

It's a bit different with S-03s, they tend to squeal (or block) more than slicks during braking which can lead to some "tail hapiness" when you brake from very high speeds (above 200 km/h). I don't claim that to the bigger rear brakes I applicated later because I had the same effect with Brembo front and stock rear brakes.

 

[MvM]

Hello Ryan,

You seem to be doing everything just fine in many ways.
As far as brake bleeding goes, I did it without speedbleeder and it's not difficult if you can get someone to help you.
http://www.nsxprime.com/forums/showthread.php?t=23050

As for the front rotors, I replaced the OEM ones with the Stoptech Aero-rotors and they seem to be working better. Replacing them is not as hard as I thought it would be, just getting the old ones off is a bit of work.
http://www.nsxprime.com/forums/showthread.php?t=23006

 

[Andrie Hartanto]

I disagree. Modulation is a function of the driver.

A driver can only be as good as the equipment allow him to.

I disagree with that, too. The ABS on the NSX is just fine. However, maximum braking on dry pavement is achieved through threshold braking, holding the brakes on the threshold of locking up without doing so, and you never activate the ABS.

Sure it is fine. It is also depend on the driver.

 

[RacerX-21]

I disagree. Modulation is a function of the driver.

I disagree with that, too. The ABS on the NSX is just fine. However, maximum braking on dry pavement is achieved through threshold braking, holding the brakes on the threshold of locking up without doing so, and you never activate the ABS.

I think what Andrie meant by modulation is one of the topics of my next DAL submission. http://www.dalmotorsports.com/shows.asp (#7)

A common misconception is that if you can lock-up your brakes, you have as good of a brake setup as you can get. That’s not a true statement- Here’s an analogy; When using the heater controls in many cars it’s difficult to get the setting from not being too hot or too cold. But in many current cars you have increased adjustability that makes it easier to get what you want. Brakes are the same, all of them can lock the wheels… the better ones have more adjustability before they do lock. If you have two knobs; Knob (A) representing OE or bad brakes, has 3 clicks before full. Knob (B) a good performance brake has 10 clicks before full. Think of full as lock-up with your brakes. With knob A you can go to click 2 before lock, but one click more and your skidding. Knob B you can safely go to click 8. That’s 4/5 braking capacity vs. 2/3 braking capacity. In addition to the higher percentage of usable threshold you have 2 clicks before a locking condition, giving you a 50% larger safety margin.

Mathematically you can get infinite variability before lock-up, but using realistic technology we have limited solutions to work with. I’m not sure if most people know that lock-up is actually first due to an imperfection of rotor surface, tire flat spot or road surface variation. Your pressure threshold can stay consistent until it hits a high, low, rough or slippery spot. Now with the road surface or tires… just avoid water, oil and flat spotting your tires. But with brakes, the HP manufacturers go with larger diameter rotors so they can benefit from leverage, and don’t have to push as hard towards the center of rotation. They also spread the clamping between two or more pistons. And last, they float the rotors from the hubs so they can absorb imperfections of the hub or the rotor surface. All of these methods help miss the high spot. More driver adjustability (Like mentioned in the first paragraph) will also allow you to closer flirt with that threshold. ABS technology aids after the lock-up has already happened. A new technology is a relief valve that absorbs spikes in the brake line pressure from those high spots. Some are experimenting with this now.