Track laptimes with stock brakes

[matteni]

Bottom line - if you want, need, or think you have to have a BBK, new wheels, new tires, new everything brake wise to be a better HPDE driver - go for it!

Will it work? I hear that people take sugar tablets all the time in blind studies and feel/get better. I hear hidden prayer works wonders. It may give you confidence and/or performance benefits. I will be jealous as I think it would be cool to have an awesome Brembo setup with attractive wheels that fit over them on my NSX. I also think (despite the weight penalty and often gearing penalty) will probably mask some technique problems that you might actually see some benefits immediately. You will be able to stab/mash on the brakes as often and as unsettling as you want and never have any fading issues to deal with.

So if the short term goal is to lower your times immediately - it may work well. If money is an object or if the long term goal is to be come a better driver and lower times methodically - they might not help at all.

IMO - the second the tires start into ABS (as one person notes seems early) your tires are now the limiting factor for you stopping power. If you are boiling your fluid or experiencing fade - there may be a need for better cooling, better technique, better maintenance (rebuild calipers/etc), better flushing, better rotor/pad combo, or better fluid. You can spend thousands and tell us "it was the calipers / brakes" but you will never know if just more regular maintenance, free removal of most of the backing plates, $20 in brake fluid, and $50 in ducting would have produced similar results.

If you have experience and confidence on the track and are running non-R rated compounds from excellent tire companies - you are going to get a lot more "bang for the buck" by getting some dedicated track wheels/tires.

Also - I would highly recommend against just getting the fronts done. I have seen rear brake temps at the track that are higher then the fronts (that have done some of our mods) and the proportioning problems and additional rear heat problems will not help you at all towards your goal. Besides that it looks really dorky IMO.

Good luck.

 

[2slow2speed]

Thanks for all of the folks who have replied.

From the contents of the responses so far it seems that there is a trend developing.

So far the majority of the folks who have stated that the stock NSX brake system is adequate are running R compound tires, use late braking/threshold braking and better rotors with better cooling and ducting, removal of the splash guards and better brake fluid.

Assuming that the cooling has been taken care of.

Going with R compound tires with better traction would result in:

Faster cornering speeds, (less braking going into the corner), faster exit speeds from the corner thus resulting in faster speeds going into the next corner.

Better traction, thus resulting in better usage of the amount of braking capacity that is available. (late braking, threshold braking become a possibility) It takes less time/distance for the tires to slow down the car.

So would it be fair to state that given the same laptimes a car running R compounds would be using at a lesser degree the capacity of the brakes when compared to street tires?

I am curious to know if anyone has stuck with street tires with a NSX with minimal weight reduction but with many of the brake upgrades who are using 235 mm wide street tires up front.

I wonder if the increased contact patch that is available would make a difference in regards to how much the brakes are taxed when compared to other sizes such as 205 or 215.

Finally, anyone else out there running with street tires who feels that their stock NSX system with the upgrades is adequate for the track?

Ken

 

[2slow2speed]

[BI also think (despite the weight penalty and often gearing penalty) will probably mask some technique problems that you might actually see some benefits immediately. You will be able to stab/mash on the brakes as often and as unsettling as you want and never have any fading issues to deal with.

So if the short term goal is to lower your times immediately - it may work well. If money is an object or if the long term goal is to be come a better driver and lower times methodically - they might not help at all.

If you have experience and confidence on the track and are running non-R rated compounds from excellent tire companies - you are going to get a lot more "bang for the buck" by getting some dedicated track wheels/tires.

Also - I would highly recommend against just getting the fronts done. I have seen rear brake temps at the track that are higher then the fronts (that have done some of our mods) and the proportioning problems and additional rear heat problems will not help you at all towards your goal. Besides that it looks really dorky IMO.

Good luck. [/B]

Actually I am staying with street tires for the same exact reason, I see drivers who end up using R compounds tires before maxing out with their street tires, the R compounds will mask many mistakes because of the extra grip that they provide.

Many times I observe and learn from drivers who are running with street tires who are faster than their R compound counterparts. Usually these drivers are better drivers overall. It's a lot easier to learn from them because the breakaway characteristics of a street tires seems to be progressive and I can actually feel and see the driver correcting the car.

These are the same reasons why I enjoy driving the NSX in the rain at track events in the wintertime, it's a good learning tool, the limits of the NSX can be reached at much lower/safer speeds.

I agree that everything is about improving the driver.

Ken

 

[1BADNSX]

Going with R compound tires with better traction would result in:

Faster cornering speeds, (less braking going into the corner), faster exit speeds from the corner thus resulting in faster speeds going into the next corner.

Better traction, thus resulting in better usage of the amount of braking capacity that is available. (late braking, threshold braking become a possibility) It takes less time/distance for the tires to slow down the car.

So would it be fair to state that given the same laptimes a car running R compounds would be using at a lesser degree the capacity of the brakes when compared to street tires?

I am curious to know if anyone has stuck with street tires with a NSX with minimal weight reduction but with many of the brake upgrades who are using 235 mm wide street tires up front.

Yes, properly driven you would need less brake performance with R compound tires. One of your statements above is very true and one is marginally true. With stickier tires you can enter a corner and exit a corner faster, but what they teach you in drivers school about carrying the speed difference the entire length of the straight is not true. For instance, go do a ¼ mile run from a standing start and check you trap speed (say ~105 mph) and then start the ¼ mile run at 10 mph and check your trap speed. It will not be 115 mph, it will be something like 105.1 mph. I am not downplaying the importance of exit speed (it is king), but I am pointing out that the top straight speed is mostly dictated by power to weight ratio and has little to do with the previous corner exit speed.

After that dissertation, what does it mean? It means with R tires your top speed at the start of braking is about the same, but your corner entry speed is higher, which leads to less energy required to be removed by the brakes.

In regards to your question about track driving in the NSX with street tires, I very rarely track the NSX now that I race the M3. When I do, it is with street tires and good pads/fluids and cooling. I can not say that I have never had them get weak, but they have performed well and in the end it is a driving school and a cool-down lap isn’t that big of deal.

Bob

 

[nsxtasy]

I am curious to know if anyone has stuck with street tires with a NSX with minimal weight reduction but with many of the brake upgrades who are using 235 mm wide street tires up front.

I wonder if the increased contact patch that is available would make a difference in regards to how much the brakes are taxed when compared to other sizes such as 205 or 215.

This is an easy question to answer.

Your question is built upon a flawed assumption, when you state that there is an "increased contact patch" with the wider tires. There isn't. The size of the contact patch with wider tires is exactly the same as with narrower tires.

The size of the contact patch is determined only by the pressure in the tires, and the amount of weight that they are supporting. If you have a 3000-pound NSX and you put 40 psi of pressure in all the tires, the size of your four contact patches will total 75 square inches - regardless of whether you are using 205/225 treadwidth tires in front/rear, or 235/285. When the car is in motion, the weight may be transferred between front and rear, but the principle remains the same.

Those who make claims that wider tires produce better lap times - and I have heard some that are so wild that they strain credulity - do so based on greater cornering ability, not greater stopping ability.

Finally, anyone else out there running with street tires who feels that their stock NSX system with the upgrades is adequate for the track?

I made all of my upgrades (rotors, pads, fluid, ducts) between 1993 and 1997. As of 1997, I had about 4000 track miles on my NSX. I put another 4000 track miles on it from 1997 to 2001, entirely on street tires (OEM Yokohama A022H), before I ever put R compounds on it. (I then switched to track tires because I thought they might reduce my lap times slightly, not because I felt that I had to in any way.)

I do indeed feel that during that period, the car was perfectly adequate for the track, with the OEM street tires, the stock brake calipers, and the upgraded rotors, pads, fluid, and ducts.

Furthermore, with the hindsight of having made these upgrades one at a time, I think it would have been perfectly adequate with the stock rotors and pads, but with high-temp fluid and the cooling ducts.

 

[2slow2speed]

This is an easy question to answer.

Your question is built upon a flawed assumption, when you state that there is an "increased contact patch" with the wider tires. There isn't. The size of the contact patch with wider tires is exactly the same as with narrower tires.

The size of the contact patch is determined only by the pressure in the tires, and the amount of weight that they are supporting. If you have a 3000-pound NSX and you put 40 psi of pressure in all the tires, the size of your four contact patches will total 75 square inches - regardless of whether you are using 205/225 treadwidth tires in front/rear, or 235/285. When the car is in motion, the weight may be transferred between front and rear, but the principle remains the same.

Those who make claims that wider tires produce better lap times - and I have heard some that are so wild that they strain credulity - do so based on greater cornering ability, not greater stopping ability.

Thanks for clarifying, OK, I understand that the basic formula that the contact patch is weight in lbs / lbs per square inch.

But, in a wider tire, isn't the area that is exposed per a given quanta of a revolution a smaller percentage when compared to the entire surface area of the tire surface? Thus less likely to heat up as much when braking, IE staying within the optimal tire temperature range longer? Thus reducing braking distances to some degree? Then again it might be completely insignificant in the end..

Is the extra grip provided by the R compounds partially due to the actual increse in contact patch areas then? R compounds usually run with lower PSI's than street tires.

Ken

 

[NSX-Racer]

Better grip with R tires is mostly due to softer rubber - I see that after about 2 or 3 events when I have to throw away the Yoko A 005s in relatively soft compound - rubber gone...

OTOH the hot pressure is really about 30 % lower - should be interesting to measure the contact patch - never done that.

 

[Brian Bailey]

Hi Brian,

Thanks for sharing the information, really interesting to read.

Are you allowed to switch rotors to some other rotors with better cooling. (I'm not that familiar about the Grand AM series.. sorry.)

I read an earlier post that stated that other NSXs were doing 2:20's at VIR and asked other members about their own laptimes but never read the replies.

BTW: Does your car meet the 2730 lbs weight limit as well?

Thanks,

Ken

Last year rotors were required to be exactly the same size as OEM. This year we're allowed 10% larger than stock rotors and are in the process of investigating the benefits of this. We've run stock Acura rotors to this point.

Car weights in at 2730 completely dry (no fuel, no driver, etc).

 

[Pulp Story Teller]

I keep hearing about folks who are able to run with their stock brake systems on their cars without any problems for entire track days while pushing the car at 9/10ths or 10/10th's.

I suffered from minor brake fade at Laguna with stock brakes and race pads(way back in say 92/93).

Before getting a big brake kit, if I were you, I would:

1. Change to aggresive race pad (R4, Cobalt, PFC, etc)

2. Add some type of brake ducting to get air to the brakes

3. Change fluid (like SuperBlue, etc)

4. Do a real good bleed

5. Go to track. Does it still fade noticeably on the first day? If yes, perhaps you are going fast enough and braking hard enough to think about bigger brakes. But, I would do it more for safety, as opposed to laptimes. Remember, if you can stop 12-18 inches shorter, it could save you $10,000 in body damage, and possibly make it so you don't hit a car that spins in front of you.

I have turned some of my fastest laps in my S2000 when the brakes were fading a little bit (perhaps I was braking too much in some of the turns?) Remember, the goal is to "more gas, less brake" when trying to get faster laptimes.

I keep wondering if the NSX stock brake system is that great, why did every single NSX that participated in OTC made use of an aftermarket BBK system?

I have the Comptech big brake kit more for safety, and so I can outbrake other people going into a turn. There is also less maintenance, as I was able to get something outrageous like 17 track days on one set of PFC pads and one set of rotors, and still have 40% left on the pad. And I am really hammering on the brakes.

In comparison, the S2000 R4 pads last me about 3-4 track days before I have to replace them. The S2000 brakes are fantastic if you just add ducting, race compound, and good fluid. If you DO NOT add those 3 ingredients to an S2000 brake system, the brakes will SUCK at the track. Which is why I think you should give the same items a chance in your NSX.

-Doug

 

[kenjiMR]

It sounds like it might be worthwhile looking into building or designing a more sophisticated air ducting system. I use the Dali aluminum deflectors, but do you guys think it would really make that big of difference to add more tubing to the backsides of both front and rear brakes? As 2slow2speed mentioned, the back and front sides of the rotors will heat and cool at different temperatures which may cause early rotor cracking.

 

[nsxtasy]

do you guys think it would really make that big of difference to add more tubing to the backsides of both front and rear brakes?

I have done that on my front brakes and I do indeed think it has made a significant difference.

I have never had any problems with the rear brakes. I have never had any shudder from the rear, and have never even worn out a set of rear rotors, from either cracking or thinness.

 

[2slow2speed]

I have never had any problems with the rear brakes. I have never had any shudder from the rear, and have never even worn out a set of rear rotors, from either cracking or thinness.

Can you clarify the above statement a bit?

You've probably have had to replace rear rotors on your NSX, but perhaps you meant to say that you have never cracked a set of rear rotors?

Ken

 

[2slow2speed]

Front pad wear vs rear pad wear

On a related subject, with the stock NA-2 braking system, I have noticed that my rear pads wear at about 2 x times the rate of the fronts.

IE, I go through a set of rear pads every 3 to 4 events and the fronts can last me about 6 to 7 events before reaching minimum thickness.
The pads are Carbotech P+'s.

How about everyone else, do you experience similar trends in pad wear? If not, can you post the trends that you have experienced?

Thanks,

Ken

 

[nsxtasy]

Can you clarify the above statement a bit?

You've probably have had to replace rear rotors on your NSX, but perhaps you meant to say that you have never cracked a set of rear rotors?

I have never had to replace my rear rotors. I have replaced the rear rotors on my NSX twice - in both cases, because I wanted them to match the fronts aesthetically, not because there was anything wrong with the rears.

When my car had 3551 track miles on it, I tried out a set of cross-drilled rotors, and put them on the rear as well as the front. After another 1260 track miles, I did the same thing, using slotted rotors. I still have both sets of rear rotors, the originals and the cross-drilled, and neither one has any cracks, and both are sufficiently thick that I can use them again if I want.

I now have another 3906 track miles on the set of rear slotted rotors. No cracks. I had them measured for thickness before my most recent track event, and they were fine.

How about everyone else, do you experience similar trends in pad wear?

Yes.

I always change brake pads only when they get too thin, and replace them with new brake pads. In the 54K total miles including 8711 actual track miles on my '91 NSX, I have replaced the front brake pads 19 times and the rears 10 times. I have used a variety of different pads, most of which have been stock pads or RM pads. Most recently I put Panther Plus pads on the front.

 

[2slow2speed]

I have never had to replace my rear rotors. I have replaced the rear rotors on my NSX twice - in both cases, because I wanted them to match the fronts aesthetically, not because there was anything wrong with the rears.

When my car had 3551 track miles on it, I tried out a set of cross-drilled rotors, and put them on the rear as well as the front. After another 1260 track miles, I did the same thing, using slotted rotors. I still have both sets of rear rotors, the originals and the cross-drilled, and neither one has any cracks, and both are sufficiently thick that I can use them again if I want.

I now have another 3906 track miles on the set of rear slotted rotors. No cracks. I had them measured for thickness before my most recent track event, and they were fine.

Yes.

I always change brake pads only when they get too thin, and replace them with new brake pads. In the 54K total miles including 8711 actual track miles on my '91 NSX, I have replaced the front brake pads 19 times and the rears 10 times. I have used a variety of different pads, most of which have been stock pads or RM pads. Most recently I put Panther Plus pads on the front.

Hmm..

I was pretty much close to the minimum thickness of my rear rotors before the BBK upgrade, after 47 events and close to about 6K track miles on them they had reached their minimum thickness.

I suspect that there are probably 2 factors, the pad material (about 35 events on the Carbotech's P+'s) and the fact that I stuck with the same set of rear rotors without swapping them. I was on my 5th set of front rotors.

Ken

 

[2slow2speed]

Re: Re: Track laptimes with stock brakes

I suffered from minor brake fade at Laguna with stock brakes and race pads(way back in say 92/93).

Before getting a big brake kit, if I were you, I would:

1. Change to aggresive race pad (R4, Cobalt, PFC, etc)

2. Add some type of brake ducting to get air to the brakes

3. Change fluid (like SuperBlue, etc)

4. Do a real good bleed

5. Go to track. Does it still fade noticeably on the first day? If yes, perhaps you are going fast enough and braking hard enough to think about bigger brakes. But, I would do it more for safety, as opposed to laptimes. Remember, if you can stop 12-18 inches shorter, it could save you $10,000 in body damage, and possibly make it so you don't hit a car that spins in front of you.

I have turned some of my fastest laps in my S2000 when the brakes were fading a little bit (perhaps I was braking too much in some of the turns?) Remember, the goal is to "more gas, less brake" when trying to get faster laptimes.



I have the Comptech big brake kit more for safety, and so I can outbrake other people going into a turn. There is also less maintenance, as I was able to get something outrageous like 17 track days on one set of PFC pads and one set of rotors, and still have 40% left on the pad. And I am really hammering on the brakes.

In comparison, the S2000 R4 pads last me about 3-4 track days before I have to replace them. The S2000 brakes are fantastic if you just add ducting, race compound, and good fluid. If you DO NOT add those 3 ingredients to an S2000 brake system, the brakes will SUCK at the track. Which is why I think you should give the same items a chance in your NSX.

-Doug

Hi Doug,

Hope you had a nice Xmas with your family and the baby .

Yep, I've pretty much done 1 throuth 5, and I still experience brake fade at Laguna. Ended up purchasing a Stoptech BBK instead of the Comptech, since it is "not supposed" to require a proportioning valve and I did not want to upgrade to 18" front wheels.

I know what you mean about braking less and posting faster laptimes, I found that out by accident when I tracked with some Porterfield R4S's when the Carbotech P+'s were out of stock. I ended up turning some pretty fast laptimes by braking less, because of the lack of bite on the Porterfields, hehe.

Ken

BTW: I ended up purchasing some Kinesis K57's and K58's in order to be able to run the wheels without spacers. From what I recall both you and Rylan were happy with the Kinesis wheels. Another one of my track buddies Kim who has a Yellow 993 3.8RSR (you might remember him.) is happy with them too.

Sadly the folks at Kinesis don't know what offsets you have on your wheels, do you happen to remember them offhand? I just want to confirm that the wheel sizes/offsets that they are planning to produce makes sense.

Are you planning to come up for the Sears event with SV on Jan 24 and 25th? the track feels a bit different after the repaving and the reference points are a bit different too, you probably want to get some more laps at Sears for you know what .

 

[Pulp Story Teller]

Re: Re: Re: Track laptimes with stock brakes

Hi Doug,



Sadly the folks at Kinesis don't know what offsets you have on your wheels, do you happen to remember them offhand? I just want to confirm that the wheel sizes/offsets that they are planning to produce makes sense.

Are you planning to come up for the Sears event with SV on Jan 24 and 25th? the track feels a bit different after the repaving and the reference points are a bit different too, you probably want to get some more laps at Sears for you know what .

I don't know the offsets, but mine needed spacers to fit over the Brembos. Wheel offsets are one of the biggest pains in the ass to figure out. If you can send a picture of how to measure, I can give it a try, but it seems no one ever gets the offsets right the first time.

I don't think I can make it to Sears, but there is a slight chance that I might be there.

-Doug

 

[2slow2speed]

Re: Re: Re: Re: Track laptimes with stock brakes

I don't know the offsets, but mine needed spacers to fit over the Brembos. Wheel offsets are one of the biggest pains in the ass to figure out. If you can send a picture of how to measure, I can give it a try, but it seems no one ever gets the offsets right the first time.

I don't think I can make it to Sears, but there is a slight chance that I might be there.

-Doug

Hi Doug,

Don't worry about the offsets if you don't know them offhand, the folks from Kinesis guaranteed that the wheels will clear the calipers, so if they don't they will have to try again.

Ken

BTW: I think that Joe B's Comp Coupe broke down on Saturday at Sears, I saw his car being towed in during the 2nd session..

 

[RP-Motorsports]

Just a reminder, wheel offsets don't really mean squat as far as fitting a certain caliper. It has to do with the shape and or thickness of the spoke patterns. The offset for the most part just moves your tire in or out of the wheelwell. Offset = the mm distance from the centerline of the hub to the vertical plane that the rim bolts to the hat. Either positive (i.e. flat faced style rims) or negative (i.e. deep dish style rims) You can have 2 identical offset wheels, and 1 may clear a caliper, and the other may not!!! So finding the right rim really IS a pain in the arse! I would suggest buying 1 rim, and bolting it to your car, and if it clears, great! If not, just return it. You may just have to pay for shipping ($25) or shipping + a 20% re-stock fee.

 

[2slow2speed]

Just came back from another track day at Laguna Seca with the Stoptech's.

Today it was yet another nice day here in Northern CA. The track was a bit icy this morning with some black ice around turn 8 and 9 in the shade.., yikes!

During the morning the track temperature was in the low to mid 40's so I took it relatively easy for the first 2 sessions. Could not push the car too hard because the track was slippery and I was giving rides to some folks. I managed a couple of 1:54's or so, I ended up having to short shift between turns 5 and 6 in order to pass the 90dB sound limit today, without short shifting the NSX speed at the top of the hill would be close to 105mph or so, with short shifting my max speed at the top of the hill was only 85mph .

The 3rd session was supposed to be the best session of the day, with a warm track, but sadly a Viper went off after turn 2 and our session was cut short and I could not really get into the grove.

Finally on the 4th session of the day around 3:30PM, I was able to have a session with about 10laps uninterrupted, was getting into the grove averaging low 1:53's and 1:54's. The Stoptech worked great, no fading, great bite and pedal feel.

Ended up chasing Richard (from San Diego, Greg Hardee's buddy) with his White S2000's running R compounds and another Yellow stripped S2000 track car running street tires, I managed a couple of 1:52's while playing cat and mouse with them, this was with short shifting between 5 and 6.

So on average this was close to 2 seconds faster than my previous average laptimes at Laguna with WOT between turns 5 and 6, not having to worry about possible fade allowed me to brake deeper into corners and actually be able to be very consistent throughout the session.

The Stoptechs worked well, with no boiled fluid, no fading, however I did notice some microfractures on the discs, tiny little ones in the area of the rotors that showed the most wear. The front left tire experienced some rubbing problems in the corkscrew when giving rides, but while riding solo it was ok..

BTW: I was lapped by a Radical that I pointed by on the first lap of the 4th session. He caught up with me after 10 laps. That's close to being 15 seconds faster than the NSX, those things fly!

Ken

 

[2slow2speed]

Just a reminder, wheel offsets don't really mean squat as far as fitting a certain caliper. It has to do with the shape and or thickness of the spoke patterns. The offset for the most part just moves your tire in or out of the wheelwell. Offset = the mm distance from the centerline of the hub to the vertical plane that the rim bolts to the hat. Either positive (i.e. flat faced style rims) or negative (i.e. deep dish style rims) You can have 2 identical offset wheels, and 1 may clear a caliper, and the other may not!!! So finding the right rim really IS a pain in the arse! I would suggest buying 1 rim, and bolting it to your car, and if it clears, great! If not, just return it. You may just have to pay for shipping ($25) or shipping + a 20% re-stock fee.

Thanks for the reminder, but the partcular wheels that I was referring to have a fixed spoke design and the only changes that are made are in the backspace area. I had chatted with Doug about this back in August while checking his Comptech brakes down in Buttonwillow, I did not realize that he was running spacers on his wheels.

The wheels are custom made and the vendor guaranteed caliper clearance and fitment with the BBK, so if it does not work, they willl have to take the wheels back, or send me something else that works..

Ken