Brakes and the track...

[titaniumdave]

I am thinking about a big brake kit that uses stock calipers and 328mm floating, slotted rotors on all 4 wheels. Am I missing something with this idea? It seems to me the weak link in our brakes is the rotors, the calipers are fairly light, and quite rigid. The are already set up for a good balance on the car, work well with the ABS and hold up for years of use. Good air ducting to pull heat out of the rotors, a floating rotor which can expand and contract, Carbotech XP-8 pads(my favorite) and DOT 4 fluid seems like it would be a very good system. Plus an E brake that works!

I am pretty sure I can make this fit under the stock 17" wheels too...

Has any one done this?

 

[RP-Motorsports]

Use Motul 6 or even better, use Castrol SRF http://www.pegasusautoracing.com/productselection.asp?Product=3343&iorb=4764&BR001

it is actually non-hydroscopic!!! And holds peaks better than Motul.

And yes use some efficient ducting as well.

 

[nsxtasy]

I'm a big believer in taking an incremental approach to improving the car. That means starting with the cheap stuff before taking the more expensive steps that might not be needed. I'm glad to hear you're thinking along the lines of the same philosophy.

That being said, I haven't needed to get a big brake kit, but what I've done is somewhat along the lines you're suggesting. I'm using stock-sized (282 mm) two-piece rotors (floating and slotted) from Stoptech on the front, and plain old one-piece rotors (slotted) on the rear (I've never had ANY problems with the rear brakes). I'm using Motul RBF 600 fluid (which has a higher dry boiling point than the expensive SRF, and wet boiling point doesn't matter if you're flushing your fluid fairly frequently for track use). I've installed cooling ducts to cool the front rotors. And, of course, I've chosen a brake pad to meet my needs - in my case, the street/track Cobalt GT Sport, because I don't want to change pads before and after every event.

I haven't found any need to do any more than that. My brakes work fine on the track, with nice bite and very good balance.

Just one data point...

 

[mystican]

I agree with Ken on this one...I have seen many people in various cars upgrade to more "expensive setups", only to be disappointed with tragic results to their car... all because they were not used to the new brake setup ...look at the NSX type R calipers!!!!...they are not any fancier than the USDM calipers...

 

[titaniumdave]

I have had Brembo Lotus calipers and 328 x 28 mm rotors front, stock rear, on my old car. I did not realize how bad the balance was on that till I tried a full BBK. I am now running Wilwood 6 pot fronts, 4 pot rears with 328 x 28 mm rotors all around. I needed to make new mounts for the rear to clear the wider rotors and get better pad contact. Currently have SS lines all the way around, Dali CF deflectors in the front. I have always used Motul 600, flushed every other track day. I have gone to the Carbotech XP-8 because I like the initial bite once there are hot, and I would overheat the Panther + pads. I do admit the back of my wheels look like crap from all the iron dust:redface: , because I am too lazy to swap pads all summer...

The thing I am wondering is if the calipers are really a problem, or do we go out and change them because we feel we should when we go with bigger rotors? Do the calipers really fail? Do they not hold up? Do folks melt seals? Do they not apply enough clamping force?

I have found folks will often make changes with out doing all the research. After using BBK for 3 seasons, I am wondering if there is a need for changing the calipers or if I can get the increased brake power and fade resistance with improved rotor life by just a rotor upgrade/re-positioned caliper. I like the idea of maintaining the balance Honda designed into the stock system, plus not needing to use wheels with increased spoke clearance would be a gigantic benefit for the person who was just getting into tracking their car. potentially this would be a setup which could be installed with out having to open the brake lines, all bolt on and completely reversible, even maintaining stock 17" wheels.

Thoughts?
Dave

 

[nsxtasy]

Hi Dave,

Dali CF deflectors in the front

Try some real ducts. They make a big difference.

The thing I am wondering is if the calipers are really a problem, or do we go out and change them because we feel we should when we go with bigger rotors? Do the calipers really fail? Do they not hold up? Do folks melt seals? Do they not apply enough clamping force?

I think, as you say, many folks get new calipers because they are sold as part of a "big brake kit", including bigger rotors and calipers. That being said, if the rotors are bigger, the calipers are usually bigger, accommodating bigger brake pads with more swept area, which theoretically should help in braking, both in braking force as well as dissipation of heat. However, I'm well aware of the physics involved, that the force placed at the outside of the rotor is more effective than at the inside of the rotor, so that you may get similar results with the stock calipers. To answer your specific questions, I've never heard of stock calipers actually failing, or not holding up. With extended track usage, people DO melt the piston boot seals (I do) and eventually crack the rotors (I do), but I've heard from users that those same things happen with extended track usage on even the best big brake kits, too.

I have found folks will often make changes with out doing all the research. After using BBK for 3 seasons, I am wondering if there is a need for changing the calipers or if I can get the increased brake power and fade resistance with improved rotor life by just a rotor upgrade/re-positioned caliper. I like the idea of maintaining the balance Honda designed into the stock system, plus not needing to use wheels with increased spoke clearance would be a gigantic benefit for the person who was just getting into tracking their car. potentially this would be a setup which could be installed with out having to open the brake lines, all bolt on and completely reversible, even maintaining stock 17" wheels.

What you say makes sense. Since you (presumably) have all the parts except for the brackets you will need to make, why not try it and see how it goes? You can always switch back if you're not happy with it...

 

[Andrie Hartanto]

Dave,

lots of people will have different input from their won data. one thing you have to keep in mind when asking this kind of data from the net is you have no control on the data.

Some of them are slow driver and the stock brake are more than sufficient.
Some of them are fast driver that need big brake kit. Remember, KE=1/2 MV^2. As you can see Velocity play major part on this one.

I would trust your own judgement. If you feel you need a big brake kit, most likely you do.

That being said, caliper is very important in pedal feel, which in turn tells the driver how to modulate the brakes. The better you tranmsit this to the driver, the better will the driver be able to modulate them.

Just like certain cars have better road feel than others.

 

[DONYMO]

Personally, I love my BBK.
I feel that it makes noticable and real difference over the stock setup.

HOWEVER, there are a few things to consider:

1. Every time I need a new set of rotors, I cringe because it costs $700+ to replace them. I need a new set about once per year given the number of events I do (I had 25 track days in 2005...it was a good year).

2. Unless you have sticky tires, and I mean R compound or better, the BBK is worth very little to you in terms of performance. When I ran S03's on the track with my BBK, I could lock them up (i.e. go into ABS) easily and had to really watch how much brake pedal pressure I used. At that time, I remember thinking that a BBK was a waste due to the higher costs of replacement rotors and brake pads (yes, brake pads cost more too since they are bigger - I use Carbotech XP8). Once I started running Toyo RA-1 track tires, the benefits of the BBK became VERY noticable and it is rather difficult to go into ABS now. With R compounds, the greater clamping force of the big front calipers give a real advantage in braking performance. The only other performance side benefit of the BBK is cooling, since there is so much more surface area on the rotors.

3. Changing the hats from the old rotors to the new ones is a pain in the ass. There are a crap-load of little, delicate nuts and washers. If you pay a shop to do it, you can add another $100 to $150 to the cost of a new set of rotors. If you DIY, you need a micro torque wrench to torque all the nuts. It is easy to strip one of the tiny nuts since they are so thin. Also, it is recommended that you get a new hardware kit every other time (or so) that you change rotors. This will cost you another $150 in parts.

4. Wheels. It is a pain in the butt to find wheels that will clear your new, fancy brakes. I also needed to add racing studs to my front hubs and run a 10mm spacer to get adequate clearance over the track wheels I wanted to run (SSR-Competition). When I wanted new street wheels that were compatible with my setup, my options were limited. In the end, I am very happy with what I have now...but there were lots of growing pains to find the right setup.

Bottom Line:
If money is no object for you, forget everything I said and get the top of the line Brembo setup from Comptech and 2 sets of Techno's and be done with it. When you need new rotors, take it to your favorite shop and tell them to "take care of it".

If you're thinking you can barely afford the BBK, but once you get it everything will be peachy, fuggitaboutit.

 

[john@johnhudakracing]

The thing I am wondering is if the calipers are really a problem, or do we go out and change them because we feel we should when we go with bigger rotors?

Machining custom brackets and hats takes good time and money. To me it seems like a lot just so you can mount slightly larger rotors using the OEM calipers. A rather small incremental improvement. However, I likely am a bad data point as I would be willing to spend a lot more on brakes than most.

Do the calipers really fail? Do they not hold up? Do folks melt seals? Do they not apply enough clamping force?

As Andrie mentioned, the real truth is some good drivers truely absolutely require a serious brake upgrade, as they may well be using 100% of the braking potential of the vehicle all the time, and also may be using grippier tires with a higher cooefficient of friction. You'll know these drivers because they arbitrarily pit when their brakes fade, or they are forced to by getting flagged as smoke is literally pouring out of all four corners of their car. Under such circumstances, all of the above likely well apply.

Given the need, I would hardly characterize an OEM caliper's performance as being in any way comparable to that of a high quality monobloc race caliper. Comparing the design of the OEM caliper to that of a high end aftermarket race caliper like Brembo or Alcon is frankly pointless. The OEM caliper is cast, no where near as rigid, missing all the construction features, larger pad profile, fluid displacement, etc... and you need to evaluate each caliper on its own merits.

That aside, just as important as the real world actual physics of the brake system thou, is how you as a driver FEEL about them. Consistency gives you good lap times; OEM or otherwise, IMHO if as a driver you don't have any confidence in your brakes, you are going to preform poorly/inconsistently out there wondering if the end of each straight away will be the precursor to a cruise through the grass instead of squeezing in all you can. That piece of mind should be worth it at any price.

 

[titaniumdave]

Andrie,
Part of my issue is I have never tracked my own car with stock brakes. Both of my NSXs had BBK when I got them...I am realizing each has it's own issues. The front only Brembos really messed with the balance of the car(I didn't know it at the time), the Wilwoods I have now, are very hard on rotors, plus they are race calipers and have no dust seals so I have to be careful cleaning them when ever I change pads(I am lazy). I should state I am using 235/275 RA-1 tires on my car, have a high boost CTSC and like to drive it hard:biggrin: , have been instructing for 2 years(for background), grew up racing Go-karts(didn't know you could make a car go around a corner unless it was sideways).

I liked the pedal feel of the Brembos, I am less happy with the pedal feel of the Wilwoods. I don't know what stock would feel like if I beat on them as hard as I beat on my own...

I am working on better ducts for the fronts, I would like to tie them in with a rear shield to direct air 'into' the rotors, instead of 'at' the calipers like the deflectors.

 

[Andrie Hartanto]

Dave,

Anybody who is a decent driver should notice how front only brake upgrade really upset the balance of the NSX. I learned it the hard way too when I upgraded mine with Porsche brakes up front.

While the Porsche brakes in my car was great, with rotor thickness of 33mm, I could run them 1hour and 25 min without any fade. They are inferior in pedal feel with the Comptech Powertec brakes. The Comptech powertec brakes is that much better.

That being said, the Porsche big red I had is street caliper with dust seals. Since you have machining ability, you might want to look into this. The Rotors are cheap and readily available through Porsche dealer ($150 each). The Calipers are relatively inexpensive at $1K a pair. Although, you might want to look into the newer Porsche turbo brakes with monobloc caliper.

Shoot me an email, I'll walk you through if you are interested in building one.

 

[Litespeeds]

I would be very interested in any kit that Titanium Dave comes up with that will be similar to the AP Racing kit that SOS sells. Please keep me informed. Thanks.

 

[nsxtasy]

I am working on better ducts for the fronts, I would like to tie them in with a rear shield to direct air 'into' the rotors, instead of 'at' the calipers like the deflectors.

That's how mine are set up. Each side is 2.5" high-temp ducting hose, running from inlets in the front air dam, squeeeeeezing alongside the bottom corners of the radiator above the core support, and onto a flange that I had welded onto the brake dust shield, around the edges of a hole cut in the shield.

You have mail...

 

[Litespeeds]

NSXTACY,
Could you post some detailed pictures of the brake duct work? Thanks.

 

[Q]

NSXTACY,
Could you post some detailed pictures of the brake duct work? Thanks.

I bought an extra set of dust shields to do the same thing. I'd like to see where the flange was located.

 

[RP-Motorsports]

I have been biting my tounge a bit on this subject. I agree with Adrie about there being a lap time threshold for each track. Some people are at that point and really do "need" a BBK. Others are not there yet, and may "want" a BBK. If you are a "wanter" like someone earlier said, you need to keep the ABS and also be running r-compounds at the least to be safe and effective period. I have NEVER driven a front only BBK car and felt it was majorly needing a rear BBK. Most cars that I see with front only BBK's (with a skilled driver) can still easily lock and drag the rears with the crappy oem rear system. This is due to weight transfer. You don't need any more cooling in the rear, or big 13" rotors or 4 piston calipers back there. (this applies to 99.9% of NSX's) if you are at the .1%, you should be entered in the Rolex 24.

For you beginners, do the ducts, fluid, pads, and s.s. lines (front and back) first.

Next step, once experienced, get r-compounds.

When you move up to the top run groups and are mid pack, you will start getting some fade, or even partial failure at certain corners. This is when you put the BBK on the x-mas list.

If you think your NSX won't ever fade, then you are not fast enough! :wink:

 

[john@johnhudakracing]

I have been biting my tounge a bit on this subject. I agree with Adrie about there being a lap time threshold for each track. Some people are at that point and really do "need" a BBK. Others are not there yet, and may "want" a BBK. If you are a "wanter" like someone earlier said, you need to keep the ABS and also be running r-compounds at the least to be safe and effective period. I have NEVER driven a front only BBK car and felt it was majorly needing a rear BBK. Most cars that I see with front only BBK's (with a skilled driver) can still easily lock and drag the rears with the crappy oem rear system. This is due to weight transfer. You don't need any more cooling in the rear, or big 13" rotors or 4 piston calipers back there. (this applies to 99.9% of NSX's) if you are at the .1%, you should be entered in the Rolex 24.

For you beginners, do the ducts, fluid, pads, and s.s. lines (front and back) first.

Next step, once experienced, get r-compounds.

When you move up to the top run groups and are mid pack, you will start getting some fade, or even partial failure at certain corners. This is when you put the BBK on the x-mas list.

If you think your NSX won't ever fade, then you are not fast enough! :wink:

I think want Tom is saying is that BBK's all comes down to your level on the pyramid of speed.

 

[RP-Motorsports]

Oh come on.....................

 

[titaniumdave]

Most cars that I see with front only BBK's (with a skilled driver) can still easily lock and drag the rears with the crappy oem rear system. QUOTE]

Thanks for the info, but it misses the reason for this thread. I am not trying to justify Big Brakes, I am trying to understand why are the stock brakes 'crappy'? Not enough swept area on the pad? Cast iron caliper to flexible? Seals melt? Lousy pedal feel? Pistons too small so there is not enough clamping force? One piece rotor can not dissipate enough heat?

They are stock so they must be 'crappy' seems to be the only consistent answer.

Brakes are a pretty simple system. They use friction to convert kinetic energy to heat. The amount of friction is controlled by clamping force, coefficient of friction of the materials being clamped and the area of that contact. The force of that clamping is resolved as torque being applied to a rotating disk, the larger the diameter, the more torque available to resist the rotation of the wheel. The limiting factor is traction available between the tire and the pavement(car weight, weight transfer, down force, rubber compound, wheel width, tire pressure, pavement material, surface condition of pavement- all effect this). The kinetic energy from this rotation is now turned into heat, and that heat must be removed from the mechanical parts of the system and dissipated into the air.

This said, better air flow is the first step to better braking. Higher temperature, fresh brake fluid is required as well.

At a certain point, all a brake system comes down to is dissipating heat. So my question is what is the weakest link? Bigger rotors increase leverage, in theory requiring less force to create the same torque. Larger diameter should increase the area to radiate heat and dissipate heat more efficiently. A floating/2 piece rotor should allow the rotor to expand and contract with heat and reduce the rate at which it fails from internal stresses. I think we can all agree on these things...

Here is my question...why do we need different calipers? Is it an issue of mechanical loss of clamping force because of the floating nature of the stock caliper? Is it an issue of the piston not being large enough so there is a need for a greater mechanical advantage through hydraulics? My gut reaction is a supplier would rather sell a complete kit with all the parts because they make more money, and you have to come back to them for replacement parts.

I will never question that a 12 piston mono block caliper on a ceramic disk will make for better braking...I am just wondering if the stock caliper is good enough for a substantial improvement in brake power/fade resistance with just a rotor upgrade and very good air ducting.

 

[TyraNSX]

Could it be that a larger caliper allows for a larger pad & therefore more swept area so better stopping? Could also be a better heatsink and protect fluid from boiling a little better. In addition to what you said about bigger/more pistons so more clamping force. Just asking.

 

[RP-Motorsports]

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 consistant 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

 

[Nguyen Nguyen]

Some theoretical back ground to the discussion.

www.teamscr.com/grmbrakes.html
www.teamscr.com/rotors.html
www.teamscr.com/rearbrakeupgrades.html

http://www.carcraft.com/techarticles/76680/index.html

check out all the sidebar articles as well.


- Nguyen

 

[robfenn]

The OEM calipers are very weak and inefficient compared to quality aftermarket kits.

As i have mentioned before, AP Racing have a new 6 pot front/4 pot rear kit including handbrake mechanism for the NSX. The one from SoS is well out of date now. Maybe SoS want to think about asking for the new kit?

As somebody has mentioned, people need to be honest about 'want' and 'need.' An occasional track day goer only really need to upgrade discs/pads/fluid/brake lines. For someone who does many track days at 10/10ths or races, then you will NEED a proper set up.

Cheers,

-Rob

 

[nsxhk]

FWIW, the new nsx-r (na2 nsx-r) uses 282mm for front rotors. There must be a reason why Honda choose to downside the 297mm front rotors back to 282mm ('91 spec).

Henry.

 

[titaniumdave]

The OEM calipers are very weak and inefficient compared to quality aftermarket kits.

Why? Beacuse they are OEM? What are the design flaws that would have caused Honda to choose a 'very weak and inefficient' caliper?