posted on July 21, 2010 19:00
Project Honda S2000 Part 3- Brakes that don't Break
By Khiem Dinh, Photos by Jeff Naeyaert
Khiem Dinh is an engineer for Honeywell Turbo Technologies at the time of this writing. All statements and opinions expressed by Khiem Dinh are solely those of Khiem Dinh and not reflective of Honeywell Turbo Technologies.
Although the Honda S2000 is one of our favorite all time cars, one of the parts we like the least about the car is the brake system. Although they are perfectly adequate for street duty, the stock brakes do not match the excellent handling ability of the car and are not up to snuff for track day use. S2000s that are tracked heavily, especially on non-staggered setups running 245 or 255 width front tires, are prone to cracking front rotors. The added traction from the wider front tires means more braking power and therefore more heat the front brakes must dissipate. This added heat is simply beyond the capacity of the stock brakes’ design, leading to oft cracked rotors.
To see what else we did to project S2000 click here!
|The stock brakes were not up to the level of the rest of the car.
On our project car, the added grip and width (245 vs. the stock 215) of our Bridgestone Potenza RE-11 tires up front added tons more braking capability to our car. Remember, it’s the traction available from the tires that determines how short the braking distances will be; not the size of the brakes. But, the size of the brakes DOES determine how many times you will be able to stop from speed! As the saying goes, it’s not speed that kills, but the sudden stop at the end. So besides making sure your lug nuts are torqued so that your wheels don’t fall off, brakes are the next most important thing for safety.
|The StopTech ST-40 4-piston caliper makes the stock single-piston, sliding caliper look dinky.
Durability and reliability are key goals of this project and easily cracked rotors do not equal either of those. So what’s the primary solution? Get bigger brakes of course! StopTech offers two Big Brake Kits (BBK) for the S2000; one is based on the 328mm diameter rotor and the other uses a 355mm rotor. For this project, we chose the 328mm kit as it fits under the 17” wheels whereas the 355mm kit requires larger wheels. The main goodies of the BBK are StopTech’s ST-40 caliper, 2-piece AeroRotor, SS brake lines and StopTech Street Performance brake pads. To supplement the parts up front, we went ahead and got SS lines and pads for the rear also.
|It's obvious that the Stoptech caliper can support a much larger brake pad.
Thursday, July 22, 2010 5:58 AM
Yay brakes! So fender clearance to be more specific- problems at the inner edge or outer edge at the top of the tire? I need to come play with your car on a lift the next time I'm out there.
Good writeup Khiem! I need more pics. ^_^
Thursday, July 22, 2010 8:05 AM
Cant wait to see this thing out on the track taking on the big boys! So far its looking like its the perfect balance of street vs race.
Thursday, July 22, 2010 8:34 AM
Do I understand that this wheel spacer/lug mount is aluminum?
axial and shear loads will now be trying to pull this 10mm aluminum piece into a warped record shape. Some simple instant load calculations vs the pull out strength of studs and yield strength of aluminum should make you think twice about this. There is a reason hubs are not aluminum in the first place.
If your studs are too short then you should take the time to get proper length units pressed into the hubs. These "trick" parts are time bombs on a track.
Thursday, July 22, 2010 9:43 AM
max: I think you are forgetting that the wheel spacers are torqued in between the wheel, brake rotor hat, and hub. So any axial or shear loads would have to overcome spacer, wheel, brake rotor hat, hub, and studs for any deformation to occur. Very unlikely.
Nice brakes Khiem.
Thursday, July 22, 2010 12:18 PM
What are you guys planning to do for the rear brakes?
I read somewhere StopTech does offer a BBK for the rear but it deletes the parking brakes....any thoughts?
Thursday, July 22, 2010 3:14 PM
I remember reading on the forums that you're headed out for a track day on August 1st. Looking forward to hearing your impressions of the brakes on track either here or in the forums :)
Thursday, July 22, 2010 3:22 PM
I noticed you removed the dust shields. What's your opinion about those? Don't they help with cooling at the track by chanelling air?
Or are they just extra weight whose main purpose is to keep brake dust off the balljoint rubber boots, etc.?
Thursday, July 22, 2010 7:35 PM
Hey Khiem, How are those studs anchored in those spacers? Max has a point. 10mm is pretty sketchy for shear unless something is really engineered in them like some sort of long steel insert. Are these things track proven? Long studs and conventional hub centering spacers are a lot less jankey.
MX5- I always remove dust shields, when I was racing IT a long time ago when cars had crappy solid rotors, removing the dust shields made things a little cooler. Some cars like the EVO and my 300ZXTT have scoops and air directors in the shields but I would still rather have bigger brakes.
Thursday, July 22, 2010 7:58 PM
The spacers are steel, not aluminum. I spoke with Eddie at Mackin Industries and he said that a few Formula Drift guys use them. I spoke with the guys at Evasive, and they use the 10mm on their track Evo; their Evo has seen a lot more abuse than my car will see. I'm not a fan of curb hopping :) Not to mention, the Evo weighs more and they're running higher grip tires.
On the S2k, to replace the studs involves removing the hubs, and that really means the hub bearings should be replaced also; not a cheap proposal. However, at the point in time when I DO need to replace the wheel bearings (quite a few 10s of thousands of miles away since I'm still below 50k), I'll go with longer studs and a normal spacer.
As for dust shields, I had them off of my Nissan for 130k miles with no ill effects. All of that car's life was spent in Florida and Texas where you can't see 100ft when it rains, so water was never an issue. I'd be surprised if the dust shields helped at all with cooling. There are better solutions like the air deflectors used on Evos and Porsche 911s. Or just a typical brake duct system.
For the rear brakes, the rear StopTech kit is not compatible with the parking brake. As such, the rear brakes are only seeing the upgraded SS lines, and just replacement rotors when the time comes. And brake pads of course.
It's getting near track ready..... still needs some more reliability mods. To be continued!
Thursday, July 22, 2010 8:05 PM
Ah Steel, many OEM hubs have that amount of stud engagement so should be ok then. FD cars really put the shear loads in stuff!
Thursday, July 22, 2010 10:06 PM
Yup, steel. It threw me off when I saw the Evasive site say aluminum, but it is definitely steel. They are heavy, and I verified with a call to Evasive. The fact that Evasive uses them on their track Evo (way more modded and track oriented than this car) puts me at ease.
I do agree that installing longer studs is the optimal, it's just not nearly as feasible at this juncture due to limited hub bearing wear (don't like tossing perfectly good parts), budget, time (car is DD), and I couldn't do it myself.
Thursday, July 22, 2010 10:14 PM
Huh, I have never made the connection between braking and energy in the form of heat.
So, if you know how fast you are going and what speed you want to slow down to, then you know the change in kinetic energy your brakes must stop and thus will heat up. Going a step further you can figure out how much air is needed to keep your brakes cool. Nice!
Really great article!
Friday, July 23, 2010 7:41 AM
I got the lowdown from Eddie at Mackin; he tracked down the materials for me from Project KICS.
The 10mm spacer uses S45C-H which is a quench hardened carbon/structural steel. The 15-30mm spacers use 2014 aluminum alloy. The 5 discs things are SCM45 which looks to be a hardended molybdenum steel.
Leighwayne, yup, all braking is doing is converting kinetic energy into heat. In the real world, you also have aerodynamic drag, rolling friction, drivetrain drag/engine braking, etc. But like in college physics, you ignore all that stuff in doing the basic calculation.
Your brakes have waaaaaaay more horsepower than your engine! Well, most cars at least!
Friday, July 23, 2010 12:59 PM
MX5, the dust shields must be removed for clearance reasons when installing the Stoptech kit. There may be other benefits to removing them such as cooling and weight savings, but the primary reason for removing them is to mount the new brakes.