Looking for the caliper bore of the NSX caliper (same caliper without the markings of the 1995 Acura Legend Coupe).

Also I need to know the caliper bore of the Integra Type R caliper.

If you already have it figured out, cool. If not, I'm trying to calculate the braking force of the NSX caliper versus the Integra Type R. If the effective clamping force of the NSX caliper is more, this could become a bolt on upgrade for people with ITR type calipers (although it will definately screw up the balance, and the front to back bias will have to be adjusted).

Shawn

 

Anyone? b20bastard, do you still have those NSX calipers lying around?

Shawn

 

Shawn,

wondering would it be possible to use NSX/Legend calpiers with the ITR spec brakes/rotors kit from fastbrakes?

 

Absofrickin' lutely. (sorry)

This is the source of my question. I have done the ITR upgrade on my Civic with the Accord Wagon caliper (the EXACT same caliper as the ITR - even has the same part number.)

Then, I find out the NSX caliper will fit. Not only will it fit, but it uses the same brake pad and bracket. Therefore, it must be able to be used with the same swaps. Additionally, Honda sells the SAME CALIPER without NSX in the casting as the caliper on the 1995 Acura Legend Coupe. I have been able to find this caliper rebuilt for less than $100 per side.

b20bastard is using this setup. (with the actual NSX calipers)

However, herein lies the kicker. Multiple piston setups are not always necessarily better than a single piston. The trick will be to figure the caliper piston area. If I can get the bore of the NSX, then I can calculate the piston area. The ITR piston MAY ACTUALLY be bigger. I have not measured mine, but its FRICKIN' HUGE. Honda put this caliper on the ITR for a reason. But, it also put the dual piston caliper on the Legend and the NSX for a reason too. I just need the measurement of one of the pistons to figure the area.

Shawn


[Modified by shawnhayes, 5:48 PM 9/30/2002]

 

nice info Shawn, I hope you get the info on the bore as I would like to know about which would be a better setup, ITR or NSX/Legend calipers! I think I am sold on that fastbrakes kit too!

EDIT - by the conversion you say on your car, you mean the fastbrakes ITR spec brakes (still 4*100) or actual ITR 5 lug conversion...?


[Modified by navin, 11:08 PM 9/30/2002]

 

Brian Hasty wasn't the first guy to do this, as far as I know. Here:

http://hybrid2.honda-perf.org/tech/bigbrakesbymcp.html.

So this is what I mean. I have this conversion on my car.

Shawn

 

Ok guys, I finally found it and you won't believe it.

The Type R calipers should, in theory, be better than the NSX calipers.

Here's the reasoning: Using the hydraulic principle, if you apply force to a small piston connected to a fluid that's connected to a larger piston, the pressure in force/area is applied over the larger area, effectively multiplying the force (but not the work - I won't go into that right now).

As a result, the best braking will be delivered by the largest caliper area.

The NSX brake has two pistons - 34 and 40 mm respectively. Using the area formula, the 34 mm piston has an area of 3630 square millimeters. The 40 mm piston has an area of 5024 square millimeters.

The ITR single piston caliper is 57mm. This is an area of 10202 square millimeters. This means the braking force applied by the ITR piston will be greater than that applied by the NSX pistons together.

I never would have thought that, would you?

Shawn

 

Good information.

But, would efficiency come into play anywhere? I don't know much about brakes or the engineering behind them and such, but would say the smaller braking force of NSX/Legend calipers with the dual piston be more efficient than the higher braking force of the single piston ITR calipers?

Again, I'm not sure what I'm talking about, just wondering if efficiency is an issue.

 

no kidding, otherwise, why would expensive exotic cars put calipers with mulitiple pistons on their cars when it would be better to put one large piston?

 

Talk 2 Migs, Shawn.

Ryan

 

The key is piston area. Multiple pistons, in general, allow for a much larger piston area to be placed in a minimum of circular circumference. Multiple small pistons allow this. A large piston takes up a larger circumference outside the area of the rotor, reducing wheel clearance area.

Additionally, most multiple piston setups place pistons on the inside AND outside of the rotor, being effectively DOUBLE the piston area. A single piston on the inside of a caliper, even if it was large, would not equal a four piston setup even if the single piston was bigger than THREE of the pistons added together.

No matter how you look at it, piston area is the key. It doesn't matter how you set up the pistons, if the total piston area is greater, then the braking force on the caliper with the greater area will be more.

Now, fade resistance and heat dissipation will be another issue entirely. Of course, competition calipers are in general made of aluminum, while OEM (both the NSX and ITR) calipers are made of very heavy duty tempered steel. Aluminum dissipates heat faster, but steel can absorb more heat without changing temperature as much. The steel caliper will do ONE LONG STOP better than the aluminum caliper, while the aluminum caliper will do multiple repeated heavy duty stops better (otherwise known as fade resistance). Each type of caliper has its advantages. However, both the NSX and ITR calipers are made of steel, but both calipers seem very well worked out.

The aluminum multiple piston calipers are in a different league than either the ITR or NSX calipers, but honestly with the usual lack of good dust seals are less suitable for street use than the OEM type calipers.

Shawn

 

Hypothetical situation:

You have your choice of 2 different calipers.

A- is a single piston caliper with a 40mm piston

And

B- is a dual piston setup with 2- 20mm pistons

They both are the same, surface area wise... Which would be the better choice...?

 

I'm sorry. Math error. A single 40mm piston has a WHOLE bunch bigger surface area than two 20mm pistons.

I'll work you through it.

Area of a circle = (pi) * radius squared.
....oh wow... I just figured out I used the DIAMETER in my original calculation. I'll have to go back and rework that.

40 mm piston has a 20 mm radius
area = (3.14) * 20 * 20 = 1256 square millimeters

20 mm piston has a 10 mm radius
area = (3.14) * 10 * 10 = 314 square millimeters
because there are two of them = 628 square millimeters

So a 40mm piston is a much better choice than two 20mm pistons.

However, if you were talking equivalent areas, then you would need two 28mm pistons to equal the surface are of a single 40mm piston.

My guess, and it's just a guess, would be that the dual piston setup would be better overall because of heat absorption and dissipation.

Shawn


[Modified by shawnhayes, 3:19 AM 10/8/2002]

 

As noted above, I screwed this up.
The piston area of the 34mm piston is 907 square millimeters
The piston area of the 40mm piston is 1256 square millimeters

Yep screwed that one up too. The area of the ITR piston is 2550 square millimeters.

This conclusion stands however. The ITR caliper WILL have more braking force than the NSX. I'm still surprised. Maybe the heat dissipation issue pressured Honda into choosing the dual piston caliper for the Acura Legend Coupe, and for the NSX as well.

Shawn

 

 

im not so sure shawn. first of all, after driving both setups, the NSX calipers stop so much shorter and even required driver adjsutment to get used to them. many times have i locked up the nsx brakes without paying attention under braking. now the way i kinda think about it, is that the presure is more spread out over teh surface of the brake pad, thus pressing more of the pad evenly over the rotor. see what im trying to say?

 

bump

 

you bitch, you haven't let me drive you car yet. i wanna feel these NSX calis, oh and i have your helmet. i didn't use it this weekend

 

"butt" brake dyno's are not accurate. The only way to really test is an equal 60-0 or 100-0 stop.

Because the piston area is different, and the pistons are quite different, they will have much different pedal feel. Additionally, if you haven't switched out your proportioning valve, the NSX calipers WILL be better at stopping your car - but not because they are better calipers - but rather because they are WORSE calipers.

A proportioning valve mismatch, or upgrading front brakes without upgrading the rears can actually decrease braking distances. There are, of course, doubters about this, and I refer them to Sport Compact Car's install of AEM's big front rotor upgrade. The braking distances went UP when they upgraded only the front brakes, and then they went down below stock distances when they matched the front upgrade with the big rear upgrade.

So, the NSX caliper may or may not stop your car quicker, but even if it does, it may be because it is a worse caliper rather than a better one.

Complicated, isn't it?

Shawn

 

Have you compared the area of the brake pads? cause that's really what it comes down to. Besides, most brake pistons that I have seen are "hollow", so area doesn't even matter.

 

EIther way, i know the ITR calipers are powereful as hell. I have a 95 civic and i haev the ITR calipers on my car, (actually 91 accord wagon which are identical.) ONce i installed these on my car, and using prelude rotors my car brakes insanely better. at times it feels like the car wants to flipped foward compared to the old civic brakes. i was thinking about using the NSX brake calipers but they were way to expensive compare to what i got. just my 2 cents.

 

Just a quick correction, an NSX caliper has 36mm and 40mm pistons, not 34 and 40. An Acura Legend caliper has a 38MM and 42MM pistons. I have some Legend calipers on my Prelude and love them, the braking is very strong compared to my old setup (stock S model).

 

Ummm. No.

Physics not your strong point, eh?

It doesn't matter how big the brake pad is. What matters is how hard you push on it. Who gives a crap if the brake pad is ten feet long, if you have a fly pushing on it then it won't stop the car. The brake piston is what is pushing on the brake pad.

Doubters of course: http://www.howstuffworks.com/brake4.htm

There is nothing about how much friction is applied being in any way proportional to the contact area. It is the coefficient of friction and the force applied. (just for your notes, though, the NSX and ITR caliper use the same pad)

What determines how hard a brake is able to apply force is the hydraulic principle. It doesnt matter that brake pistons are hollow on the outside. On the inside to the hydraulic cylinder the fluid is in contact with a solid piston. The surface area of this piston determines the force applied by the piston.

Of course, just for your education: http://www.howstuffworks.com/brake3.htm
and http://www.howstuffworks.com/brake5.htm

Just so you'd know.

Shawn

 

I'd like to know your source. Because my source: http://www.acuraautomotiveparts.net/...y5=FRONT+BRAKE says that while the BOOT on the NSX caliper is 36mm, the piston is 34mm. Can you refer me to your source?

However, you do appear to be right about the Legend calipers:
http://www.acuraautomotiveparts.net/...%2794-95+GS%29

I've been told and so has the whole world that the NSX caliper and the Acura legend calipers are IDENTICAL, but apparently not. Should have checked it out for myself, eh?

Even better, the legend calipers should be BETTER than the NSX calipers. Wow.
That even changes the calculation some

The area of the 38mm piston will be 1134 square millimeters
The area of the 42mm piston will be 1385 square millimeters

This still makes the area of the legend piston calipers 2519 square millimeters, still LESS than the ITR caliper. Wow. I'm still amazed. Thanks for the info.

Shawn

 

First and foremost - yes I'm currently taking Calculus based Physics 2 for the second time and am failing it yet again.

But I still don't agree, even after reading all that. If the brake piston was solid, like the piston in an engine, then yes the diameter/area would make a difference. But it's not. The piston is more like a ring. So in order to find the area of it you need to take the area you calculated and subtract the "hollow" area, that is, the area within the inside diameter of the piston.

Now it may or may not be larger depending on the construction of the calipers and how thick the piston is. YOU have the specs and I'd like to know them. I just think you might have an error in your calculations. And btw, you never mentioned how hard you push on them, becase area isn't directly related to that.

Of course this is coming from a physics-flunker so who knows....