[grushko]

That is not a secret for everyone, that the standard prelude brakes is not enought powerful. So here i'm gonna tell you how to install two piston calipers with minimum modification.
First - do a research. Acura Legend Coupe 93-95 have two piston calipers with the same bot patter bracket. Also as i know Acura NSX calipers would work too.
You have two ways how to put two piston calipers on. You could run new calipers on your old brackets with stock rotors (23mm thick). Acura Legent rotors suppose to be run on 28mm think rotor, so make sure you will put new brake pads to keep them on place. Or you could install Acura Legend brackets and run your setup on 28mm thick rotors. I decide to go second way.

Second - find all parts you need. I went with this setup:
- Two RAYBESTOS Remanufactured 1994 ACURA LEGEND LS 3.2L (Nissin brand; also comes with the brackets) $150
RAYBESTOS FRC10628
RAYBESTOS FRC10627
for left and right side

- Two front 282mm in diameter and 28mm thick rotors (Prelude has 282mm in diameter and 23mm thick rotors in stock). I went with ebay drilled and slotted rotors for $110 (i was happy with my and these al teast look the same)

- Brake Pads. I get Wagner TermoQuiet (i think this is the best brake pads so far; was happy with the same set on the stock brakes) - $60

- Dot 4 brake fluid - $10-20
- Caliper cleaner - $3

Third - you will need all that tools:
- Floor jack
- Jack stands
- 10, 14, and 17mm sockets
- Wrench
- Hammer

Fourth - lets start!
Now when you got all parts you can say bye to your old brakes

(as you could see i have almost brand new old setup which I'm absolutely happy with; so i will tell you the reason why i decide to change the brakes in the end).
1) Lift you car and remove the wheel.
2) Turn the steering wheel all the way to the left in case if you work on the left side.
3) Using 14mm socket remove two bolts from the caliper, and put your caliper aside.

4) Remove your old brake pads.

5) By using 17mm socket remove two bolts as on the picture and remove your old bracket.

Here is the difference between your old and new bracket:

new one is for 28mm rotor and the old one for 23mm rotor.
6) Very carefully remove two small screws which holding the rotor. I would definitely recommend you put new screws later.

7) Carefully remove your old rotor (use hammer if needed, but be very very carefully) and clean the surface.

Differfence between the old and new rotors:

8) Now put the new rotor on.

9) And remove the brake line from your old caliper by using i belive 14mm socket.

Here is the difference between the old caliper and new one:

10) Install the new caliper and bleed your brakes.

You are done! Do it the same way on the other side.

Here is the also few thing to know.
1) By doing this way you gonna keep your old master cylinder, it pretty powerful enough to handle two piston calipers, but it could be better.
2) You gonna be able to put 15" rims on your car.
3) Probably someone noticed on the left side that on my old caliper was L (left) index and on the new caliper it is R (right) index. There is nothing wrong with it.

The reason is here:

4) Helpful picture how to bleed your brakes right:

The caliper on the Legend located on the different side then on the Prelude.
5) Here is the different between the brake pads for stock setup and for acura legend calipers (both the same wagner termoquiet pads) - the same size, just a different pattern. Legend pad on top and prelude pad on bottom.

They does look just a little different.

In the end:
For $300 you not gonna find any better upgrades for your brakes, and also you could buy all those parts for a lot cheaper right from closest junk yards.
Why i did that upgrade?
I was absolutely happy with my old setup (it was same drilled and slotted rotors with same wagner termoquiet brake pads) - the brakes on my car was amazing. But my cal is pulling to the right a little and noone (i check tree different places) could tell me the reason why (my alignment is almost like on brand new car, just the caster, but the difference are minimal). And now, since i change the brakes and my car is still pulling to the right i think the the problem is in the caster. I decide to change the brakes first, because to adjust the caster on preludes you need to use shims, and noone, even honda dealership do that. So next i'm gonna change the caster by myself.

 

[Kane666]

thats weird i was looking for this type of writeup 2 hours ago. lol nice ty.

 

[Shimee]

Adding this to the resource thread.

 

[Blue01]

Since Legend brakes go on the other side of the hub, you have to decide between two options when installing:

1 - Install them with the bleed screws in the wrong place, you will need to bleed your brakes with the caliper opened up and something blocking the pistons from coming out. There is also an issue with the casting braces for the brake line...you'll see it if you try it that way.

2 - Install them on the wrong side of the car, and the staggered piston sizes will be in the "wrong" place.

Both work.

 

[Cruiserdude]

Great stuff grushko! I've been thinking this would be cool for years, seriously considering it now that I'll need new brakes fairly soon. Great to finally have a step-by-step picture reference to help me along, +rep!

Blue, I see what you're saying about the calipers, I notice of course that grushko just swapped sides, of course with the piston sizes reversed. Would you imagine this could cause any issues other than slightly uneven pad wear? Seems like this is by far the easiest way to go out of the two. But if you put them on with the bleeders upside down, could you bleed them properly with a vacuum bleeder at a shop?

Also, I have a few friends with NSX's, and they too have friends with them, so it should not be that hard for me to track down a set of NSX calipers. NSX's have the calipers in the front just like ours, and while the pistons are mm or two smaller than the Legend, they are made out of aluminum, which is a big plus in terms of unsprung weight (technically a minus! ). Anyway, if I went this route, would everything else, incl. the rotors, be the same? I know the Legend GS pads are the same as the NSX, just a whole lot cheaper. But it seems that I would have the proper bleeder location without having to reverse the calipers and mess up the piston sizing.

One last question, would I need to or want to upgrade my rear calipers as well?

 

[Blue01]

I would only worry about clipping the brake line into the holder that is cast into the caliper, personally.

 

[fei8lo]

You must install the calipers R on R and L on L. the small piston must be the leading piston otherwise you will have uneven pad wear. Doing so makes bleading the system a bit difficult, but it must be done this way. Do no swap calipers from side to side, this will just make the pads wear very poorly and negate the purpose of the twin piston setup.

Check out the last post on this forum about piston orientation.
http://www.nopistons.com/forums/topic/78145-caliper-brake-pistons-different-sizes/

Also the combined area of the legends two pistons is the same (may be a bit smaller, but damn close) and won't increase the braking force too much. The biggest advantage is being able to use a thicker rotor which will have higher heat capacity.

 

[grushko]

I have no issue with the swapped calipers location.
Also found this on the internet:

NSX vs. Legend Calipers - Brake Swap
Uh, us 5lug guys always wonder about the NSX and Legend caliper differences. Well i got a bit of info and figured i'd post it up with a good thread title for searches later.

Legend Calipers 42mm and 38mm piston sizes.

NSX Calipers 40mm and 34mm piston sizes.

-Legend Caliper Issues-
Stock the legend calipers are mounted on the back of the rotor instead of the front like most other honda/acura calipers. So to mount these on an accord using stock mounting holes you must swap the calipers L side on the R side and vice versa. This is only done to keep the bleeder screw on top.

This although puts the big piston before the little piston and some people believe this causes braking problems. I haven't had any and would like to hear from anyone that set this up different or has had some problems.

-NSX Caliper-
These are mounted like all other honda/acura calipers so like most dual piston calipers the small piston is in front of the larger piston. The pistons are smaller than the legends and i believe it may have a small part to do with the mid engine setup and the weight distribution of the NSX.

-Conclusions-

I believe the Legend calipers will give you more braking power. I'd like to know the rotor size on the NSX rotors as well. If you do the 5lug swap and use the Legend calipers you can use there stock 28t brackets and run there 28mm rotors which will take more heat and abuse over the 23mm ITR/Prelude rotors. I'd guess the NSX calipers use 28t brackets and 28mm as well but it'd be interesting to know.

 

[fei8lo]

CruiserDude, you can use Legend rotors with Legend brackets, combined with NSX calipers. This was a common setup for track use. The NSX caliper can also be used with stock Prelude rotors and bracket.

I am using NSX caliper with stock bracket, and powerslot plus rotors (13in front rotors)

 

[fei8lo]

NSX and prelude share the same piston area. I guess the Legend has overall larger piston area. What you must also consider is the brake balance. You do not want to increase braking power in the front too much without considering the rear brakes and overall tire traction. You are most likely running sticky tires and increasing the braking force in the front only may be okay. I just don't want people beefing up their front brake setup with out realizing how it can affect the brake balance and actually increase the overall stopping distance.

As a note, the NSX does use 28mm thick rotors up front.

 

[Blue01]

Just use rear brake pad choice to tune the brake balance. They don't do that much while driving hard.

Flipping the calipers works just fine as well.

Theoretical brake force won't go up but the twin pistons will press on the pad more effectively. What it is worth, who knows. If you are using autozone pads this is just a "style" mod anyway.

 

[grushko]

There is not so amazing difference (but is still different) in the brake force between one or two piston calipers, so you don't need to change the calipers on the back - just run there a new set of brake pads and you are good to go.
Also about location of the pistons when you run new calipers wrong way like i did - that is not a big deal at all, since the small pistons pushing a little harder (because of the different of construction) then the big piston, but the big piston cover more square - they both work almost the same way and all that goes to the brake pad - you and your brakes will never gonna feel difference how to locate the caliper. I know that someone have a different view on that problem, but that is not a problem at all. I also hear that opinion that pistons have a different sizes because of reliability - it's like more secured to have two pistons with the different sizes. Anyway i'm pretty happy with mine setup.
All that setup - it just possible way to go if you willing to change your front brakes, if you are happy with your stock brakes, there is no reason to put two piston calipers on.

 

[fei8lo]

Brake force will go up if the total area is increased. Balancing the braking system can be done by swapping the rear pads out as you said.

Currently my brake setup is pretty nicely balanced, but my all season tires are not sticky enough to ultilize them that agressively.

 

[Cruiserdude]

Good stuff. I've got Dunlop Star Specs, which are some of the stickiest street tires you can buy, so I could really benefit from this. They're so much grippier than stock that it feels like my brakes may need a slight upgrade in order to fully make use of them. They don't chirp at all even if I stab the pedal, though maybe its just my ABS not being made for such sticky tires?

Anyway, yeah, I thought the NSX's had slightly less piston area. But I don't see how there would be a difference between the two as far as brake balance, considering the pad area is exactly the same. I would imagine the Legends would have slightly more felt pedal response, but the NSX calipers would reduce unsprung weight enough to make up for the added weight of thicker rotors and brackets. If no one has had any problems long term in terms of uneven pad wear, I guess that's nothing to worry about. As I said though, its probably just as easy if not easier for me to get NSX calipers than Legends anyway. I like the ability to run thicker rotors, I auto-x and occasionally track the car, so I would imagine thicker ones would be better than larger diameter, if I had to choose. Still, I wonder what options, if any, there are to use a 28mm rotor that's also a bit larger with whatever their caliper brackets are?

 

[Blue01]

Well if you competitively autox you don't want to do this because it will add mass where you don't want it. I guess it is better for the track though...

 

[fei8lo]

Increasing the area of the slave cylinder in a hydraulic system will increase the force that is generated at the slave cylinder. Same pad area but great force. Increasing the area of the piston on the front and leave the back alone means you increase the force applied to the front brake pad while the rears stay the same. This causes the bias to shift to the front.

In terms of rotor size, increase the diameter will increase the torque the brake applies to the wheel and will increase the overall braking power. The larger diameter will also increase the mass which in turn increases the heat capacity a bit. In the case of the rotors I have, the hub is made of aluminum to help offset the mass of the larger rotor. Thicker rotors increase the mass and heat capacity of the rotor, but do not office any benefit in terms of added brake torque.

On tracks with heavy continuous braking, increased heat capacity will help fight brake fade but will have added inertia which will hinder acceleration. For normal driving where the heat capacity will not be too much of an issue since continuous braking is abnormal. Even the stock rotors should stop the Prelude from 120-0 without too much brake fade (assume you have good pads); it is only really an issue when repeated quickly.

The power slot rotors use a caliper relocation bracket but maintain the same rotor offset. At the moment, there is no simple way of increase the rotor thickness and the diameter without spending big money or doing some custom machining.

 

[gearshredder]

well if I did the math right, heres the surface area comparison:

Acura legend pistons: 42mm / 38mm (picture verified EDM type 2 calipers?)
honda prelude pistons 57mm (2.245 OD according to raybestos)
acura nsx pistons: 40mm / 36mm (found pictures on other thread)

Area:
Legend: 2519mm sq'd / 2439mm sq'd (if usdm calipers with 40mm pistons?)
nsx: 2274mm sq'd
prelude: 2551mm sq'd

 

[grushko]

At the moment, there is no simple way of increase the rotor thickness and the diameter without spending big money or doing some custom machining.

Also you could run 300mm rotors from Honda Accord euroR (jdm or europe) on euroR bracket with Legend calipers (or NSX whatever). But however it is going to be 23mm thick rotors. But as far as i know that is the cheapest way how to put 300mm rotors on the lude - a lot of people in russia going this way.

 

[grushko]

And here is the bad thing about those RAYBESTOS calipers i got from RockAuto. I think because they are re manufactured some idiot screw into the calipers wrong bleeder. By the wrong i mean they put (as i think) bleeder screw from domestic car which is not in a metric system (it suppose to be 10mm. I tried to put from my prelude calipers but hole was readjusted). Since that bleeder sits into the hole not tight enough when it slightly opened and the air comes inside. That is not a big deal when the bleeder screws in all the way (even without thread locker), but it is really hard to bleed the brake system of the air. I wrote to the customer support about this problem and will tell you what is gonna happen whenever they respond me.
I didn't noticed that yesterday when put calipers on because was too tired. And today i decide to pump brake system again and found that.

 

[Cruiserdude]

To be honest brake fade has really not been a problem for me at all, even with a bit of track action under my belt. This is my dd, so it doesn't see much abuse, but I tend to make a few auto-x's each season, and a track day every year or so, along with a bit of very spirited street driving once or twice a year as well (Tail of the Dragon or something similar). I like the idea of thicker rotors, but not sure I honestly need that, considering those are for heavier cars and I have removed a decent amount of weight from my car. So maybe I'd be happier with larger stock thickness rotors, but at $500 I honestly don't think its worth it, considering they're still 23mm and use the stock calipers. I'm not saying they weren't for you, and I'm sure they look better as well, its just difficult for me to justify that cost.

grushko, I assume you are talking about the CL1 Euro-R's, aka the one with H22A redtop? I don't know of any cheap way to get those in the US, though there may be another application that they're used in here, I'll have to keep my eyes open. If I can't find a larger rotor for cheap though, I'll probably still get the thicker rotors. Probably the best setup I can put together for the money would be NSX calipers and brackets, rotors and pads from a Legend (95 GS??), stock rears with good pads (I like PFC myself), and my existing SS lines. Again, I honestly haven't found the need for extra fade resistance when using good pads, but of course it can never hurt. Mainly though, I'm looking for better pedal response and braking torque without being so strong its difficult to modulate, and/or harming brake balance and increasing overall stop times/distances.