AP1 calipers 300mm discs on ek4?


Darragh

Darragh

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Anybody running this set up? ive already read the ultimate brake upgrade sticky thread , in which it says its practically bolt on but im still sussy about it after looking at a mates S2000.

What I want to know do the s2000 caliper carriers bolt straight onto eudm/jdm ek4 knuckles for sure.

Thank you please:D
 
Bump - would also like to know more info on this.

Its an upgrade I want to do but havent seen enough info on it and cant find any write ups of it being done !
 
You will need switched sides, Because S2K caliper is mount on the rear side of the rotor and ek4 is in the front.
 
I have a brand new set of Wilwood 4 pot Midilite calipers, brackets and pads to fit the standard 282mm disk sat here ready to go if you were interested?
 
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What is the appeal of these calipers? All I can see is they have a smaller 54mm piston vs the EK9s 57mm.

Surely it's a downgrade, despite the larger disk?
 
There's many more factors in brake upgrades than pure piston area.
The surface area of the pad for starters, the contact area of the disk and the total surface area the pad covers per rotation of the disk also.
It's even more aparrent when increasing the piston count. Yes, the pistons may have a smaller diameter, but they can apply a more evenly distributed force onto the disk than a single piston floating caliper.
Also, with the bigger disk, it takes less braking effort to slow the disk down as the pad is travelling further per rotation than the smaller diameter disk.
 
Hmmm, I see your point, but aren't the AP1 calipers still single piston?

I have a spreadsheet I've written here on brake forces, a Civic 282mm setup with 57mm piston makes 1553lb/ft. With everything else being equal, a 300mm disc with 54mm piston makes 1512lbft.

What makes up for the shortfall in brake torque? Size of the pad is not taken into account, but being a friction equation, it shouldn't have any effect?
 
Thanks for the info guys ! Never knew alot of this.......

Will have to think more about it / get more advice.

Anyone who has done this upgrade care to comment? There has been some ATR 300mm brake upgrades - what size of piston do they have?
 
Barryl85 said:
There has been some ATR 300mm brake upgrades - what size of piston do they have?
Click to expand...

Twin pot 38mm and 42mm pistons.

Same calculation as before gives you 1657lbft, a definate improvement. :nice:
 
One thing to bear in mind, the standard EK9 setup produces 1553lbft with a .45 co-effecient pad, increasing the cf to .50 gives you 1726lbft, more than the 300mm ATR setup. ;)
 
But with a difference of 18mm over the dameter of the disk, the pad travels further per rotation.
For example, the standard 282mm disk on the EK9 uses a 148.7x57.7mm pad.
The ATR uses the same dimensions on the pad (all be it a different shape).
With the 282mm disk you're getting a total pad sweep area of 40658mm^2
With the 300mm disk you're getting a total pad sweep area of 43921mm^2 meaning every time the pad makes one rotation over the disk, it's covering an extra 3263mm^2.
So you dont need to use as much effort to slow the car down with the bigger diameter disks. Also, you are able to modulate all that pressure you're excerting on the pads better with a larger diameter disk, meaning you have a bigger gap between first touch and lock up.
 
I see where you are coming from. Swept area is not an element I have included in my workings, which I have lifted off the Stoptech Tech pages and put into a spreadsheet.

The extra size of the disc in my calculations translates into a longer moment arm, so a given pressure at the caliper multiplied by the co-effecient of friction of the pad multiplied by the effective radius of the disc equals brake torque.

Is extra swept area not essentially the same thing? Accoring to the laws of friction, the area of contact should not be of concern. Or am I looking at it wrong?

I understand things like pedal modulation and feel are subjective matters and may well be improved despite the outright torque being lower, but you can't really calculate these things and I like to deal primarily with objective matters for the purposes of comparison.

I don't mean to come across arrogant (as I am aware I sometimes do), but this sort of thing genuinely interests me and if I have made a mistake somewhere then I would like to correct it.
 
One of the big areas to look at in brakes is actually the longer moment arm, which can be easily increased by a larger diameter disk. This is often overlooked and can been mis-interperated as a longer pedal (which is sometimes seen as a bad thing). What it actually gives you is a larger range of movement of the brakes. Some people thing stamping on the brakes and causing them to lock up means they're at optimum performance because they lock. It's far from the case. If you're coming into a bend and you want to scrub some speed off the car smoothly, you want to be able to apply a certain pressure to do that. Having the longer moment arm lets you do this.
All the calculations in the world wont replace the 'Seat of your pants' feeling though :) If you can stamp on the brakes going into that hairpin and bring the car to a stop without locking the wheels or the ABS kicking in, then you know you your setup is sound.
In all honesty, the difference between the S2000 setup being bolted on as a direct replacement to the EK9 will show very little difference due to the smaller piston being used on the same pad area over a larger disk, as the differences will pretty much cancel each other out.
Going to a larger piston count (with larger overall piston area and larger braking force) on the same sized disk will give you a more noticable difference.
Having that setup with a larger diameter disk will again have a noticable difference.

What you really need is some side-by-side testing done, with all other areas being equal (same brand/style disks, same compound pads etc) on the same stretch of tarmac :)
 
Awesome, sounds like I'm pretty much on the right track with it all then, just looking at it from a slightly different perspective. I get you on the pedal travel, I was going to mention this when saying about the ATR twin pots. As you say, a lot of people will take a long pedal as a bad thing, but it isn't, providing your pedal doesn't hit the floor obviously!

I think of it like the relationship between engine torque, gear ratios and wheel torque. A bigger piston is like shorter gearing, the extra travel as a result is like the extra revs, and the extra brake pressure is the extra torque at the wheels.
 
Thanks all for the input:)

I was originally hoping the s2000 brakes were as good as the ATR . I was getting the calipers for basically nothing! After research it seems the ATR 2pots seem the way to go,

Anybody have them fitted on ek4 knuckles?:))
 
The AP rotors will not fit a CTR/ITR 5 lug conversion because the hat is smaller and it can't fit the old 5x114.3 hubs from the EK9 and DC2. You'll need that specially made Mugen AGBS disc.
 
BrakeExpert said:
The AP rotors will not fit a CTR/ITR 5 lug conversion because the hat is smaller and it can't fit the old 5x114.3 hubs from the EK9 and DC2. You'll need that specially made Mugen AGBS disc.
Click to expand...

So if you wanted to run Spoon Monoblock calipers on an EK9, you'd need to have specially machines S2000 discs then I guess?
 
I doubt if the hat is smaller if you could get them made larger. I know Audi are the same. I'm looking through the disk catalogue and there might be problems finding something similar too, as the S2000 disk has a 39.6mm offset whereas the other 300mm Honda disks have a 47mm offset.
 
If the Spoon monoblock calipers are designed for a 300x25mm disk from the S2000, the lugs will be cast to a 39.6mm disk offset.
You could possibly fit some sort of spacer plate between the caliper and hub to bring it back the 7.4mm it needs to clear the 47mm ATR disk but it's only a theory and would ideally need it on a bench with the caliper and disk.

Just to be clear, the disk offset is the overall height of the disk from back of the contact face to the front of the mounting hat.
 
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