ATR brakes onto EP3


pateras_vtec

pateras_vtec

Active Member
Joined
Feb 16, 2008
Messages
1,364
Been asking left and right about this but can`t get a straight answer. Apparently no one has ever done it before. I`m looking into putting ATR twinpots on my newly bought EP3. I have got mixed answers. Others point out (but don`t specify why) that ATR discs are 3mm thicker than EP3 but callipers are a straight fit, others say they don`t, and some suggested dc 5`s which need s2000 discs, machining etc. Asked brake expert on here but he isn`t sure legend GS and ATR share the same callipers and if i`d need to machine my brackets. Very confused!
So turned to good ol` ek9.org where 99% of the times someone has the solution.
 
Question is, why do it? You know the twin pots aren't going to offer you anything but more front bias and extra unsprung weight right? Sounds like a lot of effort for negative gain...
 
Kozy said:
Question is, why do it? You know the twin pots aren't going to offer you anything but more front bias and extra unsprung weight right? Sounds like a lot of effort for negative gain...
Click to expand...

i don`t like standard braking as it is. Most people end up with 4/6 pot big brake kits which are overkill IMO on a standard ep3. i find current brakes easy to overheat (whereas the atr ones make a big difference) and in city conditions need hard pressing to function properly.i have inspected both discs and pads but no signs of warping. the ep3 is more balanced than ek9. its tail isn`t as light, and bodyweight is better distributed. the ek chassis has more tendencies to under steer than the ep3 due to more weight mounted on the front and chassis shape itself. i don`t see the braking bias of the car changing drastically with 2 pots and 28mm discs, but if that happens i`m prepared to use 282mm discs on the rear. about the weight; can`t make that big a difference? i don`t have realistic numbers but i estimate a couple kg`s extra.
 
Changing the calipers won't change how quickly the brakes over heat though. The discs are what takes the heat, and you'll be leaving those stock if I understand correctly?

The big 4/6 pots are not any more powerful than stock despite all the extra pistons, there might be more of them but they're much smaller and usually the overall piston area is very close to stock. The ATR brakes on the other hand are significantly more powerful than the EP3 brakes, IIRC the piston area is 3.54" on the EP3 and 3.9" on the ATR, that's quite a jump.

Another thing to bear in mind is that adding more powerful calipers to the standard discs will only excacerbate any over heating issues you have currently as you'll be working the front brakes even harder. I'll run the figures on my bias calculator later, but based on what it tells me for the EK/DC chassis, I usually recommend upgrading the 282s to the EP3 brakes rather brakes rather than the ATR. This is because the EP3 uses the same rear brakes as the EK9/DC2 where the ATR brakes are a LOT more powerful.
 
Last edited:
Sorry if I sound like an arse, I just want to help you avoid spending time and money on an upgrade that stands a good chance of not improving things, and potentially making them a bit worse!

I think the reason a lot of EP3s end up with proper BBK is because there is not really a good OEM upgrade route for them like there is with the older models!
 
Not sounding like an arse at all! really appreciate you taking the time to explain and help, me in this case, make a correct decision. I don`t intend on keeping ep3 discs. Thicker 28mm ATR which dissipate heat better. EK/DC chassis are 130kg`s to say the least lighter than that of the ep3. A heavier chassis like that could benefit from thicker discs and higher clamping force which where originally in even heavier cars (legend, accord).
Great stuff there:
http://www.ek9.org/forum/brakes/47687-front-brake-upgrades-techincal-look.html
 
Ah we'll if you're going to the thicker discs then it may be worthwhile, but again the fact that the ATR calipers are more powerful may well end up cancelling out any gains you make in heat capacity as you'll be putting more heat into them!
 
Had a look at this on the bias calc this morning.

If the stock bias is 10%, then the ATRs will give you 16%. There's more additional mass in the brakes than there is additional clamp force, so they'll still run a fair bit cooler regardless.

They'll probably work perfectly fine, however if it was me, I would be looking at the NA2 NSX brakes. These are also 300 x 28mm discs, but the twin pot calipers have slightly smaller pistons. With less front force the front brakes will run even cooler and you'll have about 5% front bias which is much better than 16%. IIRC the NSX calipers also have cooling fins cast into them to aid cooling. :)
 
Great info there!! I had seen in the epc the other day the na2 brakes but I fear they will be very expensive and hard to find.
 
You must log in or register to reply here.
Back
Top