They are.

Evo IX: 320mm front, 300mm rear
Evo X: 350mm front, 330mm rear

 

Look at you coming in with all them facts

X is going to get its bias balance from the increased leverage all around. And as we've talked about before, going bigger up front only increases the front bias further. Its why a couple of us are actually running (or planning to) smaller piston area up front moving some of the bias rearward.

But a good question was asked, does the E-brake diameter of the IX match the X? I'll find out soon when I get done with the CT9A rear and move on to the X rear.

 

Yeah if its feasible, in such case as the rotor can swap over, id like then to put X rears on. Call me crazy...

 

I'll have to run all the numbers tomorrow. I still think I'd want to run the Evo X brakes front and rear for balance. Either that, or I suppose I could run one step more aggressive pads in the rear.

 

you are right.. my mistake..

 

I would not run more aggressive pads in the rear unless you downsize piston or rotor size in the rear as well. Pad compounds have a much larger effect on braking that gaining 20mm on a disc.

Locking up the rears is a worst case scenario, it usually results in very fast and undesirable snap oversteer. It's the reason why OE's go to great lengths to design systems that will always lock the fronts before the rear. It's not like throttle oversteer where it's easy to manage, it's very abrupt and often times will either put guys off track or if they're not lucky, into a wall.


The rear brakes do very little work in stopping the car, and throwing larger brakes back there will increase your unsprung weight. You don't need to increase brakes on the rear axle just because you did on the front. Look at the typical weight distribution on an evo (65/35 ish), you don't need a huge brake system in the rear, some nose dive is good for helping to gain front braking grip. If you overclamp the rear, not only do you risk locking the rear up, but you also have the potential of lower your overall braking grip because the car is not able to "dive" or transfer weight onto the front tires as much as it did before. If you end up in that situation it also sets you up to understeer into whatever corner you're about to go into.

 

yes, the problem is that you are probably going to run ABS and stock electronic brake ballance that comes with it... so you need to keep stock-ish brake ballance by adjusting the piston size.
X and 9 rear calipers are not compatible, need some adapter to work. I never did measure the parking brakes unfortunately.. Ebrake shoes are different part numbers and cars are different platforms alltogeather so I kind of doubt it..

I have a alcon kit, 6pot fronts, 4 pot rears, with 343/330mm discs coming in in a few weeks for a friends car, if anyone wants any measurements..

 

problem with using pad compounds for brake ballance is that friction coefficient is not constant but changes depending on temp. Also, it is a good idea to check the operating temps on the rear as some compounds dont really get up to temp there..

 

That furthers what I'm saying. No one puts more aggressive pads in the rear because the rear doesn't see temps hot enough to get any benefit from a more aggressive compound. How often do you see factory chassis cars with red hot front discs? It's pretty common. Ever look at the rears while the front are red, they're pretty much never even close to where the fronts are.

 

I remember seeing at least one post from someone who installed EvoX rear brakes on an VIII or IX. Good question about the e-brake, though. I'll try to find the old post and message the person for an answer.

Yes, please! I'd like some photos too so I can admire that brake hardware.

Also, thanks for the Ralliart piston sizes. I'm running some numbers on different brake kits. I'll share my data once I'm confident I'm calculating the rotor diameter factors properly.

I wouldn't put more aggressive pads in the rear if the system was already balanced properly. My concern is with mismatched Evo X 350mm fronts and standard IX rears, which might shift brake balance even further forward. We can all agree that the front brakes do the vast majority of the braking work, but I still want the rears to do their part.

 

60/40 here bruh Full interior, 2900lbs with no real rear weight reduction. Even have wiper, washer, and seats in.

I think Zach is like 55/45 in his FP evo, but he has like 400lbs of ballast.

 

If I had to guess, I would say that the stock brake balance is setup on the "safe" side of more front bias as not to have any issues with rear stepping out under braking. We could probably run more rear bias.... I will run manual brake bias so we will see how that works..

 

Wow. My car is stripped down and 3100lbs. I'd give an organ to see 2900.
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Ya without you in it lol. I'm around 3175 running on empty race weight, overbuilt cage, fat *** fully fire suited, 5lb fire systems, agm batteries, jack plates, cool suit cooler etc. I still have the sound material on the gas tank lol. I'd also give organs to be at 2750 race weight. I don't see it without investing as a partner in a carbon fiber shop. I...WAS 2760 with absolutely nothing in the cab right before the cage got put in.

That being said I'd still run it at 75/25 distro to get that weight. Ballast is still weight, you'll always handle, brake, and accelerate better the lighter you are regardless of balance.

 

Oh true, my class is weighed without driver. But thinking about car only takes out the variability of driver weight when talking about weight thats possible.

In SM trim I can absolutely get down into the 27xx range. But my min weight is 2900lbs (2.24l), so as I pull weight from up front I have to add it to the back of the car. Right now Ive been carrying extra fuel but Zack had brought up an interesting point about that being a lot of fuel to slosh around.