honda-guy

iTrader: (55)

the rear evox calipers is not direct fit to evo 9. my understanding is that you have to widen the mounting holes on knuckles. similar to enlarging the holes on the front knuckles, but for the rear you have to make them oblong. this will be more difficult to do by hand to get the exact measurement. i dont feel there's a need to upgrade the rear brakes since most of the braking is done by the front brakes. if you're worried about brake bias, factory brake bias is usually more rearward for cars with ABS, and the system us ABS to control bias. often the rear ABS will come on before the front. if you ever have abs failure on track, you will see that the rear will lock up first. also the rear pads and rotors last considerably longer compare to front, which shows how little they are being used. btw, i'm not a brake engineer.

King Tut

Yeah I would put upgrading the rear brakes very high up on the ole fruit tree. There are tons of lower hanging fruit I would go after first.

Dallas J

iTrader: (1)

Ive heard the exact opposite and that cars in general have more front bias to prevent locking up rear tires in situations like mid corner panic. All back to the OEMs would rather us understeer than oversteer.

LetsGetThisDone

iTrader: (1)

It's really easy to tell that on most modern cars that the brakes are biased by the ABS because the rear pads almost always wear out first on late model cars. The system may still have some front bias, but when real braking takes place, the ABS does the work to move more bias forward.

Dallas J

iTrader: (1)

That's easily explained away by pad volume over any bias direction. You also cant compare what happens day to day while braking 98% of the time far below threshold to what happens at the braking limit when heavy load transfer.

http://www.stoptech.com/technical-su...alance-matters

Stoptech talks about auto manufacturers being front biased here, and when adding rear bias typically reduced stopping distance is seen up to the point of instability.

LetsGetThisDone

iTrader: (1)

When I got my Evo it needed rear pads at 15k miles, fronts were over 50% still. Since then I've gone through front brakes 2 to 1 over rear brakes.

I'm not saying the bias is rearward, I'm saying that in normal/not hard/non-threshold braking the rears seem to wear faster. There may be front bias, but like you said, due to lower pad volume or just a smaller brake package on the rear, the pad wears faster. But to me, this means that the system could have more front bias (hydraulically) as opposed to relying on the ABS to affect the bias when braking harder.

I could be wrong, but that's my thinking on it.

RazorLab

iTrader: (8)

When I had the oem Evo X brake calipers on my X, with track use, I went through two sets of ST47's on the front while my rear ST43's are still trucking. I still use the same set of rear ST43's now with my front Stoptech trophy kit.

On my X, the rears are lasting forever.

That said, my X braking system felt much more stable and powerful than my Evo 8 ever did on track. So I do think the Evo X braking system is better.

Dallas J

iTrader: (1)

Ive never managed to kill a set of rear pads, but again wear isn't an indication of braking power. Its why we're going to a smaller piston in the next braking system. For small rotor AX we'll have more rear power losing about 10% front braking force, which should be a good thing, then going to 355mm rotors will move us to 5% less front which should be a good balance on track which we can balance with front pad bite (I hope)

LetsGetThisDone

iTrader: (1)

My car locks the rears first with ABS in-op due to failed sensors. On hot and cold NT01's, FWIW.

Dallas J

iTrader: (1)

We lock up the fronts first in AX. You can also tell by the heat coming off the brake, they have done A LOT more work than the rears.

kikiturbo

The system has to have more rear bias hydraulically as this is how it works. This is done for two reasons. Firstly, ABS is used to adjust the balance, and it does so according to the longitudinal acceleration sensors. The system can lower the brake pressure, not increase it, so it has to have more rear bias for a start.
Secondly, the ideal brake bias changes depending on deceleration. The harder you brake more "weight transfer" is there and more front bias is there... Most rear bias you need under light braking.

kikiturbo

did you try ACD remap with more central diff lock under braking? That should make the rears work more..

Dallas J

iTrader: (1)

I'm just going on what I've read hear in that the front has typically more bias which intuitively makes sense. Whether that bias comes from the ABS system or other means, it seem as you brake a factory car, it would make sense the front would lock first. But I'm haven't ever seen math or schematics on the system to understand them, so I can only refer to text I can find.

I need to dig into my ACD map this winter cause I think theres things I need it to do that its not. Like mid corner off throttle, I just want it open and let the suspension weight transfer not try to induce something with the diff. I also am not sure the ACD at this grip level is able to keep up with the tires.

kyoo

iTrader: (29)

regardless of which is locking up first, there's no question the front brakes do more work on the evo under hard braking, as is the case for most front-heavy cars and passenger cars in general

LetsGetThisDone

iTrader: (1)

The point is 100% which end locks up first...lol. If my rears lock up first, I don't want to reduce front braking power.