Evo X front brake swap for Evo 8/9
May 5, 2020, 07:04 AM
#646
The Essex CP8350 front kit has almost the same size rotors as stock (325mm vs 320mm) but smaller pistons than OEM (38.1/41.3 on the AP caliper, 40/46 on OEM). Anyone running the Essex CP8350 fronts has reduced the front braking torque relative to stock.
May 5, 2020, 01:06 PM
#648
Well no I didn't see any of that. Brake torque increased significantly. 5 or so years I was running that exact setup. I was braking way later and deeper, no more taper, and without the mid race overheating with I think 4.5lbs lighter then oem per corner? It was all wins for me, literally. I'd be rocking them still if I only did AX like Dallas or hill climbs. I eventually found the limit/conditions heat capacity wise and was tired of ducting so when the oppy to use the 372's came I jumped on it. Combined with the corrected Alcon's out back I found myself overslowing a lot in March's race.
May 6, 2020, 09:55 AM
#649
I don't recall seeing any complaints of rear brakes locking up with the 8350 kit. I wonder if some of the improvement comes from shifting the brake bias toward the rear, letting the rears take more of the braking load?
May 6, 2020, 10:19 AM
#650
i pulled up some of what honda guy (op) has said on rear brakes. i'm currently even running st43s in front and girodisc s/s rear (even more forward bias):
Evo RS without ABS have restrictor pills in the master cylinder to reduce rear brake force. the ABS master cylinder doesn't have that. I converted my RS to ABS, swapped master cylinder, hard line, harness, abs ecu.
i've driven two different Evo with ABS on track that failed and the rear locks up first. when i said they have more rear bias, i dont mean the rear have more braking force than the front when the car is standing still, i mean the balance is more rear bias during hard braking. this could be adjusted with pad compound.
on my RS before ABS swap. i keep lowering the rear compound to the point where i was running street pads in the rear.
i've driven two different Evo with ABS on track that failed and the rear locks up first. when i said they have more rear bias, i dont mean the rear have more braking force than the front when the car is standing still, i mean the balance is more rear bias during hard braking. this could be adjusted with pad compound.
on my RS before ABS swap. i keep lowering the rear compound to the point where i was running street pads in the rear.
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. 
May 6, 2020, 10:23 AM
#651
Not saying your still wrong but something doesn't add up. From AP themselves they've documented this whole time a 1% shift, so your either on the wrong spec or they are? I find it very odd indeed such a company would make a kit that shifted 15+%, there'd be no point. Some expansion here.
Add my experience where I used a single set of rear pads for at least 20 races on oem calipers with meat to spare, being the same compound as the fronts then, would suggest it wasn't being used more. Same as when I had brownbo's. The dust on the wheels too was 10x worse up front as expected. The only time I ever locked up was when a sensor went bad usually due to a wire melting up front, twice in my life with the car.
Add my experience where I used a single set of rear pads for at least 20 races on oem calipers with meat to spare, being the same compound as the fronts then, would suggest it wasn't being used more. Same as when I had brownbo's. The dust on the wheels too was 10x worse up front as expected. The only time I ever locked up was when a sensor went bad usually due to a wire melting up front, twice in my life with the car.
May 6, 2020, 11:56 AM
#652
EvoM Guru
iTrader: (1)
The rears locking (in a straight line, on track) with an ABS failure (due to sensor wires melting) is my experience as well.
May 6, 2020, 01:09 PM
#655
EvoM Guru
iTrader: (1)
I'm telling you what's literally been experienced, vs numbers on paper. And I'm not the only one to experience this either. Also I don't think its because the front brakes were overworked in this scenario. The ST43's dont quit. Source- I've had them on fire in the hot pit.
May 7, 2020, 10:54 AM
#656
Originally Posted by letsgetthisdone
I'm not saying it's rear biased. I'm saying the theoretical/mathematiical brake bias based on hydraulic pressure/piston diameter/rotor diameter goes out the window when we factor in weight transfer, static weight balance, the brakes/tires being at actual operating temp after a few laps, and track surface.
I'm telling you what's literally been experienced, vs numbers on paper. And I'm not the only one to experience this either. Also I don't think its because the front brakes were overworked in this scenario. The ST43's dont quit. Source- I've had them on fire in the hot pit.
I'm telling you what's literally been experienced, vs numbers on paper. And I'm not the only one to experience this either. Also I don't think its because the front brakes were overworked in this scenario. The ST43's dont quit. Source- I've had them on fire in the hot pit.
Having ABS on my MR, also losing it ripping a speed sensor. AX I would lock up the front but one track day down a long straight i locked up the rear multiple times. At the time same hawk pads or maybe a step down in the rear can't remember.
Fast forward to my exp in the RS. Lock up front in AX and the very few times on track it was also the front.
Fast forward to the CP8350's. Initial outing at AX we were locking up the rear. It's been so long I haven't touch the rear pads I have no idea what hawk pads they are lol. On track I have yet to lock up but for a 1/2 sec and it felt like the front. In wet locked up the front as well. Fooking love these damn brakes. Zero brake fade for me. 400whp and mediocre driving on NT01's lol.
Last edited by amn_suazo; May 7, 2020 at 11:00 AM.
May 7, 2020, 01:08 PM
#657
Evolved Member
I'm not saying it's rear biased. I'm saying the theoretical/mathematiical brake bias based on hydraulic pressure/piston diameter/rotor diameter goes out the window when we factor in weight transfer, static weight balance, the brakes/tires being at actual operating temp after a few laps, and track surface.
I'm telling you what's literally been experienced, vs numbers on paper. And I'm not the only one to experience this either. Also I don't think its because the front brakes were overworked in this scenario. The ST43's dont quit. Source- I've had them on fire in the hot pit.
I'm telling you what's literally been experienced, vs numbers on paper. And I'm not the only one to experience this either. Also I don't think its because the front brakes were overworked in this scenario. The ST43's dont quit. Source- I've had them on fire in the hot pit.
May 7, 2020, 01:33 PM
#658
Evolving Member
May 7, 2020, 01:55 PM
#659
EvoM Guru
iTrader: (1)
Originally Posted by TimC909
Out of curiosity, how does ACD behave under braking in a straight line under normal circumstances and if an ABS sensor fails?
May 7, 2020, 02:42 PM
#660
If you lose an ABS sensor the ACD just goes open (0 psi). Under normal conditions, its the highest pressure under pure braking and Im seeing 70-80psi IIRC. Full throttle with a bit of wheel spin is reach close to the same pressure as well but braking hits that every time on hard stops.