my RS is pretty much gutted in the back, i haven't corner weight but i think it's noise heavy. I have a problem with rear locking up, especially with rcomp tires where there's more grip and more weight transfer to front during braking. it's not allowing me to brake as hard as i could because i have to modulate rear lock up. i've tried all kinds of rear pads to reduce the friction (ST43, DTC60, DTC30, RB ET800, ET500, RB XT960), and the pads that reduce the most rear lock up is autozone ceramic street pads. the problem with street pads is they can't stand the heat and disintegrate pretty fast (about 4 track days). i think the best solution is to install proportioning value, but i haven't found much info on here. i guess most people have ABS and don't have a need.

i think most hondas have the brake system split diagonally, does Evo have brake system split front/rear or diagonally? any info on this would help. thanks.

this is what i was looking at.

http://www.chasebays.com/products/mi...evo-69/brakes/

 

the brakes are split diagonally. I'd be wary of installing two prop valves inline with each other (stock and aftermarket). you'll get weird brake bias vs pedal pressure behavior. Can your run a more aggressive front pad?

I'd probably switch calipers/rotors (front BBK) before i tried a prop valve.

 

I have installed by rkt motors on my x the brake bias controller. Also i had it on my ix.

Talk to them.

 

I'd like to know what you figure out... Interested.

Although imo; the rear needs to do more work. You can plainly look at the discoloration of the front calipers compared to the rear on any tracked Evo and see what gets hot and does the work! I'd like to have my rear working more for me to take some of the heat off the front if at all possible. But I'm around 60% front heavy like most.

Curious why you're getting rear lockup though. I've never had issues with lockup and I ran the same pads F/R almost always. Are you running a high ride height and/or a really soft front spring by chance, leading to the rear end raising more than usual?

 

Good points, I also turned my like shiny red Brembos on my 2011 Evo X MR to a dark red/black combo after only 4 track days. Could it be that your rear toe is a bit too aggressive and causing the ABS to kick in early as it dances around? I tend to run about 2mm total toe in for the rear alignment which helps stability under threshold braking. Granted the Evo X has more integration with the ABS and AYC functions under ASC (Active Stability Control) but keeping the rear end more stable might help your issues.

I also think a more aggressive pad or pad/brake caliper combo up front would balance the setup better than trying to use a proportioning valve with a diagonally split braking system.

 

good to know it's been done before.

the front is always going to work harder than the rear because weight transfer to front under breaking (dive). even if you have really stiff front springs and stay flat under braking, there's still weight transfer to the front.

i have 10k front/12k rear setup with Ohlins R/T. have run different front pads including DTC70, XP12, ST43, DSUNO and currently on CL RC6. rear lockup is more pronounced with Rcomp because of more front grip during braking which transfer more weight.

i drove my friends Evo 8 with stock interior, star specs tires and ST43 front and rear pads. the ABS malfunction mid session (so no ABS) and the rear was locking up before the front, same as my car. one other friend said the same thing when he had ABS malfunction on track. you should disable your ABS and run a couple sessions to see how your brake bias are. a lot of people don't know that ABS is activating until it's disabled, especially if it's the rear.

i don't want to use BBK because i want to stay with 17" wheels, and also points system does not allow aftermarket calipers. like i said, i can run street pads in the rear and that pretty much solve the issue but the street pads burn up too quick because they can't handle the heat.

 

Rob, why did you have brake proportioning valve installed in the IX. i assume you want to adjust for more rear bias to get the car to rotate under braking? how did it work out for you?

 

I sometimes wonder if my rear brakes work. I have not worn down a set of rear pads ever!

 

not exactly apples/apples comparison. The abs equipped cars have no prop valves for the rear and rely on the abs to do the proportioning. So if you disable the abs you will have TONS of rear brake bias. The RS has prop valves built into the MC and as such has less rear bias.

 

seems kinda dangerous to just totally rely on ABS to control bias, in case ABS fail on icy roads. even with ABS, the wheels still locks up momentary which is enough to loose control on ice.

 

i just looked through the service manual and found this. looks like there are two proportioning valve in the master cylinder, one for left side and one for right side (since the system is split diagonally). so that mean i would have to get two external proportioning valve or find one that has two input and output. or maybe i can make a new smaller restrictor pill and put it in the stock master cylinder location.

PROPORTIONING VALVE FUNCTION TEST <VEHICLES WITHOUT ABS>
M1351001100421
CAUTION
The proportioning valves are installed independently for the right and left brake lines. Always measure each valve.

1.Connect two pressure gauges to the output port of the master cylinder and output port of the proportioning valve.
2.Bleed the brake line and the pressure gauges (Refer to P.35A-17).
3.Depress the brake pedal gradually. Then check that the split point, where the output fluid pressure begins to drop in proportion to the output fluid pressure, is at the standard value.
Standard value: 2.70 − 3.19 MPa (392 − 463 psi)
4.Depress the brake pedal more strongly than at the above step. Then check that the output fluid pressure is at the standard value when the input fluid pressure is 6.86 MPa (995 psi).
Standard value: 3.68 − 4.17 MPa (534 − 605 psi)
5.Measure each output fluid pressure at both valves, and check that the difference between the two is at the limit value or less.
Limit: 0.5 MPa (73 psi)
6.If the measured pressure exceeds the limit, replace the proportioning valve.

 

also found a section on brake bleeding. since the brake system is split diagonally, you need to bleed diagonally. not work from farthest to closest like everyone says.

 

this ABS deletion kit from Chase is plug and play and comes with proportioning valve. $400 seems kinda expensive considering you can buy the valve separately from them for $85

http://www.chasebays.com/product/mit...subishi-evo-49

 

You didn't kno that was the brake bleeding order?

 

^ that how i bleed with my honda. but most people i talked to at the track say they bleed from farthest to closest.

but i've been lazy before and didn't really care about bleeding order, doesn't seem to effect anything. the manual also say to start the engine but i have never bleed brakes with engine on.