hans512

hello friends when i push the brake pedal the car doesnt feel to brake correctly, the front end does not feel to get pushed into the ground, its a feel just like the rears are holding all the brake power and the front's are not working at 100%.
So far ive change brake fluid ( DOT 4 & 5) tried EBC reds, yellow and stoptech's, change all brake lines for steel ones, grimmspeed pump holder, new brake pump, new DBA's four rotors.
i have a feeling that when you press the brake pedal, the pressure proportion is going backwards and a little part to the fronts.
Actually im not getting any ABS codes, but i was told that in my EVO 9 MR the ABS unit works like a porportioning valve, is there any possibilities that any interior piston of the unit is locked?, bleeing is rejected because pedal is very firm.
i really dont know what else to try
any ideas please?????

WRC-LVR

iTrader: (1)

1.

check the line going from the intake manifold to the brake booster for leaks. Then pull it off and make sure the inline check valve is working correctly. if it is plugged up the pedal will feel very hard but you will not get any vacuum assist from the engine for the brake booster.. time to replace or clean it then.

2.
pull the front wheels off, remove one caliper with it still attached to the brake system and pull pads. Have friend push down on the pedal gently while observing the pistons. check other side same way. if pistons dont move or they stick you need to rebuild the front calipers


Let us know what you find.

hans512

Sorry for that missing info, i've already changed the check valve, checked the booster for leaks and rebuild the calipers with fresh seals although i found sticky pistons and repair them, there was still no difference during braking. One important thing is that i live at sea level.

barneyb

How does the car brake with the ABS fuse pulled?

hans512

These days ive been trying to put more attention to the ABS system, with the fuse off the car seems to brake slightly better, an important thing ive notice is that the front left wheel is not unlocking as much as the other wheels in a hard braking condition in wet surfrace.
i think we are now very close to find out the main problem, any ideas?

barneyb

Another person with a similar problem ended up tracing it to some aluminum flash stuck into a bleed hole in the master cylinder.

BBC

iTrader: (3)

To verify your bias theory try pulling the abs fuse and lock up the brakes. If the rears lock easily but not the front you are right.

DropTheClutch

iTrader: (1)

When i changed my lines, it was really sluggish even after we bled them. Bled em more and more and eventually it went back to normal?

fwd_josh

iTrader: (2)

Not to be a jerk, but are you sure you bled them correctly? There is a certain sequence for bleeding Brembo's since they have 2 bleed screws.

mithrandir7533

iTrader: (1)

Do you track the car? Are you looking to improved braking performance? Did the problem exist before the calipers were rebuilt?

1. Rebleed the system
2. Install a brake brake on the master cylinder. Huge difference with pedal feel.

cfdfireman1

iTrader: (11)

Check for free fluid flow to the fronts, could be some sort of restriction in a line somewhere.

hans512

So happy now the car is braking with a lot more power, its was the abs unit, left the car in an abs specialist and he told.me he found something like a sticky piston or something like that he made a full mantenience service to the unit and its been so good since that day.
I was out of town, wanted to take some pictures so i can share them with you guys thanks everyone for the support its so good to know theres always a community ready to support when any of us has a problem.

Yijahhh