Honda CRX Si Brake Woes

[darthmonkeyIT]

Hello! Have a very annoying brake problem and I am running out of diagnostic or repair ideas to alleviate it. Looking for some fresh outlooks on the problem.

Last June I ran a test day at Gingerman Raceway which went great. Car felt awesome…until around 1 PM when the brakes went spongy and it felt like I had cooked a caliper. I pulled into pits, parked the car, and began working on diagnosing the problem. The left front brake was smoking from burn off which I had never seen before so my mind went immediately to overheating.

I pulled off the left and right front wheels and allowed the brakes to cool for a bit before bleeding fluid out of them. I got some air out of both front lines and called it good to see how the system felt. Got back out there and the brakes ended up still feeling crummy. Brought it back in and did some more work to no avail.

So fast forward to today. The brake pedal has long travel (practically to the floor), feels very soft (no modulation), and the braking force feels greatly reduced. Generally feels like I am on a roller skate when I brake and I can’t get the front end to pitch down on a car weighted 60% front with maxed out rebound control on the front shocks and minimum rebound on the rear shocks. This makes it very difficult to drive in race trim because I have no idea how my brakes are going to act.

So far here is what I have tried:

• Master Cylinder (4 of them so far)
• New Carbotech XP10 brake pads (Temporarily alleviated the issue when at new size. Quickly went back to spongy in one session)
• Bleeding, bleeding, bleeding (5 liter cans or more of ATE super blue/2000 trying to get the air out along with bleeding rear T joint, brake bias, master cylinder, and using a pressure bleeder)
• New stainless steel brake hoses
• New SSBC Brake Bias
• Removed and tested Brake Booster (brake booster checked fine)
• Adjusted brake booster pedal travel

The symptoms generally didn’t get better and sometimes got worse as a result. I just dismantled the entire system to replace the brake hoses, brake bias, and rear T along with a new master cylinder. The pedal still feels very soft. I have yet to be able to test how the brake force feels. I need new brake pads on the front at this point.

Theories I am considering at this point:

• Air trapped somewhere in the system that is not moving
• Air is being drawn back into the system without a fluid leak (doesn’t seem to get worse as I drive so don’t believe this is the case)
• Brake booster needs replaced (none of the symptoms seem to be brake booster though)
• New front rotors of a different brand (Currently use Brembo blanks. Considering Centric Cryo’s or buy Brembo’s and having them cryoed. Mostly for possible brake force issue. Concerned I annealed my current rotors based on burning up a set of brake pads very fast at Mid O last September)
• Firewall flex (do not see anything flex while having someone else operate the brakes but I have considered it)
• Replace Calipers (calipers are Autozone replacements from December 2010 and have not exhibited any problems)
• Change fluid type (Brakes seemed to work fine with it prior to the issue so not convinced this is an issue)

Any ideas would be greatly appreciated. I am running out of ways to address the problem if it continues to be an issue short of pulling everything out (hard lines and all) and pitching it for new.

Thank you!

[chuck baader]

Went through everything you did and finally replaced the brake booster...been fine ever since. Chuck

[mossaidis]

Went through everything you did and finally replaced the brake booster...been fine ever since. Chuck

Ditto on my EG

[JLawton]

I would replace calipers if you still have problems after replacing booster. And absolutely change rotors to fresh ones. I've cooker rotors on my truck where even new pads didn't work. No need to go to all that fancy treatments though. The car is light enough that the problem is somewhere else

[Greg Amy]

Ditto on my EG

Ditto on my DC2/5.

[tom_sprecher]

Ditto on my IT7.

[Chip42]

definately replace the booster and rotors, don't try to diagnose any more until you have done so and have seen if it worked. car parts don't always play by the rules.

Also check to see that the rear caliper pistons are turned out to minimize the gap between the pads and rotor when sitting. just turn them counterclockwise in 180 degree increments and test fit, stop and go back one when you cant get them over the rotor. lots of sloppy brakes start here.

[1stGenBoy]

Drum or discs on the rear? The early cars came with drums that some people still use.

[darthmonkeyIT]

Drum or discs on the rear? The early cars came with drums that some people still use.

Rear discs.

Replacing the booster really fixed it? Hrm guess I should look into getting a replacement booster. What a pain to get that thing in and out though. @.@

Just doesn't seem like a booster failure mode. Always thought the booster would either not work and the pedal is very stiff or work so well that the brakes will just lock up if ya touch the pedal. Wasn't aware there could be a in between failure mode.

[chuck baader]

I thought the same thing, too....I was wrong, tooChuck