Honda CRX Si Brake Woes

[lateapex911]

First thing I thought of, when reading your list was "the booster". They are funny beasts. And even if it's NOT the booster, at this point in it's life, it's a liability, and should be replaced.

One way to tell if it's the calipers or drum cylinders (if equipped) is to take the lines off and screw on 'caps". Eliminate them from the equation. IF things get solid, attach them one at a time, and you'll find your issue.

If it's still soft, then unscrew the lines from the master cyl, and block it's openings. If it gets solid, you have issues in the lines, prop valve, or dist blocks.

Since you've done so much sleuthing, I might just start straight away by plugging the MC lines to eliminate the whole system downstream to prove it's in the MC booster system.

If it's still soft, then it's in the master, or the booster.

[darthmonkeyIT]

First thing I thought of, when reading your list was "the booster". They are funny beasts. And even if it's NOT the booster, at this point in it's life, it's a liability, and should be replaced.

One way to tell if it's the calipers or drum cylinders (if equipped) is to take the lines off and screw on 'caps". Eliminate them from the equation. IF things get solid, attach them one at a time, and you'll find your issue.

If it's still soft, then unscrew the lines from the master cyl, and block it's openings. If it gets solid, you have issues in the lines, prop valve, or dist blocks.

Since you've done so much sleuthing, I might just start straight away by plugging the MC lines to eliminate the whole system downstream to prove it's in the MC booster system.

If it's still soft, then it's in the master, or the booster.

Great idea. Didn't think to plug off parts of the system to narrow down the problem.

As I thought about it more yesterday the booster is making more sense. The pedal comes up nice and feels great with the car off. Couple pumps and I have a nice solid pedal. After I turn the car on though the pedal feels gets soft and even with pumping I can't get it to feel "good".

I will also check the rear brake calipers. The pistons threads on the rear are still in place so the system should be adjusting the piston but that doesn't mean it isn't a little loose in the back.

I have done a lot of research into this trying to find people with similar issues. Found a lot of people with similar problems but rarely saw anyone recommending replacing the booster. I feel fairly confident replacing the booster with the feedback I got here. Thanks a lot guys.

[darthmonkeyIT]

Parts question: Where should I look to buy a brake booster?

I looked them up on Rock Auto and they have AC Delco rebuilds for around $80. Rebuilds can be dicey though especially if you don't know where it came from. I am a member of HPD but I have not looked yet to see how much one from HPD would be.

Any recommendations?

Also looking to try some new front rotors. Anyone have experience with Centric Cryos? They have them on Tire Rack and was interested in swapping to them from the un-cryo'ed Brembo's I am running now.

[mossaidis]

Make sure it's available on HPD. It's the first choice for many looking at NEW quality OEM.

Cyros are definitely heavier, will hold more heat in and in general wear slower.

[Matt93SE]

REALLY stupid Q.. did you ever remove the calipers from the car?
If so, did you reinstall them on the correct side?
If you installed them backwards, the bleeders are now at the bottom, and you have a huge air bubble at the top of the caliper that will never go away. spongy brakes till the cows come home, but everything else looks right and works.

If that's your problem, you don't have to say that was it. just tell everyone rebuilding the calipers or a new booster solved the problem.

[darthmonkeyIT]

REALLY stupid Q.. did you ever remove the calipers from the car?
If so, did you reinstall them on the correct side?
If you installed them backwards, the bleeders are now at the bottom, and you have a huge air bubble at the top of the caliper that will never go away. spongy brakes till the cows come home, but everything else looks right and works.

If that's your problem, you don't have to say that was it. just tell everyone rebuilding the calipers or a new booster solved the problem.

All four bleeder screws are still pointing up.

I have removed the calipers to check the sliders. Everything seems to be in working order with the calipers.

[Tom Blaney]

I suggest a couple possible solutions:
First: Make sure that if you have a one way valve going to the brake booster from the intake manifold that it is working properly. A soft pedal can sometime be caused by the booster pressure being sucked back out by the intake vacuum.
Second: If it was a rear disc upgrade from rear drums than make sure the proportioning valve is the correct year match
Third: If you don't have brake cooling ducts (either trick or a simple hose) make them, try and direct as much air to the center of the rotor
Forth: You might be boiling the brake fluid (which creates steam albeit minute) but it is still air. Make sure you use Dot 4 or higher and don't use the bottle again once you open it. Once the seal is broken, the fluid will absorb moisture(some will contradict this but it is true).
Fifth: Replace brake system parts with the very best you can buy, there are cheap rotors available from parts stores that are poor quality, and if they get hot they warp, which will kick back the pads so each time you have to use the brakes you have to pump the pedal.
Sixth: Bleed the brakes every weekend, making sure that you don't have any air seep back in the system from the bleeder catch bottle etc.

Those are my suggestions, hope it helps.