imported_Cablerat

Hey all,

1998 GS-R w/ ABS.

I had asked the question a month or so back. I noticed my pedal sinking to the floor with average pressure. The general concensus was that the Master Cylinder was going. So I replaced it today with a NEW aftermarket MC. Bench Bled the MC first (with a kit), then placed it on the car and bleed the lines clockwise starting from Front Left. As stated in a post on toronto integras.

Now the pedal doesn't since to the floor when the car is off, and actually it was really stiff as I was bleeding the last corner. However, when it's on, the pedal becomes very soft and will go all the way to the floor again just like before.

At this point I'm assuming the brake booster or something around that area is the problem, but I really am not sure how to troubleshoot it. The car has ABS, and I don't know if I'm supposed to bleed that or ??

Any tips to help me troubleshoot this problem would be appreciated.

Thanks.

imported_Cablerat

I just did a brake booster test based on the pic below and everything passed.

I'm totally at a lose here..

imported_Cablerat

no one has any ideas eh?

At this point process of elimination is leading me to brake booster, but I'm wondering if I need to do anything with the ABS system?

Also, if my brake booster was starting to fail, wouldn't the brake assist reduce, making the pedal harder than softer??

Cynikal.Mindset

well if ur booster has no vacuum it will be soft...could be your check valve

imported_Cablerat

There is vacuum..

chris_si98

Maybe you have a small leak somewhere in the lines.

I assume this is your integra? so its discs in the rear?

It's not your abs, thats a completely different system.

How did you bench bleed your MC..?

imported_Cablerat

Yep rear disc. I have never noticed any fluid anywhere on the ground and the fluid does not go down.. Only through brake wear would I notice any change in fluid level.

Bench Bleed:

I put the MC in a vice grip. I had 2 brake lines threaded into the MC entry points bending all the way back into the reservoir. I filled the reservoir with fluid and started pumping the MC with a screwdriver. As the fluid lowered, I added more making sure the lines always stayed submerged. Once I saw no more bubbles anywhere in the reservoir I removed each brake line and quickly capped it with minimal fluid spill. Put the MC on the car, and same as before, removed cap and threaded brake line into the MC with minimal fluid spill.

chris_si98

howd you bleed the brakes?

LR, RF, RR, LF is the order, did you gravity bleed them, two-man, etc?

Honestly, a sinking brake pedal is caused by one thing, a leak. Either it be internal (MC) or external, brake lines.

A spongy brake pedal is something completely different (air in the line, most likely)

imported_Cablerat

Two-man bleed.. I bled the wrong way I'm pretty sure.. Read on a post on toronto-integras to bleed FL clockwise, so FL,FR,RR,RL. But would it make that much diff?

See, when the car is off, the pedal will NOT sink to the floor. It gets stiff within a few pumps, which tells me the check valve is working.

ONLY when the car is running can I get it to sink to the floor. It's definitely gotten better since the MC change, but still will sink to the floor if you push fairly hard and constant.

imported_Cablerat

I'm leaning towards the Brake booster, but I don't wanna just go changing stuff without knowing for sure.. I did all teh tests for the BB as shown above and everything passed.

chris_si98

Alright.. I'll give you a few tests for your BB

Start the car with your foot depressed on the brake pedal, when you start the car the pedal will move down slightly. (if it does this the BB is okay)

Another test you can do.. is depress the pedal. Shut off the car, leave your foot on the pedal for about 20-30sec, if the pedal rises the BB is bad.

imported_Cablerat

already did those.. BB passed the test.. The test you mentioned plus more are in that image I posted above..

chris_si98

Okay so your BB is fine.

I honestly just thing you need to bleed your brakes a bit more. Start in the order I already said, see if any air shoots out.

If not, that's one more thing you know is not wrong.

imported_Cablerat

Yeah I'm stumped here..

So let's assume everything is bled fine, the BB passed all tests, the ABS has nothing to do with it.. What else could it be attributed to? I'm gonna try bleeding it all again in proper order this weekend.

All the pistons are working, there are no wheel cylinders since it's all disc. Nothing siezed, nothing seems to be leaking.. it's steel braided lines all around.

imported_Nanase

correct me if I'm wrong, but try bleeding it with engine running. Bleed at the MC (where the brake lines connect to your master), and try bleeding it while you are pressing down the brake pedal.

chris_si98

No need to turn on the engine. It's all mechanical/hydraulic

imported_slowandfurious

when i did my brake conversion a few months ago i encountered a similar problem. My distribution valve was clogged and i wasted 2 bottles of fluid trying bleading lines. Give it a check you never know. If one or two lines are cloged it will give you a soft pedal.

bbarbulo

iTrader: (2)

well, the bleeding should start with right rear, left front, left rear, right front.

then go ahead and drive it around and engage your ABS a few times, then proceed to bleed it again.

the dealer has an ABS thingy that engages the pump without driving the car, so since you don't have it, you'll have to do it for real.

imported_Cablerat

I'm gonna have to find a slippery area cuz the up till now I've never been able to lock up my brakes to get ABS to kick in.. The pedal sinks in before that can happen.

Bruno I just read that the 98-01 integras use the same brake reservoir as the brakes and don't need to be bled seperately.? The 94-97 apparently do. I've also read that you should bleed your brakes starting from further away to MC and then moving closer.

Any ideas?

bbarbulo

iTrader: (2)

Hondas that share the Civic platform use a criss cross proportioning valve, meaning you start with the longest line (right rear)... and that line shares pressure through the prop valve with the left front, so you do the left front right after. The same goes for the other diagonal. That's how I bleed it, and I never have a limp pedal.

Also, If you are having issues, it might be good to use the trusty old two person pedal pump method. I dunno what you're doing now... but that's the oldest and best method. I sometimes use a vacuum pump to bleed the brakes, but I somehow just don't trust it as much as the pump method.

"I just read that the 98-01 integras use the same brake reservoir " I'm assuming you mean to say the ABS doesn't need to be bled separately... that may be true, I don't have much experience with ABS on Hondas. My dad's VW doesn't need to be bled... my old Saturn did need to be bled... so it could go either way.