Why can't I get the brake pedal to feel right?!

[adrial]

I replaced the MC (with a unit from vertex), bled it way too many times...and it just doesn't feel right.
I just measured, with the car off, I can push the brake pedal 2 inches before it hits resistance. BTW I've been using a pressure bleeder, 5-10psi, one time 15psi.

I'm at a loss, the clutch was recently bled as well. Actually, I think the brake pedal got WORSE after the last time I bled it...the pedal was never pushed to the floor, only pushed down an inch, at the most 2 to try to get air out of the MC itself.

Suggestions? Is the replacement MC bad? (pedal does NOT drop to the floor if I hold my foot on the pedal).

I've driven it 2 days since I last bled it...maybe I should just drive it and it'll get better?

Pads/rotors haven't been replaced...I see no need. Absolute braking force is there..

help me before I go krazy!

--Adrial

[Roger Hall]

Hhave you checked the brake peddal linkage

[adrial]

Do you mean adjust the brake push rod? No, I haven't. What other parts of the brake linkage can I check and how?

I found the directions for adjusting the push rod in the factory manuals, but it says it only requires adjustment when:
-The brake power assist unit is replaced
-the pivot end of the brake push rod has been remove,d or
-the push rod or pivot end has been turned

None of which have been done to my knowledge...all that was done mechanically was replace the MC.

Manuals also says, "with the engine stopped and brakes bled, approx. 10mm o fpush rod play will be noticed on the brake pedal plate when operated manually"
What does that mean?

Under adjusting it says "length from contact surface of brake power assist on connector (mounting piece) to the bearing pin center of pivet end should be 186 + 1 mm until end of mod. 86 and/or 206 + 1 mm as from mod. 87"
What does that mean? I'm not clear as to where I would be measuring...206mm is about 8 inches..

thanks for the quick response

--Adrial

[JonA]

Is the problem just excessive pedal travel or is the pedal squishy? If the pedal doesn't harden up there is probably air left somewhere. Was the new cylinder an exact replacement? Maybe the geometry is a little different.

Good luck.
Jon Aborn

[lm6y]

Sounds real familiar. I had the exact problem. It caused me to change the master cylinder. After bleeding at least 3 quarts of fluid through it, and jacking the front, rear, and each side of the car wile bleeding the brakes, it didn't get any better. I figured it was as good as it was going to get, when about 3 weeks later, I left for work in the morning and had a good hard pedal.

I guess there is a funny bend, or pocket in the line that lets an air bubble stay trapped, and will work itself out with time.

Anyone else care to guess? I would love to find out if I did something wrong.

[adrial]

I'm not really sure if its gooey or if its suppose to be like this. I've heard that the ABS system + turbo S brakes = not as firm a pedal as the non-abs cars.

lm6y, I've read a lot of stories similar to yours...It's the waiting part that's a pain in the butt..hehe

Just wondering if its alright to use the old-school pump the brake pedal to the floor method (instead of pressure bleeding) on a 2 month old MC? I would think so...especially because its been all fresh fluid in it for those 2 months..

thanks,
Adrial

[Roger Hall]

i belive that the first part of the manual is saying that there should be about 3/8 of an inch free play in the brake peddel i have no idea what the second part is describing i will look in the haynes and see if there is anything else also have you checked the brake booster

[adrial]

The booster passed the testing procedure you gave me before.

I bled all 4 again, outside calipers only...and bled the master too. It got worse right after...but now it feels better..

Basically...If I don't use the brakes for a while and then go for the brakes they'll be fairly firm but kinda mushy...not that bad really.

Then if I've been going like around town or something...the brakes will be pretty much rock solid. Is this still air in the system or what? I've bled everything there is to bleed...I think I'm just gonna leave it and hope the air works its way out??

thanks,
Adrial

[Roger Hall]

sounds ok good luck

[drew1]

In my opinion, pressure bleeders are better than the vacuum. But, to get all the air you have to do the two pereson pump & hold , crack the bleeder routine. Sounds like you still have a little air.

drew1