mmm..i think if it were the booster we would see other symptoms such as more force needed to press the pedal. The pedal is on the soft side. Hey maybe I should disconnect the booster..problem solved

 

If it was the booster, the pedal would be rock hard.



I've suspected the MC as well, prob is I can't convince the dealer to even investigate. They insist "they feel fine" and won't change it for me.


A reman MC is $110. I have no prob changing it. I know how to bench bleed an MC. I've done it plenty of times before, the only difference is this car has ABS...so i'm a little leery of it without the proper tools.

Is it possible to replace my master cylinder in my own garage without needing to tow it to the dealer after so they can bleed the brakes?

 

I don't think you have to worry about the abs. You can't disconnect the battery if you're worried about it.

I've flushed my fluid no problems

 

I've heard otherwise though. I've heard introducing air upstream of the ABS pump can cause issues requiring the dealer to bleed.

I've bleed ABS systems plenty of times. It's just like normal when they are full of hydraulic fluid...it's when the MC runs dry and air gets upstream and into the pump that you have the issues. This is what i'm worried about.


Another thread I started on this after finding someone else with the issue. One guy said they changed the MC and it didn't solve it...but he had them replace the calipers and it cured it. Could be a design flaw allowing air to draw in on the upstroke of the MC. Air is smaller than hydraulic fluid, so it can go in, while fluid will not come out. Could be bad piston seals in the front or rear calipers?

Right now, i'm more comfortable replacing the calipers than the MC due to the ABS bleed issue.

http://www.6mt.net/forum/g35-coupe/2...tml#post944645

 

Sounds like pad knock back to me. Research the topic.

I'll bet the soft initial pedal depression is always present after taking a hard corner. Subsequent depressions are firm.

 

Come to think if it, I've noticed a bit more travel on my initial brake press after I swapped in the 06z brakes. I'll try to pay more attention to it on my next drive.

I didn't think about it because I don't think the feeling is "spongy". It's just more pedal travel

 

Nope.


Sit in traffic...drive forward 20-30 feet...hit brakes....soft pedal again.

or

Sit in park. Pump pedal a few times. Let off, wait 30 seconds, hit pedal again and it's soft again.

 

Yes you are right. Soft is a bad term to use. The initial stroke is long, but once i reach the point where the brakes do grab, i can modulate them and even activate the ABS.


My whole problem is the initial stroke is maybe 1-1.5" in lenght, but then if i pump again, i get MUCH BETTER feel after maybe 1/2" of travel. Wait 10-15 seconds or so and it's back to being a long stroke...without even moving 10 feet or so. It's a HUGE difference...enough to get me to investigate this. It's been consistent though for 30K miles.


I'm familair with brakes. It's not knockback as this happens just sitting in Park. The booster is fine, no leaks, with the car off the pedal pumps up hard as a rock so i don't think there is any air in the system. I've installed custom brake systems, braided lines, custom master cylinders and prop valve setups....i'm familiar with brakes, but stumped on this.

Basically, i love the brakes on the 2nd pump...but HATE them on the 1st pump.

 

Wow, I thought I was the only one having this same observation... I have the same exact thing happening, although I hadn't given it much thought. My car only has '06 sedan 26k miles on it, and it's been doing it for a while now...

 

Glad to see there are more people out there inthe same boat. (well not really...i don't wish anyone to have any problems with their cars) Hell, you'd think this sort of thing would generate a recall if in fact there is a part which has a design defect. Brakes are one thing you don't want to mess around with

 

Strange symptoms. Doesn't sound like knock back if it's happening without the hubs moving.

 

Exactly my point. I can't figure it out. I've replaced the front and rear rotors and pads (because they were worn..not for this issue), and bled the brakes several time. I've prob passed 8-10 bottles of brake fluid through the car with the number of times i've bled.

Next step is to replace parts, or give to dealer and have them try to bleed the brakes (if they can do it more thouroughly by cycling the ABS or whatever they do).

Just trying to research right now so i can do something when spring rolls around and i can work on the car again

 

Kurtis, the damn thing is present no matter what lol. It's only firm after a double pump regardless of velocity or cornering/steering situation.

 

Bumping this thread to see if anyone has any new info to add on this brake issue.

I love driving my car, but the feel of the brakes is getting very annoying. Wondering if any new people scanning by have this issue. The thread title doesn't exactly help

 

I have an 03 with the SAME EXACT %UCKING PROBLEM AND THE DEALER IS AN *** ABOUT IT.
My story:
I would brake the first time and the pedal will go down to will a weak bite, NOW if i was to release the brake and press it again....DAM IT FEELS LIKE A WHOLE NEW BRAKING SYSTEM....
SO this weekend i changed the pads because the pads were very low and the dam pedal height is the same almost no difference....I still have the same Problem....i have a 05/06 caliper next to put on in about 3 weeks...hopefully that helps .....


If you want to work together trying to fix the problem let me know and about to do anything now