brakes pulsing

[m3f_Hitmachine_f0eee41dda]

got a weird one here guys,



my brakes are pulsing when applying,, all rotors and pads are new so nothings warped,



when i went to bleed them with a friend, ( we did the old style pump brake bleeed, ) the brake pedal went only half way to the floor every time,, fluid was comming out and there was no air in it so we were sucessful in bleeding, but the pedal only going half way to the floor before it went rock hard is whats concering me



i also changed the master clutch cyc in this car so im worried that a large air bubble is traped in my master break line/ clutch line and giving me this problem



the friction point is about 2 inches from the floor and is definatly lower then it should be



i did an entire new clutch job on this car about 10 miles ago and slave and masters were apart of that



any ideas guys,, id love to get that friction point higher and want my breaks to start working right



Merry Christmas:thumbsup2:

[m3f_WRXEATR_c6f1d80be6]

99.9999 percent sure you have deposits on your rotor that are causing hot spots. Jack up the front of the car, try to turn one of the wheels. Does it spin very freely? does it turn with a lot of resistance?

[m3f_Hitmachine_f0eee41dda]

ya thought of that -- all wheels spin very freely, so i have no idea what its issue is:chair:



and the rotors are new, at least the rear ones are along with pads and the fronts rotate very smoothly



im thinking its got someting more serious with it then rotors,, that whole brake petal going down half way and hitting a brick wall before the floors got me wondering what its deal is



master brake cyc???

[m3f_WRXEATR_c6f1d80be6]

You could try getting your rotors turned and see if that helps. If so, you know it's deposits, and you can re-bed the pads.


In my experience, a bad master (depending what is wrong with it) has resulted in all of your brakes being left under pressure (master gets stuck, and wont retract.) and not being able to turn the wheels. Because you can turn your wheels freely without resistance, your brakes are not stuck and neither is your master. If your seals are broken/cracked in the master you will get pedal travel, but not a lot of brake pressure because the fluid will seap past the seals under pressure.


Did you follow the correct wheel order when bleeding your brakes? Did you use a fresh bottle of fluid? (brake fluid is hygroscopic and takes on water while it sits on the shelf opened.)

[m3f_fiveightan_7e37700daf]

all rotors and pads are new,


and the rotors are new, at least the rear ones are along with pads


Are all the rotors new, or just the rears?


Was the car pulsating before the work, or is that problem new?


You could have 2 different issues here, and likely do. The pedal issue sounds like an air issue for sure. Did you bench bleed the master when you installed it, or put the thing in dry?


The pulsation could be the front rotors if they're not new. It could also be a caliper that's hanging up. But first things first...the hydraulic issue needs to be rectified.

[m3f_Hitmachine_f0eee41dda]

honestly i have no idea if it was doing it before i did the rotor job because the tranny and clutch were so screwed up ( ie the clutch disk was in backwards ) that i could never get it going past 2nd gear because it wouldnt go into third lol



the rear rotors are new and the front are used but they rotate freely when i turn the tires - really dont think this is the problem,, ive heard and felt warpd rotors before and it doesnt feel like it,, i may be wrong but i think the hydrolic issues are more to blame



i didnt bench bleed the master clutch cylinder before i put it in, it was so hard to put the feed line on it that i was pumped i ever got the thing on and when it went on i completely forgot about bench bleeding it,



so what does this mean, i bled the slave but i know theres still air in there -- theres got to be,, how should i get the air trapped in the master clutch cylinder out?



and i know the master brake and master clutch cylinder are on the same hydrolics, how do they effect each other?





and yes for the new break fluid and procedure -- followed the 101 projects book

[m3f_Z3MCOUPE_0a03b38016]

:hmm: - I'm watching this thread

[m3f_dark horse]

Nick is correct. You have to bleed the master cylinder first. Then you bleed the lines.

I haven't had to do it on my cars. But most master cylinders have bleeder screws on it.



I am assuming the vibration and the pedal feel issue is after you changed the MC and rotors and pads.



I agree with the guys that bleed, first. Then exchange your front rotors under warranty for new ones. I have done many brake jobs where the rotors were not truly straight. It's the rotors that's causing that(unless your tie rods are that bad).

[m3f_Hitmachine_f0eee41dda]

ok ill look for the bleeder screw in the master cyclinder, if that doesnt clear up the vibrations then ya ill switch the front rotors out



im also hoping that helps my friction point and raises it



anyone else heard and or done the bleeding of this said screw in the master?



like to know where to start looking for it



Merry Christmas guys,, enjoy the holidays:rulaiz:

[m3f_fiveightan_7e37700daf]

ok ill look for the bleeder screw in the master cyclinder, if that doesnt clear up the vibrations then ya ill switch the front rotors out



im also hoping that helps my friction point and raises it



anyone else heard and or done the bleeding of this said screw in the master?



like to know where to start looking for it



Merry Christmas guys,, enjoy the holidays:rulaiz:

There's no screw on the master to bleed it.



Google "master cylinder bench bleed".

[m3f_Hitmachine_f0eee41dda]

ug i wish i knew this before i put it back into the car, the master cyc in stall and removal is a large pita,, any way i could do this with it remaining in the car or am i just going to have to bit the bullet on this one and remove it and do it the way these guys are showing in the videos?

[m3f_Hitmachine_f0eee41dda]

ok did some research, i think i have a good way to bleed this thing without ripping it out, pump style bleeding



saw it on youtube, but basically you get a pump style oil can and hook it up to the slave



clean out the brake resovior and then pump the fluid up from the slave, into the masters and up into the resovior



only problem is where can i get this oil can guys?



heres the link



http://www.youtube.com/watch?v=wdf--suwqw0



autozone doesnt have this,, anyone gotten one before?:taser:

[m3f_WRXEATR_c6f1d80be6]

This video mostly pertains to your clutch slave specifically, not your brakes in any way.



This video was done to show you how to work around the fact that air travels upwards. Your clutch slave (as far as mounting point is concerned) is located lower than your master, making it near impossible to bleed the conventional way with the pedal, because you are pushing air down, then it floats back up.



I honestly think that it would be a good idea for you to completely remove your master, bench bleed it, and start fresh knowing that there is no air in it.



Also......because your wheels spin freely does not put you in the clear for a pad deposit problem. I would still just drop 20 bucks and have them turned.



Bench bleed your slave, then have your rotors turned.



The fact that your brakes pulse leads me to think that this is something rotational related......(rotors)

[m3f_M3_Cliff]

90% of the time "pulsing" brakes are from rotational problems.


That being said, yes there could be pad deposits or hard spots on the rotors. But unless you have been really working them hard, i.e. heating them up beyond normal use, I doubt it.


A bad tire or tires can cause it, bent or worn suspension parts will also. A sticking calliper, worn wheel bearing, a bent wheel, loose or mis-installed tire, bad alignment, contamination of the rotor or pads...There really is no end to the list of parts that can cause the brakes to do it.


But...fluid issues are way down on that list and worn or slightly warped rotors are almost always the cause.


Check the runout of the front rotors. You said they aren't new right?


The best way is with an indicator of some sort. But you can just rest a tool, like a screw driver on the caliper and spin the rotor and adjust the distance of the tool until it just touches and then back it off. The rotor should not "move" enough for you to see it. You will have to use a lug screw to hold the rotor to the hub like the wheel is installed.


IIRC the maximum runout spec. is like .004". Which is just a little more than a hair. If you can see or notice any more runout or movement of the rotor that is your problem.


As someone said before you probably have several problems. The pulsing pedal and the calipers sticking or master cylinder problem.


Good luck, but work on one at a time. I'd suggest the pulsing first as it's more than likely a rotational problem and easier to identify.


p.s. you can bleed the master cylinder in the car by running lines from the outlet to the reservoir and pumping slowly. Do not pump further than the master cylinder piston usually travels.

[m3f_Hitmachine_f0eee41dda]

p.s. you can bleed the master cylinder in the car by running lines from the outlet to the reservoir and pumping slowly. Do not pump further than the master cylinder piston usually travels.



can you explain im more detail, running lines to it?



pumping slowly? like pushing the pedal to the floor and back again slowly



thx:taser:



and im starting to agree its deposits on the rotors,