Or cracking the seam of the plastic reservoir. I bleed with 1 bar. More than enough if all components are working o.k. Watch how the reservoir behaves while applying pressure. That observation makes me cautious. Best from Germany Martin
In cases where the rubber bushings don't feel very good I have tie wrapped the reservoir to the master cylinder. I agree 1 bar is enough.
I’ve had luck just cracking the flare nut loose at the master while under pressure from either the Motive or an assistant at the pedal and letting the air bleed out. Of course put an old towel or cup under it to catch the drippings. Easier than trying to pump all that air all the way down to the caliper.
So I was able to get all 4 corners to bleed a very good, solid stream of bubble free fluid by increasing the pressure on the power bleeder to 17psi. However, pedal still mushes to the floor. Either there is air trapped in the MC or the seals are shot. Opinions? Wonder if it's worth trying to bench bleed the MC while in the car. My thought is that if I was able to bleed all 4 corners with no air, there probably is no air in the MC, thus the seals gone. But maybe I'm wrong and there is still a pocket of air in there. If you can't tell, I'm really trying to avoid pulling the MC out as I just put it in yesterday. If a rebuild is necessary, I will need a source for a good set of seals that others have used. Or I can send it out to be rebuilt, but I've had it on my lift for 3 weeks and I'm anxious to get it on the road so I'm inclined to rebuild myself if I can find a good set of seals that are known to perform. Thanks for all the help!
I just saw this suggestion. I'll try this next to see if I can get any air to blow out of the lines at the MC connection. Good idea. yes. Towels.
17 psi worked for bleeding. Didn't fix the soft pedal. But I was afraid to go higher and when I hit 15psi it wasn't helping. I gave it one more pump to 17 psi and viola, they started to flow. But now I will try to bleed the MC as I think there may be air in there still. If not, then a rebuild is in store I'm afraid.
What makes the MC so difficult to remove/install? I just installed my rebuilt booster without the MC attached and you have me concerned that I should have attached to the booster before installing. Sent from my iPhone using FerrariChat
It's not that difficult. Just a PITA. you have to take off the reservoir and risk breaking the plastic that are held in by the rubber seals. If you already have the tank off, no big deal. At least on my 308 you can't get to the bottom bolt on the MC that connects to the booster with the plastic res in place. In my case it's a pain because I just put it all in place and bleed the lines. If I have to take it off, I will need to be careful with the res and empty it and bleed everthing again. The tougher part was for me to get under the steering wheel to remove and install the booster. And the linkage is a pain, but it is all manageable. Don't sweat it.
I have always kept it under 10 psig for brakes and my one vehicle that has a hydraulic clutch. It's not exactly a firehose efflux of brake fluid but it gets the job done, and any air bubbles can be easily seen with transparent exit bleed lines. Been doing it that way for over 30 years.
The fact is, you don't need high PSI to bleed brakes. Enough pressure to simply move fluid and air is sufficient.
7 psi from the deflated spare with “ EZI bleed “ All four corners and I don’t press the peddle to the floor , only 1/2 way . Kit instructions suggest high psi can blow seals and pushing the peddle all the way down to the floor and snapping it back up ( not intentionally) can damage MC seals .
Did you check if the Brake failure indicator is good.? Possible that the valve is stuck and letting fluid only go to the back. (number 16 in drawing). Part No: 127757 Image Unavailable, Please Login
I always use 2 man. I think it works better than pressure bleed. That said I have several motive caps for when I'm by myself or at the racetrack by myself. I run my nitrogen tank to about 10-15psi and pressure bleed.
I was able to get all 4 corners to bleed clean solid stream with no bubbles... so that is not it I don't think. I do think the seals in the MC are bad. I keep asking if anyone has a good brand or distributor for a rebuild kit. There are several out there and some folks on this thread have mentioned that they had to rebuild twice due to poor seal sizing with their kits. I'm trying to avoid 2 rebuilds if anyone has had luck with a particular MC rebuild kit I'd appreciate it. Thank you! GT
I used the Superformance kit to rebuild mine with no issues http://www.superformance.co.uk/308/brakes.html
Really strange... I tried one more time to get the bake pedal to firm up last night before I decide to take the MC off. This time, under pressure of 15psi (and slightly Higher due to frustration) I could only get 3 corners to bleed. Front driver would only drip fluid. I even tried the manual process with my assistant. No go. Previously, I was able to get all 4 corners to have a good flow of bubble free fluid, but the pedal stayed soft. So now I can't get one brake to bleed. I'm throwing in the towel and will pull out the MC tonight and take apart this weekend and see what I find. I hope it's the MC and not the differential pressure switch under the car causing the bleeding issue. But I would think if the differential switch was clogged up preventing the brake from bleeding (or a line blocked to that caliper) that the pedal would get somewhat firm. Not so. Must be the MC. At least that's my WAG. In thinking about everyone's comments about bench bleeding after I rebuild (or replace if piston or sleeve is too pitted to rebuild), it will be a challenge as once the bench bleed is complete I need to remove the reservoir to install the MC (bottom bolt is impossible to get to with the reservoir in place) which will introduce air back into the MC. But I suppose if I'm careful, the fluid should stay in the MC for the most part. But I have my doubts as the reservoir will be removed and the brake line ports will be open when installing. Anyway, I"ll report back on the condition of the internals of the MC. As always, thanks for all the help and good ideas! GT
Hi Waymar, I have the same MC as your photos. The on on Birdman's rebuild is different. Did you have to remove the large 32mm nut/bolt on the end of the MC body to disassemble? I have removed the snapring, washer and rubber seal, but the main shaft does not come out. Your photos above show the large brass looking 32mm hex removed. Was that a necessary step in addition to the flat head screw from the top fill port in order to get the guts out? Thanks! GT
Also, from your photos (thank you by the way!) it looks like the main shaft came out the "front end" where the mounting holes are and the secondary shaft came out the end where the large 32mm hex bolt or cap was located. True?
GT there is a set screw inserted from the side that holds in the plungers. I removed the hex. Look at the photos bit closer.
Thanks.. I saw that... BUt I was not sure about the large 32mm screw head at the end. That obviously had to come off. I got it all apart. This MC is a bit different than some of the others. Yours and mine are identical. I will try to use the same rebuild kit. I was able to get it apart and just spend the last hour cleaning. Luckily I have a sonic cleaner so it made it much easier. But I had a horrible mess in there. Wet rusty goo. Not too much pitting so I'm hopeful the new kit works vs. replacement. I'll give it a shot for $40 and report back. Thanks for the help! GT
The MC that birdman is showing in this post is a different design. Thus my confusion. His has a hex screw. Ours has a set screw inside the fill tube under the rubber seal. His piston comes out the front. Ours comes out the rear by removing the 32mm hex. http://www.birdman308.com/service/master-cylinder/master-cylinder.htm
Great progress.... FWIW when I had mine apart I had it ‘sleeved’ with brass tube. Depending upon the pitting and condition.