brake failure on highway, please help diagnose
09-30-2008, 02:21 PM
#61
Rennlist Member
you pulled the clutch master or slave? If you are thinking about using CRC, or think you need to use it , i would give up and start replacing stuff. just do the standard pump and bleed way of bleeding the system. even the clutch system, open the bleeder, push the pedal down, pull the pedal up (or someone should be doing this for you while you close and open the bleeder screw on the slave)
If you pulled the clutch slave, i dont understand the ripped front seal, unless its the flimsy one that is just basically a dust cover. the piston should be able to be pushed in if you just put pressure on it and have patience. the fluid moves slowely back to the reservior.
You might be ok, but then again, you might not. after you do a push pedal bleed of the system, you will know.
mk
If you pulled the clutch slave, i dont understand the ripped front seal, unless its the flimsy one that is just basically a dust cover. the piston should be able to be pushed in if you just put pressure on it and have patience. the fluid moves slowely back to the reservior.
You might be ok, but then again, you might not. after you do a push pedal bleed of the system, you will know.
mk
Well besides all your sage advice and concerns...
When I bleed the system last night, I pulled the clutch master to burp it. Problem was the cylinder didn't slide out as easy as it usually does. And this is whith 10-12psi backing it up. And it didn't go back in easy, actually ripped the front seal in process (had to put a spare in to finish the job) without leaking.
I have a feeling the rubber had enough exposure to have already swelled. I know this is just anecdotal, but it was enough for me to say, hmmm...
I'm going to try the rubber oring and CRC trick Stan spoke about.
And my guess is Pentosin will not respond. Too much liability to give any advice. Maybe if I sign a waiver... but I can't write german.
Danke.
When I bleed the system last night, I pulled the clutch master to burp it. Problem was the cylinder didn't slide out as easy as it usually does. And this is whith 10-12psi backing it up. And it didn't go back in easy, actually ripped the front seal in process (had to put a spare in to finish the job) without leaking.
I have a feeling the rubber had enough exposure to have already swelled. I know this is just anecdotal, but it was enough for me to say, hmmm...
I'm going to try the rubber oring and CRC trick Stan spoke about.
And my guess is Pentosin will not respond. Too much liability to give any advice. Maybe if I sign a waiver... but I can't write german.
Danke.
09-30-2008, 02:36 PM
#62
Rennlist Member
Thread Starter
you pulled the clutch master or slave? If you are thinking about using CRC, or think you need to use it , i would give up and start replacing stuff. just do the standard pump and bleed way of bleeding the system. even the clutch system, open the bleeder, push the pedal down, pull the pedal up (or someone should be doing this for you while you close and open the bleeder screw on the slave)
If you pulled the clutch slave, i dont understand the ripped front seal, unless its the flimsy one that is just basically a dust cover. the piston should be able to be pushed in if you just put pressure on it and have patience. the fluid moves slowely back to the reservior.
You might be ok, but then again, you might not. after you do a push pedal bleed of the system, you will know.
mk
If you pulled the clutch slave, i dont understand the ripped front seal, unless its the flimsy one that is just basically a dust cover. the piston should be able to be pushed in if you just put pressure on it and have patience. the fluid moves slowely back to the reservior.
You might be ok, but then again, you might not. after you do a push pedal bleed of the system, you will know.
mk
Bleed order:
Brake Master
RR (in then out)
RL (in then out)
FR (in then out)
FL (in then out)
Clutch Slave
Lastly, Clutch Master burp under pressure.
I had just replaced the Clutch Master cylinder. It's been in the car 3 days. I know how it goes in with and without back pressure. The cyliner typically slide out easily w/a little back pressure. That was not the case this time.
Spraying CRC on an oring was Stan's suggestion to show how quickly and rubber will expand when subjected to petroleum.
09-30-2008, 03:04 PM
#63
Rennlist Member
Rather than using CRC why not use the power strg fluid on the O-ring test for expansion?
Good you got the fluid replaced..........now comes the hard decisions. I like your idea on opportunity
Good you got the fluid replaced..........now comes the hard decisions. I like your idea on opportunity
09-30-2008, 04:07 PM
#64
Rennlist Member
Thread Starter
09-30-2008, 04:17 PM
#65
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Can you really put S4 front calipers on the rear? If you follow the required direction, then the bleeder nipples would be pointing towards the road - no?
09-30-2008, 04:25 PM
#66
Rennlist Member
Thread Starter
On another note, a very gracious Rennlister gave me a set of rear calipers!
I'm just amazed by the people here. Thanks, Jim M. Edit:
Nicole,
The reason they won't work is because the bolt mounts front to back are perpendicular to each other (90 degree opposed).
Last edited by Jadz928; 10-01-2008 at 09:47 AM. Reason: added reason front calipers won't work on rear
09-30-2008, 05:14 PM
#67
Rennlist Member
Jim............if I take the plunge for 'big reds' we can discuss my S4 fronts.............let me know.
Good to see the sense of humour back
Good to see the sense of humour back
09-30-2008, 05:23 PM
#68
Rennlist Member
Thread Starter
09-30-2008, 05:37 PM
#70
Rennlist Member
Thread Starter
Good thing is I didn't smoke my front rotors, and the pads look good.
So, either I rebuild the front calipers and about $180 a pop or spring for the big reds and rotors.
I'd say your S4 calipers are worth around $400. And thanks for the offer.
09-30-2008, 05:52 PM
#72
Rennlist Member
Thread Starter
09-30-2008, 06:33 PM
#73
Rennlist Member
09-30-2008, 06:59 PM
#74
Rennlist Member
For this issue/situation, it would get any residual PS sterring fluid out from around the seal and any film on the cylinder walls. Also, you cant get as good of a pedal by only using the power bleed. Ive done it many times at the track, and one time the finished product was near dangerous. doing the open/close valve with pedal push is the traditional method and gets all of the air or bubbles out of the lines if done properly.
pressure bleeding wont get all the PS fluid out , as it can rest in corners of the cylinders or calipers. since the calipers, masters and slave cylinders can activily evacuate all the fluid out of their chambers, it is the most logical way to completely flush the system. Ive also done a pressure bleed and then push bled the calipers and found that the old gold super blue was still in there. when you use the pedals, you eject all of the fluid.
mk
pressure bleeding wont get all the PS fluid out , as it can rest in corners of the cylinders or calipers. since the calipers, masters and slave cylinders can activily evacuate all the fluid out of their chambers, it is the most logical way to completely flush the system. Ive also done a pressure bleed and then push bled the calipers and found that the old gold super blue was still in there. when you use the pedals, you eject all of the fluid.
mk
09-30-2008, 09:00 PM
#75
Team Owner
Jaydaz at this point you need to replace every rubber part in the hydralic system, no bleeding will rescue the rubber bits,
Too bad about the clutch system its also toast so a new clutch flex line as well as the master and slave, this will give you a chance to bleed the whole system on the bench before you install it, you can really appreciate how easy it is.
Aso replace the blue line and the resivour cap/rubber seal,
Toclean out the resivour first use some brake cleaner slosh it around then follow with a simple green rinse and the hot water, shake it dry then add a few oz of isopropil alchohol slosh it around then use a hair drier set to cool and blow out the resivour it will look like new. The Iso takes out any remaining water.
Good luck on your new project.
Too bad about the clutch system its also toast so a new clutch flex line as well as the master and slave, this will give you a chance to bleed the whole system on the bench before you install it, you can really appreciate how easy it is.
Aso replace the blue line and the resivour cap/rubber seal,
Toclean out the resivour first use some brake cleaner slosh it around then follow with a simple green rinse and the hot water, shake it dry then add a few oz of isopropil alchohol slosh it around then use a hair drier set to cool and blow out the resivour it will look like new. The Iso takes out any remaining water.
Good luck on your new project.