View Full Version : Bleeding clutch master
09-24-2007, 04:59 PM
Almost finished with my A4LD to M5OD R-1 swap. Trying to bleed clutch master with little success. Have new release bearing and slave cylinder in bell housing. Am using used clutch master, reservoir and line.
Tried gravity bleeding and got a thin steady stream out the bleeder, but no pedal after closing it. then unbolted the master and turned it downward and gravity bled with same results.
Could my used clutch master be shoot or is there another method to try? The posts on what to do after unbolting the master and turning it down seemed a little vague, but that might just be me.
09-24-2007, 05:20 PM
You need 2 people. First open the bleeder and have somebody push the pedal all the way down and hold it there. Close the bleeder after the pedal gets pushed all the way down. You should only need to do this 2-3 times at most. Just make sure as he is pushing the pedal there is a nice smooth stream of fluid comming out.
09-25-2007, 03:26 PM
I just finished putting a slave in my '95. I had a similar problem with mine.
I had read on here before about taking the master cyl. out and turning it upside down, so I tried it.
Took the master cyl out, turned it upside down and used the sidewall of my tire to push on after the bleeder was open. Did that a few times and put it back together and it worked like a charm. Just make sure you take the time to check the resevior each time you bleed it so you don't suck air in the line like I did.
09-28-2007, 03:00 PM
As I just posted in another thread:
I bleed the master cylinder while holding it in my hands with the reservoir and clutch line attached (no slave cylinder)
I have a friend hold the reservoir up and I orient the master "nose up" and press in the pushrod by hand (air is compressible, fluid is not) I keep moving the clutch line and the master cylinder around to work all the air out of the line and cylinder and up into the reservoir
When you can no longer push the pushrod in by hand the job is done, (it feels like you are trying to compress a steel bar) you can then install the master into the firewall (bend the plastic inner fender out of the way with a small ratchet strap)
Though this is easier to do if instead of using the pushrod to bleed a NEW master cylinder you use instead a screwdriver as a pushrod and only install the pushrod AFTER you've mounted the master to the firewall
the '93-94 and '95-current master cylinders CANNOT (absolutely cannot) be bled
when mounted to the firewall (I may be wrong, but I've never accomplished it)
The '85-92 master cylinder bleeds out rather nicely when bolted into place, but
though the '93-up clutch line will attach to it allowing the use of the '93-up slave cylinder you probably wouldn't like the result....
09-28-2007, 03:51 PM
I'll try the method you suggest. Not hard to believe that the master can't be bled in place. I have a couple questions. The firewall has a lip which prevents the bottom of the master cylinder from sitting flat against the firewall. Is this how they all are, or do I need the metal mount from an 89 to twist the plastic master into?
Also, when bleeding as you described, do I have to prop open the self sealing disk at the end of the line near the slave, or just let it be? Thanks
09-28-2007, 09:58 PM
Refresh my memory, what are you working on?
There are three master cylinders in RBV's.
As for the valve on the dry break?
No, you leave the dry-break fitting alone and orient the plastic hard line down, but move it around as you pump to let any air bubbles rise into the cylinder where you can then "pump" them up into the reservoir.
09-29-2007, 08:43 AM
I'm working on an 89 Ranger 4x4 2.9L converted from A4LD to M5OD R-1 with the 4.0L clutch/starter upgrade also being done. You supplied the 93-94 master cylinder, line, and reservoir. I,m using a new 93-94 slave with gold line collar as you suggested.
I,ve got about an inch of free pedal play (only internal spring pressure) then stiff resistance all the way down till the pedal arm hits the firewall. The t/o bearing moves about 1/4" to 3/8" which does not seem like enough. The master piston stroke is about 1" to 1 1/4" when assembled in the truck. The clutch pedal sits about 1/4" below the brake pedal at rest.
I'm guessing that either the master is not completely bled, or the cylinder rod is too short for a full stroke,or the 93-94 master does not provide enough fluid volume to fully extend the slave. The pressure plate and clutch is new so resurfacing is not an issue. I,m at a loss since starting with an auto trans there is nothing to compare the present setup to.:fie:
09-29-2007, 12:08 PM
Update. Took the whole magilla except the slave off the truck today in one piece and bled it in the basement per AllanD,s instructions. It's now rock hard when pushed except for an initial 3/32" travel which may be part of the design.
Will continue to try to get more air out before installing.
AllanD, Do you recommend a bleed after putting the assembly back in the car, or should I just try shifting right away if the pedal seems stiff and let the rest of the air, if any work itself out on the road.
09-30-2007, 04:24 PM
OK. I bled out all the air with the master, line and reservoir off the truck till I couldn't push it in at all even putting all my 200# against it. Reinstalled it in the truck, but without hooking the line to the slave.
What I got was 3/4" of master cylinder free piston travel, just a little better than before. There is no firewall deflection, loose master, or pedal slop. It is definitely in the piston stroke. Could the rubber part of the line be flexing? Any ideas?:shok:
09-30-2007, 09:05 PM
if the clutch is NEW then some lack of release is more or less "normal"
as the "fuzz" wears off the disc.
Why were you pushing on the ledal with your FOOT without connecting the line to the slave?
10-01-2007, 08:36 AM
"Why were you pushing on the pedal with your FOOT without connecting the line to the slave?"
I was pushing the pedal without the line connected to the slave to eliminate the slave as a reason for the piston travel. I thought that without attaching to the slave, there should be NO movement like when the master and line are bled at the bench. Looks like the increased force possible using your leg through the pedal flexes the rubber portion of the line; I can feel the rubber line bulging and trying to straighten out when someone hits the clutch pedal hard (w/o slave attached) while I hold it under the hood.
Enough theory. I,m going to attach it to the slave, bleed it a bit, then check how well it shifts today. If I can't get enough pedal travel with this cylinder, do you think I should switch to the larger bore master?
Problem solved. Lengthened the master pushrod 1/2" and the Ranger shifts like new now. Whooha
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