yet another clutch bleeding thread

jvandyke

jvandyke

True Classic
Recent clutch R&R left pedal feeling crappy.
Doesn't start to resist (engage master) until over halfway down.
Much bleeding but a one-man job with a stick. Will try extensive bleeding tonight with helper.
Just wondering if that is a symptom of air:
no clutch action until pedal well past half, then decent movement of slave (about one inch).
Car is drivable but pedal sometimes doesn't want to come up again.
Last night I pumped and held (with a stick) and cracked output at master, banjo and slave bleeder and only got a couple really small bubbles after about 10oz of juice moving through.
Just wondering if bleeding is the issue or if I have a master not happy (it's pretty new as is slave).
I can watch the rod on the master going in with pedal movement but there's no resistance until about half way down, then "fair" clutch action.
I was running a pedal stop before I tore into it, now I can't or I don't decent disengagement. I did not disturb hydraulics other than a quick test for bleeding before I started, which may have been enough to make it grumpy. Maybe I need to rig up a pressure bleeder. Be nice to find a generic reservoir cap that fits, I remember I found a weed killer bottle cap fit my old Opel nicely.
 
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Doesn't sound right...

I seem to remember that a pedal that won't return is a sign that there is insufficient fluid/back pressure (not sure what the technical term is) in the system. Meaning either a bad seal or air. The pedal should be very direct in how much any movement at the master moves the slave.

I would suspect some air in the clutch system somewhere. It sounds like you've been very thorough in making sure you have fluid at every joint. Have you flushed (or re-flushed?) the line completely? I recommend a pressure bleeder or some sort for bleeding, but for the clutch ruining the m/c seals are not as much of a worry as with a brake m/c, since the clutch m/c uses most of its travel every time you use it.

This doesn't mean you can't ruin a clutch m/c by pedal-pump-bleeding. If the m/c is dry upon installation, or has sat on a shelf for many years, the bore could be corroded and/or the seal stuck or misshapen. I guess this is why bench-bleeding is a good idea.

Last question; how new is the slave flexible hose?
 
I always thought that part of the brake and clutch bleeding issue is that due to the long reservoir hose routing run, and that the reservoirs are only marginally above the level of the masters, there is so little "head pressure" built up to aid in the front to back bleeding procedure.

In some cases, depending upon hose routing, and how far one lets the level fall in the reservoir while bleeding, the level of fluid in the reservoir can dip below the highest point of fluid in the hoses and introduce backflow in the hoses back towards the reservoir and develop air bubbles in the hoses.

Someone who has converted to the Tygon clear hoses with that special chemical resistant formulation would be able to see this happening.

I haven't had a chance to try this, but my theory is that prior to bleeding, dismounting the reservoirs from their stock location and raising them up as high as the hose slack permits should aid in bleeding.
 
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The slave hose is probably original and I should probably replace it. It does seem to be overly bent and the exterior coating shows a split. Maybe internal collapse check valve syndrome in play? Will go shopping.
 
I would...

The slave hose is probably original and I should probably replace it. It does seem to be overly bent and the exterior coating shows a split. Maybe internal collapse check valve syndrome in play?
Click to expand...

Your clutch or brake system is only as good as the weakest part. And this way you could at least know it's no longer suspect. :D
 
jvandyke said:
Doesn't start to resist (engage master) until over halfway down.
Click to expand...

This is easier to do if you can borrow a 12year-old kid (small nimble hands, sharp eyes, and ability to curl up like a pretzel).... But check to see whether the how far the pedal moves before it starts forcing the rod into the master cylinder.

I once had a clutch pedal that engaged low and stuck at the bottom - turned out that the opening in the master rod that the pedal arm acts on had worn oval, so that the pedal moved a long ways before it did anything.
 
Also, about bleeding the clutch...

Among other things I think you have to push the slave rod in to properly bleed it, this exposes the slave bleed port to the fluid chamber otherwise it's covered by a seal or something. I remember this being important when bleeding this part of the system. This is where a pressure bleeder or helper comes in handy, as you have to hold the rod (and therefor the piston) in the bore while opening the bleed screw.

Can others verify this? Is it hold it in or hold it out a certain amount? I wonder if this is why there's less action if this is needed and not done? :huh:
 
I personally have not found it necessary to keep the clutch slave cylinder pushrod pushed into the cylinder bore in order to bleed the system. I did, however, have to make numerous sacrifices to the Bleeding Gods, as well as mumble incantations in seven ancient languages, in order to get the job done. Please see my other post (a response to Erwin Timmers, a.k.a. artbasement) for the nasty details of what worked for me (eventually).
 
Tried holding the clutch slave rod in different positions by blocking the the lever so it couldn't extend, made the pedal stop much earlier but didn't seem to change bleeding much. I ordered up a clutch hose. I did watch the pedal engage the master rod and it starts pushing it in almost immediately but doesn't meet resistance until it has traveled a fair ways. Probably air somewhere.
 
I can't recall...

If it needs to be pushed in or let out a little to bleed properly. But there was something about it.

As for the rod, I was referring to the slave rod.

FWIW, I never got the full 1-1/4" travel at the slave, more like 3/4".
 
One other idea...

Crack the line coming immediately out of the Clutch Master and bleed any air out at that point FIRST. Takes three hands...

Then move to the Banjo Bolt on the slave... then lastly, the nipple on the slave.

HTH...
 
jvandyke said:
Tried holding the clutch slave rod in different positions by blocking the the lever so it couldn't extend, made the pedal stop much earlier but didn't seem to change bleeding much. I ordered up a clutch hose. I did watch the pedal engage the master rod and it starts pushing it in almost immediately but doesn't meet resistance until it has traveled a fair ways. Probably air somewhere.
Click to expand...

Yah.... That's air, or crap hose, or both.

I've started using speedbleeders on my clutch slaves. They work well, and there's something deeply satisfying about whamming my foot down on the clutch pedal really really hard to make the brake fluid SQUIRT out the tube :headbang:
 
ditto on the bleed it at the master post. I spent days on this.. get a small pan on the floor to catch the fluid, loosen the line so that youll be able to open and close it with on hand 'line wrenches help". pump the clutch by hand and loosen the line while holding down on th pedal.. di that a few times, then move on. air gets trapped right there.
 
wildman said:
ditto on the bleed it at the master post. I spent days on this.. get a small pan on the floor to catch the fluid, loosen the line so that youll be able to open and close it with on hand 'line wrenches help". pump the clutch by hand and loosen the line while holding down on th pedal.. di that a few times, then move on. air gets trapped right there.
Click to expand...

OK tried that last night too, flare nut wrench, cracked the output, pushed pedal, got a dribble, tried to finger tighten and let pedal back up, repeated a few times, then cracked banjo, then did slave bleeder, no evidence of air in line, pedal feel did not change, will try new hose and a bleeder nipple, might be able to get off shelf, saw chapter and verse on that at one point (correct size and all, will look for it). I hope it's just air as I don't really want to go after the master again.
 
At the slave, it is best to extend the push rod out (as if to disengage the clutch) about a quarter inch. On some slaves, the internal pusher can block the bleed hole if it is all the way in toward the banjo bolt. I jam a broom stick in there to keep it extended. And a power bleeder works best for me.
 
I am not convinced that air in the hydraulics is the issue. I'd rather suspect that your release fork / shaft / lever has a problem as was discussed in your earlier clutch thread.
<slave> Doesn't start to resist (engage master) until over halfway down
Click to expand...
You won't feel any resistance until the throwout bearing starts pressing up against the spring fingers on the pressure plate, so if the shaft for the release fork is twisted (or the lever bent or the fork rotated on the shaft etc.) it would match what you are seeing.

Starting with the clutch pedal in the rest position and the slave rod pushed all the way in: Press down and the clutch pedal and observe slave cylinder. Does the slave rod start moving when you press the pedal, or does it not move until the pedal is beyond half way on its stroke?
Car is drivable but pedal sometimes doesn't want to come up again.
Click to expand...
Clutch pedal not returning can be a symptom of a bad slave cylinder, but I still don't think hydraulics is the problem. The spring on the clutch pedal is an over center spring; The spring will pull the pedal up at the first part of the stroke. Then as pedal goes further down, the spring will start pulling the pedal down. The pedal will only come back up again if the force of the spring on the pressure plate is stronger than the force of spring on the pedal. If the release shaft is twisted, that may not happen.
 
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Photo?

Can you post a photo of the position of the clutch release lever at the point where you are just feeling resistance?
 
I sure hope you're wrong but secretly fear you're not! I started this thread when I thought the same thing. It sure didn't "look" twisted but like others said, you pretty much need a known good one side by side to know. I will try to snap some pictures but I lost my bleeders (kids had to go) tonight and the wife sure ain't gunna do it, not now anyway. Fiat's grounded. I think I can probably coax it back into driver status even if the lever/rod is bent/twisted, it was working so it can again. I can try to score a known good used lever/fork and screw up my courage for a second attempt to pull the gear box IF it comes to it. I could not get the fork to slide on the lever rod and I was scaring myself with my frustration induced violence and I thought I'd better just leave it. Photo essay to follow in a bit. Dang, can't find camera.
Anyone care to measure where the clutch lever arm is in relation to some common point on the bell housing? Both engaged and disengaged if possible. I think mine is actually hitting the bell housing on full clutch disengagement. There's some marks right near the timing numbers. Dang, probably twisted fork after all.
Best I can do for now.
If it is twisted, can I apply some force to untwist it? Or would I just destroy the bellhousing or something? Or cut the arm, drill and bolt a plate to offset it back to "normal".
file-2.jpg
 
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Don't forget the tennis ball

A tennis ball will allow you to drive with a clutch pedal that occasionally decides to stay on the floor.

1. Get a tennis ball.
2. Put a 2" slice in the tennis ball.
3. Force the slit in the tennis ball onto the pedal arm behind the pedal.
4. Duct tape in place.

As you step on the pedal you will compress the ball. When you let off the pedal the ball springs back into shape and kicks the pedal up. I did this in 1980 on my brand new X when the dealership told me the clutch not returning was a known issue due to a mis-aligned return spring. It was a three week wait fir the fix, so I had to come up with something. :)
 
ah yes, good point. I followed your advice on the tennis ball when my master started to fail a while back. I think I will try some tricks to get back to driver status while I gather measurements on the lever. Pretty thick plate, not going to want to take "adjustment". I'd think forcing it back away from the block would press the fork so hard up against the little stand offs in back of the bellhousing that something would break.
Maybe split it almost all the the way, bend it back and bolt or weld a plate on top to hold it. Just thinking out loud.
file-4.jpg
 
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