Silky's clutch - Finally fixed

[Silky_Johnson]

And I'm not going to make it to Canby. :crying:

Maybe someone can help me out on a diagnosis? Around two weeks ago, I was pulling into my driveway, and the clutch pedal felt really weird. I noticed right away that the transmission also didn't want to go into gear at the same time. The shifting was really hard, but I could force it into the first and pull it forward. Reverse grinds. I immediately checked under the hood and opened up the master cylinder, and it was bone dry.

I thought to myself, "sweet, I'll just use that slave cylinder rebuild kit I got and bleed the system and all will be good." Previously, the slave boot was all dried and torn, so I bought a rebuild kit for the next time I would work on it. I've had problems off and on with the slave letting air into the system. The next day, I did all of the above, bled the system, and no dice. The clutch pedal felt somewhat more normal, but the shifting was still very difficult. I figured the hydraulics were all messed up, so I ordered a new master, slave, and soft line from Rockauto.

My Beck Arnley parts showed up a few days ago, and I finally got around to replacing all of my clutch hydraulics. Everything went in fairly smoothly. I bench bled the master, and just finished bleeding the whole system. I put a ton of fluid through the hydraulics, and there are no more air bubbles. The problem persists. Shifting is still hard, and it still grinds going into reverse. I thought that since the problem occurred when the hydraulics went dry, then it was a problem associated with the hydraulic system, but now I am wondering if the throwout bearing died on me? I tried getting a nice long throw on the pedal by adjusting it out farther, but it doesn't help.. not really. The pedal is out about as far as it can go right now.

I can confirm that the slave is pushing the clutch for about 3/4" when the pedal is pressed. It seems like everything is in working order, but I just can't really shift. Rather than one specific spot on the pedal where you can feel the clutch grabbing, it feels like it slowly grabs more and more as you release he pedal. Kinda weird.

Any ideas???? I'm kinda bummed out.

[musicman]

Hey Silky, musicman here,

I'll see you tomorrow--let me know if and when you decide to pull out the transmission.  Moral support!

[LenRobertson]

I'll tell you the problem I had with new clutch master and slave on my '72 510. I replaced both and bled everything, but still a weird clutch. I found a post from datzenmike where he mentioned you must have a slight amount (maybe 1/16", maybe less) of free play before the pedal starts to move the rod in the MC. This was my problem. The threaded end of the rod in the new Made-In-China MC was too long. When I adjusted the clevis far enough back on the threaded rod so I could get the pin through the pedal arm, it wasn't letting the rod have any free play. Anyway, I hack-sawed about 5/8" off the threaded end of the MC rod, and then I could adjust it to get free play in the pedal. I was hesitant to saw up a brand new part, but I was getting mad and desperate. I sawed it off with the master still in the car, using a vise grip to hold the clutch rod while I sawed. I think I put double nuts on the rod and snapped the vise grips on the nuts. It took awhile that way, but I got it. Then I backed one nut off over the cut end of the threads to clean them up, and reinstalled the clevis.

 

So check your pedal free play and make sure you have at least a little bit. If not, then the clutch may not be fully releasing. If you are having the problem I had, 15 minutes with a hacksaw and you might make it Canby. Good luck!

Len

[athoose]

Check fluid level in transmission, adjust clutch pedal height and free play, bleed it again being very meticulous.  I just did my clutch and slave cylinder and one or more of these contributed to poor shifting.  

[LenRobertson]

If your clutch MC is too long (and that may not be your problem), you can try backing off the pedal arm bump stop bolt. This lets the pedal return to a higher position when you take your foot off and lets the too-long rod come out of the MC a little farther. That didn't work for me though. I even removed the stop bolt completely and still couldn't get any free play. Hence the need to resort to the hacksaw.

 

Len

[Silky_Johnson]

Thanks for the input guys.  I'll try all of your suggestions later sometime.  Right now I need to take a break from the project, if you know what I mean...  I'm kind of through with the project right now.  I'll just hitch a ride to Canby with musicman.

[Silky_Johnson]

Okay, I gathered up the Factory Service Manual (FSM), and I adjusted all of the clutch hydraulics per factory spec.  FSM says to adjust the pedal out to 8.224 inches from the floor wit the pedal stopper free.  After adjustment, it says to adjust the stopper about 2mm closer to the floor.  I did all of that.

 

Next, I adjusted the slave cylinder to have about 2mm of play, again per FSM.  Lastly, I bled the system, over and over and over and over and over and over and over and over and over and....  well, you get the idea.  There definitely aren't any bubbles coming from the bleeder.

 

I still have really hard shifting into all gears, and reverse always grinds going in (don't worry - I'm not continuing to drive it like this).  I have free play at the master/pedal junction -- the master is fully releasing when the pedal returns to the stopper.  No amount of adjustment fixes the problem, and I'm getting around 3/4" of throw at the slave cylinder.  I figure the T/O bearing is shot.  Any opinions?

 

I thought that it had to be the clutch hydraulics, because the hydraulics went dry when the problem started.  The T/O bearing isn't making any whining sounds, but maybe it's still bad anyway?  I bought a Sachs T/O bearing, so maybe I'm regretting that purchase...

 

Looks like I'll be pulling the engine and tranny this weekend.

[athoose]

Did you check fluid in the tranny? 

[Silky_Johnson]

Did you check fluid in the tranny? 

 

Not in the past couple of weeks.  I replaced the fluid less than a year ago, and I don't have any leaks, so I assume it's fine.  That said, I'll do quick check this weekend.

[datzenmike]

If the clutch is working properly... nothing is moving inside the transmission when the peddle is down so it shouldn't grind at all..

 

The normal travel distance for a Datsun slave cylinder piston is 1.18"

 

I would say the master isn't delivering volume. Maybe because it went empty and the deal is now torn?

[Silky_Johnson]

If the clutch is working properly... nothing is moving inside the transmission when the peddle is down so it shouldn't grind at all..

 

The normal travel distance for a Datsun slave cylinder piston is 1.18"

 

I would say the master isn't delivering volume. Maybe because it went empty and the deal is now torn?

 

Thanks.  I'll more carefully measure the clutch slave travel.  Might not be enough?  The clutch master I'm using is a new Beck Arnley unit.  After the old hydraulics ran dry, I bled the system to no avail.  I assumed "the master isn't delivering volume. Maybe because it went empty and the deal is now torn?"  So I got a new master and slave.  The new cylinders are no better.

[banzai510(hainz)]

make sure the trans bolts to engine are tight. Mine work loose sometimes

[athoose]

My slave cylinder only moves a half inch. ( different geometries on the fork maybe?)

 

try this, without the motor running put it into gear, if you try and roll the car back and forth ( i do this by having one foot outside the car on the ground) it should lock up due to being engaged to the motor.  Push the clutch in a little bit and rock the car.  See how far you have to push it in to roll/disengage.  Hopefully before the clutch pedal hits the floor you should hear no drag of the clutch.  Listen for when it disengages.  If you hear it dragging when the pedal is on the floor it's not disengaging fully.

 

Gravity bleeding doesn't work as good as two people or propping the clutch pedal on the floor with a stick/rod. 

[Silky_Johnson]

make sure the trans bolts to engine are tight. Mine work loose sometimes

 

Ha!  A little more than two years ago, I was crawling around under the car and discovered a gap between the engine and tranny.  They were probably at least 2mm apart, and I was surprised that the clutch was still working at that time.  Everything's good now.  Those bolts are one of y regular checkups.

 

My slave cylinder only moves a half inch. ( different geometries on the fork maybe?)

 

try this, without the motor running put it into gear, if you try and roll the car back and forth ( i do this by having one foot outside the car on the ground) it should lock up due to being engaged to the motor.  Push the clutch in a little bit and rock the car.  See how far you have to push it in to roll/disengage.  Hopefully before the clutch pedal hits the floor you should hear no drag of the clutch.  Listen for when it disengages.  If you hear it dragging when the pedal is on the floor it's not disengaging fully.

 

Gravity bleeding doesn't work as good as two people or propping the clutch pedal on the floor with a stick/rod. 

 

I'm going to try the engine off technique.  Makes sense that it would isolate the clutch disengagement vs. throwout bearing hanging things up.  We shall soon see.

 

I've had family over pumping the clutch pedal for me, so I don't have to gravity bleed.  My technique involved having the in-car guy pump the pedal four times and holding it down on the fourth pump.  With the pedal held down, I open the valve until the pushrod retracts back in the slave cylinder.  Of course the fluid is going down a line to a container with fluid already in it.  The 510 FSM only mentioned something like "hook up a line to the bleeder, open the valve, and pump the pedal until no more air bubbles appear."  I got my technique from one of the 620 FSMs.  I have now put at least two pints of fluid through the clutch system.

[athoose]

I'd also check your clevis pin and pin hole in the pedal for slop/ out of round.  If it's worn beyond factory you are not maximizing pedal throw/piston movement.  It's also possible the new CMC has more or less piston/rod slop then the one you had on it.

[LenRobertson]

What tranny do you have - original 4-speed, dogleg, not-a-dogleg 5-speed? It may not make an difference, other than (maybe) which slave cylinder you put on. Maybe they are all essentially the same length and throw; that is something I'm hazy on. I seem to remember a couple of different slave cylinder diameters, but it may not matter which you use.

 

It still sounds like a hydraulic problem, as in not enough travel at the slave, but I don't know why not. I'll measure the slave throw on my 510/dogleg tomorrow when I get to work and post tomorrow evening. Maybe by then someone else will have a solution for you.

 

I think Harbor has a cheap version of the power vacuum bleeder, although I don't know if those really do a better job of bleeding.

 

Len

[banzai510(hainz)]

I just use a hose open the blled and pump a few times till all the air is out and line is full of fluid so I can see it and tighten the bleed. done.

 

maybe soemthing jammed up inside on the fork arm or maybe the fingers on the pressure plate bent busted. or T/O bearing collatr has no grease to slide?

otherwise Im just guessing from my chair here

[Silky_Johnson]

Okay, tranny fluid is full.

 

athoose - The clevis pin in my pedal does have quite a bit of slop, but I can adjust the slop out of it and it makes no difference.  Right now I have it adjusted at around 1mm of slop at the clevis just to make sure the piston fully retracts.

 

LenRobertson - I have an early zx 5-speed, the one with the short overdrive.  I was under the impression that it didn't make a difference as to the clutch slave?  I have all 200mm clutch parts: 510 disc, 200sx 200mm six-bolt flywheel, roadster pressure plate, 510 T/O bearing and collar.  The clutch arm is from a 510 and has the hole in it so that it mates to the 510 adjustable slave.  If the different slaves have different bores, then maybe I need a slave with a smaller bore so that the piston travels farther?  Unless I'm mistaken, I can put the adjustable arm in any slave, right?  Although, I don't see how that could be the case, because I've driven with this setup for the better part of three years now...

 

I had a bad experience with the Hazard Fraught vacuum bleeder.  The two man bleeding is definitely the way to go.

 

Hainz - You're sitting down!!!???

___________________________________________________________________________________________

 

On to the results of athoose's engine-off test.  I got in the car, and rather than rocking it back and forth with my own foot out the door, I just had my father-in-law rock it for me while I sat in the driver's seat.  The result?  With the clutch fully depressed and in first gear, he couldn't rock it much more than with the clutch out.  My first thought was, "YES!  Maybe I don't have to drop the transmission!!!"  And then my second thought was, "Shoot, I still don't know how to fix this..."

 

Anyway, I could tell that the clutch was starting to let go.  I could feel and hear the friction of the clutch disc, and that was different than the clutch being totally out, but man, that sucker was tighter than I expected.  Any bright ideas anyone?  Should I just keep on bleeding?  It seems like a lost cause since no air bubbles have been coming out for the last few times, but maybe I should just keep putting fluid through?  I suppose there's gotta be air trapped in there somewhere?

[banzai510(hainz)]

Really I dont think it takes much to disengaged the clutch.

I seen what looks like a a 1inch or less under the slave . but just going by memory.

 

I had a slave suck in air but never leaked. swap slave and was fine. the other was a taiwan unit.

[athoose]

Don't run it like this, but adjust the rod,pedal (even if this means eliminating any slack) and see if you can ever get clutch release. 

 

Unless you see something leaking your bleed is probably fine.

 

Oh and like Len said do you have the correct diameter slave and clutch cylinder?  You might have to measure. 

[Silky_Johnson]

Well, shoot. Yeah I haven't driven my 510 for a month now...

 

I think I'm maxed out on adjustment now. The stopper on the pedal doesn't have that much farther to go, and the clutch pedal is presently way farther out than the brake pedal. I have the slop taken out of the master. If I adjust the slave any closer, it will be resting or even pressing on the clutch fingers which I definitely don't want to do..

 

My former fix for all of this was just to get new parts and replace everything, bu that's not working. I did notice on the Beck Arnley boxes that both cylinders, slave and master, were made in Taiwan. Bummer. Rockauto also has Exedy cylinders. Sould I get those and hope that they're made in Japan? I' not sure where to go from here other than just continuing to bleed the clutch.

[athoose]

you could always drop the trans and check for mechanical failure.  Broken, bent, worn fork, release bearing, shaft, clutch etc...

[LenRobertson]

I think I'm maxed out on adjustment now. The stopper on the pedal doesn't have that much farther to go, and the clutch pedal is presently way farther out than the brake pedal. I have the slop taken out of the master. If I adjust the slave any closer, it will be resting or even pressing on the clutch fingers which I definitely don't want to do..

 

This high pedal sure sounds like what I had when the threaded end of my new MC rod was too long. And I had to take the hacksaw to it. I never could get freeplay at the pedal until I shortened the MC rod about 5/8". Do you still have your old MC and slave? Measure the length of the MC rod and be sure it is the same for old and new cylinders.

 

I keep thinking that you had a working clutch before you installed new parts, so something is different with the new parts. And buying new parts anymore doesn't assure they will be the right fit and fix the problem.

 

I think the inner diameter of the slave cylinder is cast is raised numbers on the outside of the cylinder body. I don't know if all the after market makers do this or not. I can't remember if MC are marked on the body, but worth a look.

 

Len

[Ranman72]

have someone push the pedal in the car while you watch the slave cylender

have them tell you when they start pushing and see how long it takes till the slave moves

it should move almost imediatly as the pedal is pushed then have them hold it to the floor and watch to see if the slave returns at all  while the pedal is held down

[Silky_Johnson]

I did some more bleeding on the 4th of July.  I'm late in posting updates since I'm kind of bummed out as to how the project is going.  :hmm:

 

This time, I did a three man bleed job: one guy pumping the pedal, one guy filling the res, and one guy watching for air bubbles.  I just opened up the bleeder valve and had the pedal guy pump to his heart's content while I kept the res full.  We got REALLY CLOSE!  But not close enough.  For a little while, I could shift into reverse without grinding, but that quickly translated into a little grinding.  Mind you, with all of the bleeding, we never saw any air bubbles, but the pedal feel got better nonetheless.

 

I used Ranman's technique for watching the slave in relation to the pedal, and the slave moves immediately once you have gone past the "free play" on the MC.

 

Thanks for the tips on the MC LenRobertson (whose true identity remains unknown).  I am able to get the proper free play on the MC by adjusting the pedal stopper, which then translates to a longer throw of the clutch pedal.  Now, everyone is probably thinking that a longer throw of the pedal would be great, right?  I'm kind of thinking that maybe the pedal is too far out?  Is that possible?  Am I pushing the rod into the cylinder too deep (I don't know any other way of saying that without it sounding dirty)?

 

Here's my game plan now:  I went ahead and purchased new slave and master cylinders, this time made by Exedy, so I'm really hoping for Japanese made parts.  In addition, I looked up the parts in Exedy's catalog, and rather than listing one MC for many different vehicles, it lists one MC for the 510 only.  This can't be bad?  If the Exedy MC comes with a longer rod than the old MC, I'll cut it down to length.

 

Anyway, I plan on restoring the pedal to it's location when I bought the car.  After having it even higher than it is now, I read the FSM and set it to the position as per the FSM, which is roughly 8.22" from the floor.  This setting is still higher than when I initially bought the car?

 

So, new parts, restored pedal height, plenty of play in the MC, and enough play in the slave adjustment, then plenty of bleeding.  Is there something I'm missing?  This is a stupid issue that is driving me nuts.