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Thread: arrrggh...clutch bleeding issue

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    Default arrrggh...clutch bleeding issue

    Hello,

    I am in the final stages of assembling my car after extensive restoration and I'm kicking myself for not having bench bled my clutch parts. Anyway I have bled the clutch per the FSM, and using a pressure bleeder, the former with more success. I have fun about a half litre through the system now using the FSM method and when I crank over the car I can still feel the car move forward ever so slightly. Which is a massive improvement over how it would lurch forward initially. The slave is brand new Nissan as well, all new hoses, and clutch master. The car is also slightly more difficult to roll if the car is in gear and the clutch engaged than if it is simply in neutral. Which means the slave isn't moving the fork enough in my mind. The car is a '73 and I believe there isn't any adjustment on the slave.

    I searched around but if I have missed something obvious my appologies.

    Thanks in advance!

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    There are many possible combinations of pressure plate and release bearing collar, some work and some don't. Can you describe the collar and pressure plate that you are using? Your hydraulics might be fine, it could be the other parts.
    1976 280Z, with some minor modifications

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    Sure the pressure plate, clutch disk and release bearing are all stock Nissan parts procured through Courtesy. I don't have the invoices in front of me but I can likely dig up the part numbers. Not thrilled about pulling the transmission but I will if need be.

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    I"m gonna concur with Zed's diagnosis. You very likely have mismatched parts.

    Unless there's a loose fitting, clutch should be brain dead simple to bleed on this vehicle by any of a dozen different methods, hell, even just letting it drip.

    Do you have yoru old parts? Can you compare the new and old slave, master, mounting bosses, throw, etc. to see if the new one is IN EFFECT giving you 1/4" less throw or more? Man, it can be subtle...I've been bit plenty of times, had to machine a slightly longer rod to compensate, built adjustable rods, etc.

    If you got a slave that's slightly larger bore diameter then the original it will ALSO produce less throw, yet another way to get bit.

    Sometimes putting all the OLD hydraulic parts back on and testing it is the FASTEST way to determine if your problem is in the hydraulics, or in the collar, throwout brg, etc.

    Sometimes we replace all these parts thinking it's a nice, fresh start, and all it does is bite us in the bum....
    Last edited by Wade Nelson; 12-28-2012 at 05:55 PM.

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    I'm inclined to agree, and the system is bled so I'm thinking the slave is possible. I need to have someone engage the clutch while I'm under the car. As for old parts I might have the old slave, and the slave could be bad too. It is sluggish when I toggle the fork.

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    I pulled the invoice from Courtesy and here are the parts:

    1 x Pressure Plate - 1970 to 1974 240Z, 260Z (CLPP-001)
    1 x Clutch Slave Cylinder - 07/1972 to 1976 240Z, 260Z, 280Z (SLCL-002)
    1 x Clutch Master Cylinder - 1970 to 1978 240Z, 260Z, 280Z (MSTERCL-001)
    1 x Clutch Release Bearing - 1970 to 1989 Z, S30, S130 and Z31 (TOBRNG-001)
    1 x Clutch Disc - 1970 to 1983 S30 and S130 Z 2-Seater (CLDISC-001)

    All items were Nissan original but I did not record the part numbers off the boxes...I have bled the system again, and I'm making a bit of progress it seems. I'm going to go at it again and I think this will stand as a lesson learned in that bench bleeding is mandatory with a system which has no fluid to begin with.

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    Sometimes the bearing will come installed in the collar. With those parts you probably need the tall collar shown on this link - http://zparts.com/zptech/articles/tr...ar_specs1.html

    Did you install the parts or did someone else? I had a very similar situation, way back with one of my first cars, when I put the clutch disc in backwards. The hub springs were jammed against the flywheel bolt heads. Unlikely for you, just an example of how things can go wrong.

    Also, if your slave cylinder is leaking, you'll probably have some fluid inside the rubber cover. The cover seals pretty tightly and will hold quite a bit of fluid. Watch out if you decide to peel it back and take a look. I had a leaking slave cylinder (Schucks-bought) and it had your symptoms.
    Last edited by Zed Head; 12-31-2012 at 02:45 PM.
    1976 280Z, with some minor modifications

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    >I think this will stand as a lesson learned in that bench bleeding is mandatory with a system which has no fluid to begin with....

    No, it will not. I have never bench bled anything in my life, and the few times I tried anyway, hell, half of the fluid leaked out during the trip from the bench to the vehicle and during mounting anyway. I'd guess I've been involved in bleeding clutches and brakes on well over 100 vehicles and I reckon I done seen damn near every prolbem out there than can make a vehicle difficult or impossible to bleed.

    Not once was the solution bench bleeding. (I think there was one SINGLE Ford Ranger that required bleeding from the bottom , manually shoving the slave cylinder to burp the master - the clutch line had an inverted U in it that would trap bubbles, which I read about on the Internet / Alldata.

    So here's how I"m going to convince you you do NOT have a bleeding problem...or how to confirm it if you actually DO.

    Ok, so here's the deal. You've got to get your car up on a rack or else on 4 jack stands so someone can be UNDER it while another is in the driver's seat. At the very end you may need the engine running, attempting to engage / disengage the clutch without driving it off the lift or running anyone over.

    First have that person depress the clutch pedal (engine doesn't need to be running) and see how far the rod coming out of the slave cylinder moves. Measure it, mark it, whatever at the furthest point of travel.

    Next pump the clutch repeatedly. If you have air bubbles, they will get compressed and you will get additional travel as it pumps up. You've just diagnosed a bleeding problem, if you have one. Measure the furthest travel you can obtain.

    Now, manually, using Channellocks or whatever tool seems appropriate, from beneath the car, MANUALLY move the clutch lever, same as the rod out of the slave would.


    See how much futher it willl move, and whether or not THAT gives you full disengagement, allowing you to shift gears without grinding synchros, etc.

    At this point it may be necessary to START the engine and disengage the clutch with yoru tools, and SEE if it will shifti nto gear without grinding.

    Try real hard not to drive off the lift or run your assistant over. Please.

    If it will, either slave cylinder bore too large, different mounting boss height, master cylinder bore too small, etc. The usual fix is to construct a longer, or adjustable rod.

    If moving it by hand, requires more than 1/2" additional travel, (like 3/4 or 1") you probably have mismatched clutch parts, something installed backwards, worn parts, incorrect parts, different bore cylinder, shallower throwout bearing, whatever. Something ain't right and just stabbing a longer rod is probalby NOT the right answer for you.

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    Last edited by Wade Nelson; 12-31-2012 at 05:07 PM.

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    You may try to eliminate the easy solutions first. What you haven't said is when you put your clutch back together. If it's been awhile your clutch plate may be rust frozen to the fly wheel. Looks like you are in Vancouver, which has a moist climate.

    I had a similar issue which lead to a replacement of clutch master and slaves, only to find out that didn't fix the issue.

    what we had to to rock the car back and forth, in neutral, and in gear with the clutch out. It took two guys to get enough movement. After about 10 minutes of this, we heard a "clunk" and everything went back to normal.

    Good Luck.
    Last edited by auzziez; 01-01-2013 at 08:39 AM. Reason: spelling
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    2 quick points; the car was assembled over the fall at the end of a lenghtly body restoration. It has not been out of the shop and is on a lift. I know the clutch isn't engaging all the way as when I crank the car with the clutch engaged I can feel the starter motor slightly rock the car. Further if I roll the car in gear, with the clutch engaged, there is resistance compared to rolling it in neutral, plus gear noise. When I first bled the clutch I could not turn the car over with it in gear and the clutch engaged as it would move the car forward. So that led me to believe there is air trapped, which has imporved but obviously the fork is not moving forward enough yet. The bore on the slave seems to fit the fork perfectly. I'm going to get a helper to be in the car while it is in the air to see how much more the fork should be moving forward. Thanks to all.

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    I was able to measure the throw on the fork and I have 5/8's, not the 3/4" called for in the FSM. The other note is the slave piston is what I would call sloppy at rest, in that it sits rather dead and doesn't really make contact with the fork until the pedal is moved...is this correct? I'm leaning towards ordering a new slave and seeing how that goes. Thanks agian for reading and offering comments.

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    Tackled this further last night, no doubt the transmission has to come down. No way will it engage with the motor running so something is not right. Either the fork isn't in the guide slots or the throw out bearing is off sized compared to the new Nissan disk / pressure plate.

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    The slave cylinder has a spring behind the piston that pushes it out to a certain spot and holds the rod tip against the fork. If things are right, the spring will take up all of the play between the rod tip and the seat on the fork, so that the next stroke give maximum travel. You can actually push the rod in to the cylinder to remove it if you wanted to, if things were right. It's fairly easy to take the slave cylinder apart, you might do that before you go too far. I think that there is a simple circlip holding the piston in. Maybe there's an obstruction in your slave cylinder.

    You could also take the rubber dust boot off of the fork at the transmission and get a better feel for if the fork is seated on the pivot pin and held correctly by the springs. And somewhere out there I have seen a diagram of the angle of the fork when it's seated properly. If the fork is on the pin correctly, it will have a little bit of play fore and aft but will be held firmly by the springs. If it's not held by the springs you'll be able to tell. It's hard to feel with the boot on though, you'll need to pop it off (it's hard to get back on though).

    Just a few ideas before you take it out. And, by the way, I think that you're using engage and disengage backwards. Engage is when the clutch pedal is up and the engine is tied, or engaged, to the transmission. Disengage is when the engine is released from the transmission by pushing on the clutch pedal.
    1976 280Z, with some minor modifications

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    Thanks Zed for your comments. I removed the dust cover easily off the fork, and the fork appears to be in the correct position with exactly the play you referenced, fore and aft. I am starting to think the release bearing collar could be the issue. The car is on a hoist so pulling the transmission isn't a big deal, just frustrating when all seems in order but obviosuly something is not. I will get the transmission out tomorrow night and will start measuring....kicking myself for not having kept the original clutch parts for sure.

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    Here's a recent thread that's relevant. Opposite of your problem. We figured out the "magic number" - http://www.classiczcars.com/forums/s...ack#post416109

    If the collar is too short there should be lots of room for the collar to move back and forth on the front cover before it contacts the pressure plate fingers. Just another thing to maybe confirm your suspicions.

    I feel your pain, I took a transmission back out in less than a week after I installed it because it was leaking 2-3 drops of gear oil per day. The pivot pin threads in the cover hadn't been sealed. It had to be done.
    Last edited by Zed Head; 01-03-2013 at 02:36 PM.
    1976 280Z, with some minor modifications

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    Is your clutch pedal adjusted correctly? The push rod is adjustable from under the dashboard. First enlist the help of a friendly leprechaun to climb up under your dash. Tell him to loosen the jam nut on the push rod, adjust the length to take up the slack, and then re-tighten the jam nut.

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    On the eve of pulling the tranny I decided I would yank the clutch master. Sure enough it was seizing at the end of the throw, limiting it by 1/2". I bench bled the new master then bled the line, done. Thank you all for your input.

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