Milenko2121 Posted May 23, 2013 Share Posted May 23, 2013 (edited) I have a 1977 280z with an L28ET swap. I'm using the centerforce dual friction clutch for the turbo model. I have a lightened turbo flywheel(240mm) I have the correct clutch collar for the turbo. I replaced the master/slave with brand new ones. I installed the clutch and it worked perfectly for the first day. After that day, it slowly started to not disengage as well. At the end of the 2nd day, it would not disengage at all. I have bleed the entire system 3 times, and the slave cylinder moves the fork(not sure how much it's supposed to move). I have the master cylinder to pedal connection fully extended to get as much pedal throw as I can, and it still will not disengage. What would cause this problem? ============================ UPDATE! PROBLEM SOLVED! I bought an M8x1.25mm coupler and a threaded rod (cut the rod down to one inch), and now I have more throw. Clutch disengages and engages PERFECTLY and smooth. Edited May 25, 2013 by Milenko2121 Quote Link to comment Share on other sites More sharing options...
motomanmike Posted May 23, 2013 Share Posted May 23, 2013 How old is the master cylinder? Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 23, 2013 Author Share Posted May 23, 2013 (edited) bought it last sunday because I had believed the master was the problem to not pushing the slave enough, but with the new master, the problem is still there. also, while pressing the pedal and watching the slave, the slave cylinder moves the entire time until my pedal runs out of throw. It's almost as if I can't get enough pressure on the slave. Edited May 23, 2013 by Milenko2121 Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 23, 2013 Share Posted May 23, 2013 Have you checked the slave cyinder for leakage? I had one that leaked fluid/pressure in the middle of its stroke. It held pressure at the end and moved the entire time but didn't travel the full distance. The rubber dust boot was ful of fluid. Quote Link to comment Share on other sites More sharing options...
daddydonuts Posted May 23, 2013 Share Posted May 23, 2013 (edited) Sounds like bleeding issues, I replaced mine with the exact issues as you are having, once I bled the slave cylinder (correctly) it worked fine... Edited May 23, 2013 by daddydonuts Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 23, 2013 Author Share Posted May 23, 2013 how do you correctly bleed the slave? I've been having someone pump my master cylinder 10 times then hold, then I release the bleeder screw, tighten it, and repeat until a steady stream comes out (i have a rubber hose attached to watch bubbles/fluid) Quote Link to comment Share on other sites More sharing options...
daddydonuts Posted May 23, 2013 Share Posted May 23, 2013 No need to pump 10 times, press in clutch and open bleeder, release clutch and tighten before pedal returns to normal. Directions attached from a Chilton's guide. Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 23, 2013 Author Share Posted May 23, 2013 never tried submerging before. is there a specific bleeder hose for the 280z slave? Quote Link to comment Share on other sites More sharing options...
daddydonuts Posted May 23, 2013 Share Posted May 23, 2013 never tried submerging before. is there a specific bleeder hose for the 280z slave? Use a clear hose, my clutch slave came with one, but its the same size as one of those cheap brake bleeder kits from any of the auto part stores. Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 24, 2013 Author Share Posted May 24, 2013 Use a clear hose, my clutch slave came with one, but its the same size as one of those cheap brake bleeder kits from any of the auto part stores. oh I have one of those, i thought it was something that physically screwed onto the slave. Quote Link to comment Share on other sites More sharing options...
loy Posted May 24, 2013 Share Posted May 24, 2013 The collar should match the pressure plate for the clutch. Try bleeding a few more times. Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 24, 2013 Author Share Posted May 24, 2013 I have the turbo collar (the short one). I bleed the system multiple times using that method listed above. made no change in clutch pressure. With a crowbar I'm able to push the fork further than the slave cylinder. Also, not sure if this information helps, but in 5th gear I went WOT and smashed the clutch pedal down as fast as I could, and every time I did that, the clutch disengaged, and let me free rev for about 500 rpms before engaging again. Does that information help at all? I'm about ready to order a 7/8 MC and upgrade all my lines to SS braided for extra clutch pressure if that's all that's required. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 24, 2013 Share Posted May 24, 2013 (edited) I installed the clutch and it worked perfectly for the first day. After that day, it slowly started to not disengage as well. At the end of the 2nd day, it would not disengage at all. This says that you have all of the right parts, but one or more of them failed. You're searching in the light, when the source of the problem is in the dark (my new catch phrase). Edited May 24, 2013 by NewZed Quote Link to comment Share on other sites More sharing options...
daddydonuts Posted May 24, 2013 Share Posted May 24, 2013 Do you have any manuals to reference? Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 24, 2013 Author Share Posted May 24, 2013 I have haynes for 280z and 280zx, and all the manuals from xenons130/s30. Nothing tells me why this problem is happening. Quote Link to comment Share on other sites More sharing options...
daddydonuts Posted May 24, 2013 Share Posted May 24, 2013 I have haynes for 280z and 280zx, and all the manuals from xenons130/s30. Nothing tells me why this problem is happening. If your slave is moving the clutch fork with no leaking, then it has to be the assembly of clutch components...have a look at the TOB and clutch fork... Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 24, 2013 Author Share Posted May 24, 2013 I called centerforce, and even they had not heard of this or could offer me advice other than to remove the clutch assembly, and use a hydraulic press to simulate clutch movement. I look at the TOB through the fork hole, and it is just barely touching the pressure plate, and as the slave moves, it pushes it against it. The part I'm still highly confused about is how it can disengage for a second if I throw enough force on the clutch pedal fast enough. If I do it rapidly, It's the same effect each time, so it is consistent. There are no weird/different noises coming from my car at all as well. Quote Link to comment Share on other sites More sharing options...
NewZed Posted May 24, 2013 Share Posted May 24, 2013 The part I'm still highly confused about is how it can disengage for a second if I throw enough force on the clutch pedal fast enough. If I do it rapidly, It's the same effect each time, so it is consistent. Sounds like either your master or slave cylinder are leaking. The column of hydraulic fluid is shortened when the leakage occurs. The leak is slow, that's why you get a moment where it works, then it leaks down to where it doesn't. I forgot to say in Post #4 that the slave cylinder that leaked was new. And the replacement I got, under warranty, had leftover grit from the honing operation inside. The clylinders weren't cleaned before they were packed and shipped so the first one failed early. Just poor manufacturing procedures. Quote Link to comment Share on other sites More sharing options...
Milenko2121 Posted May 24, 2013 Author Share Posted May 24, 2013 i've been searching, and cannot find a leak. I'm going to remove my master cylinder later today, and see if I can find something because I have no leaking coming from my slave. Just curious though, the fact that I can disengage my clutch for a moment(consistently), does this tell me my clutch is functional, and has to be a problem with the hydraulics? Quote Link to comment Share on other sites More sharing options...
beermanpete Posted May 24, 2013 Share Posted May 24, 2013 I called centerforce, and even they had not heard of this or could offer me advice other than to remove the clutch assembly, and use a hydraulic press to simulate clutch movement. I look at the TOB through the fork hole, and it is just barely touching the pressure plate, and as the slave moves, it pushes it against it. The part I'm still highly confused about is how it can disengage for a second if I throw enough force on the clutch pedal fast enough. If I do it rapidly, It's the same effect each time, so it is consistent. There are no weird/different noises coming from my car at all as well. There is a difference between full disengagement for starting, stopping, shifting, etc. and partial disengagement that allows the clutch to slip a little bit. Your test at full throttle does not tell us the clutch is fully releasing, only that it released enough to allow the power of the engine to cause slipping. Based on what you have said so far it seems the hydraulics are working correctly. Check the free play at the pedal and the pedal height. I know these should not change but perhaps the lock nut is loose and it change or it is off a bit and the clutch "settled in" a bit and is now not getting enough travel to fully release. Once you eliminate the hydraulics, free play, and pedal stroke the only thing left is the clutch itself. If you cannot find a problem with the release system you have to remove the clutch for inspection. Quote Link to comment Share on other sites More sharing options...
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