Ejkej Posted June 4, 2012 Share Posted June 4, 2012 Hi Guys, here is the story: After buying my Z I didn't have much ocassions to drive it before restoration, but I don't recall that problem. When rebuilding I decided to lighten the flywheel using tips on the "safe" weight reduction found here on hybridZ. When finished the restoration, which included replacing the clutch disk, I noticed that after few minutes of spirited driving the clutch was starting to slip. This winter, when I was working on the engine (now ca 200 BHP, 250 Nm) I replaced the clutch with "stronger" road-race set (disk, clutch cover, bearing), supposed to work fine up to 350 lbs. After few days, again, the clutch started to slip. I quickly found 6 puck ACT clutch disk, replaced it, and today - after few weeks - it started to slip again... The clutch disk size is stock (225 mm). Did any of You have similar problems? What could be the reason? My guesses are: flywheel deformation under load (possible??), driving technique (lack of it)... Quote Link to comment Share on other sites More sharing options...
Miles Posted June 4, 2012 Share Posted June 4, 2012 More info: Type of car? Engine/trans? Clutch/slave set up? Throwout arm movement? Did you follow break-in procedure for the clutch? Quote Link to comment Share on other sites More sharing options...
Leon Posted June 4, 2012 Share Posted June 4, 2012 Sounds like a hydraulic problem. Properly adjust the rod going to the clutch master and then bleed the system. Quote Link to comment Share on other sites More sharing options...
Ejkej Posted June 5, 2012 Author Share Posted June 5, 2012 Sorry... the car is a '75 280Z NA with stock 4sp transmission. The clutch is as I have written - lightened stock flywheel, 6 puck ACT disc, HD pressure plate (beefier than the stock one). As for the slave - Iremember I replaced stock one with some other dedicated to newer Nissan - I guess it was a 200sx or 240sx. But I can't remember 100%. I didn't check the bearing movement. As for the break-in procedures - I did bleed the system and checked if the clutch was working... but that's it generally. Thanks Quote Link to comment Share on other sites More sharing options...
loy Posted June 5, 2012 Share Posted June 5, 2012 Might be that the throwout bearing collar is the incorrect one for the clutch set.. Quote Link to comment Share on other sites More sharing options...
Ejkej Posted June 5, 2012 Author Share Posted June 5, 2012 Some additional info: - the pressure plate came with the bearing and disc, however it was dedicated for a 200sx (I find it difficult to buy clutch sets dedicated to S30 in EU, so I went that route). We used the stock 280Z collar with that bearing - as far as I remember that new bearing has bigger diameter than stock, other dimensions are the same. - I am starting to think that the hydraulics might cause this issue - as Leon suggested - the problem occured after changing 2 things: lightening the flywheel and replacing the slave cylinder. Any change made after that (replacing clutch kit, 2 x replacing clutch disc) didn't solve that problem... I don't think that flywheel could cause that - I checked it twice and it was straight. The slave cylinder is from other Nissan - and I am not sure if it isn't "self-adjusting", and maybe the rod lenght/work are different than stock. What do You think? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 5, 2012 Share Posted June 5, 2012 I'm with Leon, it sure sounds like the throwout bearing isn't fully disengaging. You might try removing the hose from the slave cylinder (to eliminate any residual hydraulic pressure) and then remove and reinstall the slave cylinder. You should be able to insert and start the 2 mounting bolts without much pressure from the fork against the slave cylinder's rod. If there is any significant pressure, that's a sign that the throwout bearing isn't fully disengaging. Quote Link to comment Share on other sites More sharing options...
Ejkej Posted June 5, 2012 Author Share Posted June 5, 2012 (edited) Hmmm, I remember that last time I installed the slave cylinder I needed to press the rod quite deep into the slave cylinder in order to make it fit the fork... Zmanco, can You explain the test You suggested? Should there be no pressure on the fork or/and on the rod when mounting the slave cylinder? Thanks! Edited June 5, 2012 by Ejkej Quote Link to comment Share on other sites More sharing options...
loy Posted June 5, 2012 Share Posted June 5, 2012 Sounds like you've might have found your problem. "I installed the slave cylinder I needed to press the rod quite deep into the slave cylinder in order to make it fit the fork... " Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 5, 2012 Share Posted June 5, 2012 Hmmm, I remember that last time I installed the slave cylinder I needed to press the rod quite deep into the slave cylinder in order to make it fit the fork... Zmanco, can You explain the test You suggested? Should there be no pressure on the fork or/and on the rod when mounting the slave cylinder? Thanks! Please ignore what I wrote - my brain must have been in neutral when I wrote that - of course you have to press the rod into the slave cylinder when you install it, otherwise how would it extend to move the fork? The point I was trying to make is you should check for residual pressure building up in the slave cylinder. This just happened to me when I switched to an aluminum flywheel. First drive the clutch worked perfectly, but later it began to slip under boost. When I opened the bleed valve, a small amount of brake fluid spurted out into the hose due to built up pressure. Since then the clutch hasn't slipped. I know that once the rod fully extends (such as when I remove the slave when changing the tranny) it will not go back in unless I open the bleed valve, leading me to suspect there is a check valve somewhere in the circuit. Perhaps the valve in your system is allowing pressure to build up in the slave thus preventing the throwout bearing from fully releasing. Hopefully there's a clue in this that will solve your issue. Quote Link to comment Share on other sites More sharing options...
NewZed Posted June 5, 2012 Share Posted June 5, 2012 If there's residual pressure after the clutch pedal is released I think that that means the rod in to the master cylinder is not coming back fully. It's adjusted too tight. It should have a small amount of play to allow the piston in the master cylinder to come all the way back, opening the port to the reservoir, relieving pressure. There's a similar problem occasionally described for brake master cylinders where the brakes slowly stop releasing and eventually lock up as the fluid gets hot. The master cylinder piston blocks the return port in to the reservoir, the fluid heats up and expands, brakes get applied. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted June 5, 2012 Share Posted June 5, 2012 Thanks NewZed, that make sense. I had been adjusting my clutch pedal height before the swap and now suspect that was the culprit. Ejkej, try adjusting the clutch pedal height - I'm going to raise mine a bit to be sure it doesn't happen again. Quote Link to comment Share on other sites More sharing options...
Ejkej Posted June 6, 2012 Author Share Posted June 6, 2012 (edited) OK Guys, thanks for the help, I will try to work on it and then post feedback. Edited June 6, 2012 by Ejkej Quote Link to comment Share on other sites More sharing options...
Ejkej Posted March 2, 2013 Author Share Posted March 2, 2013 (edited) OK, It has been 8 months since I started this topic, but - as promised - I am back with some more info... I removed the transmission for the winter in order to check 2 things: - slipping clutch - hard and noisy 3rd gear when shifting As for the clutch I noticed that the collar with the bearing has problem with travelling on the mainshaft. It gets stuck in about half way and doesn't move further. On the pictures I marked with green arrows the places where the problem occurs: When the clutch is depressed the bearing is traveling back, in the second picture the green arrow on the right shows the part that fits perfectly on the mainshaft and bearing sleeve on the front cover, but then there is this "deeper" section in the collar (marked blue) - this is causing it to move (transverse) a little bit. The collar travels further back until the part marked with the second green arrow (the one to the left) meets the throwout bearing sleeve marked with green arrow on the first picture... Do You think this causes my clutch to slip? Edited March 3, 2013 by Ejkej Quote Link to comment Share on other sites More sharing options...
Ejkej Posted March 2, 2013 Author Share Posted March 2, 2013 (edited) up... sorry, double-post... Edited March 3, 2013 by Ejkej Quote Link to comment Share on other sites More sharing options...
Orangetang Posted July 16, 2015 Share Posted July 16, 2015 Old thread I know, but it's most relevant to the issue I'm having with my clutch at this time. I'd appreciate any help, though after reading this and other threads I'm fairly confident I have the correct (or close enough) TOB collar and my master cylinder may just need adjusting. I'd feel better hearing some advice before I make my next move though, since I'm learning as I go and have no prior clutch adjustment knowledge. I recently put a 79 280ZX type B 5 speed in my 240Z. I used the bearing collar and fork that came with this 280ZX transmission. I'll post some pics shortly to compare between the B type 4 speed TOB collar/fork I swapped out. The 280zx fork had an indentation where the clutch slave rod would sit against, vs the 4 speed with an indentation and and hole. I used the clutch slave that was already in the car, (a generic 240Z replacement, size I'm uncertain). This slave has a threaded rod, with adjustable nut on it. In order to use with the new fork, I drilled a hole the same diameter as the piston threaded rod in the fork indentation, allowing the rod to slide through and sit happily. Currently, I believe the TOB to have a slight pre-load against the clutch. I get complete disengagement in the first 1/4 of pedal travel. If I were to dump clutch at 6000 RPM, it would slip rather than spin tires. If I shift aggressively, you can feel it slip a small amount. Engagement under throttle is soft, not firm. Clutch is a cheap eBay KUPP Racing Stage 4 - 6 puck rated at ~400 HP... Flywheel is a 143281 Fidanza aluminum Engine is 3L L28 producing 282HP/272TQ at flywheel. Because it seemed the slave was releasing the clutch far too soon, I crawled under the car and backed off the adjustment nut on the slave cylinder rod to see if the clutch would take up the slack. There was no play and I couldn't move the fork by hand, at all. I backed it off about 3/4" where there was still significant pressure behind held between the fork and slave cylinder. I hoped in the car and pressed the clutch to the floor and released it. The clutch now engaged roughly 1/4 stroke off the floor and felt totally normal. I went for a quick boot and the clutch grabbed VERY hard, and held well in all gears allowing wheel spin in 1st and 2nd. Though after a few clutch depressions the pedal/slave began to release again in the original spot, just barely depressed, and the clutch would again begin to slip. SO.... I believe the TOB collar may actually be the correct length, but instead perhaps the clutch pedal to master needs to be adjusted. I don't know, but it sounds from my reading that the master plunger may not be releasing far enough to allow fluid to return to the reservoir, so a preload is being held against the slave, which may explain how the "slack" i created has been taken up. Am I on the right track? It seems this cheap clutch is holding up fine even after some slipping abuse, as it seems under full release it sticks like glue to that flywheel. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 16, 2015 Share Posted July 16, 2015 Could be that the TOB collar is too tall as you thought, and that expansion when everything heats up is causing the slipping. If you let it cool and it starts working right, then slips when it gets warm, that would be a clue. If so, that can only be fixed with a shorter TOB collar. You have an odd assortment of parts so nobody can really give you a combination of parts that might work. With the stock flywheel, the collar ears (where the fork rides) should be 92 mm +/- a few from the surface of the flywheel (bottom of the pressure plate cover). I'd guess that Fidanza dimensioned theirs for a straight swap, so 92 should work for you too, but who knows for sure. Quote Link to comment Share on other sites More sharing options...
Chris Duncan Posted July 16, 2015 Share Posted July 16, 2015 (edited) The easy way to tell if the TOB collar is right is to remove the slave and check the release fork to see if it's loose. It should be loose until you push in the clutch release direction. Pull the dust boot back and make sure you are staying on the fork pivot when you check this. We are not talking looseness by coming off the pivot. It will be obvious looseness, like 1/2" to 1" movement before it starts pushing on the pressure plate. With the slave on if you back the adjustment off the fork should also be loose. A slave with an adjustable push rod is the old style. Make sure you have the master that goes with it. A good upgrade is to the new self adjusting master/slave setup. When properly adjusted the old style should have free play at the pedal and at the slave. With the new style there should be free play at the pedal and at the slave it will have just slave spring pressure. You should be able to push the slave back in the release direction when the car is sitting with clutch released. If you can't push it back the clutch is worn out. Edited July 16, 2015 by Chris Duncan Quote Link to comment Share on other sites More sharing options...
Orangetang Posted July 16, 2015 Share Posted July 16, 2015 It'll be at least a couple days before I can check any of that. The heating up doesn't seem to be relevant. The clutch operates at the same pedal throw and pedal height after being parked or while driving. Backing the adjustment at the slave back as far as possibly maintains pressure against the fork, but the slave piston may have some force against it already... I'll try some stuff when I'm able and check back. Quote Link to comment Share on other sites More sharing options...
NewZed Posted July 16, 2015 Share Posted July 16, 2015 The clutch now engaged roughly 1/4 stroke off the floor and felt totally normal. I went for a quick boot and the clutch grabbed VERY hard, and held well in all gears allowing wheel spin in 1st and 2nd. Though after a few clutch depressions the pedal/slave began to release again in the original spot, just barely depressed, and the clutch would again begin to slip. Sounded like you made an adjustment, things worked right, then they didn't work right. Not clear what's happening, or what the final state of the situation is. Anyway, the hydraulics should never hold pressure after you release the pedal, unless you have the rod to the MC extended to far. All pressure is released in to the reservoir when the pedal is up, on a properly adjusted setup. Someone just posted on this. If you can press the slave cylinder piston in by hand (that's what they did, it's a good test) and fluid gets pushed in to he reservoir, there's no way pressure can be maintained by the hydraulics. The problem is between the fork and the pressure plate. If you can't press the cylinder in because the slave cylinder rod is too long and piston is all the way back, that would be a problem, but with the adjustable rod, should be fixable. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.