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HybridZ

240z new clutch problem


TrikeZ

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So I just installed a new stock LuK clutch kit in my Z, new slave, master, T.O. bearing and springs, and pivot ball. I had the flywheel resurfaced. Old clutch disc broke a Marcel spring so out it came.

 

The problem I'm having is that the trans wont go into gear. The clutch is not disengaging completely. I have bled the system to the best of my ability manually and also with a vacuum bleeder.

 

I had the car up on jack stands, it WOULD go into gear and spin the tires, as soon as I pushed the clutch AND brake pedal in the engine would begin to stumble a little(clutch not fully disengaging)

 

I then dropped the car to the floor to attempt to go on a test drive, but then the car won't go into gear.

 

I have adjusted the pedal forwards and backwards and no luck. Rebleed the system, no luck.

 

I then measured the stroke of the slave cylinder rod. From face of the slave to face of the clutch fork was 1.256 inches. Then with the clutch pedal DEPRESSED(pushed in) measured 1.675 inches. Service manual says the stroke should be 35mm or 1.378 inches. I had just over 0.4 in of travel.

 

I am not sure if it can be adjusted any if possible. But I am sure that everything went together properly, the only things I can think of are air in system, bent fork, or misadjustment.

 

Any advice or tips would be appreciated. As I do not want to have to pull the trans out again unless absolutely necessary.

 

Thanks,

TrikeZ

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 Service manual says the stroke should be 35mm or 1.378 inches. I had just over 0.4 in of travel.

 

I am not sure if it can be adjusted any if possible.

I would guess that this is your problem.  I'm not sure what you mean by "any if possible" but the clevis at the master cylinder rod can be adjusted where it attaches to the pedal.  You can do it with a pair of pliers.  Loosen the lock nut and turn the rod to make it longer.  Run it out until you get proper play at the pedal.

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You said you got a new master cylinder?  Did you keep the old one?  I know a lot of people have had problems with newer clutch master cylinders having too short of a master cylinder pushrod, causing the clutch to not get enough travel.  If you kept your old master, see if you can put the old master cylinder pushrod into the new one.  Otherwise you're gonna need to figure out a way to lengthen the master cylinder pushrod.  Now I may be wrong here, as I think it may have been model specific somehow (240z or 280z) but worth looking into. I'm in the same boat as you right now but haven't really started chasing down my problem yet.  Also did you bench bleed the master? 

Edited by luseboy
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If you have tiny fingers or are good with a tools, the simple way to check the MC rod length is to remove the clevis pin.  If the clevis hole isn't lined up with the pedal pulled up to its stop by its spring, it's probably too short.  Actually, that adjustment should be made when the MC is installed.  Makes it much easier to get the pin installed.

 

p.s. if you have fat fingers or large hands, you can run a thread through the hole in the clevis pin, then run the thread through the pedal and clevis holes, and pull the pin in to place.

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Edited by NewZed
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Did you replace the throwout bearing and collar? There are a few different collars out there, and if you put a new one in there without the proper offset, you will have the problem you describe. Been there, done that....

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I would guess that this is your problem. I'm not sure what you mean by "any if possible" but the clevis at the master cylinder rod can be adjusted where it attaches to the pedal. You can do it with a pair of pliers. Loosen the lock nut and turn the rod to make it longer. Run it out until you get proper play at the pedal.

 

 

Yes, I have adjusted the clevis at the pedal in both directions, no luck.

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You said you got a new master cylinder? Did you keep the old one? I know a lot of people have had problems with newer clutch master cylinders having too short of a master cylinder pushrod, causing the clutch to not get enough travel. If you kept your old master, see if you can put the old master cylinder pushrod into the new one. Otherwise you're gonna need to figure out a way to lengthen the master cylinder pushrod. Now I may be wrong here, as I think it may have been model specific somehow (240z or 280z) but worth looking into. I'm in the same boat as you right now but haven't really started chasing down my problem yet. Also did you bench bleed the master?

 

Yes, I still have the old M/C I will check the rod lengths ASAP. And yes, I also bench bleed it as well.

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Did you replace the throwout bearing and collar? There are a few different collars out there, and if you put a new one in there without the proper offset, you will have the problem you describe. Been there, done that....

 

Yeah, I replaced the TO bearing and collar. They were the same as the old ones.

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If you've done all of these things, then check the slave cylinder dust boot for fluid.  It might be leaking.

 

The reason that the pedal adjustment is so important is that the slave cylinder piston will only move as far as the MC piston moves.  That's how hydraulic systems work.  If you only get 0.4 inches of movement at the slave cylinder, and there's no air in the system, and the cylinders are the same diameter, then the MC piston is only moving 0.4 inches.  That's the basic principle.  

 

If you want to get rigorous, measure the distance the end of the MC rod moves, at the pedal.  It should be 0.4 inches, if you have a properly bled, non-leaking system, and the slave only moves 0.4 inches.  Slave follows master.  If you have more movement at the master than the slave, there's a problem in the hydraulics.  Break it in to its two parts, mechanical and hydraulic.

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You assume that the slave and master are the same diameter, NewZed.

 

Not all of them are. I know that in my Z, I have a 3/4" clutch master and a 5/8" slave...my slave moves further than the master. If I install a 3/4" slave then they move the same amount, and if I was to install the 5/8" clutch master and 3/4" slave, then the slave would move LESS than the master.

 

Check and see that your slave cylinder and master cylinder diameters are correct, while you're down there, TrikeZ

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Actually the thought crossed my mind.  But stating equal distances implies equal diameters, hydraulically speaking.  You can only elucidate so much on these forums.  Besides that, he sad that he was not in spec on distance, by the FSM.  0.4 / 1.378 = 0.29.  That's a giant slave or a tiny master.

 

Reman cylinders are known for grit grime and poor quality.  He might have a dust boot full of fluid.

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You assume that the slave and master are the same diameter, NewZed.

 

Not all of them are. I know that in my Z, I have a 3/4" clutch master and a 5/8" slave...my slave moves further than the master. If I install a 3/4" slave then they move the same amount, and if I was to install the 5/8" clutch master and 3/4" slave, then the slave would move LESS than the master.

 

Check and see that your slave cylinder and master cylinder diameters are correct, while you're down there, TrikeZ

Both slave and master are both stock replacements. I know the master is 5/8, the slave seems to be the same diameter but it is not stamped. And neither are leaking.

 

I tried some more things out but none lead to an answer. I put in a much longer pushrod for the slave(was VERY DIFFICULT to make fit and bolt up) and trans finally went into forward gears with a little bit of extra push on shifter, reverse grinded everytime and HARD to go in. Did not like that at all, didn't feel right. I was sure that the TO bearing would be pressing against fingers and then get burnt out fast.

 

I pulled the trans out again and inspected further, I recompared the clutch old/new. I noticed that the new pressure plate fingers were just a hair over 1/4 inch further OUT from clutch disc than they were on the old. Just overlooked it the first time.

 

My car was swapped with an L26 by previous owner, it's mated to a 4 speed. Is there a difference in clutches between 240z and 260z? The new clutch I got was for a 260z.

It is a LuK clutch kit part #06-029.

Edited by TrikeZ
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Since you have the clutch exposed now you can address z-ya's suggestion about the collar.  It's the distance from the two ears (on the collar) the clutch fork sits on, to the surface of the flywheel that matters (assuming that the flywheel is the factory-set distance from the engine).  That distance should be about 92 mm.

 

You didn't answer the question about if the kit came with a new collar.  Or if you checked the slave boot for fluid.  Or if you measured stroke at the master cylinder

 

One thing on the slave travel distance - it's seemed to me that the slave piston would get pushed out of the bore if the short collar was used, since the next stroke after the master cylinder refills should "over-stroke" it..  Since the slave piston gets pushed back in its bore only as far as the fork pushes it in it would start way down its bore.  A long collar stopping full engagement makes sense but I can't figure how a short collar stops disengagement.  It should just allow the slave piston to pop out.  If you've already put it all back together you can get an idea of how far down the bore the slave piston is by pushing it back in by hand when it's mounted.  It will just push fluid back in to the reservoir.

 

Wouldn't be surprising if you just had a bad seal in the master cylinder.  There are two seals, one to create pressure and one to keep all of the fluid inside.  The pressure-producing seal (primary cup) can leak inside without an external leak.

post-8864-0-03494900-1459698884_thumb.png

post-8864-0-23257200-1459698897_thumb.png

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Did you replace the throwout bearing and collar? There are a few different collars out there, and if you put a new one in there without the proper offset, you will have the problem you describe. Been there, done that....

Yes, I did replace both the throwout bearing and collar. I got them both from Zcardepot and both were in factory Nissan packaging. The old and new collars are the same. I will take pictures of everything tomorrow.

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You're not getting the whole picture.  The collar and the pressure plate are a matched set.  There are several pressure plate heights and several collars to fit those plates.  The matched set should have the ears of the collar 92 mm away from the flywheel surface with the collar in position on the pressure plate release levers (fingers).  Hold a straightedge on an ear and get that measurement.  I will never install a transmission in a Z without ensuring that 92 mm distance.  +/- a couple mm probably okay, but 92 is the target.  Several others have verified it.  

 

It works because the pivot point for the clutch and the mounting position of the slave are the same across many years of Z's and ZX's.  71B and 71C transmissions.  Not sure about the FS5... series.  Likely the same though since the same clutches are used.

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You're not getting the whole picture. The collar and the pressure plate are a matched set. There are several pressure plate heights and several collars to fit those plates. The matched set should have the ears of the collar 92 mm away from the flywheel surface with the collar in position on the pressure plate release levers (fingers). Hold a straightedge on an ear and get that measurement. I will never install a transmission in a Z without ensuring that 92 mm distance. +/- a couple mm probably okay, but 92 is the target. Several others have verified it.

 

It works because the pivot point for the clutch and the mounting position of the slave are the same across many years of Z's and ZX's. 71B and 71C transmissions. Not sure about the FS5... series. Likely the same though since the same clutches are used.

I was not aware of this. I will definitely measure this out. And get back to you. Thanks for the info.

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