Clutch engagement issue

[reddie73]

1971 240Z I replaced the clutch pressure plate, throwout bearing, bearing sleeve with a longer 280Z sleeve per information in another thread. I have bled the slave cylinder numerous times with pressure bleader as well as with the wife pushing the pedal down method. The pedal still feels to easy to push down, but the relase fork is moving the rod on the slave. I have adjusted the rod a number of times and can change gears with the engine off, but have not been able to change gears with the engine running and still on jack stands. I don't know what I'm missing with the adjustment of the rod. I've also adjusted the clutch pedal to 8" from the floorboard. New master cylinder, slave cylinder, etc. I compared the old pressure plate to the new one and the new one is thinner than the old one that had the shorter release bearing sleeve, thus the reason for using the longer 280Z sleeve. I've searched the archive and have gotten some good information, but thought someone out there might have some input or suggestions.

[Nigel1943]

Does'nt sound like you have the correct release bearing carrier to me. This is the problem with mixing and matching clutch components. How do you know you need a 280z carrier and do you know you have actually got one?
I think you will end up taking the tranny out again to measure up. Also, have you put the clutch disc back in the right way round?

[Curtis240Z]

Do you have the later style (non-adjustable) slave cylinder and clutch fork?

The "acid test" to check for proper clutch travel is to have the car in neutral, press the clutch and slowly try and put the car in reverse. If the gears start to grind then you don't have enough travel. When you get to the point where the clutch pedal is about 2" off the floor and then the reverse gear starts to grind, then you should be good.

[reddie73]

The 280Z release bearing sleeve was used because in another archive on this site it said the original 240Z clutch pressure plate was thicker than the ones that are sold to replace them. The replacement pressure plates fit 240,260 and 280, thus the need for the longer sleeve. The clutch kit is from Black Dragon (Rhino) , the master cylinder and slave are from Courtesy Nissan. The new sleeve/bearing came as an assembly from Black Dragon for a 280Z and is longer than the one I had that was on the car, which was from Black Dragon. I don't think the clutch disc is on backwards and the bearing is making contact, I just don't think with enough force to push the fingers on the disc. I have the pressure plate and disc that was on the car when I bought it for reference/compare to the new pressure plate and disc. The slave is the adjustable correct one for the car. The fork is the one that was on the car and has the hole in it for the adjusting rod etc. I have gotten the car into first and second with it running , but could not go into 3rd or 4th. I'm wondering if the master or slave could be the problem even though I don't see a leak from either. I also tried bench bleeding the master during the bleeding process.

[Nigel1943]

Firstly,Black Dragon show a different part no for the 280 and I'm sure you know some 280's have a 240mm clutch as against the 240's 225mm one. I'm assuming you have the 240 0ne
What we need is some dimensions of the new clutch to determine which sleeve you need but of course that will mean taking the tranny out again.
If you disconnect the slave cylinder pushrod and then push the clutch fork by hand, how much movement is there before the bearing hits the clutch?

[reddie73]

The clutch kit is 60-000 for the 70-75 240-260Z.The box shows 8-7/8" on it. The distance from the back of the slave to contact with the fingers on the clutch is 1 3/4 ". I had the smaller collar on the car and worked for quite some time trying to get the clutch to work properly and last week I took the transmision out, ordered the different collar and put everything back together. The collar that was on the car when I bought it is the one I used with the new bearing in the clutch kit. If I'm not sure about installing a part I look on this site or in one of my two manuals for reference. When I got the car to go into gear while running the adjustment was closest to the back of the slave cylinder with the spring on it still had more than an inch before the lock nut would hit the rubber boot. The article about the collars show 4 collars and one is for a 5 speed, so I've tried the longest and shortest, so the only one left is the middle one (kinda like the three little bears) which it shows as L26-Unknown under the picture. The difference in the Type A and the L26 is very minimal and even the Type B collar is not that much difference in the dimensions considering they are millimeters.

[Nigel1943]

Well, at least you have the right clutch! As for the rest of your problem I don't think you are going to get a definitive answer until you take the tranny out again and do some measuring up, in partcular the depth of the pressure plate from face to clutch fingers. The type B collar uses a different fork and non- adjustable slave cylinder.

[dimitri_zee]

I had that same problem when I installed an RB engine into my 240, I used a Skyline slave cylinder instead of the 240Z one. Turns out the bore size on the Skyline one was bigger meaning less travel for the same amount of pedal movement. Installed the original zed one, problem solved. Measure the bore on the original one and it was smaller ie more travel for the same pedal movement compared to the Skyline one.

I'd measure and compare bore sizes of both slave cylinders; make sure they are the same. It could even be the clutch master as well.

[reddie73]

Below is the reason for the use of the longer sleeve on the release bearing. Althouth I haven't swaped transmisions like the question asker Cutlass 372, I am having the same issues after putting in the new clutch pressure plate with a thinner pressure plate than the one I took out.

Yes. The original clutch Pressure Plate used in the 240-Z's was thicker - so it needed the shorter sleeve. If you order a Clutch Pressure Plate for a Datsun 240-Z today, from your Nissan Dealer (as well as most aftermarket sources here in the US) you will get a Pressure Plate that "fits" 240Z, 260Z, 280Z and 280ZX models. Over the years all sources have consolidated what were many different parts - into one part, that does the job for all. That one part is actually the 280Z Pressure Plate.

If you are dealing with a knowledgeable Nissan Parts Counterman - they will tell you to order the 280Z throw-out bearing sleeve, when you order a new Clutch Pressure Plate for the 240-Z - - because they know they don't actually get the old style 240Z parts any longer...

Yes - the 280Z Pressure Plate has greater clamping force than the original 240Z Pressure Plates. The 280Z Pressure Plate has less clamping force than the 280Z / ZX 2+2 unit - but to use the 2+2 Clutch Assy. you need to install the flywheel from the 2+2 (it is a larger diameter machined surface for a larger diameter clutch disc and Pressure Plate...

For anything other than all out racing - dollar for dollar it's hard to beat the OEM 280Z Clutch Assy (Pressure Plate + Clutch Disc). For Drag Racing the 2+2 set up offers a little more durability and higher clamping force.

FWIW,
Carl B.

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Last edited by Carl Beck; 05-08-2008 at 01:35 PM..

[Nigel1943]

I'd be interested to know the thickness of your old pressure plate as I'm fairly certain the standard zx 280 is a "thick" plate and still uses the longer collar. I have one to measure so I'll let you know. If this is true then something else must be different, ie, the slave cylinder, clutch fork or tranny fork pivot height.

[reddie73]

The old pressure plate is 7/8 inch thick. I went to a repair shop in Little Rock, Arkansas where the owner has worked on Z cars for 30 plus years and talked to him. He told me he had always used the same collar that came out of the car when he replaced the clutch. I showed him the one I used and he didn't think the longer collar would cause the problem. He thought it sounded like I still had air in the system. He told me to bleed the master cylinder by pumping the pedal, holding it down and loosening the hard line and to do this until no air came out, then go to the slave cylinder and bleed it. I tried this and still no decent pedal feel or engagement when the engine is runing. He asked me about the fork condition as well as the pivot ball and I told him they looked to be okay. He said the pivot ball could be cracked as well as the fork. I've looked at these and they look to be okay. I have another new master cylinder that I took off because of the length of the rod and connecting it to the clutch pedal for adjustment. I still feel like their is not enough pressure when the clutch pedal is pushed in to engage the release bearing against the clutch fingers. As much as I've bled the clutch I can't believe their could still be air in the system.

[reddie73]

I now have a working clutch after putting another master cylinder on and a kit in the slave.The master I replaced was new and the slave was also new. I also blew out the hard line going from the master to the slave and bled the system. The pedal is pretty tight, but the car moves and the clutch engages about 1 inch or so from the floor. I'm sure I'll need some adjusting , but at least it is working. Thanks for all of the responses to this, I really appreciate it.