Trouble with "z" clutch...

[Pinbill]

Hey Everyone,

I almost went for a test ride today, but the clutch will not engage. There is way too much play between the throw out bearing and the pressure plate springs. With the slave cylinder hooked up the clutch isn't engaging at all. Here are a few pictures of what it looks like. When the clutch fork is engaged and the bearing is all the way forward, the bearing extends to where the splines start on the shaft. When the fork is disengaged there is a lot of shaft showing. I checked my invoice from MSA and they sent a 70-74 clutch kit. The springs on the pressure plate look different but measure the same height if they are laying on the work bench. Pic 1 is the fork not engaged. Pics 2 and 3 show the max travel of the fork engaged. I took it to the place that rebuilt my transmission and the tech inspected the throw out bearing and fork mechanism. He thought the bearing/ fork  was assembled correctly and the problem had to do with the clutch or pressure plate. The car build date is 6/71 and it has the A transmission. Does something seem out of place to you?

Edited October 7, 2019 by Pinbill

[Pinbill]

I checked the Exedy clutch website. The pressure plate and the clutch plate numbers are correct for a 1970-1974.

[Zed Head]

You might need a longer throwout sleeve/collar.

https://www.google.com/search?q=site%3Aclassiczcars.com+92+mm+zed+head&rlz=1C1SQJL_enUS862US862&oq=site%3Aclassiczcars.com+92+mm+zed+head&aqs=chrome..69i57j69i58.35595j0j8&sourceid=chrome&ie=UTF-8

[Diseazd]

If these numbers stack up, you are good to go. Like Zed Head said.......it is probably the wrong collar.......plenty of threads on this subject.

[Zed Head]

2 hours ago, Pinbill said:

 

I almost went for a test ride today, but the clutch will not engage.

Also. to be sure, "engage" means the engine is moving the transmission shaft, via the clutch,and the car goes.  "Disenage" is what happens when you press the pedal to put the car in gear.

Your pictures seemed to describe disengagement problems.

[Pinbill]

Sorry to be confusing about engaged/disengaged. I had it backwards. I meant slave cylinder was engaged and disengaged. It is a disengagement problem. The symptoms make me think a longer collar would work. I called MSA and they confirmed the clutch kit I ordered is designed for the shorter collar that I have. I checked the Exedy clutch website. The pressure plate and the clutch plate numbers are correct for a 1970-1974.

Here are some pics of the collar/ bearing/ fork from the other side just to make sure I have it hooked up right. Can't hurt to have some reference pics on the web. I couldn't find any.

I am going to install the trans to see if the old pressure plate/ clutch mates up better. I am getting good at taking the trans in and out. LOL.

Edited October 7, 2019 by Pinbill

[Zed Head]

Your fork looks right.  Get A measurement.  Diseazd gave the simple straight-up picture and I linked  a bunch of threads about it. 92 mm is the key.  No need to guess or put things back together without knowing. 

Put the stack together and measure from the surface the fork touches to the bottom of the pressure plate.

[Pinbill]

Gotcha...

[Pinbill]

I stacked everything up, stood up a thin screw driver, and made a mark at the top of the collar. The measurement I got using a dial caliper was 90.5. My work table is a little beat up so it must be +/- 1.5mm.

[Pinbill]

OK, I went out and put the stack on the ground. I really checked and double checked. The number I got was 89.5 It looks like my original bearing was a bit thicker than the new one. The fingers on both plates are exactly the same height.

It looks like the Type B 5 speed collar from bearing to top of tab is 25mm and mine is 16mm. A type B would add 9mm putting me at 98.5mm.

Does that seem like the right collar? 98.5 seems like a lot.

 

 

[Diseazd]

Call Motorsports......Give them the part number of the Exedy Pressure Plate you bought. Then, tell them to send you the correct collar for that clutch. BTW......the throw out bearing is not your problem.....throwout bearings for all 240Z’s, 280Z’s and 280ZX’s are exactly the same.......seems your problem is the wrong collar....IMO.

[Zed Head]

I don't see where you bled the hydraulics after the swap.  With no fork holding it the slave can extend and get some air in it.  I'd rebleed and be sure..89.5 is pretty close to 92.  92 is not a an exact requirement.

Don't go crazy.  If your new plate is exactly the same as the old one and you're using the same collar/sleeve just with a new bearing, then it seems like you might have a different problem.