Pinbill

Trouble with "z" clutch...

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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?

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Edited by Pinbill

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

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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.

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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.

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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.

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Edited by Pinbill

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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.

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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.

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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.

 

 

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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.

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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.

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I really appreciate all the input. I have read most of the links you sent at this point.

I called MSA this afternoon before I posted. They confirmed the clutch kit I ordered is designed for the shorter collar that came in the A transmission cars. I also checked the Exedy clutch website to cross reference the part numbers. The pressure plate and the clutch plate part numbers are correct for a 1970-1974.

I didn't think a 2.5mm difference would be a huge deal. I will bleed the system and see if that helps.

Thanks again,

Bill

 

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I am starting to believe I need a new collar. The old pressure plate didn't have any "spring" to the bolts when I took it off. The new pressure plate had spring when I tightened the bolts. I was reading the fingers will suck in when the pressure plate is tightened. So the pressure plate fingers have the same height on the bench but the new one gets sucked in on the car.

I am thinking about trying the medium size one from MSA. 21-2123. It seems similar to the 280z and 280zx 2+2 on the picture above. I don't like to guess but I don't have any other ideas.

As the clutch wears in do you need to lengthen or shorten the adjusting rod on the slave cylinder? If you need to lengthen it as the clutch wears I am already maxed out with my current collar.

Edited by Pinbill

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Alrighty, I am going to order the 1970-1974 collar from MSA.

Here is my theory.... They list the collar as 70-74 but there were two separate collars at that time. One for the type A and one for the type B transmission. I think all new 240z clutch kits require the type B collar. I type A collars must be NLA. I don't think there are many cars on the road with type A transmissions and their first clutch.

It makes it confusing when they say clutch kit for 70-74. It is really a clutch kit for late 71 and 72-74. No mention that early cars require a type B collar.

I hope to remember to let you know how it worked out. It is not easy to order parts for these cars. LOL.

 

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So you bled the system and still had the problem?  Did the fork bottom out on the bellhousing hole when you tried to disengage before?  That would have been a clue.

If you haven't put it back together yet and are just going to try another collar anyway that's your prerogative.  If I read your logic right and fill in some parts you're suggesting that you have the thinnest collar, the "A" type, and need the one that's a bit thicker?  Seems reasonable.  Maybe those thick pressure plate assemblies need all of that travel.

The newer slave cylinders with the newer pressure plates don;t use the adjustable rod anymore.  Don't need it, apparently.

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I have the A type collar. I also forgot to mention that I will be temporarily hooking up the transmission with the A type collar tomorrow night for some further testing. I will bleed the system then watch the slave cylinder while a helper steps on the clutch pedal. I will take a few pictures.

Its pretty cheap to get a  B collar and bearing shipped two day air from zcar depot. I feel like there is enough evidence to try it.

I didn't have help the last time I had it together so I couldn't see if the fork bottomed out on the bell housing, but the slave cylinder rod was almost fully extended it when it was adjusted right. The rubber boot was pushed to the rear of the car when the slave cylinder wasn't actuated. Definitely more clues. I should have done more testing when it was together. I was really excited to drive the car around. I just kind of freaked out and took it apart. 

As the clutch wears does the rod need to be lengthened or shortened?

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If the pressure plate is the same height as the old, then the existing collar would be correct as I see it.

The B collar is needed for the same pressure plate for the later transmission because the B transmission bellhousing measures at a different depth.

 

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Also do check on slave cylinder rod movement.

I have seen hydraulic failure before with a new stronger pressure plate. Usually with very old master and slave cylinders.

One or both sometimes. They cannot hold pressure properly.

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I didn't realize you need to have the plates torqued to the flywheel to get a true measurement on the fingers. My first measurements were with the pressure plates on the table and so they looked the same.

I torqued the old pressure plate and clutch to the flywheel and got 80mm +/- .5mm flywheel to fingers. I torqued the new clutch and pressure plate to the flywheel and got 70mm +/- .5mm flywheel to fingers. 

It looks like I need to make up 10mm.

I ordered the collar/bearing for the 240z from Zcardepot. I am assuming its for the B transmission. It will be here in two days.

Edited by Pinbill

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Looks like the collar got shipped to Minnesota instead of Denver. Not sure when I will receive the collar.

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Collar made it the other day. It was the collar for the 240z B trans. It was higher than the collar for the A transmission. I could get the car in gear and it is better. I can get the car in gear and drive it. It shifts better when the car is moving. There is no way to get in reverse without grinding. I maxed out the pedal height and have the slave cylinder rod almost fully extended. The fork hits the transmission housing when clutch pedal is pressed. I am going to order the next size collar/ sleeve. The one for the 280zx 2+2.

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On 10/9/2019 at 11:08 AM, Pinbill said:

I torqued the old pressure plate and clutch to the flywheel and got 80mm +/- .5mm flywheel to fingers. I torqued the new clutch and pressure plate to the flywheel and got 70mm +/- .5mm flywheel to fingers. 

It looks like I need to make up 10mm.

I kind of lost track of your project or I would have said something.  You need to make up 20 mm, ideally, not 10. Actually 22 mm, the magic number is 92 mm.  Your old one must have been on the edge.

At least you seem to be going the right way.  Good luck.

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Thanks man,

When I say I need to make up 10mm. I am saying I need a collar that has 10mm more throw than my old A style.

I don't blame you for tuning out of this. It has gotten convoluted and crazy to keep up with.

I had a talk with a guy at MSA this morning. He was very certain that a B collar would work. I didn't want to argue so I ordered a type B collar from them and a 280z 2+2 collar. If the B collar is close to what I am running now I will put in the 2+2 collar. 

With two day shipping I should have an update by this weekend.

Besides hard shifting, with the new suspension parts the car was very pleasant to drive. Took the turns real well and didn't smell like gas leaking from the tank. LOL.

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