Clutch Won't Disengage

[Mark Maras]

 Disconnect the slave cylinder spring and push the clutch release lever until the release bearing makes contact with the pressure plate. Ideally the release lever should move about 1/8" to 1/4" before making contact. If the distance is greater than 1/4", lengthen the rod.

[Zed Head]

I watched the video again.  When I first watched it I assumed/hoped that the "thunk" at the end of the stroke was from the pedal in the cabin hitting the floor stop.  But I think it might be from the fork at the back of the hole in the transmission.

Remove the rubber dust cover from the hole and see if the fork is bottoming out.  If it is, and the fork is seated on the pivot ball correctly, then your throwout sleeve is probably not tall enough or the fork is broken or something.  You've achieved maximum movement.

[adivin]

28 minutes ago, Zed Head said:

I watched the video again.  When I first watched it I assumed/hoped that the "thunk" at the end of the stroke was from the pedal in the cabin hitting the floor stop.  But I think it might be from the fork at the back of the hole in the transmission.

Remove the rubber dust cover from the hole and see if the fork is bottoming out.  If it is, and the fork is seated on the pivot ball correctly, then your throwout sleeve is probably not tall enough or the fork is broken or something.  You've achieved maximum movement.

Thanks Zed, I will do this and report back.  I will also take note of where the "thunk" is coming from.  I am glad to know my slave cylinder is operating in the full range of motion.  That eliminates everything from the MC back.

By the way, what is the origin of the magical 92mm stack height?  Can you take a look again at the picture I posted of my stack measurement and give me your thoughts?

[adivin]

1 hour ago, Mark Maras said:

 Disconnect the slave cylinder spring and push the clutch release lever until the release bearing makes contact with the pressure plate. Ideally the release lever should move about 1/8" to 1/4" before making contact. If the distance is greater than 1/4", lengthen the rod.

Thanks Mark, I will check this out.  What do you mean by, lengthen the rod?  How?

[Yarb]

Run that adjustment nut in the pic out to the desired length. Right now you have it backed off quite a bit.

[adivin]

11 minutes ago, Yarb said:

Run that adjustment nut in the pic out to the desired length. Right now you have it backed off quite a bit.

I had it adjusted out until the fork was putting pressure on the pressure plate springs, so much so that the rod itself started spinning and I could no longer advance the nut.  Hmm...

[Zed Head]

1 hour ago, adivin said:

By the way, what is the origin of the magical 92mm stack height?  Can you take a look again at the picture I posted of my stack measurement and give me your thoughts?

You have to measure down to the mounting surface of the pressure plate.  It's shown in that thread.  You have only measured to the top of the fingers, it's not clear how tall your pressure plate is.  92 mm is a number that should work on any transmission, because the clutch fork pivot ball is at the same distance from the back of the engine on all transmissions.  The mechanisms of the clutch system fit between the engine and the transmission.  There are many different TOB sleeve heights because there are many different heights of pressure plate.

If the fork is hitting the back of the hole and the clutch disc does not release there's nothing that you can do to make it work except get a taller sleeve.

[adivin]

5 minutes ago, Zed Head said:

You have to measure down to the mounting surface of the pressure plate.  It's shown in that thread.  You have only measured to the top of the fingers, it's not clear how tall your pressure plate is.  92 mm is a number that should work on any transmission, because the clutch fork pivot ball is at the same distance from the back of the engine on all transmissions.  The mechanisms of the clutch system fit between the engine and the transmission.  There are many different TOB sleeve heights because there are many different heights of pressure plate.

If the fork is hitting the back of the hole and the clutch disc does not release there's nothing that you can do to make it work except get a taller sleeve.

Ok, I didn't realize 92mm was universal.  Thanks for that info.  On my measurement picture, the end of my ruler is touching the workbench that the pressure plate is on.  I am measuring from the workbench on up to the collar. 

[Zed Head]

I see now.  I didn't look closely before.  That's a simple measuring method, why did I make mine so complicated?

If I adjust for the angle of the camera it looks like yours might be about 85 mm.  So about 7 mm short.  29, 25, 24, and 16 seems to be the range of choices, so 13 mm covers the range, with 4 mm and 8 mm steps, about.  Just eyeballing your picture it looks like you have a short one.  I think that you need a long one.

 

[Zed Head]

Put your car description in this Signature box and click Save and people won't have to try to remember or search for what car you're working with.

https://www.classiczcars.com/settings/signature/

[Zed Head]

Just remembered that there is an assumption that the surface of the flywheel is the same distance from the back of the block across all engines and flywheels.  It seems reasonable but maybe Fidanza's is not.  I doubt that Fidanza would change that critical distance but you never know.

Regardless, if the fork is hitting the back of the hole and the clutch fork is solid you need a taller sleeve.

[adivin]

1 hour ago, Zed Head said:

I see now.  I didn't look closely before.  That's a simple measuring method, why did I make mine so complicated?

If I adjust for the angle of the camera it looks like yours might be about 85 mm.  So about 7 mm short.  29, 25, 24, and 16 seems to be the range of choices, so 13 mm covers the range, with 4 mm and 8 mm steps, about.  Just eyeballing your picture it looks like you have a short one.  I think that you need a long one.

 

So assuming this is my problem, and I'm about 7mm shy of 92mm, I should get the L26 or Type B 5 Speed?