Clutch Slipping very badly... but why?

[VaGuS510]

I have a problem, I just finished swapping a fresh engine in my z and a KA transmission. And when I went to take it for the first drive, it went nowhere. with the clutch completely out, I barely felt it pulling.

Here are the parts I am using:

75 bellhousing

75 bearing/sleeve/fork

72 clutch/pressure plate

73 slave cylinder

I had a problem with the slave cylinder fitting but I fabricated a slightly shorter push rod and everything seems to be working with that. The fork has room to move (the throwout bearing away from the clutch), and the clutch was definitely engaging and disengaging (i rotated the driveshaft while someone pushed the clutch in... it engaged about 2in from the top of the throw).

Does anybody have any idea what could be going on here?

[hogie]

Sounds like you had the same problem as me. I had the clutch collar out of a differant car that didnt match with my pressure plate. You need the shorter collar...check out this link for the differances.

http://www.zparts.com/zptech/articles/trans_swap%20parts/4tobear_specs1.html

Also, my earlier thread had a ton of info from other sources listed in it.

http://www.classiczcars.com/forums/showthread.php?t=4119

[VaGuS510]

Thanks for the reply

That is what I was thinking...I know the collar is off a 75 280z but maybe it could have been a swapped 5 spd (it was at the junk yard).

Would the fork still have slop in it if this was the problem? With and without the slave installed I can move the fork a little bit in both directions with essentially no effort. I can move the slave cylinder end of the fork forward and hear the sleeve hit the front cover of the transmission.

I would think a sleeve being too tall would be a problem because might be jammed between the front cover and clutch... Am I thinking wrong?

[hogie]

If you hadn't modified the slave rod you wouldn't have any slop at all. I couldn't move mine. Now that I have the proper sleeve I could.

Without the slave the fork should be able to move at least a little bit freely.

Yes, the sleeve being too long puts pressure on the Pressure plate which allows the clutch to start slipping. Mine was driveable and only slipped at full throttle in higher gears.

[chaztg]

I agree with hogie...are you sure that the sleeve moves on the slider shaft (as it would normally but just a little bit for clearance sake) and it's not the fork? The fork will have a little slop especially if it's moved the wrong way. If the sleeve is solid and stationary with the clutch pedal fully up then it is too tall and pressing on the pressure plate fingers.

[VaGuS510]

That was it... the throwout bearing sleeve was too large, I got a 70-74 bearing from motorsport and it was perfection