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Discussion Starter #1
I have a 2000 Z3, 2.8. About 9 months ago I got a deal on a 6sp out of a 2000 M3 that had nearly identical Milage as my car (60k), someone couldn't pay their mechanics bill and so the car was parted out to pay off the tab... Along with it came an aftermarket performance clutch (I'm not entirely sure what one). All told parts and labor cost me $2250 to purchase and get it installed.

The problem is that the disengagement point for the clutch is now down near the floor, and anytime I shift while at high RPM (like accelerating from a light or up an on-ramp) the clutch doesn't want to 100% disengage between 1st and 2nd. I can reduce the occurrence if I smash the clutch pedal ALL the way down to the floor as hard as I can, but it still happens frequently. This also means that when accelerating in 1st, I cannot physically get the gear shifter into 2nd until the engine RPMs have dropped to match the wheel speed, the transmission is locking me out as if I am shifting without using the clutch at all.

The problem does decrease when the clutch is hot, so the more sporty the drive the less it happens, but after a few miles cruising down the interstate it starts coming back...

I can 100% confirm that it is failing to entirely disengage as sometimes when downshifting to engine brake (and yes I rev-match), coming into a stop sign/light in 2nd, when I try to get it out of gear with the clutch all the way to the floor I have to force it with a lot of effort out of gear, and if I take my foot off the brake the car will start moving, even on small uphill inclines. in other words, the engine is still driving the transmission a little even when the clutch pedal is all the way to the floor.

I have asked the mechanic for ideas several times, he is out of ideas, says buying a new clutch is the only solution he can think of... seems like something is wrong with that approach as you normally replace the clutch when it will no longer fully engage and it slips, I have the opposite problem where it doesn't want to disengage!

Any ideas where on the conversion to the 6sp and the aftermarket clutch would be causing it to fail to disengage fully?

This is the same clutch that was used with this transmission when it came out of the M3 and had no problems...
 

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2000 E46 323i, 2000 3.0L and 2000 2.0L Z3's
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Hi

General forum wisdom would suggest:
1) air in the clutch slave cylinder- Bleeding the clutch system can be tricky. I remove fluid from the reservoir and use a hand pump to push new fluid from the slave cylinder backup to the reservoir.

2) replace the clutch flexible tube that connects to the slave cylinder with a DOT rated flexible stainless steel tube. The old rubber ones have a tendency to start expanding/ballooning when they get old. This moves the clutch engagement point on the peddle very close to the floor. A Sports clutch may increase the peddle pressure to control the clutch (stronger pressure plate springs). This would increase the pressure in the flexible clutch line and push it into the expanding/ballooning pressure range for an old line.

If you do item 2 first, then item 1 will get done anyway.

Hope this helps
 

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Yoda with a library card
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You have two issues. The rubber slave line should be replaced with either a new one, or a stainless steel one. You mention that it happens worse when hot, that is the culprit for that issue. The second is that you need a different slave cylinder to match up to this transmission. I had the opposite problem when I put my 6 speed in, the take off was way high up. I needed to adjust my clutch stop way up and actually shim the pedal so that the clutch sensor would work properly so I could start the car. I am using the stock M slave cylinder. With a little research, I could find the correct slave for that transmission but I don't have it off hand.

If I were you, I'd change the slave line, make sure I had it good and bled (huge PITA), and adjust the clutch stop on the floor before changing the slave.

I'm not sure a visual inspection of the line will show if its ballooning or not. Spend the $25 and get a new line.
 

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Discussion Starter #5
You mention that it happens worse when hot, that is the culprit for that issue.
actually no, the problem partially, and sometimes entirely goes away when it gets hot, and is worse when it's cold... it is really bad when first starting the car in the morning
 

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Brake fluid becomes compressible with age. You need to replace it, and with the effort to do that, you might as well replace the line at the same time. And if you're going to replace the line, you might as well install a stainless-steel braided one. That should solve most of your problem.

Be sure to read-up on how to bleed the clutch system properly. It's not that hard, but most mechanics won't know how to do it right unless they're familiar with old BMWs.
 
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