Somewhat looking for input, but also somewhat just posting this so the information is available to others.
Description of the problem:
Harder than it should be to get into first gear from neutral at a stop, or into first while coasting down without rev matching (clutch pedal down). When pushing the shifter into first in the car will creep a little bit on a flat surface. Engagement is lower than with previous clutch (UUC 9 button "cerametallic") but not excessively low. Before the transmission came off for a second time the car was borderline undriveable. Very low clutch engagement, very difficult to get into first gear.
What has been done:
First go:
Second go:
Misc info:
Flywheel 12-12.2mm (going by memory) from step surface to top of ring gear, using a flywheel of rusty but otherwise ok condition ring gear to back surface distance was measured at 18.4mm, yielding a total flywheel height of 30.4-30.6mm. This is below the minimum spec given in the Bentley manual:
The rusty flywheel was a dowel pin donor, its height measures in at 31.27mm floor to lower step and it is of unknown history but presumably has been resurfaced multiple times judging by the measurement. Spec clutch representative was unable to provide an acceptable runout specification and only could offer troubleshooting help and to take the clutch back for inspection with a turnaround that is unacceptable given my car's DD status.
My best guess at this point is that the Bentley spec of 32mm is correct and the clutch drag is the result of the flywheel being 1.4mm too short now. I'm going to extend the slave cylinder pushrod (on recommendation) by 6mm but do not expect that to make any difference, if my reasoning is correct if I was reaching the end of slave cylinder travel it would be pushing past the seals and leaking.
Description of the problem:
Harder than it should be to get into first gear from neutral at a stop, or into first while coasting down without rev matching (clutch pedal down). When pushing the shifter into first in the car will creep a little bit on a flat surface. Engagement is lower than with previous clutch (UUC 9 button "cerametallic") but not excessively low. Before the transmission came off for a second time the car was borderline undriveable. Very low clutch engagement, very difficult to get into first gear.
What has been done:
First go:
- Flywheel resurfaced, second time since I have owned it, 0.013"/0.33mm step machined, machine shop removed roughly 0.015"/0.38mm.
- New clutch and pressure plate (spec stage 3+)
- New Sachs release bearing
- New clip
- New brass pivot (taller than OE plastic one by 3mm)
- New pilot bearing (FAG brand)
- Flushed clutch hydraulics (both cylinders and lines ~4 years max and 50-70k old) bled by pushing the slave cylinder repeatedly with the hose held at the highest point, a method prescribed by a mechanic familiar with E30s.
- Removed aftermarket adjustable clutch stop and replaced it with a bolt that fits in its place and is much shorter
- Clutch pedal eccentric adjusted so that the pedal is high
Second go:
- Clutch disc runout measured crudely at 0.34mm by measuring height from hub to disc at each "pad", out-of-round at 0.8mm by measuring diameter from spline flat to outside edge
- Pressure plate inspected visually and with straight edge
- New release fork, after cleaning the old one was found to be worn by about 1mm at the release bearing contact points and 1-2mm at the pivot/slave cylinder pushrod contact point. I did not notice any bends.
- Bled clutch hydraulics by pushing the slave cylinder repeatedly with the hose held at the highest point
Misc info:
Flywheel 12-12.2mm (going by memory) from step surface to top of ring gear, using a flywheel of rusty but otherwise ok condition ring gear to back surface distance was measured at 18.4mm, yielding a total flywheel height of 30.4-30.6mm. This is below the minimum spec given in the Bentley manual:
Originally posted by Bentley manual minimum flywheel thickness
My best guess at this point is that the Bentley spec of 32mm is correct and the clutch drag is the result of the flywheel being 1.4mm too short now. I'm going to extend the slave cylinder pushrod (on recommendation) by 6mm but do not expect that to make any difference, if my reasoning is correct if I was reaching the end of slave cylinder travel it would be pushing past the seals and leaking.
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