I have a 2009 WRX sedan and am in the process of replacing the transmission, which had incurred some damage. While I had the transmission out, I pulled off the clutch cover and the clutch disc to check for wear. The clutch disc was well within acceptable tolerances, so I went ahead and put it back on, along with the clutch cover. I used a clutch alignment tool and kept the clutch centered while torquing the clutch cover bolts to the proper torque using a star-shaped pattern, per the factory service manual. However, now that I have everything back together, the clutch is much stiffer than before, and about midway through releasing the clutch pedal, it tends to really spring out. I am really puzzled as to what might be the cause of this, because I didn't replace any parts--just took it apart and put it back together. I wouldn't think that the throwout bearing on the new transmission would affect clutch feel that much.
I can think of three things that might have contributed to this:
1.) The clutch disc fell out as I was removing the clutch cover, so I didn't have a chance to observe it as it was installed. It's possible I put it in backwards, but the factory service manual seems pretty clear as to the proper orientation:
The way I interpret that diagram is that the flat side of the clutch disc goes against the flywheel, and the side with the raised center goes toward the transmission. I couldn't find any pictures/videos clearly showing the orientation, so any confirmation of this would be appreciated.
2.) I depressed the clutch pedal before the operating cylinder was installed against the clutch fork. I don't know why I felt compelled to do this, but it seems to me that it shouldn't matter. The operating cylinder extended fully, but no fluid leaked out, and I was able to easily press it back to its contracted position.
3.) The clutch alignment tool was slightly wobbly. I got one of the plastic alignment tools from Rallysport Direct, and it seemed to work ok, although it wobbled around a bit in the engine output shaft. I was able to center it pretty well, as far as I can figure, and the transmission slid into place without issue.
Honestly, the whole install went pretty well, and the above are the only issues that I think could have contributed to the very noticeable difference in clutch feel. Any help would be greatly appreciated.