Clutch won't disengage after engine swap
 

Ok so here's the story. I have a 97m with an FM turbo kit, ms3x, 6speed, FM level 2 clutch, and a bunch of other goodies. I just replaced my old engine with a freshly rebuilt engine with Manley rods, acl bearings etc. After the swap, I crank the car in gear and it tries to lurch forward. Tried adjusting the rod at the pedal. No change. New slave and master cylinders bled properly. The slave cylinder is actuating the clutch fork with plenty of motion. I pulled the fork boot off and looked with a mirror and the fork appears to be on the pivot ball and doesn't have any significant play in and out, you can even feel the spring clip pulling it back into place slightly. I just tried driving the car by starting it in gear and with the pedal rod adjusted as far as it can go without falling out of the pedal, just to see if maybe the clutch would pop free from the flywheel by some miracle but I'm not that lucky. Although with the clutch pedal depressed it did slip a little under full throttle and not when it was out. Is there anything else to look for before I pull the trans and inspect the clutch itself (which has less than 2k miles on it)? I really don't want to pull the transmission back out. This would be the 5th time I will have pulled the trans and/or engine out of this thing and im getting tired of it. Any help would be greatly appreciated.

Probably not the answer you're looking for, but I put the clutch disc in backwards one time and it did exactly what you describe.

​​​​​​But did it slip with the pedal depressed? I would think it wouldn't change at all with clutch pedal position if the disc was in backwards. Also I distinctly remember thinking to myself as I was putting the clutch in: "big side towards transmission"

It happened to me once and the splines on the disk were boogered up from trying to rock the transmision on. I had to file them a bit and add some lube.

Well my nightmare continues... I pulled the transmission out AGAIN. First I checked the clutch fork and the pivot ball... fine. Next I checked the clutch alignment... Fine. Pulled the pressure plate of and the clutch disk is in properly. WTF!? I don't understand. The only thing that's different in this drivetrain is the flywheel which was used on a different clutch and worked fine then. Is it possible that flywheel is causing the clutch to stick? Seems unlikely to me but I'm out of ideas. HELP!

Just spitballing here. I have an FM Level 1 clutch on my '95 and have had similar issues. I know that's not the same as your Level 2, but I wonder if it's similar enough that you could be running into the same problem I saw.

It turns out the FM clutch has an engagement point that's very close to the floor. They designed the springs for lower pedal effort and the lower engagement point is the result. The issue is that there's sometimes not enough travel in the hydraulics to make the clutch disengage. I found a couple internet posts describing this issue and I confirmed it on a phone call with FM. Their adjustment instructions at https://www.flyinmiata.com/support/i...structions.pdf say that most customer problems they hear about result from improper adjustment.

To fix this, I had to ensure the clutch rod was touching the master cylinder piston then I had to bleed the heck out of the system to ensure there were no bubbles. I was finally able to get everything working pretty well, although I still have issues when the engine is cold, and especially in cold weather and with reverse gear. I have to pump the clutch pedal a couple of times to get things going.

Could this be your problem or am I off in the weeds?

Edit: nevermind, I'm dumb.

You say you know the slave end of the clutch fork is moving. Are you able to determine that the TOB end of the fork is moving enough to press on the PP fingers?

This happened to me with the FM clutch. Fixed it (mostly) by following those instructions. I also still had the cold engagement problem, just as Ace explained.

My brand new FM2 clutch had a very, un-flat pressure plate. Worked like complete doo-doo until I convinced a shop to surface it.

Just finished installing my FM1 clutch this weekend. "It’s critical that you’re able to push the slave cylinder into it's bore by hand once you’ve adjusted the pushrod - you CANNOT skip that step, regardless of how much of a pain it is." For me I barely had to turn the pushrod to feel resistance, then I backed off a 1/4 turn.

ACT now and again if I ever need to replace it. Works correctly.