Installed new clutch, car won't go into gear (Miata)

So me and my roommate just got done installing a new clutch on his miata and the car won't go into gear... 

Because of some trouble getting the transmission back in, much time was spent sanity checking the old stuff vs the new stuff. everything is the right part, everything is the same, its a stock replacement clutch and a lightweight flywheel. This is 4th clutch I've done now and to the best of my knowledge everything was installed correctly and torqued to the right spec.

So what's going on? With the car off it goes into any gear fine. With the car on it will not go into any gear like the clutch isn't depressed at all. With the back wheels off the ground and the car started IN gear with the clutch IN the wheels still turn.  The clutch entirely doesn't disengage.  

Our first thought was the Clutch master or slave cylinder, but even before bleeding the clutch pedal felt fine and the slave actuated the clutch fork perfectly. But just in case we bled it completely but had no air in the lines and no difference afterwards.

What are we missing here? 

My money is on Clutch disc installed backwards, hard interference between clutch disc hub and flywheel. No amount of perfect master / slave / etc gonna fix that. :-(

In reply to AngryCorvair (Forum Supporter) :

The Clutch disc was flat on one side and sticking out on the other. It can't go in the wrong way or the extruded side hits the flywheel before you can even try to bolt it in. We tried just as part of the sanity checks

Sure sounds like a backwards clutch disc. No matter what, you're going back in there.

In reply to Keith Tanner :

I swear on whatever god you fancy that we put it in the right way but whether its that or something else I think your right, we have to go back in there...

I really didn't wanna accept that but its lookin to be true 

The exact same thing happened to me a few months ago. I pulled the transmission twice! In the end, I found out that the pressure plate I had was defective. To test this, I removed the flywheel from the car and bolted the clutch and PP on it. I used a big bolt and the throwout bearing to compress the pressure plate. I tried to find at which point I could insert a small pick between the PP fingers to move the clutch disc. To my surprise, I couldn't move the disc even with the PP bottomed out. I ordered a new clutch kit, tried the new PP with both discs and about halfway through the PP travel I was able to move the disc. Good luck!

If you fought to get it in, and spent any tine with the trans hanging off the disc, you might have bent the center of the disc, so its wobbling and rubbing on the flywheel.

My B-I-L installed the disc backwards in his Miata. It's definitely possible to do so.

ddavidv said:

My B-I-L installed the disc backwards in his Miata. It's definitely possible to do so.

I've done it too . . .  so much for "helping" my friend.

I've always loved doing clutch R&Rs. No really, I mean it... Same can be said with automatics (torque converters can be a pain even on a lift with a decent transmission jack). Doing the above with nothing more than your standard floor jack just makes things even more interesting. But than again, a friend and I swapped the clutch out of my '65 Pontiac back in the mid '70s with nothing more than our backs and J stands.

Alright turns out it was the wrong clutch disc, earlier we had the wrong pressure plate and clutch disc. We sent back both, but apparently they sent back the same clutch disc. 

Car works now, and I can sleep at night knowing I still know how to install a clutch but God dammit that sucked

Glad it runs, sucks you had to do it twice.