When Konis get stuck...

Found the rear adjusters for the Konis on our clubs runoff Miata are only moving about a 1/4 turn one way or another. Car sits most of the time. Searching around and people say over torquing the center bolt can mess up the shock, but I don’t think that has happened as they worked the last time we used the car and nothing has been done to the center bolt. 

Any suggestions on freeing it up?

Call KoniNA and ask them.

You know what I think happened. I took off the rears as a whole assembly to put the shocks to a higher spring perch. I didn't loosen the top bolt and I bet the shock got moved enough to overtighten the bolt. I'll have to loosen it up and see if it starts working again.

Don't ask me how I know this but, yeah, using an impact gun on the center nut can cause bad things to happen with your Konis. Well, maybe not permanently bad, but it can jam up the mechanism.

The fix? We were told to grab the adjuster shaft with an adjustable wrench and work it like the world's most delicate impact gun--just slightly bump it back and forth. That shaft goes all the way through the damper, so you don't want to tweak it. You just want to apply enough gentle forces to loose the mechanism. Gentle. In our case, at least, after some gentle working back and forth, the mechanism popped loose. 

Was told by a Koni rep that bottoming the shocks hard can screw up the adjustment mechanism.  Not being able to turn the adjuster to the full extent was a symptom.  Otherwise he claimed that the yellow adjustables last nearly forever.

I had one stuck on full soft thanks to a previous owner. Koni told me to take a crescent wrench (flat jaws) and just semi-lightly "bounce" it. I did that, pushing it away from soft and letting go, for like 10 minutes and it broke free. Compressed because it was a compression to adjust. Worked fine after that. Just don't turn it so hard you break the shaft. 

Thanks for the suggestions guys. I did intentionally avoid using an impact or torquing that center bolt more than 10 ft/lbs. I’ll send this over to the fellow that is garaging the car.