Just did new pads and rotors on my '90 a couple weeks ago. One of my rear calipers was seized so I took both the rears off my '99 parts car. After the brake job I keep having to re-adjust my e brake using the 4mm hex key, over the course of about a week it will continue to get looser to the point where if I'm parked on any kind of incline I can pull the handle up all the way and the car will still roll. Are my calipers just bad?

 

This happens to me too - only on my passenger side. I ended up buying new remanufactured calipers off rockauto (centric). We'll see if that settles it once and for all.

 

Interested in this too.

 

Chances are, the adjuster, or the threads on the caliper are stripped out. People unfamiliar with the adjustment over torque them, and something gives. You can try a different screw, but the best solution is to get a new caliper.

 

From the garage thread at m.net -

I'd like to take a minute to thank Lance for his valuable information re the parking brake. I had a problem with my parking brake and after reading over my Miata shop manual many times, I could not resolve the problem. Thanks to Lance and his informative piece on the proper operation of the E brake I was able to correct the problem. The key to the problem was releasing the parking brake cable fully to allow the actuating levers to fully release, and then, adjusting the allen screws in until the pads just touch and backing off 1/3 of a turn. The last step is to readjust the parking brake cable to the proper number of clicks and lastly verifying that the brakes do not drag when released. Thanks again Lance. PS Nowhere in the shop manual does it say anything about returning the levers to the fully released position before making the allen screw adjustments. Someone had messed with this problem before me and apparently didn't realise that there were manual adjusters. I had one new caliper with no adustment made, or it was backed off fully because of the intermittent overclocking of the lever and the resulting brake drag on that wheel.

I just tried this this morning. Guess I’ll find out in a few weeks if it works.

 

That blurb explains why my adjustment finally worked this last time. I released the tension at the handle adjuster and the cable ends before setting the screws this time and it worked.