Rear Caliper Issue on Our '94
02-24-09, 11:12 AM
#1
Recovering Miataholic
Thread Starter
Rear Caliper Issue on Our '94
Posted this question as a reply in my previous thread, but realize it's really a new issue, so here goes again:
So my front brakes are finished... new pads, new rotors, wheel cylinders overhauled. Just started working on the right rear caliper. Before and after I removed it, the parking brake setup looked normal, and the operating lever on the caliper was in the right position. But some time between taking the caliper off, and removing the piston, something changed, and I don't know if it should have or not. With the piston out, the end of the threaded "adjuster" sits just about even with the end of the cylinder, and the operating lever is fully toward the caliper body. I can't move the lever away more than about 15°, and the threaded rod moves outward instead of inward, about 0.010" before the lever jams.
Does unscrewing the piston somehow mess up the position of the lever or the stuff inside that I haven't touched (i.e. the snap ring and everything behind it)? It was very hard to turn the piston, and I'm wondering if something went terribly wrong. I haven't done anything yet to the left rear caliper, and its operating lever looks correct.
Does anyone have any idea what might have happened? I followed the '94 manual to the letter.
It looks impossible to re-install that snap ring at the bottom of the threaded post, even if I could remove it. The manual mentions nothing about a special tool, but I cannot see how it could possibly be done with a spring trying to push it up, and with that threaded rod sticking up in the middle of the cylinder. Can it be done? Should I attempt to remove the snap ring, take the thing apart, and try to see if it can be fixed?
Or should I just give up and buy a new rear caliper? But then what about the left rear caliper, which I have removed and for which I have a "kit?" 
So my front brakes are finished... new pads, new rotors, wheel cylinders overhauled. Just started working on the right rear caliper. Before and after I removed it, the parking brake setup looked normal, and the operating lever on the caliper was in the right position. But some time between taking the caliper off, and removing the piston, something changed, and I don't know if it should have or not. With the piston out, the end of the threaded "adjuster" sits just about even with the end of the cylinder, and the operating lever is fully toward the caliper body. I can't move the lever away more than about 15°, and the threaded rod moves outward instead of inward, about 0.010" before the lever jams.
Does unscrewing the piston somehow mess up the position of the lever or the stuff inside that I haven't touched (i.e. the snap ring and everything behind it)? It was very hard to turn the piston, and I'm wondering if something went terribly wrong. I haven't done anything yet to the left rear caliper, and its operating lever looks correct.
Does anyone have any idea what might have happened? I followed the '94 manual to the letter.
It looks impossible to re-install that snap ring at the bottom of the threaded post, even if I could remove it. The manual mentions nothing about a special tool, but I cannot see how it could possibly be done with a spring trying to push it up, and with that threaded rod sticking up in the middle of the cylinder. Can it be done? Should I attempt to remove the snap ring, take the thing apart, and try to see if it can be fixed?
Or should I just give up and buy a new rear caliper? But then what about the left rear caliper, which I have removed and for which I have a "kit?" Last edited by wstrohm; 02-24-09 at 11:19 AM. Reason: Adding Image of rear wheel cylinder
02-24-09, 03:52 PM
#2
Rotary Freak
Can't offer anything on the lever, as it's a bit too long ago.
Removing the circlip and pressed metal piece is definitely a two (or more!) handed job with the caliper in a vice and requiring compression of the internal spring.....and several attempts on reassembly - do not apply, with cheesy circlip pliers.
Aftermarket rebuild kits over here come with seals for the handbrake mechanism, may be best to just do the piston seal and leave the rest alone if no obvious issues.
Removing the circlip and pressed metal piece is definitely a two (or more!) handed job with the caliper in a vice and requiring compression of the internal spring.....and several attempts on reassembly - do not apply, with cheesy circlip pliers.
Aftermarket rebuild kits over here come with seals for the handbrake mechanism, may be best to just do the piston seal and leave the rest alone if no obvious issues.
02-24-09, 05:24 PM
#3
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You need long snap ring pliers which fit inside the cylinder.If you have the right pliers it is easy to remove and reinstall the snap ring.
It is likely that the cam was turned too much and the piece between the cam and the pushrod got jammed.
I take the spring and arm off when rebuilding.
It is likely that the cam was turned too much and the piece between the cam and the pushrod got jammed.
I take the spring and arm off when rebuilding.
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