1991 N/A

First...my reservoir is leaking from the bottom. I need to replace the o-rings. Anyone know what size they are?

Second...

Well the front right brake is dragging. Not glowing hot, but enough to sizzle water after 18 miles. I took the caliper off and greased the sliders and soaked the whole assembly in WD40, then went back with lithium spray after that dried a bit. I pumped the brake pedal a few times to push the piston out a bit and it moved without issue. I then opened the bleeder and used a c-clamp to push the piston back in...which it did with no more complaint than I've ever gotten from doing this kind of thing to any other fully functioning caliper. When I assembled it all back up and pump the pedal...pressure still didn't bleed off the piston. If I used a prying bar and applied some pressure...not even a lot of pressure...it opened right up and allowed the wheel to spin freely.

What else can I do? What else could it be?

 

If you're relatively sure that the caliper is OK, then it could be the master cylinder.
Since you already have a leaky reservoir- and by the way, the res doesn't have "o-rings" per se, it's held in with special rubber grommets that aren't generic- you might consider replacing the MC and see what that does for you.

 

Sounds like you need to rebuild your calipers or buy rebuilt calipers.

 

I wouldn't think it's the master cylinder. It's been my experience that when there's a problem with the master, the results are shared among all the slaves. My situation is isolated.

I will check the master thoroughly, though. If it's okay, I'll head to Mazda for the grommets I suppose.

I will likely end up replacing the culprit caliper...but if it can be spared, I would prefer to save the expense/time.

 

Sounds like corrosion in one of the cylinder bores on the caliper. Either rebuild it and hone the cylinder or replace with a reman.

While you are at it, replace that master cylinder and get one that includes the reservoir . I have heard of issues with compatibility of master cylinder to reservoir seals. They are not mix and match between suppliers. When the master is replaced, the old reservoir won't always seal up right. Solution is to only buy master cylinder comes with the new reservoir.

Good Luck

 

First Off you should never use WD 40 or Lithium based grease on the caliper slides. you should use a high temp silicone grease. it sounds like the caliper slide pins need to be replaces or replace the caliper itself.

 

The lithium spray is very suitable for this...I know what it's intended purpose is, and this isn't far from it. WD40, however, works great for displacing water, penetrating corroded crevices, and helping break down old greases.

However, I did check out the slide pins when I had it disassembled and they seemed to be fine.

I don't know how much effort I'm willing to invest, though...4-piston brakes look so pretty and they don't cost much more than replacing/rebuilding my stocker.