Brake master cylinder?

[KeMBro2012]

Hey guys, quick question...

I put new brake pads and rotors on my 99 a couple months ago, checked the rear drums and shoes, those were almost like new so didn't replace them. Fluid was kinda dark, so I bled everything until new, clean, clear fluid ran from each bleeder valve (one at a time, of course). Braking power seems a bit weak, which I attributed to the new rotors and pads needing to wear in.

2 weeks pass, over 500 miles on the new pads and rotors, only minor improvement. Figure I should try bedding them in;p again only minor improvement. Tonight, 1600 miles later, decide maybe I should bleed everything again, maybe I didn't get all the air out last time. Nope, no more air bubbles, and no improvement.

I know my booster is fine, as it will still be pressurized even after the car has sat overnight or over the weekend. I'll come out and put my foot on the break with the engine off, goes down easily; after a few pumps, it firms right up as the booster loses pressure. However, once I start the engine, pressing the pedal gives a slight whooshing sound as the pedal goes down. Everything feels fine, no squishiness or sponginess, but the pedal does reach the floor if I give it a good push, not even standing on it, just a good push while firmly planted in the seat.

I'm quite possibly selling this car later this week and can't, in good conscience, sell it to the guy without at least telling him what the problem is, if it's the master cylinder. At best, I'd like to be able to tell him "yes, the master cylinder is bad, I'll be replacing to this evening" after tomorrow's test drive, and let him take it for another spin after that. He won't have the cash on hand to buy it until Thursday, anyway.

I can get the part, brand new, for $60 and this won't be the first master cylinder I've replaced (I've done 2 brake and 3 clutch), though it'll be the first one in this car.

Unless, of course, someone wants to (legitimately) tell me that's not the problem. If it's something cheaper (or just labor) to fix, that would be great; if it's something more expensive, good to know going into it so I can get it fixed correctly before I sell it.

That said, I'm asking 1700 for a 99 Corolla with 192k on it, solid engine and trans, new struts and springs 15mo ago with less than 10k on them, that's been running royal purple for the last 13mo and was running redline for the 2yr before that when my coworker owned it. Tranny has had frequent fluid changes, and an additional filter change in November, after my coworker and I determined that the fluid we got out of it LAST November when we replaced the pan (he stripped the drain plug) and filter was the original ATF with 180k on it. Given the condition of the car, it's definitely worth more than 1700, even with a bad master cylinder, and I'm only selling it cheap because I want to buy my coworker's 2000 (manual, I miss driving a manual) and he's asking $2250 but needs $1700 ASAP to pay it off to get the title.

I seem to have gotten a bit off-topic, so I'll move the rest of that though to its own topic. Really just looking for comments regarding the brake issue; anything related to pricing and/or the 2000 I'm trying to pick up, look for my other thread

[KeMBro2012]

No replies this morning, so I decided to play it safe and just replace the part. Seems that was the problem.

Just for reference, though, what else could cause my symptoms? Someone else might still get some use out of this thread.

[Bennie]

To be honest I only read about half your post,

Make sure the rear shoes are adjusted correctly. If they aren't it can cause the issue you are having. The shoe's need to be adjusted so they are as close as possible to the drum without causing any drag. If they aren't then the pedal will not be as firm as it should be.

[KeMBro2012]

You read more than I would have, I can get a bit long-winded at times. Thanks for the tip, it's something I'm sure is often overlooked. In fact, when I put the new parts in the front and inspected the rears (and returned the new parts I had purchased), I did forget to do this. No worries, I did it the next day.

My methodology is to adjust them out until the drum no longer fits, then back them off until it does. I'll then engage the parking brake and let them adjust themselves from there. Never any drag or rubbing when I do that on my 99 or my coworker's 2000.

Everything is a billion times better with the new MC. At first, after installing the new MC (yes, I bench-bled the hell out of it) and giving my brake lines a quick burping (thorough bleeding, for those of you not reading in humor mode), the improvement was there, but was minimal.

Looking at my rotors, the factory crosshatching was still present (they're about 2k miles old) and they were still a nice shiny silver. Off to the freeway to bed them in (which I had attempted previously, but obviously wasn't getting enough pressure to heat them up correctly)!

After that process, my rotors have a nice feel when I run my finger across them and a nice blue tinge to them. Oh, and the car stops like it's hitting a brick wall, now.

Fitted with PFB carbon metallic pads and BrakeBest Select rotors (hey, they were in stock, and they came with an already-roughed-up surface -- and they're actually good from what I can tell), properly broken in and bedded in, definitely loving it. 2k miles and I haven't bitten through the crosshatching of the original finish on the rotors yet. Properly bedded in, I don't think I'm ever going to.

Semimetallic pads because they just "feel" better when I'm braking. I don't care about noise or dust, but I do care about having better linear control of the brake pedal; having the brakes engage incrementally to how hard I push the pedal, with a wider pressure range before they fully bite. Another thing I love about SM pads is that they bite harder when they get hot; when you stand on the brake pedal with SM pads, you can feel them digging in. They're also less prone to overheating, since the steel fibers draw heat to the pad backing and caliper (use of DOT4 fluid recommended if you're a heavy braker or stop from high speeds frequently). A lot of people will tell you that SM pads don't last as long and that they eat your rotors faster. I've never waited until my pads need replacement, I replace them yearly (I know enough people with Corollas who love getting free pads with tons of life left on them, so it's not really wasteful), so I can't speak to the first part. For the second, yes, if you just run SM pads on clean rotors, they will eat them; let me refer you once more to the last bit of the paragraph above: 2k miles and I haven't bitten through the crosshatching of the original finish on the rotors yet. Properly bedded in, I don't think I'm ever going to.

Bedding in is important.