Brake issues, might tie everything together

LOL, thinking about this a little more in a completely different way.  Maybe I just blundered into it out of innocent ignorance, but a good troll is still a good troll.  A person so inclined could use this on the other forums.  Corvette, Mustang, Porsche, Bimmer... a whole bunch of 'em... even the Miata forum or, say, AdChat.  🤡 

Sweeten the bait by asking if the filter is really necessary, and would a piece of toilet paper be OK if you don't have a coffee filter?

Use an aquarium pump for a thorough overnight flush?

 If I seem extremely indignant its only because I want to sensationalize my posts and its not at all directed at you.

 One of the many quirks of this car is having a bit of squeal after a rain and the rotors develop surface rust which is normal and usually goes away quickly. 

 Semi metallic pads are just fine however this car is better tuned with organic pads because they offer better modulation of the brakes. This means that they have less initial bite so you can scrub off speed precisely though the pedal.  With pads that have too much bite it will be more or less like an on off switch and will activate the ABS early as it locks up the wheels.  

In regards to why certain methods of bleeding fails to work which no one writes about is the problem with the bleeder threads that suck air back into the caliper.  This is a real problem and why people struggle with repeated bleeding.  When you crack open the bleeder the threads are a point of entry of air and that is why gravity bleeding just works because fluid is flowing only in one way. I can bleed most cars without having to use a jack by just opening the bleeder and having a little fluid leak out and then tighten. I would have to wash the wheels afterwards but I can be done in minutes and have rock hard brakes and clutch. 

@dev,

When I was getting informed and misinformed last week I saw someone else who was using a more conventional bleed approach suggest that applying some bearing grease around the edge of the bleeder valve where it meets the caliper would create a temporary seal to prevent the caliper from sucking air back in.  That also seemed like a good idea and it worked well for him.  So there's at least one guy out there talking about sucking air back into the bleeder, but I didn't see it mentioned often either.  One other guy said to be careful of it, but didn't suggest using the grease seal.  Grease guy also said to clean the whole area first (duh, but it needs to be said).

I get why the calipers trap air - same thing that helps them burp: the bleeder valve is on top. But I don't see how gravity alone is enough to pull a bubble that is much further up toward the master cylinder down to the calipers.  Unless there is some force overcoming the bubble's buoyancy, like from the pedal, air will handily overcome gravity and will not go down and out the caliper bleeders.  If air always going upward was fine, we wouldn't ever get any air trapped anywhere except in the caliper.  Are you saying that the calipers are the only/almost-always place that air gets trapped?

Also, what kind of life are people getting out of the OEM pads?  I realize it can vary based on the weight of one's braking foot, but the point of my question is whether I should expect these pads to be the originals or if that is simply outlandish.  I have about 85K miles on it and my best guess is that The Frog has never been to a track or otherwise driven that way.

I have also heard of those that add grease on the threads but I don't think its a good idea because it contaminates the brake fluid which would be bad.  Most of all messy and completely unnecessary.  

The way I did it when I use to vacuum bleed was to use a little Teflon tape around the threads and that helped. If you use speed bleeders they will have the threads coated with Teflon that helps them seal but over time this breaks down and you will have to reapply the liquid and re-coat the threads.  All of this is just a waste of time and more junk in the way. 

 No worth it when gravity bleed is just better. If I was doing many cars like at a shop I would consider a faster method but for the home mechanic gravity bleed is just better. What I plan to do next time is do both rears  simultaneously. I would just watch the level on the master and add when it gets to a certain point and then fill it up and then close off the bleeders and then do the fronts. 

 In regards to the bubbles bouncy to go against gravity, it is a factor but it is overcome by the pressure of gravity  and specific gravity of the fluid pushing the bubble.  If you ever hooked up an IV line you can sometimes see a small bubble make its way down into the arm but as long as its not too big it will not cause an air embolism.

If you have run the master completely dry it might require you to do a quarter pump of the pedal to get the fluid to flow similar to sucking fluid though a siphon to get it started but its easy and if you are just bleeding the brakes in a system that has fluid it will flow out once you break the bleeder free. 

The only exception to this is if you are installing new components like new masters which will have to be bench bleed or wetted before installation because you can have trapped air that even pressure bleeding will not resolve. 

 Typically the stock brakes should last close to 90k miles. There are a few that have gone past 100k.  The brakes for our cars are overbuilt and being a Toyota they tend to last a long time unlike other cars that usually need to be changed at 40-50k miles. 

My bleeding method:  I set up the bleeder bottle so the hose has to go uphill from the bleeder.  This keeps fluid at the bleeder.  Then I just bleed it by pumping the brakes.  This allows fast 1-man bleeding and no chance of getting air in the calipers (unless I let the reservoir empty).

And am I correct in noticing that just under the seam about halfway down the reservoir is where it will start to suck air?

Posted by: @nottamiata

And am I correct in noticing that just under the seam about halfway down the reservoir is where it will start to suck air?

 If you suck as much fluid as possible from the reservoir you will not introduce air in the system as long as you fill it back up before you bleed. 

 If you bleed and it goes empty only then you will introduce air.  

>>> If you bleed and it goes empty only then you will introduce air.

Well, yes, I think that's what I did.  Nobody witnessed the actual air go into the tube, but it made a couple of slurps.  We covered that.  I think I flushed it out.  The brakes are seemingly different now, and they do still get progressively stiffer with lock-up/ABS at about the 2/3 point.  They just take a bit longer to engage, which at first take seems like they are softer, but they aren't soft or squishy.  I've felt that before, and this ain't it.  It is taking a bit of getting used-to, but it is not that different. It is better, if anything.  I can get plenty of modulation out of them... when they are dry or wet+hot.

I do think we removed the air right after it was introduced, but again, I would need one of those little harsh-environment nano-bots that I can just drop in there to film it from the inside to be absolutely sure.  Until they start stocking those at The 'Zon for 23.89 (maybe sooner than we think -- think of all the applications, some disruptor is going to clean up), I am stuck with my current degree of security that we made a proper recovery from that mistake, until I flush it again. After driving it a while, I don't have as much concern about air.  When I do the brakes, I will burp them, though.  No reason not to, and I have a spare can of TR.3 (Tasty Red dot 3). Totally a disciple, sometime soon I will start taking your advice a bit sooner.  Pain is a great teacher, but maybe there's a better one?

I was just asking about the whole thing so I will do a better job that next time.  Also wanted to get confirmation that the halfway seam on the reservoir is pretty close to the danger point, but nobody else wants to admit they have had the same unpleasant experience with this, maybe? 😉

Speaking of which, could anyone offer the not-so-obvious pro-hacks for pad changes.  My vision of it is along the lines of:

remove one of the caliper slide bolts (bottom or top?),

loosen the other (not too much, don't booger up the threads at the tip),and

tilt the caliper away and off the rotor and wiggle the pads out. Retain all shims and spacers if any remain.  Where do you get replacements for these?  I don't see them at The Parts Giant, and my pads did not come with them; is this an obsolete thing? Am I sorta hosed if I have none?

Use the cube tool to wind back the piston - Which way?, and what kind of force is involved?  If I need to bear down against the piston to keep the tool engaged, does it risk deforming the caliper slide pins? I am smart enough to understand the importance of stripping the tool and that the issue makes the tool a PIA, but I can manage that.  Just not wanting to wreck the pins.

Replace pads. Use best wiggling skills here, reserve profanity for emergency use.  Accept that it will be fiddly up front, try to enjoy it.  Remind The Frog that you love him.

Grease pins while yer in there, replace caliper on rotor.

Burp brakes.

Top off brake fluid.

[Repeat for each wheel]

Pump brakes generously before driving.

Test at gradually increasing speeds on deserted roads.

Replace rotors within (a week or two?) if brakes are assy.  This involves taking the caliper off, babying the brake line by tying the caliper to the springs and supporting weight, etc.  I know how to get the rotors off, the two relief holes and so forth, and mine are most likely not stuck anyway.  Gotta wind back the pistons again, etc.  Don't wait too long to decide, or my opened bottle of brake fluid will go bad.  Maybe I'll evacuate some of the air with CO2, cuz I am paranoid and like to waste my time.

What did I miss?

... or I might be smart and just replace the rotors and hang on to the old ones long enough to at least find out if they can be re-surfaced. I do plan to hang on to The Frog for a while. We can go another couple of weeks and just avoid the highway in the rain.

Do these particular rotors glaze, and is that irreparable by resurfacing? How deep does the crystal crust actually go?

@nottamiata  I do not remember where the seam is, but if you want to know just how far you can go down before the MC will suck air, you can figure it out by shining a bright light through the brake fluid reservoir as you get close to the danger point.

A couple of points. 

 The fronts you can just separate the caliper and leave the bracket in place to change the pads and then put everything back together. For the rears I was never successful doing it this way because of clearance issues and will generally put the pads on with the caliper off the car and then bolt up the entire caliper assembly as a unit.  

 As far as the piston for the rear goes you need to go clockwise in rotation to push in the piston. It can be very hard and you need to straddle the caliper between your knees and then fit the cube on the piston and turn. Its better to have an additional person to help with this. 

 Some pads have shims attached and some dont because the newer designs are squeal free but what I do is add a thin layer of moly grease on the back of the pad. 

 The little clips the pads slide on that is attached to the caliper is called a fitting kit. If yours is in bad shape you can get new ones for $15 at the dealer.  You can add a little moly grease here so the pads slide freely. 

As far as rotors go I would get them  resurfaced.  Resurfacing does a few things. It will clear up any minor hard areas due to hotspots that may cause pulsing and it will be an abrasive surface that can help with burning though the surface of the pad that has some kind of release agent that needs to be removed and transferring brake pad material on to the surface of the rotors. If the new pads do not play nice with the old rotors you will be back to the same situation. 

When its all done you will need to bed in the pads and if you have new rotors you will need to season them which means you need to bring up the temp of the rotors gradually before you begin the bedding process which can be a few hundred miles of city driving. During this period you will have fade until everything settles down and the pad material is transferred to the rotor.  

 With performance pads that I have used in the past they can create issues if you are too nice to them and on a rare occasion you can get them to glaze. It can be one rotor causing the car to pull during braking. I have found that if you re-bed the pad by doing a few hard stops will generally fix it and it will not come back. 

@dev,

As always, thanks for taking time to reply.

@dblotii,

Thank you, as well.

LOL, yes, but w3hat is that danger point, exactly? We think we saw it happen just under the seam, but that includes the rear was lifted about 10 inches. That point we are sure of - we think it slurped, and when it did it was about 1/8" below the bottom of that seam.  However, that data is irrelevant, since we don't know if it actually sucked air right there. I am looking for confirmation that it does suck air at that level, without doing it again.

@nottamiata I really think the danger point becomes obvious when you shine a bight light through the reservoir, especially when it is half-empty

Posted by: @dblotii

I really think the danger point becomes obvious when you shine a bight light through the reservoir, especially when it is half-empty

 

Ah, forgive me for being dense. I don't need a light, I remember the interior.  You refer to the stem rising up from the center where the sensor float sits? The liquid was right at the top surface of that guy, but it "appeared" that the outer barrel that the float sits in was still fully submerged. Barely.  I suspected that is a pickup tube, but again, it looked submerged at the time.  I suppose it was not and my observation skills need improvement.

However, my understanding of the MC is that the feeds to the pistons are at the bottom of the reservoir which gravity-feeds the pistons.  Why would they not be?  Seems odd to just have a pool at the bottom that cannot be cycled, but then, that might just be a spot for a return to squirt into, and/or the raised pickup tube is are there to keep crud from getting pulled in as well as house the float?  This raised pickup/gravity debris trap is a common configuration for many fluid systems. I clearly don't know the specific anatomy of this reservoir as well as I should.

Still, the stem still seems awfully tall to this layman engineer.  My reasoning there is that the vehicle can tilt a pretty steep degree during normal driving, which would expose a taller stem more readily than a shorter one. But if that's the actual gosh-darn top, then that's where Mr. T put the top.  I clearly don't know the specific anatomy of this reservoir as well as I should.  Or maybe that "slurp" sound was actually a "squirt" sound from the return tube shooting just across the exposed surface instead of into the usual reservoir liquid as the level got lower?  I clearly don't know the specific anatomy of this reservoir as well as I should. I also didn't think the return went into the reservoir directly, but again, I clearly don't know the specific anatomy...

"Gee, Wally, ya think maybe I coulda used that float sensor somehow to help me when I bled the brakes?  Maybe it can detect when the fluid is getting low, in addition to that other thing it normally does?"

Holy crap. I really am a moron sometimes.  :-/

I'm not panicking, the brakes work well enough except under those avoidable conditions, no sponginess now or ever, really, nor any ABS shenanigans since dumping the L-V DOT4.  Now I'm just trying to outsmart my future-dumbass self if/when he comes around again.  I'll likely hold off a bit longer while I order The Frog some new rotors, but I have a PCV valve I can fiddle with in the meantime if I get bored.  He needs a good interior detailing too but he has a nice coat of wax to keep the ick off his sensitive skin.  Poor little The Frog, his dad is a part-time imbecile (with an unpredictable schedule), but he means well, and he does keep you reasonably shiny.  And most of all, he does love you.  We'll get through the 90K standard everything-at-once maintenance event, The Frog!  We will...

@nottamiata I can't take a look at my reservoir until I take my car out of winter storage.  Perhaps someone else can help?