Having a hard time getting brakes to feel normal.
 

I have been doing a lot of work to my car. It sat for about 1 year and a few months. It even sat with the front brake lines open for a couple of months while I stripped and painted the engine bay. I also used an 86 gxl(had the 4pot brakes) to convert my 88tii abs to non abs.

What its doing.
My brakes were always kinda of mooshy. From the leaky abs pump to the swapped gxl non ABs parts swap. And now after all the time It sat it has gotten way worse. I have since changed the mc twice for reman units. Bench bleed and bleed the system over 10 times. I also checked to see if any of the calipers were seized. They are all in working order although I'm in need of new caliper hardware. Fluid is clean and no air bubbles coming out if calipers when bled. I have not seen any leaks at all and have looked several times. My brakes lines are bf goodridge SS. So that's not the prob. I have also tried adjusting the pedal adjustment nut. When car is off and you pump the brakes they get firm as if they went so bad. When car is started they sink further into the floorboard. Booster 1way valve has been checked. I'm lost of what false to try.

Please help?

Someone enlighten me with some possibilities

IMO, the "mooshy" feel was what the engineers/test drivers liked, an intentional decision.

Compared to other cars with similar calipers, Mazda used undersided MC/booster combos, which leads to longer/softer brake pedal (although the stopping power is fine).
You'll solve your issue by putting in a larger booster and MC, the options for which are quite extensive.
I can personally vouch for the setups from an Acura Integra (1" mc) and the Subaru Legacy (1 1/8" mc) as (almost) bolt on upgrades that will drastically (in a good way) alter your pedal feel.

sometimes junk can collect in 3 way splitters at the rear of the car or the proportioning valve which won't allow the air to be bled out properly.

other possibilities are new pads on unmachined rotors. if your rotors have a step in them and the pads have not been seated the mush you are feeling is the calipers pressing the pads into the "U" shaped groove and not making much actual contact on the rotor.


when bleeding a system i use a vacuum operated canister(a 2 gallon vacula), it helps pull air out regardless of where it may be trapped, unlike the traditional method of manual bleeding which sometimes won't get to some air pockets.

if the pedal is just mushy it is probably air trapped, if the pedal sinks slowly and gradually then you are just unlucky with junk reman masters.

you may just want to remove the proportioning valve and the 3 way near the rear of the car and clean them out.

Clokker
Clokker
Your threads have been very informative and I plan on trying some of your ideas once I get my brakes to feel normal. But current brakes are beyond mooshy. I remember the brakes being way better then they are now. Currently my brakes could not lock up dry rotted bald 215/40/17 tires stretched on a 17x9. They also have crappy response. As if calipers had a slight delay after jumping on brake pedal or somehow apply progressively.

Ben.
Thanks for chiming in.
I will try to feel for pedal sinking slowly.(while car is off right?) I have been told it is possible to get faulty remans back to back and that I should try a new unit. This is a maybe.

It can't be my pads because these pads and rotors were installed together new. I suspect these the least since they are same pads/rotors that worked way better than now when car ran over a yr. ago.

Proportioning valve and splitter... well.. I will try this first. I will remove these and go to town with brake cleaner.

About the bleeding vacuum pump... I know nothing about using these and will be researching a bit to see how it works.

with the car on, a bypassing master cylinder will be much more noticable with vacuum applied to the booster.

More info that could help identify the prob.

Bleeder valves on the front calipers seem to be in bad shape. I went and purchased a vacuum bleeder. I noticed that bubbles kept coming no matter how many times I bleed the caliper. Did some reading and I have learned air gets through the threads. Well my bleeder valves are super old and are pretty much rusted. The bleeder valves have to be snugged pretty hard for bubbles to not continue coming into the vacuum pumps reservoir. Oh, read about lithium grease around bleeder valve threads and tried it with no success

Is this keeping me from bleeding my brakes properly?

Ben.
The brake pedal doesn't even hold much pressure when car is on, it almost bottoms out immediately. It build a little pressure when it nearly reach the floor.

a vacuum bleeder will pull air as well so it doesn't mean it is coming through the line. i just run about a quart through the whole system starting at the RR>LR>RF>LF wheels in order and then checking progress.

keep at it and hopefully this procedure will help get the air out, because it does sound simply like air trapped in the system.

check the reservoir often, if it ever runs low you have to start all over.

What if I told you the bleeders are letting so much air through next to no brake fluid is comes out.

try cleaning out the bleeder passages with degreaser and compressed air.

if they're that blocked up though then it could be the bleeders or it could be pointing to a restriction somewhere else in the brakes which is where the air pocket is holding out.

make sure you leave the cap off the reservoir also so that it can breathe. my bleeder can empty the reservoir in about 5 seconds so if it is working well it may be creating a vacuum and stopping flow.

I went and tried to run a lot of brake fluid by bleeding it in correct order. rears fill up the reservoir pretty quick. Front left does pretty descent also. Front driver however.. Took me a million bleeds(sarcasm, did not keep count) to get the vacuum pump reservoir 1/2 full. Either way the pedal still feels like garbage.

I think tonight I will buy new bleeder valves for all 4 corners. These things are rusted pretty good in the front and I don't want them to be a worse problem in the future.

probably a good idea, once they're rusty even if you clean them they will get crapped up quickly again.

Faced with your problem and circumstances, I'd junk the whole system and start from scratch.
I'll take your word that the pads, rotors and stainless lines are good, so they can stay.
Rebuild the calipers, it's neither hard nor expensive, use new bleeders and hardware.
Premade hardlines are cheap and readily available at the big box auto stores, I redid my entire front hardlines for @$20.
Tee fittings are also cheap and easy (@$5), if you think yours is gunked up, just replace it.

Considering upgrading the booster/MC?
Well, now's the time to do it.

The point is to arrive at a perfect baseline, you're not guessing what component could be faulty because you just overhauled them all.
With regular fluid flushes and normal pad/rotor replacement you should get years of service from such a setup.

I just remade the front driver hard line, it was suspect for leak. Now there its no leaks for sure. I rebled the system the old way with a helper. Still no go.

Clokker. As much as I would like to do what you suggest, I don't think it's necessary. I have bought some brake cleaner and plan on cleaning prop. Valve and rear T. Although if that doesn't work I will probably do what you suggest.

When cleaning the proportioning valve. Should I remove the big 22mm bolt and clean in there?

Went ahead and took 22mm bolt and spring out. There was a red peice in there that would not come out. I used tons of brake cleaner on it. To be honest it didn't look like it needed it. Either way, I put it all back and bled the system the old way with helper without any success. Still in the same boat.

did you put the new bleeders on?

if you leave the bleeder removed, with a rag over the port and press the pedal slowly does it come out steadily?

Front bleeders have not come in yet. Waiting on those for right now. About the bleeder install. Can I use any sort of Teflon to keep air from going through threads?

On your question/suggestion. Could you be a little more specific? Am I just looking for fluid to come out as soon at the pedal starts being pressed? At beginning of stroke?

i would install them dry, don't worry about the air being pulled through with a vacuum system.

on the other subject, removing the bleeder from the caliper completely opens the passage. just trying to gauge how well the actual port, line and caliper are flowing.

I'm wondering...
How many master cylinders and boosters have you had on the car now?
If there was mixing and matching, did you check the MC>booster pushrod clearance?

Second booster, original and this one, and who knows how many mc's Ive had. The booster to Mc clearance has not been checked.

My car is original 88tII and all I know is my booster is n/a. Not sure if its s4 or s5. I am using an mc. From s4 n/a.

you can check the pedal free play with the car off, it should only be about 1/4" before it starts to feel the slack taken out.

Pedal feel is the first wrong thing I noticed. Even though it always comes all the way back up the pedal is dead for about half to 3/4 of the stroke with it finally getting a bit stiff like 2 inches from hitting floorboard

Update, with more fail.

I installed new bleeders and I also adjusted the booster/mc rod.

Initially when I adjusted the booster rod(longer) and bleed the brakes, the brakes pedal felt like this was it. I had finally found what it needed.
Before rod adjustment, when bleeding the brakes the pedal would be near the floor and when bleeder valve was opened the pedal traveled no more than 1-2 inches. After rod adjustment the pedal felt better while bleeding- the pedal would travel further when bleeder valve was open during bleeding process. The pedal was gtting firm higher in the stroke and was feeling more normal so this led me to believe I was getting close to fixing. I went to warm the car up to test drive it and while the car was on I pressed on the brake pedal and it sunk fast and easy(not bottoming out just travels too easy).. same crap as always.

this really sounds like just another failed cheapo 3rd world country labor rebuilt master cylinder. something to consider is: pedal travel is divided and the first 2/3 of the pedal travel is for the front brakes and the last 1/3 is from the rear brakes, when the fluid can actually compress the springs works against one another and both work nearly equally. you can verify the master cylinder by clamping it in a vice, get some port plugs, bleed it and cap it and then work the plunger, if it even moves more than 10% while pushing it in slowly the master is junk.

Why is it when the car was off it felt pretty normal, but when car was on it all felt like garbage.

Also is it possible to over extend the booster rod? I extended it about 3 to 4 full turns. I did not use any tool.

it could just be due to the additional pressure applied causing it to bypass when it is marginally holding pressure without the booster assist.

extending the rod won't hurt the brake system but if it is extended under normal conditions it can cause the brakes to drag.

you could try jacking the car up at all 4 corners and begin applying the brake until the wheels lock and note which do first, the front brakes should begin locking before the rears do.

if the pedal is sinking nearly to the floor i suspect your problem is solely with the front brakes still or the front brake port/rod/seal inside the master. the hydraulic pressure between the 2 pistons is what actually applies the rear brakes, if the fluid is bypassing inside the master(or has a massive air pocket) it will sink until the spring forces the rear brakes to apply as a backup measure(like a failsafe so you at least have some brakes in the event of a front rod seal failure or air in only half of the system).

it sounds like you can't even do a simple brake test to see which wheels lock up first to try and divide the system aside from the unloaded test above.

i would also physically watch the calipers and make sure all 4 pistons are moving on each caliper, even if just one is seized it will cause all sorts of problems. especially focus on that RF wheel where it is having difficulty bleeding, the piston on that bleeder port may be stuck in and partially blocking the bleeder port.

It seem like system flows well. When I was changing the bleeders it gravity bled good. And all bleeder have a lot of pressure when opened. I will inspect pistons on front caliper tomorrow.

The pedal isn't going near the floor after rod adjustment. But it sinks so easy to the middle of the stroke I could do it with my pinky.

Today I inspected the front calipers to make the 4 pistons were moving.
The inspections left me with some questions.
This is what happened.
When checking the front driver only one piston would come out while other barely or didn't move with descent pressure applied at the pedal. I had to hold the "functioning" piston by hand and had someone apply the brakes to make the other come out. The passenger front was worse than the driver side. With the pressure applied at the pedal now being "hard and as low as itll go", the pistons did not extract at all. After pumping the brake pedal about 3 to 4 hard times one piston came out finally. I clamped that one down and slowly got the others to extract.
Im not expert and do not know if my calipers are trash or not.

Questions.
1.My pistons will obviously do not extract at the same time, what does this mean?

2. The pistons on this calipers might not slide in and out with ease, are they trash?

the pistons won't all move at the same rate but it does sound like they are partially seized by crap inside the calipers.

i would recommend rebuilding them or replacing them off a car that had properly functioning brakes. the GXL and GTU models had the same calipers btw.

i would rebuild, its very easy, and cheap

Your weird pedal issue could easily be the adjustment between the booster>MC.

I'll reiterate the advice I gave two weeks ago in post #12...rebuild the calipers and replace the booster/MC with a matched pair.

at some point, if normal stuff isn't fixing it, you need to start eliminating possibilities.

so rebuilding calipers is a cheap and easy way to take those out of the equation. adjusting the booster to pedal, and booster to master adjustments. making sure all the bleeders are clear, etc etc.

eventually you will find the culprit

I had rebuilt the front calipers about 3 to 4 yrs with Mazda parts. I guess it wouldnt hurt to try it again, its only like 45$ for rebuilt parts. I also have an extra set in the back shed that have been sitting in there since 05'. I dont know if they would be good after sitting for so long even though they had come of a working car. I'll order the rebuild kit tonight.


Im getting desperate. I would hate to leave her at a shop.

My car did all of these things including after replacing pads and MC.

The issue was my front calipers being absolutely trashed. Half the pistons were seized and teh ones that weren't were pitted so bad inside they couldn't be repaired. Buy new Calipers online for cheap and test again.

Also try bleeding the master cylinder itself. Have someone pump it get them to hold the pedal and crack the lines on the master all while the pedal is being held. Do it a few times.

I will look into replacing the front calipers or rebuilding them. I had bench bled the mc so I never did bleed it at the mc. I will try this first since I'm off tomorrow.

Since remain calipers are only 45$, I chose that route instead of rebuild kit. Limited lifetime. So we will see tomorrow when they get here.

OK so it wasn't the front calipers.

I just got done installing them and bleeding them with a helper. The brake pedal quickly sinks all the way to the bottom and has incredibly weak braking force.

Might be time for clokkers advice of ripping a matching pair booster and mc from the same car.

I'm curious though. Why does the front passenger brake line run thought the prop. Valve. Does it even get regulated? If a 2 port mc is used, it is correct to T off the front line?


I think tom. Is a junk yard day.

D'oh.
Neither front line is "regulated", they are merely a reference for the rear line which IS getting regulated.

Before you go nuts, try adjusting the booster >MC pushrod and see if your symptoms improve.

I extended the booster/Mc rod already. I extended it about 3 full turns. Its between 1/4 to 1/2 in. Longer. Read a couple of posts back. It fooled me at first thinking it was improving. But prooved to be same after starting the car. And feeling the pedal.

Are we talking about the same rod?
I'm not sure the FRONT pushrod can even be extended 1/2" out.

I'm trying to visualize and guesstimate how much i adjusted it.
The rod that makes contact with the mc. It was a 7mm.

Yeah, OK.

So, now what?

Idk. I haven't gone to the junkyard and picked up and matching booster and Mac yet. My friend has some sort of pressure bleeder that attaches to the mc filler cap or something. I want to try that.

So I had a friend come take a look. He saw no leaks. We also rebled them,we bled both bleeders on the rear calipers ; he used his technique and got a few more bubbles out of the rears. The fronts had no air bubbles coming out.

He suspects the master and proportioning valve. But again, we have no obvious signs of where the problem lies. I sat in his fc and felt the brakes... and boy.. his are 10times better. His travel like 1/4 to 1/2 inch and the begin firmness. Mine travel a couple of inches of Dead travel and then get barely stiff. When car is off I cannot bottom out the pedal, but when its on the area of dead travel seems to be way bigger and I can bottom out the pedal. I test drove it and tried to apply The brakes aggressively and the pedal just sunk with extremely poop braking power. Even the e brake works like shit; Tried to pull it when car wouldnt slow down. Also, we checked if the fronts apply brakes before the rears and this checked out OK. Also when you pull the e-brake and your foot is applied on he pedal, you can feel the foot pedal move. So that checks out, if it means anything.

You may have a small pinhole sucking in air. Easiest way to find that is with soapy water.

Your pedal feels like that because there is still air in the system. Bleed the master like I said, and if that doesnt work go from there. Proportioning valves almost never fail. I havent seen one go bad yet.

I forgot to mention that we also bleed it at the master. He bled the horizontal port on the front of the master. He said a bit of air did come out.

IF all hardware is fine, the brake booster pushrod is still the secret sauce. If you adjusted a 7mm nut, that's the right thing to adjust. Just to make sure you moved it enough, pull the pushrod back out (you really only need to remove the two nuts for access and not disconnect any hydraulics). Loosen the nut a significant amount until it is over-adjusted. When it's over adjusted, the brakes will drag. You will know when it's over-adjusted after you start the engine and test it.

Then adjust it the other direction until the brakes don't drag but the travel is acceptable. This is the only thing I've ever been able to do to fix the mushy/high travel feeling on FC brakes that don't have obvious mechanical failings. Adjusting the pedal, bleeding everything, etc basically does nothing.