Bigmotoxer

I was having trouble w/the front and rear brakes stopping equally. I've bled(didn't help), looked for any leaks(were none),changed master cylinder w/a new one, then changed equalizing/proportioning valve and booster at the same time.
So I go to bleed the brakes and notice that I start pumping the pedal and it starts to get a little hard or at least feeling some pressure, just as I'm about to hold it so my bud can crack the bleeder the pedal just slams to the floor. So I do it again and it starts to build tension on the pedal and all of a sudden bam to the floor.
So feeling as if I have eliminated one problem but creating another*very angry*!
Any thoughts?

Bigmotoxer

what would cause this?

Bigmotoxer

Have I been black-balled, hehe? I just came back inside to see if I had any direction/advice on brakes, so I'm going back out, I'm not going to sleep tonight until I figure this POS out. Suppose to go south tomorrow and wanted to drive my 7. After replacing intake gasket and o-rings this morning(which the rear water port was completely clogged...no water running through it at all)whew! O-rings were broke too. I noticed something was wrong when I started blowing white smoke and had anti-feeze on top of the motor where the intake connects to the engine. It left me stranded at the Post Office, got it bak home fixed intake, now need to fix brakes any input would appreciate and almost pay for at this point because I'm feeling a little pissed right now, like my car hates me or something...My partner Bill knows all about this crap but is going out of town so in need HELP! please.
Doc, Trochoid, wulff, and all you other gurus please throw me a bone.
Or am I in the wrong section again

RXnos1200

iTrader: (24)

I'd check and see if you have air in the system. Hook up a hose to the bleeder valve and get a bottle with some fluid in it. Stick the hose in the bottle with the fluid so that the end of the hose is below the fluid line. Crack the bleeder valve and have someone press the brake pedal. See if you have air bubbles. If you do then keep on bleeding till it's gone. I had to bleed my system 3 times when I changed the master and my steel braided lines on the 7. Good luck.

85rotarypower

1st gen brakes are known to be problematic. I've got a problem with my brakes where the booster seems to be providing too much boosting action. The brake pedal is quite firm when the engine is not running, but I can put the pedal on the floor with the engine running. I know I need to bleed the brakes again as there probably is a little air in the lines, but I don't think this is the whole cause of the problem. My problem lies in the brake booster I think.

Sgt.Stinkfist

iTrader: (6)

have you gravity bled yet ? open all bleeder screws and just let them drip, while making sure the master's fluid level doesn't get too low. this will help get the air out of the system a little faster, and w/ all the new parts, i suspect there is a good amount of air in there now. I would also avise on getting a vacuum bleeder, whether its hand pumped or compressor driven (makes bleeding a 1 man job and a hell of a lot easier)

Rx-7Doctor

iTrader: (13)

Did you bench bleed it first or just throw it on a start bleeding?

Also did the fluid reservoir go down at all during your attempt to bleed?

trochoid

iTrader: (6)

Suddenly dropping to the floor sounds like a seal in the master is failing or there is a leak somewhere that takes a bit of pressure before actually does leak.

Bigmotoxer

85rotarypower Thanks as always bro, I've found no reason for the problem as of yet and through the constant profanity I will find something tonight. Thanks for the input, i did not know that the 1st gen brakes were problematic, at least that makes feel better, why? I have no idea but it does. The only thing that isn't NEW is the booster but it came off of a 7 w/20,ooomiles. ?Somehow I believe it's the booster seing how the master is new, the proportionating valve is also new. I couldn't have gotten alot of air in the lines doing this change because all bleed valves were closed and the only air introduced to the lines would have been directly at the master/valve.
I expected to have to bleed that air but I can't because once pressure builds on the pedal the pedal just slams to the floor. When I'm bleeding by myself I have a small one way check-valve off of a dirtbike gas-vent hose so it will squirt b fluid but won't alow air to draw back in(it's genius,lol), just wish I could get to that point(point of bleeding), i've been doing brakes since I was 12 but I'm feeling stupid on this one. Let me ask, when the car is running should I be able to hear a vacuum inside the booster, because I do, a small sucking sound , sounds like it is coming from w/in the booster...normal? no?
The booster I'm using is from a manual tranny, wonder if that makes a difference, like a difference of pedal travel or something and once I go down w/the pedal maybe too far it's ..uh. I dunno, just a guess.
i'll keep brain-storming, and check back shortly
Sgt.Stinkfist, thanks.
RXnos1200, yeah when I first refurbish my brakes I went through 2 quarts of b fluid to make sure I got out all air, especially the rear, thanks for the reply.

Bigmotoxer

No bench bleed Doc, i installed, filled w/fluid and pushed the pedal down slowly 10-15 times, pedal went down easy so I figured it was good to go?
No the fluid resivior did not go down which is the ONLY reason I suspected the NEW master but want to believe it is the booster because it's used, but othing says a master couldn't be defective. It was in a bag for 10 years, new in bag! so...?

Rx-7Doctor

iTrader: (13)

The booster cannot cause the pedal to go to the floor. If the booster was not working you would just have a very hard pedal when the engine was running.

I would recommend seperating the systems. Meaning disconnecting the lines from the master and bleeding the master while hooked up to the booster.

Bigmotoxer

Yeah I think you and Doc are heading to the same diagnosis, which is going to break my heart if you're right, I hate my life! when you say "takes a bit of pressure before actually does leak" it really drives it home because that is exactly what is happening(I wish there was a "smilies icon" to display my feelings on the matter but there isn't one,lol.

Bigmotoxer

hmm. hence bench bleed first? This would be the same principal correct?
I'll try that right now, and it better work Doc! or else...or else we'll try something else,lol. jk brother.
Thanks, seriously 'cause I've been about to loose it today.

Rx-7Doctor

iTrader: (13)

Well, If you get good pressure at the master then the problem is elsewhere.

Bigmotoxer

Ok I just did it. I removed all lines on the master(all three), crancked the car pushed the brake pedal which feels good as far as the boost goes, except every 5-8 pumps I get that slamming to the floor thing...BUT out of about 40 pumps I didn't get one damn drop of fluid to come out of the master!

Bigmotoxer

I'm thinkign about taking it off and taking it apart, uh like right now..or in a minute, I need a beer

Rx-7Doctor

iTrader: (13)

.Normally you would put fittings into the 2 main lines with hoses that run back into the reservoir. The 3rd or lower one would stay blocked off completly.
I have never tried to get pressure out of a master with the lines completly open.

Bigmotoxer

Can you elaborate on that? "2 main lines" meaning the two facing the engine? And the "3rd or sensor" would be the one on the bottom?

Rx-7Doctor

iTrader: (13)

Disregard that statement. The sensor is not pressure feed. All lines are for brake system being seperated thru the porportioning valve.
Try leaving 2 of the 3 hooked up and have someone else pump the brakes while you hold your finger over the exposed open fitting.

Bigmotoxer

too late, haha..Ok I'll try this one

Bigmotoxer

crap, doing same thing...I think it's the master. I'm going to put the old master back on in the A.M. and see if I get the same (pedal dropping to floor). I do think it's the master, if the old master stops this, I'll open the new one up and see what is really going on. Bill has all the seals, ect, i can rebuild it. I guess setting on the shelf for 10 years aint good,(if in fact the master is the culprit)???. Thanks for stayin' up helpin' me out Doc...and to everyone else.
LaterZ

Bigmotoxer

I took the master off(the new one)and the plunger inside is setting like half-way back. The old master is like it's suppose to be... the plunger is all the way out and has resistance all the way in while pushing it in w/a screwdriver. I'll put it back on a take the NEW one apart to see what's up.

7aull

iTrader: (2)

Hey Bigmtxr- make sure you keep us posted on the final fix!!!
I dropped a "new" (not OEM, aftermarket) Br Master in my SA last summer - does not engage till near the floor - so I'm betting its crap too. unfortunatley, mazda no longer sells these new, so we are stuck with aftermarket units...
Stu Aull
80GS
Alaska

trochoid

iTrader: (6)

If the new master sat on the shelf for 10 years, I would be really really suprised if it was still good. Without being bathed in brake fluid, it's bound to dry out, develope a 'set' in the seals If the piston is not coming out all the way, then the seals/piston are stuck, probably leaking and who knows the condition of the spring.

I would order a new rebuilt unit and quite messing with the dead new one.

Bigmotoxer

I'm back, thanks for the responses, well here's the dealeo. I took the master apart, seals were new, no corrosion on the aluminum pistons but cylinder had surface rust from sitting.
The fix; My partner Bill has ever master cylinder part under the sun new in Mazda bags, SO...There are two pistons inside the master cylinders' cylinder so first remove c-clip...then I pulled out the primary piston, then removed the phillips screw underneath the master and removed the secondary piston out of cylinder. I used a small two stone hone, and honed with some brake clean briefly, then honed w/brake fluid until cylinder was smooth but only honed as much as was needed. Then on the pistons I pulled off all the seals(you have to stretch the seals over the flanges on the front of the pistons and stretch the new ones back on(note direction of seals before removing sos not to get 'em backwards). On the rear of each piston(secondary and primary)you have the springs...one will just pull off and then you can remove the rear seal and replace, the other piston has a long phillips screw going through the center of the spring that you'll have to unscrew to replace the rear seal on that piston...then reassemble.
Once you're done w/this over-rated project put a thin layer of grease on seals and re-assemble just as you disassembled(the piston that goes in first when reassembling will have to be pushed back w/a screw driver slightly to be able to screw the phillips screw back in properly, the screw holds the piston back and leaves it w/very little travel then the next/last piston goes in the cylinder and it's spring sets right on the face of the piston held back w/the screw). And you have a simple re-build. There are three types of seals you'll need for this simple rebuild(well it's simple now that I've done it...actually a retard could do it if they follow the right steps).
Never use brake clean or any solvents to lube the seals and NEVER leave brake clean or solvents in the cylinder or on any of the seals including the reservoir cap seal, brake clean seems to swell the crap out of these seals(learned the hard way on that one).
So w/master cylinders now I'm all like
If anyone needs some seal sets(factory Mazda)let me know and I can send you some for a small fee...I know Black Dragon has rebuild kits for $19.95 or something and I'll bet they're tawaniese made but I don't know that. Rebuilding to me is way better than aftermarket master cylinders, or at least that's what I think now, a week ago I might have had a different opinion.
Later bros