AreExSeven

Ok, since most people probably don't know the background, I will explain that first.

March of 02 my motor popped. I bought an atkins rebuild, but before I put that in, I wanted to paint my engine bay, so I removed EVERYTHING from the bay, including the brake system. I painted, put everything back together, and dropped the engine in. This was about 3 months ago.

I got the car running and tried to drive it, only to find out the brakes weren't working. After inspecting the whole system, I found that the abs pump was leaking bad out of one of the connectors to a line, so my brakes didnt have any pressure. I decided rather than fixing that, I would just remove the ABS all together, since I don't like it anyway. I went to the Junkyard and got the 3 main metal tube brake lines, a proportioning valve, and the brake booster from a base model car. I rodered a brand new non abs master cylinder from mazdatrix. I did the whole conversion, replacing all the parts, and leaving the stock calipers and lines.

I re-bled the brakes and tried it out. No leaks! But the pedal seemed to lack stiffness and I could not lock up the brakes no matter how hard I tried. The pedal also engaged very close to the floor rather than up top like it seems it should.

So I thought maybe my lines were bad, so I got some SS braided brake lines from mazdatrix, and did the same procedure. It is a little better now, but I still can't lock up the brakes.

One other note I should point out, is I was doing this myself, and used SPEEDBLEEDERS. Those little one way check valves that allow you to bleed the brakes yourself. Has anyone ever used these, or believe them to be inadequite, possibly letting air back into the lines causing my squishy brake feeling?

Im in a bit of a predicament here, because my engine has maybe 4 hours run time and less than 50 miles on it, so I don't want to take it to a brake place where someone else will be driving it around, in fear of over revving or something. And I don't want to drive it around to put miles on it without fully functional brakes.

Anyone who has any idea of what could possibly be causing this problem, please let me know. I am willing to try pretty much anything to fix this.

Thanks, and sorry about the long post!

Gene

iTrader: (1)

It's possible but unlikely that you have a bad master cyl, even though it's new. Are there any fluid leaks? The non-abs master is a smaller diameter and thus has a longer travel than the ABS one, but it should still feel ok and lock up the brakes. Even though you have the speedbleeders, its possible that one stuck open and allowed a back-flow. Go to peboys and get a one-man brake bleeding kit, it's a little bottle with a hose and a check valve, and the one I have even has a little magnet so you can stick it to the brake disk. Mine cost like $3.99. I have the speedbleeders too but it's nice to have this also.

C. Ludwig

iTrader: (27)

You didn't mention that you bench bled the MC before you put it all together. That could be your whole problem. I've used speed bleeders a bunch and never had a problem.

Chris

specRX7_22

ok im a first gen guy.... but ill put in my 2 cents anyway.....

same problem last year... soft pedal. i had speedbleeders on, thought that maybe that was the problem but it wasnt. replaced the master cylander 3 times, soft pedal. well actually, when i would finish, the pedal was solid but as soon as the car would move, back to soft pedal. already had braided steel lines. rebuilt all 4 calipers... nope, not the problem. gravity bled it, etc etc etc.

the problem turned out to be the power brake assist booster. the last damn thing i tried and that was the problem. i hesitated to try becuz ive never heard of anyone having a problem with it. i really dont know much about 2nd gens, but i hope i helped, or at least gave you some ideas.

--eric

rotarygod

iTrader: (1)

Which model car did you get the non abs brake lines from? If it was from an '86-'88 base model (4 lug) the front lines were physically smaller than the other cars (5 lug). I had this problem when I did the 4 to 5 lug conversion. Also did you replace the brake booster line with one that doesn't have the one way valve? You'll never develop pressure without it. Thats all I can think of.

Gene

iTrader: (1)

Hmm wouldn't a dead booster give a very stiff pedal? If I hit my brake pedal with the motor off the pedal is super-stiff... the system is also designed to allow you to stop the car in case of a booster failure...

I had forgotton about bench bleeding the MC... that could be his problem right there.

AreExSeven

Lol. Ok, alot of good stuff here.

First things first.
I got the lines off of a 4 lug base model. They all fit, and appeared to be the same size as the ones I had prior. But maybe they aren't.

When I put the brake booster on, i just cut the old rubber hose, but made sure I left the valve/pill or whatever in the tube. Did I need to remove that?

And what Is bench bleeding? Never heard of it, so I doubt I did it

Thanks for the help guys!

Cwaters

The FSM should have the procedure for bench bleeding your master cylinder. It's how you make sure there isn't any air in the works before you put the thing in the car. Sounds like this is your problem.

Cory

AreExSeven

So is it possible to remove the air from the MC by just bleeding the brakes for a long enough time? Or do you have to bench bleed it?

specRX7_22

i dont think so, because the booster helps push the piston into the master cylander, therefor lessening the pressure you have put on the brake pedal. so if the booster weren't working properly, it would NOT help push the piston into the master cylander and therefor you would need more pressure on the brake pedal to make up for the booster's part, right?

--eric

eljefe62

You can keep bleeding the brakes and eventually will push the air through w/out bench-bleeding th MC, but it takes awhile
had to do this a month ago, took about 5-6 bleeds before gaining pressure again
make sure the MC is full after every time

eljefe62

you have to push the air through the whole length of the lines, which is why it takes awhile

specRX7_22

i was questioning what i wrote 2 posts up, and i realized that im wrong. yes, gene your right... a dead booster would cause for a stiffer pedal. however, this was STILL mysteriously the problem... so i dont know.

--eric

AreExSeven

Ok, so with speedbleeders, appoximately how many pumps of the pedal until the air would be cleared out? Doing one corner at a time of course.

eljefe62

dunno, maybe 20-30?

opelbits

iTrader: (5)

I have seen instances where a brake booster can cause a weak pedal. It happened on my mom's Yukon. The pedal had a weird firm at first then sinking feeling. Just like my 87 RX7.

Did you adjust the piston in the booster to fit the new master? This is my suspicion for the soft pedal I have.

specRX7_22

what i do is.... 2 pumps, and hold for a few seconds. that seems to be plenty of pedal. and if you can still see some bubbles coming out of the hose, then pump a few more times until its solid fluid.

and to opelbits... yes i tried adjusting the piston. it was a strange that the booster is what fixed it, but its a solid pedal now, not quite like it used to be tho.

--eric

AreExSeven

Hmm. I never really thought of that. It could be that the piston isn't pushing far enough. That would also explain why it engages so close to the floor.

AreExSeven

Ok, Little Update here:

Went and checked the piston, and it was fine. I went to Kragen and got one of those little one man brake bleeders that Gene suggested, and tried it out. I found out it was because of my master cylinder not being bench bled.

I hooked up the clear tube and watched the fluid coming out of it and for about 5 pumps on the front brakes it was solid brake fluid coming out, then after that lots of air bubbles. Same thing on the back but more like 20 pumps. Now they are all bled and the pedal can actually lock up. I love it.

Thanks for the help guys!