Erifx

I have 1985 RX7 Manuel GS 12a. My brakes don't really work until I have pressed them 2-4 times then they brake decent. I have replaced the master cylinder and I also don't think I have loosing pressure on the brakes when pressing down. I was thinking the booster?!?

Siraniko

iTrader: (13)

do you hear swoosh or noise on the booster when you step on the brake pedal? how did you bleed it? bench bleed or full bleed it starting with the longest run (I cant remember if its the left or right rear), last is the DS brake. I dont do bench bleed as I like to make sure that the entire system has a clean and non-contaminated fluid, it takes a little longer but not bad when using a power bleeder

Erifx

Yes I hear a slight noise coming from the booster?

Siraniko

iTrader: (13)

did you inspect the booster's diapram when you remove the calipers? if its the original and prior master cylinders bad seals, there is a chance that fluid leaked through the booster and damaged the diapgram

Erifx

I just read that if my brakes are still not hard to press or I can not stop the car with out the booster is has to be something else...? We just bled all the brake besides one brake due to a tap out bit broke while trying to get the broken bleeder valve out. I know I need to replace that once but my other brake should stop the car a little with out pressing it so much right?

Erifx

I did not inspect the seals, I well have to, but I was hoping to see if it was broken with out taking anything apart, because of work and stuff I am tightly scheduled.

Siraniko

iTrader: (13)

true about bad booster; if its not the booster, you need get an extractor to get the broken bleeder out and replace it. that could be your problem also.

Erifx

Thank you but, what I was saying is I should still be able to brake with 3 working bled brakes right?
Also if it were a bad booster I would jut not be able to push down the brakes hard enough right?
I just kind of confused on all this because it does not make sense to me what is going on. Also I am not loosing any brake fluid...

CobraStngSVT

If your not losing any fluid than it has to be the booster. Like Wacky said check your diaphragm. Otherwise I would say air in the lines (but since you said you bled them I would go back to the booster).

Erifx

Thank you I well try that

t_g_farrell

iTrader: (1)

Air in any of your lines will comprise the system and may cause you to need to pump
up the brakes. Also, the air tends to migrate to the top of the system over time
and ends up around the master.

Fix the broken bleeder and then evacuate the master reservoir with a turkey
baster or equivalent tool. Then fill it completely with clean fluid.

Then go to the longest brake line (right rear usually) and bleed. I usually
gravity bleed at first and then go around and pressure bleed with someone
pumping the brakes. Make sure you always keep the master topped off, never
let it empty or you will defeat the whole purpose and have to redo it all over
again.

Make sure you work RR, LR, RF then lastly LF. This will make sure you have
cleared all the lines of air.

If your still having issues then make checks of your vacuum line to the booster.
Make sure its not leaking. Make sure the restrictor is on there and working.
If you still suspect the booster theres some more booster specific diags you
can do to test it. Don't remember them offhand but search on here, its been
talked about before.

83Limited

Let me get a couple of things clarified so we can tell what part of the brake system isnt working properly....you do have functioning brakes that will stop the car, correct? The pedal is just hard to push? Or is it if you push the pedal you have no brakes and the car will not stop? Trying to get clear as to whether you are saying its too much effort or the brakes are non functional. If you needed to bleed your brakes due to air in the lines and only bled 3 brakes, then you more than likely still have air in the system. A stiff pedal is usually not an indication of air in the lines. If the brakes are "working" (the car stops) and the problem is effort applied to pedal is excessive, then you more than likely have a booster problem. The brakes will function without the booster, just the pedal will be a good bit harder to push....

clykins

iTrader: (1)

You need all 4.

NCross

iTrader: (18)

Remove the proportioning valve and make sure it is clean inside. Make small adjustments on your brake pedal assembly to assure you have proper clearance.

I had this problem on my 79. After I did the above mentioned steps I unbolted the cylinder from the booster and bled it with a phillips screw driver by pushing it down the chamber so I knew I was getting full travel of the cylinder. I placed a full glass jar (old pasta sauce jar) of fresh brake fluid and a tight fitting hose running to the bleeder valve (cracked open). Place the jar above the height of the caliper, but below the cylinder (gravity reasons I guess). Continuously press and release the screw driver all the way down the cylinder over and over like 50-75 times. It will suck and blow air bubbles for a bit until the air is displaced into the glass fluid jar. Do this on all bleeder valves 2-3 times and I guarantee you'll have the sharpest brake pedal ever.

Speeder165

iTrader: (7)

A good thing to do also is put some heavy grease around the bleeder screw. Will insure that no air gets sucked back into the lines to cause you headaches.

Siraniko

iTrader: (13)

thats a good idea, never thought of that. grease around the bleeder screw before cracking it open.

Erifx

Sweet thank you guys! I well be trying this on Monday morning i well let you know ...Thank you

NCross

iTrader: (18)

Patrolium jelly or bearing grease works fine. Forgot to mention that.

Erifx

I got one of those one man bleeding kits, so i hope that well work. My plan is to bleed each one to heck.

83Limited

Be sure you start at the farthest away brake and work to the closest.

Erifx

ok i only had time for one brake due to the girl at the store handing me the wrong bolt and my transmission almost falling out, but the transmission is fixed. we taped a 7/16 i think. The brake were really good but they seemed to go back to almost what they were with in a day of being used.

CobraStngSVT

Just by bleeding them again? Sounds to me like air still if it went away and came back like that.

Anyone else agree?

t_g_farrell

iTrader: (1)

You still have air in them brakes and bleeding just one isn't going to fix it.

Slow down, take a breath, and then do all the wheels in the right order and
you should be good unless its a booster issue.

83Limited

When bleeding brakes to purge air from the system you need to do all 4 brakes. Start at the farthest brake away from the master cylinder and work to the closest. The last one done should be the drivers front brake.