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Discussion Starter #1
the master cylinder and booster where they meet has some fluid leaking between the 2, i can see actual fluid dripping, i add 1/4 cup every 2-3 weeks. if i fill it all the way its very low the next few hours, but stays functional but at low fluid level but at some point the fluid runs out and the pedal goes to the floor with only the front passanger caliper doing most of the work. looks like there is only one grommet there? is this my point of failure? and other things to look for?
no leaks at the pads, ABS controller, calipers, or lines.
 

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Rear seal on the brake master cylinder is most likely the issue. Replace or rebuild the master cylinder.
 

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Discussion Starter #3

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No, that is the grommet to attach the reservoir to the master cylinder. I suggest you just buy a new master cylinder, it's cheaper and faster to just replace the whole thing. Don't forget to prime it before you install it.
 

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Discussion Starter #5
No, that is the grommet to attach the reservoir to the master cylinder. I suggest you just buy a new master cylinder, it's cheaper and faster to just replace the whole thing. Don't forget to prime it before you install it.
i dont see any seals on the replacement cylinders. its just the reservoir and a piece of metal tube... those 2 are leaking????
i also dont see any seal on the actual booster..

is this the problem? the back of the master cylinder? the picture.
40714
 

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It's the seal at the back of the master cylinder that's leaking. It's internal to the master cylinder. Just buy a new/rebuilt master cylinder and be done with it. Buy one with the reservoir and save yourself more grief for install.
 

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The seals are all interior. To replace a seal or rebuild the master cylinder you would have to disassemble it. Which is a pain in the ass, I did it once...in school, a million years ago. It's better to just replace the whole thing.
 

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Discussion Starter #10
okay okay i get it now.i dont even see a rebuild kit, nor do i want to attempt it.
im surprised it lasted this long. im sure theres about 300k of use on it. plus ive towed, and now smash breaks when racing..

im going to order the new unit like y'all are saying, should i upgrade to the heavy duty?
i have the tool to mushroom the break lines from my ABS conversion and could get new fittings thats easy if needed.
 

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Your existing brake lines will bolt to the master cylinder regardless of whether it's HD or not.
 

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Discussion Starter #12
Your existing brake lines will bolt to the master cylinder regardless of whether it's HD or not.
good to know....

the ABS module has different size line ends vs a non abs module.

so i can get a HD unit and it will be a direct replacement?
waiting for response to click buy.
ronbo your the best! thanks to valdrane too!
 

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You may want to replace the booster while you have the master cylinder off. The seal at the front of the booster often fails after leaking brake fluid gets to it (it may take a while for it to fail, or it may happen next week). If you want to cross your fingers and not replace the booster, that's fine.
 

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Discussion Starter #14
You may want to replace the booster while you have the master cylinder off. The seal at the front of the booster often fails after leaking brake fluid gets to it (it may take a while for it to fail, or it may happen next week). If you want to cross your fingers and not replace the booster, that's fine.
i was thinking about it and that replacement looks like its awful. i should have done it when i replaced the heater core... was considering buying the part and replacing when the problem arises. like the new fuel pump i have still in box.
 

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i was thinking about it and that replacement looks like its awful. i should have done it when i replaced the heater core... was considering buying the part and replacing when the problem arises. like the new fuel pump i have still in box.
Boosters also accumulate water (from condensation) over the years unless you're in a dry climate - i.e., Phoenix or Denver. Eventually the water level in the booster reaches the booster's internal valving which causes total lack of boost and strange whistling noises when the brakes are applied in freezing weather (until it thaws out). No practical way to remove the water. Another reason to consider replacing the booster.

Aftermarket boosters are good (consider that it's a safety liability item, so, unlike with a lot of other aftermarket parts, the mfrs have incentive to have reliable design and quality). Some people had to adjust the length of the replacement booster's push rod at the nose of the booster to get proper timing of the boost action relative to the master cylinder piston as the brakes are applied.

If you have to do the push rod length adjustment, it's a minor pain in that it's a trial and error process to get the length just right and the master cylinder has to be removed to make each trial adjustment. But it's not too bad in that the lines to the master cylinder are flex lines, so they can stay connected while the master cylinder is de-mated from the booster. I think either it's rare that the push rod length has to be adjusted or I was just lucky because I replaced the boosters on both of my Concordes, and they operated plug-n-play perfectly with no adjustment.

The replacement process is not too bad. Everything is pretty straightforward and obvious except for how to remove the spring clip that holds the booster input rod-to-brake pedal pin in place. If you don't know the secret of how to get that off, you'll spend a lot of time trying to figure out how to get it off and end up breaking it out of frustration. For $20 to my PayPal account, I'll tell you how to get it off.

It also wouldn't be a bad idea to completely coat the push rod with a light to medium coat of silicon grease as they tend to heavily corrode over the years - to the point that they could get weak (they're threaded and less than 3mm in diameter). You don't want to use regular grease due to the proximity to the rubber seal in the ass end of the master cylinder.
 

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Just kidding about the $20 to my PayPal.

The booster-to-brake pedal clip looks similar to one in the photos below. There's a machined groove around the diameter of the pin very close to the end of the pin. The slot of the clip fits in the groove of the pin and is pushed into the groove until the end of the clip pops over the end of the pin - locking the clip securely to the end of the pin. To remove the clip, you have to catch the end of the clip with a jeweler's screwdriver or similar, and pull that part of the clip axially out from the end of the pin while you slide the clip out of the pin's groove, and when it comes flying out into the air, hope it doesn't hit you in the eye and that you can find it wherever it lands. When everything is together, you can't see how it fits and locks over the end of the pin because there's stuff blocking your veiw of that end of the pin, and you'd never figure out how to remove it unless you'd seen something like that before.

If you lose or break that clip, where are you going to get another one to replace it other than off an LH car in a junk yard? It's not something that could be easily jerry-rugged and that would be reliable.


Clip looks like one of these (can't remember which one looks most like it, but the concept is the same):

40715


40716



Pin has groove near end like this:

40717


You'll need a 1/4" ratchet with extension and 10mm socket to remove the four nuts (inside the passenger compartment) that hold the booster to the firewall. Space is too cramped for a larger size ratchet.
 

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Let us know how it turns out.
 

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Discussion Starter #20
now im digging around my tools / spare parts because i think i kept and end i pulled off from my ABS upgrade. It may be the right size.
the car is tore apart and i cant even go anywhere to get anything.
 
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