Master/Booster upgrades?
 

My master has development an intermittent leak between itself and the booster...I only notice brake fluid drips on cold/humid days, but otherwise it's hold pressure fine.

I'll have to replace it soon, or at least the gasket. I figure while I'm at it, if there's any upgrades would it be worth my while to replace it with such?


so, comments?

Myself and my car have had no issues since 1993, I don't see how an upgrade would be worth it unless I consistently did more track days, and really got to know my brakes. And their faults.

So I guess the better question for you, is if there's anything you don't like about your brakes currently. Ignoring leaks.

too much front bias and too scared to put a wilwood valve back on with the brass fittings, and too cheap to buy another and get the TSE steel fittings for it.

I just figured if i have to remove it, if there's a prefered master/booster combo, I might as well do it.

An 01-05 master and booster have found their way into my car. Based on FM's research, the 02(and probably all NB2) non-ABS prop valved have the least amount of front bias. I have that setup.

Thanks for that comment, Bryce. I'm in the same boat as Brain right now.

I figured since I'm going a brake swap, might as well fix my leaky parts, too.

Preferred master/booster combo is a sport master/booster, plus a TSE prop valve. ;)

Larger bore on the sport master is beneficial to pedal feel, and you need the sport booster to run the master. You will have to tweak some of the brake lines as the sport master's ports are located in slightly different locations.

This is pretty chock full of info of models and master cylinders:
http://forum.miata.net/vb/showthread...t=brake+master

This lead me to a sport brake upgrade on my 99 (stock MC + booster). I like everything the way it is, but it wouldn't kill to have a slightly stiffer pedal from a larger MC. I think I'll end up doing that relatively soon.

while we are on topic, whats the best way to test for a bad booster?

ok yeah, i pulled the vacuum line off the booster, right at the master.

If I suck it off, it doesn't ever build vacuum...I can hear it vibrating a gasket of sorts and pulling air in behind the booster somewhere. I wish i had a real vacuum pump, but I'm sure it's bad...however, the tests with the pedal seem to be okay.

if i pump it without the motor running, it firms up like crazy, feels awesome. turn motor on it drops a little.

but with motor running, it never really firms up, if i hit it in a panic, it will be firm...but otherwise i cant build the pressure up.

when i turn off the motor holding the pedal, it seems to hold the same spot....but it's hard to tell as i can actually get the pedal really low...but it may be dropping ever so slightly.


what say you?

See if it holds vacuum?

see next post. i can make it hold a tiny bit, sucking and putting my finger over line.


but it can constantly "pull" vacuum, like it's not building more than 60-40kPa. and i can feel like there's always more air to keep pulling out. and i hear it leaking pretty much...

:giggle:

If its not holding vacuum, its junk. See if its pulling air from around the master though.

it sounds like it is... will try to vacuum pump it tonight.

Replace it and see if anything changes :giggle:

nice. well played.

Sport master crew signing in...it's bauce as ---- if you like brake torque.

I haz said sport master/booster on our parts car if you needz

I was thinking about doing this and what's the best way?

Sport brake master only has 2 outlets, vs 3 on the other ones. So you AT LEAST need a tee fitting. Finding a tee in M10 45 flare is near-impossible. So I was thinking, since you need to make your own brake lines anyways, does it make sense to use different size ends? e.g. 10x1mm on booster side, then a more common fitting on the other end? IDK!

oh... hrm... is that the case? the sport only has 2 outlets? I know mine has 2 for the front, and the rears go through the bias valve of a third.

ABS sport brake masters have 2 oulets, which would require a tee for the front lines. OR you can get a non-ABS sport brake master which has 3 outlets and you hook them up just as they were on the old master, the ports just moved around a little bit.

Easy answer: buy the right part in the first place and get a non-ABS sport master.