bought a new MC

[shelby987]

I decided to go out and buy a new MC while doing my PB install. I went to NAPA, and they sold me a new master cylinder....that is different from the parts one that was sold to me with the booster I bought. The MC I bought has a larger front resevoir and smaller rear resevoir than the original. Will this work? Also, its not a rebuilt, so there was no core charge....which meant that bad boy cost $50......advanced quoted me $15 plus a $12 core.....I would rather go with something that will work better....and I am not going to cheap out on $35 where my brakes are concerned....but if I am better off getting a rebuild, I would rather put that $35 to filling the tank.
Any advice would be appreciated.

[Palf70Step]

Sounds like a MC for one with disc brakes. Will it work? I would imagine it would, but I am not positive the fluid resivior would be balanced enough.

[shelby987]

well, I am planning on putting a disc brake axle in the front....and possibly putting discs on the rear down the road......

[truckdude239]

umm my disc and drum mc the resevoirs are the same size lol of corse it came from advance auto but it was the same as what i had

[69-350]

your larger reservoir will be for the disc brake part. Since most vehicles have them in front, obviously, the MC will have a bigger forward reservoir than the rear one. If you plan on doing discs in front, it should work for you. But if/when you decide to put discs in the rear also, you'll have to find a new MC with two LARGE reservoirs for the two disc sets.

And you really should have a larger reservoir for your disc brakes than your drum. Mainly, this is because you only need a little bit of fluid for the drums, since they adjust themselves by the self-adjuster, whereas the disc brakes must go farther in once the brake pads start to wear down, to compensate for the lost friction material, thus requireing more distance to be travelled, which is why you always have more brake fluid for your discs than your drums. Therefor, if you're using a drum's reservoir for your discs, you're asking for it.

[Longhorn Man]

69-350 hit it right on the head.
A couple things to look for.
Make sure the brake line fittings are the same on your truck verses the new master.
The discs take way higher pressure to work than a drum, so in all reality, you may have VERY sensitive brakes.


I would go get my 50 bucks back, get a cheapie reman unit (since it'll be temparary anyways) and then go fill up the tank.

[69-350]

thanks, Longhorn.
and yeah, don't forget fittings and stuff like that. And yeah, like he said, I forgot to mention how touchy discs are over drums, whether stock or added.

And I would just redo the MC. If you know what you're doing, it's actaully really easy. As long as you have a small enough hone, you should easily just stick it in there, flick your drill over, hone the one part of the MC out, and put your cylinders and spring back in (you'll want to buy a new set of those things, a rebuild kit should have em) and that should about cover a good chunk of the master cylinder rebuilding.

If I get really ambitious, I'll probably retouch on my old skills and rebuild the MC that's on my parts truck. Anyways, back to the subject on hand... Rebuilding something really isn't generally hard, especially with brakes. You basically hone stuff out, buy a rebuild kit with cylinders, springs, seals, etc, and stick em in. Also, while you're doing that, I would rebuild the wheel cylinders in your drums (and while you're at that, it's a good idea to check your brake shoes and springs, since shoes wear down, and springs can get damaged or wear and fatigue out) So just my little shpiel on brake safety and easiness.

That reminds me... I've already replaced the shoes on my front brakes, I really should replace the ones in my rear drums... even got a couple kits with seals, cylinders, and springs for my wheel cylinders...