Need a new MC which is best?

[aray327]

I'm running a hydraboost with CPP big brake kit. The kit includes their MC which is cast iron with 1 1/8 bore (I blieve). The brakes actually work great, so my issue isn't function it's form.



I hate the way the cast iron MC looks!!! fluid can spill when you check the level and it looks very dated. Plus it's really nice to see the fluid level and to use modern pressurized bleeders that screw on to the new style plastic reservoirs.

What modern aluminum MC with the plastic reservoir will work? I see/hear others using the C5 vette and LS1 camaro MC, but i believe they are both a 1" bore. Would the 1" bore effect the braking much or is there a better suggestion?

[bmiller]

Another good looking option is the aluminum master from wilwood, I picked up a 1 in bore off ebay for quite a bit less than retail. But i agree a late model plastic resivoir is a cheap effective way to go. I've seen people use F bodies, corvettes and s-10's but I don't know the specifics of each off hand.

[cluxford]

I just recently went through the exact same buying decision after a nice (company will not be named) shiny billet MC proved to be a second hand recon piece of crap.

I bought this (1 1/8 bore)



Link to company who makes em
http://www.ssbrakes.com/commerce/det....cfm?nPID=8821

Love it and it has worked flawlessly and looks great


Pic of it on my car with a Hydratech hydroboost



I'm sure I have a better pic somewhere or can walk out to the garage and take a better pic if you need one

[aray327]

that's a good looking MC and the bore size is correct!

But i like the idea of an OE looking MC. I like that the OE style MC doesn't draw as much attention to it. Plus you can't see the level without removing the lid. it's also a few bucks more than i was wanting to spend.

thanks for the suggestion.

[aray327]

Maybe i need to revise my question a bit.

What could i expect if i use a 1" MC on my current set-up? Whould the peddle be too light with the hydraboost?

the last time i post in this section i recieved very technical information. This time i can barely get a suggestion. I know you guys are much smarter than I and can help me out here.

[Apogee]

If you run a 1" bore MC on your hydroboost unit versus a 1.125" bore unit, you should exprience a 20% increase in pedal travel and a corresponding increase in caliper pressures. For most applications, this will result in very touchy brakes and poor modulation, especially considering the fact that you're running a relatively large caliper piston area brake kit from CPP. A good example of a hydroboost unit tuned for a 1" bore MC and smaller caliper piston areas would be the ones used on the late 90's Mustang applications, but that doesn't pertain here since I assume you have the Hydratech kit sold by CPP.

As for master cylinder options, you might check with Paul at Hydratech. He may know of a modern style MC (aluminum w/ plastic reservoir) compatible with his kits.

Tobin
KORE3

[aray327]

Thanks Tobin i will check with Hydratech to see what he has to say.

[a67]

Look at Astro Van M/C's. Many of them ran hydro-boost and use the aluminum M/C's with large bores.

Example: 1996 Astro:

RAYBESTOS Part # MC390321 More Information About this Part Professional Grade; Bore Size=1 1/4" Number of Ports=2 Primary Outlet Size=9/16x18 Secondary Outlet Size=1/2x20

Bob

[Hydratech®]

We are not aware of a conventional late model plastic aluminum standard twin piston MC with the 1 1/8" bore size that will properly interface with one of our brake assist systems at this time. The ones that provide the look everybody wants are in 1" bore sizings, like the Raybestos MC390572, but have had good success with the Raybestos MC390257.

http://www.raybestos.com/wps/portal/...true&langId=-1

This MC uses conventional old school flare style brake line ports with standard GM thread pitches, is a 1 1/4" bore that would work well with the large CPP brake kit, and will fit the brake assist units we provide with the late model / short GM MC pushrod interface. There is one rub though, in that the port sizes are reversed from the typical C3 Corvette type MC that CPP provides, so you would have to rework the brake lines for the different port sizes (or use adapters): Front 9/16" port = Primary / Front brakes & Rear 1/2" port = Secondary / rear brakes. We have also tested this MC with disc / drum and disc / disc aftermarket brake combos to find proper operations. The installation of the 1 1/4" bore MC in place of your existing 1 1/8" MC will provide less brake travel and will require more pedal effort.

Or? We can provide you with the 1 1/8" chromed MC shown on the white Camaro on our home page for $ 149.95 www.hydratechbraking.com (in stock - call to order) Will not change your pedal feel / reponse as compared to what you currently are running, though will give you an improved appearance. If you do choose to put this chromed MC on, you may also consider complimenting it with one of our chromed accumulator slip covers:

http://www.hydratechbraking.com/accessory.html

[nullshine]

How about this one? I haven't had it in my hands to know for sure if it's aluminum or not.

I know someone on here has an Express/Savanna that they can do a magnet test on!
(And tell us which ports go front/rear)

1-1/8" bore
9/16"-18 & 1/2"-20 left side ports
1996-2002 Express/Savanna 1500/2500
Dorman# M390363, GM# 18029955, AC Delco# 174-778


Looking at it now, the body of the master cylinder looks REALLY similar to the MC390257 mentioned above, so hopefully it will mate up to the hydroboost units.

[Hydratech®]

Good find! Here are the online Raybestos details for the MC390363:

http://www.raybestos.com/wps/portal/...ductId=1155735

This is a non QTU (quick take up) standard twin piston MC, and as such WILL fit the Hydratech brake assist units with the short / late GM MC pushrod interface. The GM QTU MC's have a very large rear register size due to having a high volume third MC piston in the rearmost area of the MC, and will not fit (due to how large the rear register is). The MC port sizes discussed with the MC390257 still apply, as this is the same MC just with the 1 1/8" bore size.

Thanks James! We now have options in the 1 1/8" range thanks to your research. Do note that this MC is good inch taller than the typical musclecar / C3 Vette type MC's. With our systems being run at the 6 degree installed angle, this MC will clear the hood just fine with plenty of room to spare, though would never clear with the steep factory type 17 degree upward angled vacuum boosters.

[nullshine]

You're welcome, Paul!

Found that bad boy clicking around on rockauto.com, while searching for a master cylinder like the OP was looking for:
OEM, 1-1/8", aluminum/plastic, to fit hydroboost.

[Hydratech®]

The very first thing to point out about the factory G body hydraulic boosters is that you will need to swap out the brake pedal:

http://cgi.ebay.com/ebaymotors/1985-...item53e441309d

I have seen so many guys trying to run the OE G body units on the vac spec pedals that it makes me cringe (!). The pedal rod connection point is about an inch higher up the pedal on the factory G body hydroboost and Powermaster systems, and installing the G car h-boost on a vac spec pedal spells disaster (due to a very harsh angle on the brake pedal rod going into the brake unit to cause severe linkage binding)(which can fail the brake pedal rod!)

Next, these OE G car units where only used for a five year run ('80-'85), then put out of production due to the internal accumulator function flat out not working (even when brand new, never mind reman). GM had MANY lawsuits regarding this particular model back in the day...

Power level? Just a bit better than a factory vacuum booster (being fed proper levels of vacuum that is).

Summary? Still a decent option, but...

[nullshine]

I see! Thanks.