Master Master cylinder thread

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Master Master cylinder thread

Postby burnouts&rotorblades » Sat Mar 07, 2020 2:07 am

Preface:

I have 2001 Chevrolet Blazer rear axle and brakes. At this time I have the stock Vega front brakes, combination valve, and all lines. I intend to install the same era front brakes on the Vega eventually.

The stock HBody master cylinder will not work because it is designed for a set-up with disc brakes up front and drums in the rear. There are numerous resources that explain why and I do not want this thread to get dragged down with that debate.

The goal:
To find a master cylinder that is a direct bolt-in swap, has the right pedal feel and travel distance to allow for spirited driving (heel and toe).

Keep in Mind:
If we consider maximum braking the point where all 4 wheels lock up at 40mph, then;
A bigger bore makes the pedal harder to move and it will need to move less distance to achieve maximum braking
A smaller bore will have a softer pedal and have to travel a further distance to achieve maximum braking

All part numbers and stats are from the Cardone Website

Stock HBody Master cylinder:
The bore size of a stock All Vega brake master cylinder is .75" (3/4") power or manual brakes makes no difference.
The bore size of a stock 1975-and-up Monza brake master cylinder is .875" (7/8"). Does not specify power or manual brakes.

Alternative Master Cylinders

1972 C3 Corvette master cylinder has a bore of 1.00" for manual and 1.125" for power brakes. The same is true of equivalent Camaro and Nova M/C's.
2002 Blazer Master cylinder has a bore of 1.00"

First I used a 1972 Chevrolet C3 Corvette power brake Master cylinder (1.125" bore):
The brake pedal feel is rock solid. Not in a good way either.
The pedal moves about 1" with a significant amount of leg effort before locking up all 4 wheels. This makes heel-and-toe downshifting impossible.
It did not come equipped to accept the pedal rod.
The lines were the correct size and it bolted to the firewall with no problems.
I would not recommend.

Second, I used a 1972 Chevrolet C3 Corvette Manual brake Master cylinder (1.00" bore):
The brake pedal feel is firm. Slightly firmer than the Wife's 2015 VW Passat.
The pedal moves a very natural 4" before locking up all 4 wheels. Heel-and-toe downshifting is still impossible because the gas pedal is too low.
It did not come equipped to accept the pedal rod.
I modified a 40mm freeze plug to act as a pedal rod cup.
The lines were the correct size and it bolted to the firewall with no problems.
100% would recommend!
Last edited by burnouts&rotorblades on Mon Mar 23, 2020 11:02 pm, edited 7 times in total.
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Re: Master Master cylinder thread

Postby Smiley » Sat Mar 07, 2020 5:34 am

Vega 3/4"
76-80 Monza 7/8"
early S10 7/8"
later S10 15/16"
also early Vega brakes had a distribution block not a proportioning valve.
when using single piston S10 front brakes the 76-80 Monza 7/8" master will be close for manual brakes.

dual piston or big bore metric calipers 15/16" or 1"
1" seems to have a larger aftermarket selection than 15/16"
If you have the 1" on it now then it is time to put the S10 brakes on the front.
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Re: Master Master cylinder thread

Postby burnouts&rotorblades » Sat Mar 07, 2020 12:51 pm

Information pulled from this thread: viewtopic.php?f=10&t=27594

For a .75" bore M/C that is compatible with disc on disc application and has a pushrod, use Raybestos part number MC36300.

https://www.brakepartsinc.com/raybestos ... er=mc36300

Website does not specify the M/C is disc disc application.
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Re: Master Master cylinder thread

Postby burnouts&rotorblades » Sat Mar 07, 2020 1:21 pm

[b]Master Cylinder Pushrod Cup[/b]

Information pulled from this thread: viewtopic.php?f=10&t=27594

There is a pushrod cup that mounts externally to hold the pushrod in. Replacements are manufactured by a company called Inline Tube. P/N INL12439. Like everything else it's available on amazon.

https://www.inlinetube.com/products/inl12439

Another possible option:

cosvega76 wrote:Fred,

When I was using the Monza master in my Vega, I just took a 1-5/8" freeze plug and drilled a hole in in just larger than the pushrod to fit through. Then I siliconed it (cup side toward the master cylinder) on the boss of the master cylinder. I now use the pushrod cup that I found when I was scrapping a '76 Cosworth. It fits in the hole in the firewall, and the pushrod slides through it.

Chuck
1972 Vega Wagon; 283 V8, 4 speed video 1
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Re: Master Master cylinder thread

Postby cosvega76 » Mon Mar 09, 2020 9:39 am

When I first got my Vega, it had the solid front Vega rotors (although they were Don Hardy 5-lug), stock Vega calipers, and Camaro-style 9-1/2" x 2" rear drum brakes. Since the front calipers were small, the Vega master worked well. However, it's hard (especially now) to find aggressive performance friction for the stock Vega calipers. And then, there really isn't enough rotor there for aggressive driving. I didn't need to change the master until I upgraded to the S-10 front brakes and calipers.


Chuck
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Re: Master Master cylinder thread

Postby Monza Harry » Thu Mar 12, 2020 9:32 pm

Chuck I for one am glad that you are still hanging out here, even though you are now without an H-Body. :cry: Once an H-Bodier always an H-Bodier Thanx Harry :th:
I'm not a hoarder I'm a preservationist 78 Monza Spyder (~Soon(ish +/- I guess) To Be 2+2 with Spoilers)
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Re: Master Master cylinder thread

Postby burnouts&rotorblades » Fri Mar 13, 2020 3:12 am

cosvega76 wrote:When I first got my Vega, it had the solid front Vega rotors (although they were Don Hardy 5-lug), stock Vega calipers, and Camaro-style 9-1/2" x 2" rear drum brakes. Since the front calipers were small, the Vega master worked well. However, it's hard (especially now) to find aggressive performance friction for the stock Vega calipers. And then, there really isn't enough rotor there for aggressive driving. I didn't need to change the master until I upgraded to the S-10 front brakes and calipers.


Chuck


I have the front brakes for a 2002 Blazer on the shelf. I'm just waiting on parts before I get busy on it. I needed to do the master because of the rear disc brake upgrade. The car was just not safe on the road with the stock master still in there. The pedal would go nearly to the floor before locking up just the rear. People driving in Las Vegas are just too crazy on the roads to have questionable brakes on a car I take the kids in.

I have learned an immense amount from this forum. Most everything in this thread is just repackaged information from other parts of this forum. It was mostly available in other threads but a bit buried and disjointed. I only wanted to put everything master cylinder related in one thread and make a collection of notes for myself to document my own mistakes and eventually, hopefully, success. So, thank you guys who have commented and keep the information flowing. I'll edit/carry information up to the initial post as the thread gets longer to make sure it's as succinct as possible.
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