Master Cylinder Swop

[High Roller Ron]

Ok here it goes....
I have 1977 K-10 that has stock metal master cylinder its needs replacing so I would
Like to replace it with 1981 ( newer ) plastic style resavoir master cylinder....when I do the swop I want to include the brakebooster as well.
So I callled Auto Zone... had them run some years and part numbers thinkin they might interchange.... ( they dont ) according to their computer..... So my question is has any one put the newer master cylinder and brake booster ( 1981 ) on the older style ( 1977 )....
Thanks guys.....

 

[PrairieDrifter]

My question is why? I doubt anyone has done this, since the factory brakes are more than adequate in the 70's. The plastic ones always break off the tabs on the cap anyways..

 

[Keith Seymore]

I tried swapped the plastic/aluminum master onto my Chevelle, back when I was a brake engineer (trying to get a few ounces of weight savings). I went through about a dozen versions and never really found a setup I loved - except - for "L Van" (AWD Astro/Safari; hydroboost). It had good pedal travel, onset of braking, and feel, but the reservoir was so small I had to park at the end of the sloped driveway and jack the rear of the car up in order to top it off. I finally went back to the cast iron m/c and haven't fooled with it since. (Jeez - That was about 30 years ago!).

At any rate - It should be doable. The only thing to be aware of is that for some systems the front reservoir goes to the front brakes; for most of the newer systems the front reservoir goes to the rear (because the smaller reservoir allows for better clearance to the hood). Just keep that in mind as you are plumbing.

Also - some are "Quick Take Up" systems and some are not, which affects the outside diameter of the master cylinder where it goes into the booster. As long as you are using the corresponding booster and not mixing and matching you should be ok here.

Here are the brake charts for both '77, and '86 K10s so that you can compare. You really only have one choice if you go with the '86 JB5 system.

K

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