Replacing or Upgrading the Brake Master Cylinder

g60mcicon.gifATS Technote: How to upgrade, or replace your Master Cylinder.  This technote shows the install of a 22mm Master Cylinder. This upgrade is a must if you are installing larger brakes, such as the 10.1″ 16v setup on an older car.

 Deciding that I was going to convert my brakes to a 16v setup, I had to find a better Master cylinder for my car to handle the new bigger brake system, after much debate and finding information on the subject, I discovered (thank you Masun Dixon from Scirocco.org list) that the 1990 G60 NON-ABS Master Cylinder is the same size has the Scirocco 16v, (it being 22.2mm instead of 8v 20.4mm) and considering that the G60 M/C can be had at a lower price (new part) than the Scirocco 16v M/C I opted for the G60 M/C for my car.

Useful Part Numbers:
Corrado G60 Master Cylinder: 357 611 019 B
Scirocco 16v Proportioning Valves: b 533 612 151 A

in a first step I removed my Eurosport upper stress bar to give me more room to work with, if you have your coolant bottle on the driver side (mine was relocated a while ago, see tech note posted previously) you will need to move it also out of the way.

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empty the brake fluid from the m/c brake reservoir.

02_mc_removefluid.jpgDisconnect your brake lines from the master cylinder

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Here we see I removed the reservoir to access the rear passenger side last line, makes it easier that way and since you need to transplant your reservoir to the new M/c, you might as well.

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Remove the two nuts holding the master cylinder from the brake booster. Clean the area of debris that might of collected around the booster-M/C access hole, and spread a thin layer of brake fluid around the edge of it (this will help seal the new M/C rubber seal on to the booster on installation and prevent leaks of air.)

Master Cylinder Removed

After rinsing the reservoir with some brake fluid to get rid of any deposits in it, I placed the new G60 Master cylinder in a vise, and use a thin layer of brake fluid around the two rubber seals atop it, and worked the reservoir into it (using slow rotational movement you will feel it “sit” itself properly inside.

Bench Bleeding the Master Cylinder

Install the Proportioning valves (I used 16v ones) unto the new M/C, I used a bench bleeder kit, and block off the proportioning valve with the two screw provided for this purpose. and ran the other 2 lines to the master cylinder, poured some fluid into the reservoir . and using a long screw driver into the connecting shaft of the M/C we pushed slowly in and out the cylinder of the M/C.

Bench Bleeding 2

My Friend Brian Wagner, continues bleeding the master cylinder until no more bubbles are seen in the tubes.

Brian Wagner Bench Bleeding the Master CylinderRe-attach the Master cylinder unto the booster making sure the shaft meets up properly with the booster pin, tighten the screws, and re-assemble the brakes line unto the M/C. your done. If you are not converting your brakes (see tech note referring to this process) such as upgrading an 16v M/C to a G60 M/C , bleed all wheels starting with the rear wheels first then the front ones. re-install your coolant bottle and if applicable your upper stress bar back in place your done!

New Master Cylinder Installed