Raybestos MC390542 Professional Grade Brake Master Cylinder

worked

Works great! No more sinking pedal.

Great replacement. Easy install if you know how to bleed and put on.

I purchased this MC to replace the MC in my 2003 Hummer H2. It is an exact replacement for my Hummer. I bench bled the MC and installed it and bled the complete system using a power bleeder. I had to rebleed the system, (spongy pedal). After that very good brakes. I don't know how long this MC will last, but, so far, so good. I have used Raybestos brake products for many years. Now even Raybestos products are made in china.

So far so good. I installed this on my vacuum-boosted 1999 Yukon (which is GMT400). Even though this is made for GMT800 trucks between 99 and 03 with hydroboost, it works just fine as the geometry of the push-rod seems to be exactly the same, hydroboost vs. non-hydroboost. This booster has a 37mm bore compared to the 34mm on the version which is made for vacuum boost.. i've had a 34mm installed before (theoretically it should yield more clamping force), but they both feel about the same to me. I plan to swap over to a hydrobooster soon.