Dorman M630031 Brake Master Cylinder Compatible with Select Cadillac/Chevrolet/GMC Models

I was doing brake work on my truck and its 20 yrs old and I was doing calipers and flex lines already, so I figured heck, the master cylinder can't be far behind and its pretty cheap to do, so I ordered this part. Direct replacement and with the bleeding kit (sold separately) I did the "bench bleed" on the truck which for me was easier, however still required two people to see when it was done bubbling. My new brakes are awesome, the pedal is high and hard, no mushy pedal! I'd recommend this part and doing replacement as I did if your vehicle is old and the existing fluid looks crappy and dark. The brake fluid is hydroscopic and adsorbs water from the air, and that is a cause of corrosion to everything in your system - ABS pump, calipers, master cylinder.

My truck is 23 years old and the brakes were getting soft. Replace brake pads and rotors and the last item was the master cylinder. After reading how to bleed the master cylinder before installation, I installed it into my truck. took about 20 minutes to installed. Then took the next 90 minutes to bleed all my wheels. Hardest part was getting to the brake cylinders under the truck. Once done, it worked perfectly. Brake are feeling harder and stops as expected. Good product for my Chevy Truck!

Perfect fit and easy install, fingers crossed it holds up 🤞🏽 plug and play for connections as well so that’s one headache gone

Good price. Works as it should.

Easy install to upgrade the brakes on my 88 Silverado, I did eliminate the ABS, it was easy, and I had to use an adapter on the one fitting but it was easy to find and my once spongey, long travel brakes are alot shorter and firmer. A grade mod for my obs truck. First one was bad out of the box but the seller replaced it pretty quickly and was not much hassle

If you are thinking about this to upgrade your OBS master cylinder, don't hesitate. Massive improvement for me and it was a simple job. Including the bench bleeding the swap took about 40 minutes. There are tons of videos on YT about this upgrade and it really does improve the overall brake performance on the older trucks.

Easy to install came with instructions and the plugs to make bench bleeding easy.

Used this to replace the master cylinder on my 1994 GMC K1500. Followed many of the website threads and many Youtube videos. Fit just fine and does seem to have shorter pedal travel. Hard to tell though since my rear wheel cylinders were leaking, replaced those also. I like the increased fluid capacity over the original master cylinder.

Great upgrade for any 88-98 Chev or GMC. Finally I have brakes as good as a brand new truck, no more spongy/soft pedal. Only reason I didn't rate it 5 stars is the price was a little on the high side. . but we always pay alot more in Canada.