The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - 47-55.1 Master Cylinder/Booster HELP!!

NeoJuice · 06-28-2017, 11:28 AM

Hello fellow forum members,

I really hit a road block yesterday when it comes to my brakes and I need some help with what to do with my master cylinder/booster in my truck. I was getting ready to plum all my break lines and thought I would pull out the MC/Booster last night to bench bleed it before getting started.

As some of you might know I purchased this truck from a guy who started the build but lost interest and I wanted to make sure I had the correct unit in the truck for my disc/disc setup.

Here is the link to my build thread just in case along with pictures of my rear disc setup on the last page.

http://67-72chevytrucks.com/vboard/s...d.php?t=723325

I finally got in all my break parts like copper/nickle break line & all my fittings organized to start the job. I also got in my flaring tool from eastwood tools & 2lb residual valves, 3 way splitters & frame clips so I was totally ready to start the job.

The only part I havent figured out yet is what I was also going use for a proportioning valve. I was thinking about using this one from wilwood because it also has a built in brake switch.

http://wilwood.com/MasterCylinders/M...emno=260-11179

Ok so here is the problem. The MC/Booster he put in the truck was for as far as I can tell for Disc/Drum setup. On the MC/Booster the only informaiton I can find is on the rubber plunger it says MBM and then on the bracket MBMPRAFMCT4754.

So looking up MBMPRAFMCT4754 on the MBM site says that its the frame bracket but it also lists all the MC/Boosters being only disc/drum or drum/drum.

http://mbmbrakes.com/search.php?Sear...MBMPRAFMCT4754

So what do I do now? Can I just replace the master cylinder and keep the booster? Should I call MBM and see what they say? Also I noticed when i tried to push in the rod on the booster it wouldnt move in/out. Is that because there is no vacuum or fluid in the booster? looking at the fluid bowls i believe the front one was larger then the rear if I recall correctly.

Or I could just be freaking out over nothing and it has this MC on it but i would need to find a stamping of some sort or model number.

http://mbmbrakes.com/mc2912h-gm-univ...er-1-1-8-bore/

Or scap it for a underhood booster/pedal assembly?

Thank you for your help and time.

06-28-2017, 11:28 AM	#1
NeoJuice Registered User Join Date: Nov 2016 Location: Beaumont, Alberta Posts: 468	Master Cylinder/Booster HELP!! Hello fellow forum members, I really hit a road block yesterday when it comes to my brakes and I need some help with what to do with my master cylinder/booster in my truck. I was getting ready to plum all my break lines and thought I would pull out the MC/Booster last night to bench bleed it before getting started. As some of you might know I purchased this truck from a guy who started the build but lost interest and I wanted to make sure I had the correct unit in the truck for my disc/disc setup. Here is the link to my build thread just in case along with pictures of my rear disc setup on the last page. http://67-72chevytrucks.com/vboard/s...d.php?t=723325 I finally got in all my break parts like copper/nickle break line & all my fittings organized to start the job. I also got in my flaring tool from eastwood tools & 2lb residual valves, 3 way splitters & frame clips so I was totally ready to start the job. The only part I havent figured out yet is what I was also going use for a proportioning valve. I was thinking about using this one from wilwood because it also has a built in brake switch. http://wilwood.com/MasterCylinders/M...emno=260-11179 Ok so here is the problem. The MC/Booster he put in the truck was for as far as I can tell for Disc/Drum setup. On the MC/Booster the only informaiton I can find is on the rubber plunger it says MBM and then on the bracket MBMPRAFMCT4754. So looking up MBMPRAFMCT4754 on the MBM site says that its the frame bracket but it also lists all the MC/Boosters being only disc/drum or drum/drum. http://mbmbrakes.com/search.php?Sear...MBMPRAFMCT4754 So what do I do now? Can I just replace the master cylinder and keep the booster? Should I call MBM and see what they say? Also I noticed when i tried to push in the rod on the booster it wouldnt move in/out. Is that because there is no vacuum or fluid in the booster? looking at the fluid bowls i believe the front one was larger then the rear if I recall correctly. Or I could just be freaking out over nothing and it has this MC on it but i would need to find a stamping of some sort or model number. http://mbmbrakes.com/mc2912h-gm-univ...er-1-1-8-bore/ Or scap it for a underhood booster/pedal assembly? Thank you for your help and time.