Brakes Master cylinder ID help, bad brake performance after PBR swap.


Founding Member
Jun 12, 2001
Need some help on figuring out what master cylinder I have?? I thought it was a SVO master as its aluminum and the car has rear disks and had 73mm front calipers. I ran the numbers on it and can’t seem to find any info? All these parts were put on the car back in the 90’s by the guy I bought it from

I’m converting the car to 5 lug and went to the PBR calipers while I was at it, the stopping power is horrible! So, after doing some reading I thought I was dealing with the SVO master which would explain my lack of brake power. I ordered a 93 cobra master (MC390125) and removed the old master today, pulled out the calipers and measured it and its about 1.020” in DIamter??? I pull out the 93 cobra one I ordered and its about 1.010” in Dia. So putting in this Cobra master doesn’t appear that it will do anything for me since they are basically the same size? I also ordered the 93 cobra brake booster as I thought that would help also, I really don’t want to swap the booster unless I have to as its kinda PITA to install, plus it seems like something else may be causing my lack of stopping power?
The Cobra master has different type threads and end style of the hard lines compared the the master I pulled off the car, not sure what hard line I need to make if I put this Cobra master in the car
I’m running out of ideas as to why the car has zero stopping power, brand new rotors and pads all around, Brake pedal is quite firm when the car is off, actually when it running it has a pretty stiff pedal also, just moves a bit further with the brake booster assist. I Pulled the plug out of the proportioning valve to make sure it was gutted and it was. It has the original rubber flex lines that came on the PBR calipers, they may be flexing but I cant believe they would be flexing that bad that the stopping power would be this bad, I literally need about 3 times more stopping power to make this thing safe to drive again.
Any ideas would be appreciated on what to look for next to solve my brake problem! Thanks!
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