MG Midget Forum

The brakes on our 76 were working (they stopped the car reliably) but I noticed that the rubber hoses looked old when I was replacing the clutch hose, so I decided to change to SS lines. I installed the new SS brake lines, and attempted to bleed the system but couldn't get any fluid to the rear wheels. The front wheels were fine. I tried the Mity Vac but couldn't get a good stream of fluid to the rears so I removed the new SS hose and I did get a trickle, but not much. I replaced the SS hose and went online in search of an answer.

After reading about all the joys of the PDWA, I pulled the PDWA switch out of the car to have a look. There was about a drop of fluid at the tip of the switch, but when I looked inside with an inspection mirror I didn't see any fluid. What I did see was that the piston wasn't centered, it appeared to have moved towards the rear. I've read conflicting comments about the piston, but most comments say that you can reset it with a small screwdriver so I tried that. The piston moved, but as soon as I removed the screwdriver, it went back to where it was. I've tried it a few times, it moves (with some resistance) and then snaps back. That made me wonder if there was pressure on the front line, or a vacuum on the back line. I bled the fluid from the front wheels (ran the MC dry) and the piston still snapped back. I removed the bleeder valve from the right rear wheel, and disconnected the back line at the MC to clear the back line. I was unable to disconnect the rear line from the top of the PDWA with an open end wrench so I'll pick up a flare end tomorrow and see what happens. I was hoping that by removing the top rear fitting I could see the piston inside the PDWA. I've looked on this site and others, and on Triumph sites, and everything I read says that it should be easy to reset the piston, but I've never seen a report of one that won't stay reset. I've also seen conflicting reports about whether or not the flow will be cut off or severely impeded if the piston sticks.

I probably won't have a chance to work on it again until Thursday, so if anyone has a theory before then I'll be happy to put it on my to-do list.

TIA,

Adrian