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Triumph TR6 - Brake Bleeding

Spent a few hours yesterday removing rebuilding and installing the master brake cylinder on my 74. Bled the rears with no difficulty. Used both the mity vac and pedal methods. Worked like a champ. When I got to the front, I could evacuate no fluid from either side. I am really puzzled. Have read in other threads and the Haynes manual about the PWDA. Would this be a source of my difficulties. If so, how is it reset? I followed the instuctions in the Haynes manual but never heard a click as the book describes. Any help greatly appreciated.

Hi Ashley. I went through the same exercise a few weeks ago, but was able to reset the PDWA per HAYNES instructions. Did you have the opposite side of the system open when you tried to reset the PDWA? It takes a gentle touch to get the lamp to go out. Does your brake lamp work? As a last alternative, you can remove the PDWA switch from the body and move the shuttle with a screwdriver to recenter it. If this doesn't allow you to pull fluid from either of the front bleeders, then I believe your master cylinder may need some work. Other listers will add their .02 worth on that issue.

Good luck, and let us know how it goes.

Rick O.
'72 TR6
Rick Orthen

Hi Ashley
So here is my .02
I have to assume that everything was working before u started the rebuild of the master cylinder.
The following on the PWDA is for information and I do not think this is your on. The PWDA, if working properly, will NOT shut off fluid to either front or back systems if it is actuated. Notice your reservoir has a front and rear chamber to supply fluid to front and back brakes. (in case of front or back failure u still have one set working). I do not have the Haynes manual but have absolutly no idea how you could even hear a click...there is nothing inside the PWDA to make a clicking sound. Go to the Zimmerman WEB page..maintenance section and you will see Triumph PDWA (PDWA is spelled out in the words). Now u got a picture of the switch and its insides. I Simply "center" the switch with a tiny screwdriver. This definitely is a "feel" thing. The place where the plunger of the actual electrical switch rides in has bevelled edges. Basically try to feel for those bevelled edges on either side of the hole. If u still do not get fluid to the front then you might have to do some work on the PDWA itself...there are O rings inside that might be deteriourated and blocking the fluid passage to the front.
Now to the possible real problem. You rebuilt the master. Disconnect the line from the MC to the PDWA for the front you get fluid out when brake is applied? NOTE: It is probably easier to remove the end at the MC but u obviously have to attach some "spare" fitting here to your mity vac bottle so u do not get fluid all over the place (especially if u are using DOT 4). If u get fluid out then continue to the PWDA. If not ...well....sorry guess what u gotta take back off. There is an article on bench bleeding a MC at Zimmermans page. I did not do this and had no problem doing the bleed.
Good luck Ashley
Rick C
Rick Crawford

Don't have a clue as to how, but the problem is fixed. I live very near a cemetary and could not resist a VERY short drive through with the little brakes I had. Previously I had no real pedal feel no matter how much I pumped. As I was bringing the car into the driveway, I suddenly had brakes. Not real brakes, but promise of them. I was then able to bleed the fronts. Have spent the last two hours enjoying the first outing of the year. Hooray!! Thanks guys!

Ashley are welcome but u do not have to rub it in that you went for a 2 hour drive.
Rick Crawford

Won't help Ashley now, but I remember reading somewhere to start with both passenger side bleeders open, then do the same thing on the driver's side. Sounds like this approach would keep the shuttle centralized. But you wouldn't be able to vacuum drag the system. I've never done it that way, but just a thought for those "out of the box" tinkerers out there.
Rick Orthen

Ashley the problem may not be your bleeding method but inside the master cylinder it's self. I rebiult mine several years ago. The primary piston ( the one that operates the front brakes, closest to the power booster) was sticking in the bore and the return spring was not strong enough to push it back. The secondary system (rear barkes) will bleed fine. Try tapping the side of the master cylinder (gentle), or remove the master cylinder from the booster to see if the piston is at the end of the bore.
Good Luck Phil
PS I ended up buying a new one two years later.
Phil Law

Just read another reason why vacuum bleeding is the preferable option. When you do the traditional mash-the-pedal procedure, you're moving the MC piston into areas of the bore that aren't normally traversed. These areas are more likely to contain corrosion/pits that could abrade the piston seals and you know what'll happen next.

Rick O.
Rick Orthen

This thread was discussed between 10/03/2002 and 15/03/2002

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