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TR6 PDWA Issue

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Martin Secrest

Senior Member
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My PDWA shuttle is off-centered, and has been for a few years, just finally getting around to this and other things. I'm not really familiar with this item. I'm pretty sure it's moved to the rear brake side, because when I remove the plastic switch, I see a small gap to the right that I can just barely get a small point into. However, I cannot get it to budge to the left with the tool. So it occurred to me that opening a front bleeder might help .. nope. So just now I asked my son to press the brakes while I again opened the left front bleeder, we did the routine twice, still no shuttle movement.

Thoughts? Hoping it's not stuck b/c of my neglect, and that I don't have to R+R it. Thanks.

Martin Secrest
Arlington, VA
72 Triumph TR6. It's cool.
 
I guess the shuttle is jammed to one side. Next thing I'll try is opening both front brake bleeders and try centering the shuttle again with the brake pedal. For those with experience, is this more easily accomplished with two brake bleeders open, rather than just one, as I've already tried (and failed with)?

Also, am I correct that the little tiny gap I'm seeing thru the switch hole on the right side of the shuttle (and into which I can get a tiny tool) means that that is the side to which the shuttle has moved? I don't see the same gap on the left (front brake) side of the shuttle thru the switch hole.
 
Trace back the hydraulic line from the PDWA to the Master Cylinder.
The forward line on the M/C is for the Rear brakes...Knowing that might help you determine to which end of the PDWA the shuttle shifted.
 
Right, I did that, and on my '72, looking down at the PDWA, the rear brake lines are to the right, the fronts to the left. As best I can tell the shuttle has moved right, so I've been bleeding the fronts, but to no avail. I'll try the rear on the off chance I'm wrong, but I think I just have to pull the unit and rebuild. ****.
 
Hopefully some of the links below will prove helpful as you work through the PDWA.

From the Buckeye Triumphs website:
https://static1.squarespace.com/sta...058350/Overhauling+Master+Cylinder+&+PDWA.pdf

If you find after working on the PDWA that you need to machine a new piston for it to use o-ring seals... see the archive link below from Buckeye Triumphs:
http://web.archive.org/web/20030506...yetriumphs.org/technical/Brakes/PDWA/PDWA.htm

And from restoration blogs:
https://72triumphtr6.wordpress.com/...setting-pdwa-to-fix-bright-lightoil-light-on/
and
http://www.74tr6.com/pdwa.htm
 
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