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Remove the plastic switch. It is likely that the plunger on that switch is what’s preventing the valve to go in?
I don’t see that bushing called out in the diagram nor do I recall a bushing being in the shuttle valve.
can someone else clarify?
Yes, I screwed up and had the switch in first. I'm concerned about the where the O-ring goes and the bushing now.
So, the O-ring DOES NOT go in the groove? I your pic the piston has a bushing behind the O-ring? When I installed the fitting/end cap, it seemed to need to push the O-ring into place reluctantly. It just didn't feel right. Am I just overthinking it?
If there is one thing of importance to learn from this thread, it is this……..
whenever you are disassembling some component, take photographs at every step. 📷📷📷🤳🤳
There are two grooves and one depression, the depression is for the switch plunger.
each groove needs to have an O-ring installed into it.
I asked myself the same question as you, it seems very strange to me, but it works very well on my car. Parts are available at Muscle car research.
To reassure you on the assembly, see the link for rebuild the shuttle:
OK, it's official, I guess, not unless someone wants to interject. The O-ring does not go in the groove. Bushing and then the O-ring. It operates and goes back together better with the O-ring in the groove. I'm about ready to chunk this thing in the trash. Larry, have you looked at the above link?
It is counterintuitive they would machine a groove and then not use that groove for an O-ring.
The drawing previously posted in this thread clearly shows a seal placed in each of the two grooves
that same drawing does not identify any component as being a bushing
that drawing is for a Ford pick up of similar vintage to our Pantera‘s. Is it possible there were different versions of this shuttle valve?
photographs can be deceptive. Are the O-rings the same size or is one larger than the other? If they are the same size then they are both designed to go in a groove. If one is larger than the other than it would seem to follow that it does not go in a groove but remains on the piston
I will say this again as it is the reason we are having this …..looooong ….discussion
take photographs whenever you take something apart.
the 2 O-rings have differents diameters:
The smallest one goes into the throat.
The larger one goes after the ring, if you put the O-ring in the groove (before the ring) there will be a leak at the contactor lamp switch because the O-ring seal is not suitable for the groove (the internal diameter is too large).
I still do not understand why there is this groove ? maybe what is used on another shuttle valve ?
Two different O-rings definitely means only one of the grooves depicted in the drawing receives the smaller O-ring
with that established I guess the position of the bushing and larger O-ring is correct as shown in the photographs posted
There are other designs for this semi-useless '70s device. One has return springs on each end so shuttle sticking is not an issue. Aerican Motors used to make one that was sometimes substituted on Panteras.
The Pantera shuttle valve "block" is stamped D0OA-2B257-C. That number is in the last line of the "Engineering Number(s)" column on the musclecarrearch.com link posted above.