It is a later valve:

 

Duh..... I posted the differential brake pressure switch above.

Here are pics of the prop valve for a later Z for completeness. I don't think I have ever posted these but I took the photos way back in October, 2006.

 

Edited May 1, 20177 yr by 240260280

Not having the assy in my hands to take measurements, I'm clearly guessing, but... How about a piece of thin walled tubing where the OD is a slip fit down into the body of the valve where the spring and snap ring goes, and ID is as small as you dare to compress the snap ring.

Compress the snap ring and place it into the ID of the tubing. Put the spring into place. Push the tube down into the hole compressing the spring. And then use a rod to push the snap ring out of the end of the tubing into the groove. You could even make sure you drop the ring into place a little beyond the groove, and the spring will push it back out until it snaps into place?

The concept is kinda like a piston ring compressor keeps the ring compressed until you get it into the bore? A piece of thin walled tube to keep the snap ring compressed until you get it down into the bore.

One last thing... You said the pic is the order the parts came out. Are you sure about the location of the washer? Not saying it never happens, but it's unusual to have a spring riding against a snap ring like that. I would have expected the washer to be between the spring and the clip. Again, not having ever seen one before, I'm just guessing here.

Patcon, SteveJ, Cap't. Obvious,

Thanks for your suggestions.  It might take a day or two for me to get back into the shop, but I'll try them.  The fact that the piston / push rod has to be in place before the spring, may crowd things a bit in there, but we'll give it a shot.  

As for the order of the spring clip and the flat washer, I thought of that too after looking at the photo I took.  I did look back on my notes, and that's what I wrote at the time.  Also, if the flat washer was between the spring and the spring clip, that would leave the other side of the spring clip pressing on the rubber seal, and I would question the rationale for that.  Mind you, if everything on Z cars was rational, we wouldn't need this forum, would we?

 

Thanks All

Yeah, I was thinking the same thing about the location of the washer. Doesn't seem quite right regardless of which side of the clip you put it, but not having ever messed with one, I defer to your notes.

Good luck with the reassembly and remember that there has to be an easy way because they sure didn't spend a whole lot of time on it at the factory. There is a trick or a tool. You just have to figure out what that is.

Wait a minute... Are you calling us all irrational?   

14 hours ago, 240260280 said:

 

It is a later valve:

 

Duh..... I posted the differential brake pressure switch above.

Homer Simon moment. . I get them a lot lately

Edited May 1, 20177 yr by EuroDat

1 hour ago, EuroDat said:

Homer Simon moment. . I get them a lot lately

You just had one. Homer Simon

"Eureka."   Or "Mr. Watson, Come here."  That`s how I feel today.  

Thanks for all your thoughts and ideas guys.  After more than a couple of hours fiddling, pondering, writing, reading, and more fiddling, I have the spring and its snap-ring in place.

While I think there is some merit in SteveJ's suggestion of compressing the spring with fishing leader, the only fishing line I have is about 40 years old, and it was not up to holding a steel spring in compression.

I tried Cap't Obvious's suggested of carrying the clip into position by squeezing it into a tube or pipe, then compressing the spring using the resultant assembly, but as you can see from the first photo attached, the clip was simply too big to fit into a 3/8" i.d. piece of pipe.  

Finally, I took my snap-ring pliers, and set the pins in for maximum exposed length (see photo), as the groove is 16 mm. below the outer end of the cylinder.  On this latter point I should mention that the factory service manual drawing BR-8 is just about exactly to scale.  It took many tries, and in fact the notches on first spring clip I used simply wore out.  Fortunately I had another old proportioning valve, courtesy of ZKars (thanks Jim), and was able to salvage its spring clip.  With the spring in place, I set the clip on top and pressed down with the snap-ring pliers, while simultaneously forcing the opposite side down with a small pin punch. After xx tries, it finally set.  

So it`s done.  But having said that, I remain a bit concerned that the inevitable scratches on the side of the piston may cause some grief down the road, although it appears to me that the real work of the piston all happens at the bottom end.  

With respect to the repair kit from Motorsport, i think I`ll drop those folks a line and suggest that for $1   

 

 

Not sure what happened there.  Must have pushed a wrong key.

Anyway, the point I was making was that for $1

REALLY not sure what is happening.  Try again:

For $12 for a kit consisting of three tiny pieces, I think Motorsport should be providing some instructions.  As seen on this forum, we, a number of people who are familiar with Z-car repairs, have all been uncertain as to how this job should be done.  How many of those $12 kits are going to remain unused?

For now, I'll attach the relevant photos.

Thanks again All 

Two more pics

Just to clarify, @Namerow thought of the fishing line. I was thinking of taking strands of wire to compress the spring myself. Now I wonder if wire would also risk scoring. 

Let us know how well the rebuild functions.

Excellent. Glad you got it together! Hope the scratches don't cause any problem.