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Would like some input on whether or not to re-use what I believe is the original proportioning valve from my car...see pix. My restore philosophy is to keep original parts unless either 1) they are so hideous that they significantly detract from the car, and/or 2) there could likely be or would be performance issues. In this case the valve is by no means pretty...but it's location is not in a place where that would bother me and I would prioritize keeping this original part....UNLESS I am potentially creating a likely leak problem that would require me to drain the brakes and then replace it anyway. Thoughts? And I guess same goes for the small brass blocks in the rear. If there is a reasonable chance they will perform ok then I prefer to keep. OTOH it IS the brake system so I need to keep that in mind. And re-using does save me the $90 or so for another one. I am NOT chasing awards so that is not a factor and please no comments about points this or that or awards.
If you feel it wise to replace, who makes the best repro? My sense is all the usual retail places are sourcing from the same place...or two...but who makes the best.
TIA
Very rarely have I ever had to replace a prop valve. Usually they were on newer trucks, where corrosion ate them up to the point where they wouldn't reset after a brake line broke.
Since brass is non-reactive to all of the brake fluids (and won't rust) follow Duke's advice over on the other forum and soak/clean in alcohol. There's not much to go wrong with it as long as the little piston moves inside. You should be able to gently move it back and forth from both ends with something like a BBQ bamboo skewer. The block works as a pressure switch if unequal pressure occurs on either circuit. The still functioning side will force the piston away which then makes contact and triggers the dash warning light.
Thanks all. Consensus seems re-use...with some cleaning/prep first. Can I assume this applies to the smaller blocks in the rear....meaning good to re-use?
Yes. If it doesn't have moving parts or very few moving parts, what's to break?
Later years had the prop valve. Lot more sophisticated. And some could be rebuilt. Yours is a simple design.
Clean & reuse.
Just a warning. If you have the urge to replace the warning switch, make sure you get the correct one. They changed design over the yrs and your wire harness may or may not work.
Just make sure the threads are not crossed and that the cone-seats that mate with the tubing flares are free of nicks. I believe there is a seat hone available to clean up the surface if needed but I've not used one.
First off.....the early C3 Corvettes were equipped with what the OP shows.....which is really a distribution block with the brake sensor switch. Later model C3 Corvettes, these block were modified and did have a "proportioning" function by a block added to the back, and they also provided the switch function. But....whatever you call it....the OP was not asking for definitions.
My experience with these original blocks are that it depends on the condition of the conical seats in the brass threaded recesses. If they are nicked by the original installation of tubing into this block, you may have a problem with a new set of tubing that may not interface well with these previous nicks. So....it depends on that. Also of course the threads need to be in good condition. There really is not way to dress out any nicks down in the cavities. Also...you would want to buy reseal kits for that switch function....as there are o-rings in there that probably are original and dryed out. Someone sells those reseal kits for that valve.
I tried to use my original brass block in my 77...and it was okay for awhile after resealing it....but it eventually leaked and I replaced it with a new one from Zip Corvette.
My 1968 distribution valve was stuck/gunked up internally/the piston would not return to center/the dash light stayed on. I disassembled it/cleaned it with new brake fluid/made sure there was still "tension" on the orings and the bore/reassembled everything...it works like new now........
The funny thing about that warning light it lets you know that you have a brake problem after the pedal hits the floor. I think by than you don't need a light to let you know that you're in deep s**t!
My 1968 distribution valve was stuck/gunked up internally/the piston would not return to center/the dash light stayed on. I disassembled it/cleaned it with new brake fluid/made sure there was still "tension" on the orings and the bore/reassembled everything...it works like new now........
What did you use to pull the cone seats out of the body?
(A recent NCRS forum tutorial shows cutting threads on the cones and using a small bolt and washers to pull them.)
What did you use to pull the cone seats out of the body?
(A recent NCRS forum tutorial shows cutting threads on the cones and using a small bolt and washers to pull them.)
I put a small diameter rod into the cone on one end until it seated against the back of the piston then I tapped the rod lightly with a hammer until the other cone and the piston popped out of the bore.
Then it was easy to see the back of the first cone which I tapped out with the rod.
Just take your time...it doesnt need hard taps to pop either cone out.
NOTE: You can see the small rod sticking thru one of the cones for reference.
The O-Ring seals should be replaced if you have it apart. They have a life span just like other parts. If one leaks, your "brake" light will illuminate. I used Muscle Car Research parts on my 74 also. My O-Rings were hard, falling apart and leaking.
I plugged the ports in mine and sand blasted it, so the brass looks good now. I also bought the kit from Muscle Car Research, but have not done the final rebuild yet.
Re-use proportioning valve?
The O-Ring seals should be replaced if you have it apart. They have a life span just like other parts. If one leaks, your "brake" light will illuminate. I used Muscle Car Research parts on my 74 also. My O-Rings were hard, falling apart and leaking.
