Has anyone ever had a valve assembly brake pressure differential (commonly in this forum referred to as a shuttle valve) crack and leak brake fluid?
Are they repairable? Can they be welded back together with great reliability? Or just suck it up and buy a new one...if one can be found.
Does anyone know of one from another make/model vehicle that would work just fine and readily available?
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Yes, I have cracked one by over tightening one of the tube nuts. The shuttle valve is brass and the steel nuts can readily crack the housing and cause it to leak.
I don’t think they are repairable.
I once bought a used one and it was already cracked. Someone had overtightened the brake light switch and cracked the housing.
Mustangs and other cars use a shuttle valve that looks the same as Pantera but the thread sizes for the tube nuts and brake light switch are different.
Brass can be TIG welded by using a silicon-bronze rod.
Larry
There is rubber inside the valve so if you TIG weld it, it should first be disassembled. Since the housing has already been distorted by over torquing the tube nut it may or may not seal once it’s welded.
Sounds like I am about to take out the wallet and drop a couple of hundred bucks. Lesson learned. Thank you guys. I wish I knew 10% of what you two know about these cars. You always have informative insight on everyone's posts. Good to have you guys here. Thank you again.
If you search here, there is at least one thread on rebuild kits from “Muscle Car Research” or someplace like that. See the link below.
You have to get the valve body fixed first, though.
Rocky
When I click on the site is says page not found. Also, the differential assembly's block/body cannot be fixed. I called Steve at Pantera's by Wilkinson and he said once cracked thoroughly, they cannot be welded back together. Mine has the crack going all the way through the body of the block, from one side to the other, and half-way across one of the inlet holes. I also took it to a very experienced metal shop and the owner examined it at length and said it could be fixed, but it would cost so much money it would never be worth it.
I was lucky enough to find two used ones on eBay, and bought them both quickly yesterday. I also bought two rebuilding kits, so once I get them I will attempt at rebuilding them and hopefully have a spare.
Found that page. I think this is the correct one:
As an alternative, you could also eliminate the valve with a tee and a coupler. You can get a tee with a port in it for the brake light switch or you could use the Pantera Electronics brake light switch. Do you really need an idiot light to tell you when your front or rear brakes have failed? It’s also another place for air bubbles to get trapped.
There may be another option. Add a proportioning valve with a light switch into your system. Remove all the other valves which have been known to give our cars poor braking. The proportioning valve allows you to change the front to rear brake bias. This also will depend on if you feel comfortable doing these changes to your system and understand how to adjust the system...not that dificult IMO. There are many different brands of valves that are cheaper and more expensive. The positive is you can now allocate the braking pressure front to rear for your brakes. This is typical on race cars that have two master cylinders operating the front and rear calipers. The valve pictured is for the type of mastercylinders our cars have. Steve Wilkinson recommended to me to go to a 1" bore mastercylinder. Don't recall if he said to add a porportioning valve for precise control of front to rear bias, but that is what I'm planning on doing.
Just to clarify; the proportioning valve goes in the rear brake line and only serves to reduce rear line pressure by the desired amount. The valve mentioned in the previous posting simply aids packaging by splitting the front line. It's unlikely anyone with OE rear calipers would want to reduce rear line pressure although the valve in question would be a simple substitute for the shuttle valve.
Not trying to upsell you, but I am using the SACC master and proportioning valve package. The proportioning valve is the same one shown above, or very similar.
It’s all integrated, and removes the brass splitter. It comes with the appropriate, pre-bent hardlines to mate to the master.
there is still some custom work to do with the existing lines to integrate it.
It has worked very well for me.
Rocky
These are all really great suggestions. Certainly superior to the OEM stuff they worked in there. I did a bit of research and found out the brake pressure differential valve (shuttle valve) came from 1970 Ford's with drum brakes...not even disc brakes. They made it work, but marginally.
Rather than rebuild these valves, with new O-rings and seals, you can have a machinist make a threaded plug that permanently separates the front and rear circuits. This converts the valve to a distribution block.
Calling this a shuttle valve is a misnomer, it is actually a pressure differential switch and it's only purpose is to alert if one side loses pressure. As has been noted by others, it really isn't needed since you will know by extended pedal travel if one circuit has lost pressure.
