Master Cylinder-to-Proportioning Valve Line Routing?

[MT_Mopar]

I got my Pirate Jack Disc/Drum Master cylinder today, got it all bench bled really well.

Question: Is it a major problem (air at high point) if I route part of my master cylinder-to-proportioning valve lines above the master cylinder? They would have a bend at the top going into the P valve but I am thinking that I can bleed that out if I do not introduce any air into the master cylinder.

It is very easy for me to install the P valve at the pictured location.

What do you guys think?

I have heard of rat rods and other cars built with the master cylinder under the floor attached to the frame, so in that case the MC would be the lowest point of the system and any air bubbles are pushed out of the system during bleeding.

Thanks

 

[YY1]

I mounted my prop valve where the factory splitter was- on the inside of the driver's side frame rail, in the same hole.

 

[MT_Mopar]

I mounted my prop valve where the factory splitter was- on the inside of the driver's side frame rail, in the same hole.

And that is above the MC? Yes?

 

[YY1]

No, down on the frame rail.

Kind of a pain to get to, and I had to shorten the line coming from the rear about 6 inches.

 

[Propwash]

You're right john, some hot rodder's do it that way. Thinking about it, any air would rise to the highest point of the system (which in your scenario would be the proportioning valve). Braking systems are designed to have the master cylinder at the highest point in the system. One of those reasons is so any air in the system will work up to the master and weep out harmlessly into the reservoir. Having it lower than the highest point, you won't have that luxury. I'd keep that in mind. Like YY1 said, from the factory it would have been mounted on the inside driver's frame rail, pretty much directly below the master.

Also, where did you get that booster? It looks like a factory single diaphragm Midland booster for drum/drum cars. Is it a aftermarket dual diaphragm? I'd highly recommend a bendix style dual diaphragm booster like the factory used, or just a dual diaphragm in general. Sorry to keep adding bad news & an empty billfold to your daily life...lol Just trying to get you dialed in right man.

 

[MT_Mopar]

So I can't use the booster with the new MC? It is the same booster but I thought the MC was the only problem (residual valve)

 

[Propwash]

Sent you a PM John..... The residual valve holding pressure on your disc brake calipers because of a master made for drum/drum w/residual valves is one thing.... Running a drum/drum booster on a power disc brake car is another.