I have a 66 fastback with drum brakes. Looking from underneath from the rear above the Left side of the differential the left brake line and right brake line join at a union and it looks like a vent off the top, that on mine just goes to an empty hose. Can someone tell me what this is? Is it an over pressure line that dumps the fluid? I have good line pressure, so it can't be venting fluid. Any help would be appreciated. thanks

 

Can you post a pic of it? It sounds like a proportioning valve. Its sense your vehicles ride height and adjust rear brake pressure accordingly. So when the car is loaded down itll allow more force to be applied to the back brakes. Im not positive if thats what youre talkin about, but thats what it sounds like.
-P.

 

He's probably talking about the differential/axle vent tube. Not anything to do with the gas line. It's a rubber hose going to the ground, right? And the vent is on top of the axle on the driver's side of the pumpkin, Right?

 

I agree with Soaring. The hose goes from that little tube on top of the differential to a bracket i believe up on the undercarraige. I need a new one myslef...

 

That is a vent line that vents pressure build up from the rear end its self. Not supposed to have anything in it and has nothing to do with the brakes. Not worries!

 

So, quick question for my own curiousity, why make it so long? Why didnt they just take like a 3 inch piece on there?

 

Don't know bro, but my hose has been rotted off for years. I see no real reason to even have a hose on it, except for may keeing dirt out of the vent. I guess I will have another project tomorrow. New hose on my axle vent.

 

Mine somehow got riped off and packed full of dirt. So did that little vent tube, but i took it off and cleaned it out..

 

My vent is directly on the pig. No tubes or anything. The only factory vehicles Ive seen with actual rubber hoses for differential vents are jeeps. And he did mention a brake line in his description, so I was thinkin braking system not drivetrain.
-P.

 

All classic stangs have them. It also serves to keep water out of the housing if you submerge the rear end. Like an upside down P trap on your sink.