Master Cylinder Rust/Leaks

[ArdWrknTrk]

Hmm, I didnt realize it was that easy. Although I might still take the clear approach just for period correctness.

Thanks gents.

If switching to the later aluminum and plastic master cylinder, there are two important things to keep in mind. The little valve I'm pointing to in the picture below is not included with a new master cylinder. The new master cylinder does come with a new o-ring for it, but that's it. I went to the junkyard and grabbed two of them, one to install, and one for a spare. I think they were $5. The other important thing is that the front and rear brake ports are reversed from the old cast iron master cylinder.

I'll have to apologize, because I do not know what that little valve is called. Maybe Jim knows?

I get the period correctness part as that is something that is always on my mind when considering parts and/or modifications. I struggled with that as there are certain things I prefer to leave original if at all possible.

I'm pretty sure that's the residual pressure valve for the rear brakes.

There's really nothing else to the swap.

You have to be sure to get the the correct bore M/C.

150 & Bronco or 250/350.

The bores are different.

And the C-C of the mounting studs on the booster has to match.the base flange.

[Frogger2662]

I'm pretty sure that's the residual pressure valve for the rear brakes.

There's really nothing else to the swap.

You have to be sure to get the the correct bore M/C.

150 & Bronco or 250/350.

The bores are different.

And the C-C of the mounting studs on the booster has to match.the base flange.

Do you to do away with the original proportioning valve?

Does the residual pressure valve do the same thing?

[ArdWrknTrk]

Do you to do away with the original proportioning valve?

Does the residual pressure valve do the same thing?

This has been discussed multiple times here on the forum.

It is considered by Ford a 'combination valve'.

Shows failure of the brake system and the internal shuttle should shut off flow to a leaking front or rear circuit.

The later master cylinders -once RABS came about- have a float to show they are running low.

[Rembrant]

Do you to do away with the original proportioning valve?

I did remove it, yes. I ran all new brake lines on the truck, so it was a convenient time to swap to the later style master cylinder. I took the two wires from the old prop valve and ran them to the float in the new master cylinder, so I still have a functioning brake warning light for a leak (well, low fluid really, for whatever reason). It really is a very easy swap. Of course it is not period correct, but there are some benefits...mainly for me that it wouldn't rust, but it is also nice to be able to do a visual brake fluid level check when under the hood.

I believe I re-used the old fittings (from the old master) as well. There was one of them that I was having trouble finding locally.

 

[Rembrant]

I'm pretty sure that's the residual pressure valve for the rear brakes.

Right. I couldn't remember what it was called. It is a definite requirement when installing the later master cylinder as you cannot bypass it. It seals to the master with an o-ring, and has a port to accept a standard flared brake line fitting.

The good news is that they are easy to find in the junkyard, and very easy to remove. I cleaned mine up on the wire wheel and it looks like new. I even grabbed a spare, although I'll likely never need it.