The Stovebolt Site Forums The Parking Lot Big Bolts 51 1/2-ton AD brake line adapters?

Howdy All,
I've been searching the site but cannot seem to find exactly what I am looking for. Can someone help or point me to a past thread?

We are doing a frame off for a 51 1/2-ton and are up to replacing all the brake components; keeping it original except for the master cylinder. So all new parts inside each drum including wheel cylinders and a new dual reservoir master cylinder. The questions are with the lines and the fittings. I bought a coil of new 3/16" nickle-copper line with the black coated 3/8-24 flare nuts foolishly assuming that all the parts I had bought from Classic were plumbed the same. It looks like the wheel cylinders and the master cylinder have three different size connections. The wheel cylinders look to be 7/16-20, the rear reservoir fitting looks to be 1/2-20 and the front reservoir looks to be larger than that.

So here are the big questions:

Do I need different size lines for all of this or can I successfully use 3/16" line to all four drums? The dual reservoir upgrade on the Tech Tips says 1/4" up front but others on here say 3/16" everywhere works fine.

Do I just need to find the correct adapters for each connection or am I missing parts?

I was planning on simply routing the front reservoir to the front drums and the rear reservoir to the rear drums. There would be a simple block-tee fitting on each end. Is that correct? It looks like the rear reservoir is larger slightly.

I have seen mention of a proportion valve. Do I need one these since I now have the dual reservoirs?

Thanks.

Hy Ken & Sons, you can find adapters through your friendly local auto parts store (flaps), the Weatherhead line of parts should yield what you seek. You should be able to find adapters to bring the master cylinder ports down to whatever line connection size you want to use, they also make tees and other components that may be needed for your job. There will be no need of a proportioning valve in a system which is all drum brakes, however the master cylinder you use should be designed for drum brakes in both the primary and secondary reservoirs, those master cylinders will be equipped with residual pressure valves in each system which are required for drum brakes, hope that helps.

Ken, 3B is right on the money. NAPA carries the Weatherhead fittings but some may say Eaton on them now. I actually just purchased some fittings for my gas line/fuel pump at NAPA today.
When you went to a dual master cylinder there is a need, usually, to have a fitting that screws into the master cylinder and then the line screws into it.

I'm not positive but I think on yours it has/had a 1/4' line going across the rear cross member to a tee on the chassis rail just under the passenger seat. At the tee one line will go to the front and one to the rear. These are 3/16.

If you have enough ports on your M/C you could run a line to the left front.....which would mean the line from the tee on the right side would only go to the right front.
Did your lines have a bango fitting where it goes into the wheel cylinders? If so the 3/16 lines should, I think, fit right into them as the lines to the wheels are actually 3/16.

Hope something I've said may help you.

Master cylinders usually have some level of proportioning in them, but they are typically designed for the rear well to provide fluid to the front brakes, front well to the rear. If your dual master was originally used with disc brakes and you have drums, you'll need to add an inline 10 lb. residual pressure valve, available from Wilwood. Place it in the line right outside the master cylinder. Not knowing what your master came from, you may need a proportioning valve but its not likely.