So i have this 1962 F250 and the incredibly small sized brakelines. Im guessing 1/8" id. I pulled one leg than ran from junction block to drivers side wheel cylinder.....wow, with all the crude/50+ years of rust, its amazing it was operable. I searched threads back to 2010 regarding enlarging the brakeline to the next size up. Alot of good replies, but i came away not being able to conclude its such a smart idea. Im going to replace all the line and ss braided lines for hoses anyway. Id love to hear from members that earn a living working on auto brake systems, or for that matter opinions from those that have replaced their lines. Could it be possible that enlarging the lines could be a detriment? The truck is bone stock & original. Aside from replacing all the hardware, shoes, drums, cylinders, master, et cetera, i simply thought more fluid would be a good thing. Where am i going wrong?

 

Standard brake line tubin is 3/16"' and there must be a logical reason for that. I would suspect that trying to pressurize/move a larger volume of fluid would be undesirable. I have rebuilt several brake systems using standard size brake lines and there are no problems, nor would I see any advantage to changing size. Your old lines will be corroded on the inside due to moisture and the bore occluded. If you have replaced all the other components and rebuilt the master cylinder, at the age of your vehicle, just install all new steel lines as well...of standard dimensions. I see no point in reinventing the wheel. You might consider dot 5 silicone fluid if you have any concern about preserving paint. Its a little tricky to bleed but there are definite advantages to it.

 

Thanks resonateur......understood. but i dont remember 4wd's having this small sized line. Perhaps im understating it. It is so small, which by the way, maintains a higher psi, but dang, this line is dinky. There is no way this is 3/16".......this line would fit into a 3/16" line. I have yet figured out how to post photos, but maybe i will to illustrate its size.

 

I replaced my 62's brake line with 3/16" not too long ago and haven't had any issues once I got the brakes adjusted. I actually replaced every brake component except the pedal. I believe the line was the same size as the one I pulled out.

I also put in a tandem reservoir master cylinder from a 68 Mustang to split my system front/rear. I used RAYBESTOS MC36222. Bolted right up to the firewall and the new push rod was even the correct length.

I didn't want to use a pressure switch for the brake lights, so I went down to NAPA and got a brake light switch for a 75 F250 without cruise control and installed it where the rubber bumper is on the brake pedal. No drilling required! I wired the switch to a relay that connects to the existing brake light wires at the master cylinder.

I wouldn't say that these drums can make it stop on a dime, but they will lock up the tires.

 

Im unable to post two pics of my truck. The two pics are on my phone, so in order to insert a photo, you must first get one from a url? When i select from device, it shows my android camera app button or take a photo. I dont want to take a photo, i have two in my phone i want to post. By selecting from device then selecting the camera, it shows my viewfinder without the album button. I dont get, can anyone tell this retired old phart how to post pics from my phone, while on my phone? Thanks. I guarantee its me, not the forum site.

 

WFO: Pipe size is expressed as inside diameter. Tubing (like brake lines) size is expressed as outside diameter.
Eric

 

Partial help on phone pics. Add a new contact to your phone. Name it, "My EM Address" and put in your EM address (on mine I scrolled down to the letter icon and put the address there). Save the new contact.

Open photo album on phone, scroll to pic your want and press send. There may be a choice on how to send, I use, Multi Media. You will send the pic as to E-mail on your computer. This works fine on my, nothing fancy, flip phone.

Once in your inbox, open it, make sure pic is there. You have to save the pic somewhere on your computer. NOW your on your own. I can't tell you how to put it in a post, here on FTE. Have to learn that for myself.

Hope it works for you

 

Any given master cylinder is only designed to move so much fluid. If you add more fluid to the system in terms of larger ID lines then you are asking the master to move more volume of fluid to create the same effect on the slave cylinders than it was designed for.

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Sorry, but that is not exactly correct.
If the line is full of fluid (and bled), then the size (and volume) of the line is irrelevant, as when you step on the brake pedal, all you are doing is displacing fluid from the master cylinder into the system. the amount of fluid displaced when you push the pedal a given distance does not increase or decrease regardless of how big the lines are...........

 

Yes, I wouldn't argue with that are long as they are bled well.

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I just re-plumbed my whole truck, 1966 F100, after completely redoing all the brakes over the last few months, as time permits. I'm no expert, but pretty capable. All my research indicated that 3/16 inch tubing was the correct size. I added discs up front, and a new master cylinder too.
I got a 25 foot roll of 3/16" with a bunch of fitting from Jeg's for $32. I thought this was a good deal.
I will say the rear outlet port of the PV2 valve looked like it really wanted a bigger tube, 1/4 inch, and I had 1/4 inch tube from the reservoir of the dual master cylinder to the proportioning valve for the rear brakes, so I came out of the rear of the PV2 with 1/4" tube for two feet, then added a 10 lb residual pressure valve, and then put on a fitting to come out 3/16" all the way to the rear brakes.
It's a manual M/C too. And it works great!

 

The standard diameter for the hard brake lines throughout the trucks was 3/16". The standard flare nut fitting size for 3/16" hard line is 3/8"-24.

The standard fitting size for 1/4" hard line tubing is 7/16"-24. There are ports in the brake system (some MCs, some brake valves) that have 7/16"-24 flare nut fitting ports in them. Some MCs and some brake valves had 3/8"-24, 7/16"-24, 1/2"-20, 9/16"-18 or 5/8"-18 port fittings. However, these ports did not have 1/4" or larger diameter hard lines going to them. The larger fittings all had the smaller holes in the center of the flare nuts to fit 3/16" diameter hard lines.

The difference in line fitting sizes on the 3/16" tubing was done to keep the lines from being swapped up so they wouldn't be installed into the wrong ports.

As you can see in the photo below, I have (from left to right) a 9/16"-18, 1/2"-20 and a 7/16"-24 fitting installed on a piece of 3/16" brake tubing. The outer diameters are larger than a 3/8"-24 flare nut but, the inner diameters of the larger fittings are the same for installation on the correct 3/16" diameter tubing.



Brake plumbing I did on my truck when I swapped to front discs and power brakes. The MC has ISO metric bubble flare fittings. The rest of the brake line plumbing has SAE inverted double flare fittings.

 

Well, i'm convinced on the standard 3/16". I tried taking a photo my line, couldn't, but i was wrong about the size, but thanks FTE members.