The Stovebolt Site Forums The Shop Area Driveline Copper-Nickel brake lines fittings?

Hi all,

I would like to use 3/16" cu-ni brake lines for my 1950 AD. From what I have seen online,they specify to use a black oxide fitting with this type of line. Can I use the standard metal brake line fittings or does it have to be Black oxide?
The fitting are 7/16" thread correct?

Thanks,
skipper

I replaced all the lines on a 55 3600 about 6 years ago and used the Copper-Nickel with standard fittings. It is still working great with no problems. I don't recall it being an issue at the time. If I remember correctly the vendor that provided the line also furnished the fittings.
Fred

I've used a lot of it and like stainless tube nuts, but have used many standard tube nuts as well with no problem.
Have not seen black oxide treated nuts, I'm sure they're fine but not necessary.

Grigg

Ok, great thanks for the input.

Another question, I just measure several different pieces of my old brake lines. Everyone one of them has an OD of .25" and not 3/16". Could it had come from the factory like that I thought all the line were 3/16" Should I go with 1/4" or with 3/16" any benefits one way or the other? I

What size truck?
I don't have a 1/2 ton but I think they may have used some 3/16"?
On my larger trucks they are all 1/4" front to back, no 3/16".

Typically drum brakes on a pickup truck use 1/4". In some cases a truck with small wheel cylinders use 3/16"
Typically disc brakes on a pickup use 3/16".
Sometimes 1/4" is used going to the rear axle where it then splits to two 3/16" lines, either disc or small drums.

The real answer is you need enough fluid flow to actuate the brakes quickly. On the other hand oversize lines contribute slightly to a spongy brake feel.

Simple answer is to use what the factory used for the original vehicle if you have the original brakes. Or if you have unoriginal brakes you should use the size lines that the factory used on whatever vehicle the brakes came from.

Grigg

My truck is a 1/2 ton AD. I have coverted to disc brakes up front. So I would be ok with 3/16 all around?

So you'll be using a proportioning valve, the brass GM kind with 2 inlets, 2 outlets for the front, and one outlet for the rear?

If I were doing it I'd use two lines 1/4" between MC and proportioning valve if I could. Then use 1/4" from valve to rear axle hose. Use 3/16" for each front brake line. On the rear axle 3/16" only if that's the original size, or if originally 1/4" I'd use all 1/4" for it again.

I'm sure you could get by with other methods, the one above is what I think is best/right, might not be what everyone else has done. I could also be off some; if so I'd like to hear a better way of doing it with good reasons why.

Grigg

The Size of the line should have nothing to do with the pressure
applied to the cylinders as long as it can deliver the volume.
You could use a 3/4" conduct to deliver the fluid and it would
still apply the same pressure, as far as that goes, even a 1/8"
line would again, deliver the same pressure only not filling
the cylinders as fast. The reason we see a couple of different
size lines on an AD goes back to that same old thing we've run
into many times in the past, if they could save a few penny's
on each truck it was more profit for GM stock holders.

If it were me I'd just make it simple and standardize it by
running 1/4" lines through the whole system that way all the
nuts would be the same and you would be guaranteed or having
plenty of fluid volume to all cylinders.

Denny Graham
Sandwich, IL

Depending on the proportioning valve and other components in your brake system you may not have the option of using 1/4" line if the inverted flare fitting(s) won't accept the smallest 1/4" tube nut size. The two front brake ports on the valve may be an example where 3/16" is the max size?

Grigg

I did not get a chance to have a look at my MC and propotioning valve set up. I am using the POL brake kit with the dual MC. I try and check tomorrow what size line it has.

Usually brake hardware will accept a couple different size lines if you use the appropriate tube nut.
There are a number of different thread sizes to choose from to match your hardware, and often your choice of line size, here is a handy picture with most (not quite all) of them. 7/16"-20 for both 3/16" and 1/4" aren't shown, at the time I couldn't find them in stainless and haven't looked for them lately.
https://picasaweb.google.com/lh/photo/NRKuDQEmlKs1crsrTKN7ENMTjNZETYmyPJy0liipFm0?feat=directlink
It's been a little while now but I imported and sold CuNi line and sourced stainless tube nuts, now the line is easy to get at the auto parts store.
The stainless tube nuts I was getting in large quantity form BrakeQuip as well as assortment packages from Summit Racing.
http://www.brakequip.com/tubenuts.html
http://www.summitracing.com/search?keyword=stainless%20tube%20nut&dds=1

Grigg

One fine, visual chart on the fittings, Grigg! Thanks!