The Stovebolt Site Forums The Shop Area Driveline Brake line fittings

I have a 1958 model 3200. I am upgrading to a dual master cylinder from CPP but retaining the stock drums. Truck has 1/4 inch brake lines to the front, 3/16 on the rear. I was intending to use new 3/16 line for the upgrade. The new master has adaptors for the 3/8-24 fittings on the 3/16 line. Will the 3/8-24 fitting work on the existing connections for hose/brake cylinders or will I need adaptors?...if so does anyone know the sizes?

Hy 86Brat, I believe the adapter you need is Weatherhead p/n 7818, that goes from 1/4" male to 3/16" female, hope that helps.

Or you can usually get tube nuts with whatever thread you need for either 1/4" or 3/16" tube.

Grigg

That's how I would do it. Also, a 3200 should have 1/4" line all around, the only 3/16 line is the one across the back axle.

Thanks for everyones input....I shortened the frame on the model 3200 to a model 3100 spec.....so hopefully the 3/16 line would be adequate.........I never heard of a tube nut are they an adaptor and where do you get them? thanks again

It's not frame length that determines what size brake lines you need, it's the brake system components that are important. If you still have 3/4 ton brake system you need the right size lines for it.

Tube nuts are what go on the tube before you flare the end.
They look exactly like these, and you can see the different sizes available.
http://rides.webshots.com/photo/2824036070080251109kYsvFR

Grigg

Thanks for the response Master Gabster....I'm not disagreeing with....I just don't know....but when I looked at some of the related threads it seemed the 3/16 would work all around with a dual master.....the 3200 is still a 1/2 ton, so is there a difference in the brake componets for the front of a 3200 (where the 1/4 line goes) and the front of a 3100?

Maybe I am confusing the issue by using the old number system.........it would be a 1958 model 32 1/2 ton shortened to a model 31 spec........

Sorry, I thought you had a 3/4 ton shortened to a 1/2 ton.
My answer is still to to use the size line that came with the original brake system if that's what you still have under the truck..

Grigg

Ok thanks for the help.....I am probably making it more complicated than I have to, probably no reason not to use the 1/4 on the front and adapt those lines to the Master cylinder and the residual valves......

Not sure what you mean by "adapt" then?

Did you look at the picture of tube nuts I provided in an earlier post, and understand that they come with different thread sizes?
Can you simply use the proper tube nut for the MC and residual valves with whichever size line you need (sounds like 1/4")?

Grigg

I looked at the pictures that were supplied....they very helpful........If I remember right the 1/2-20 & the 9/16-18 will match the master cylinder......I think the residual valves I got are 3/8-24......so if they don't make a 3/8-24 tube nut that fits the 1/4 line I may have to adapt there.....thanks for your input

OK, Check this Weatherhead catalog, page 123
http://hydraulics.eaton.com/products/pdfs/E-BRFI-MC001-E3.pdf
I don't think there is an adapter made to do what you're asking, and I would advise against cobbling together a bunch of fittings to make it work..

However, I think you can find a different residual pressure valve with larger threads so you can use 1/4" line. I'm pretty sure I've used some on another truck I had, so shop around for another valve if necessary.

Grigg

Your right....I haven't bought the brake lines yet, but it appears that the various precut 1/4 lines come with a 7/16-24 tube nut...... When I searched Speedway they have a 7/16-24 fitting that should fit the residual valve........hopefully the local NAPA has it also......Thanks for helping me work this out.....been known to jump in without knowing how deep the "water" is....

The 3200 shares the chassis with the 3600 3/4 ton, including the hydraulic components of the brake system.