(Thread) sizes of Inverted Flare Nut used on CUCV M1009/8/...?

[Jake59]

Hello all,

Been searching to find any revealing data in the older posts but came out blank until now.

I am in the process of restoring a 1985 M1009.
Part of the job requires the radiator to be removed, new brake lines to be installed and lots of sandblasting, panel replacing and painting of course...

I would like to purchase me a package of Inverted Flare Nuts, which are commonly used on the M1009, mainly because sadly the supply lines to the EU are unfortunately not as flexible as within the continental USA.

I am hereby referring to the Inverted Flare Nuts as used to attach :

• the automatic transmission cooler hard lines to the radiator
• the automatic transmission cooler hard lines to the transmission
• the hard brake lines to the brake hoses in the front and rear
• any other location where our M1009 uses inverted flare nuts? (no doubt I forgot some other uses!)

Any information about the actual inverted flare nuts (thread) sizes would be most appreciated
I think the transmission cooler hard lines use 1/4" tube inverted flare nut 1/2"-20
No idea about the brake lines and others?

Most appreciated!

Jake

 

[cucvrus]

The automatic transmission cooler lines are 5/16" / 8mm. The fittings are 1/2" x 20 inverted flare nuts.

The fittings and lines are standard sizes, not metric, unions to connect two standard replacement 1/4 in lines together are 7/16-24 inverted flare but up at the master cylinder the fitting size is 1/2-20 or 9/16-18 inverted flare, so you may have to cut the old line to get the larger fitting off it and then re-flare your new line after you put the correct fitting on it.

On the 3/16 lines the fittings are 3/8-24 inverted flare normally but our trucks may also have larger tube nuts like 1/2in - 20. I am NOT carving this is stone. It is as memory that I posted this. I replace brake and cooler lines all the time. I just done the 3/8" hydraulic hose for transmission cooler lines on one project. Worked out well for me. Good Luck. Be Safe. On the rear axle weight sensing valve of the pickup and cab chassis models it does have a metric flare nut. That is the only one I ever encountered. All the flare nuts are readily available at a parts store.

 

[frank8003]

View attachment FLARE tubing brake flare chart common flares6.pdf

 

[porkysplace]

Take the NSN or part number of what ever you want the specs on and go to https://www.parttarget.com/

and it will give you all the info you want on a part.

 

[Sharecropper]

The fuel inlet nipple on all DB2 mechanical injection pumps is 7/16”-24 inverted flare.

 

[Jake59]

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[Jake59]

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[Jake59]

Thank you All!

@CUCVRus,

Thank you sir for your time and very helpful reply!
Great pointers!
Most appreciated!

@Frank8003,

Thank you for this link/PDF; I have downloaded it and more importantly, this learned me a few new things!
Thanks,

@PorkysPlace,

Thank you Sir, I will be searching here as well.
One difficulty I have is that I have not been able to find any NSN nor part number for the various Inverted Flare Nuts used on M1009, since these part numbers are not listed in the 52D_1984_87_CUCV_Parts_and_Illustration_Catalog.
Perhaps I am looking in the wrong document, so if you can point me to a better source, please do.
Thanks,

@ShareCropper,

Thank you Sir; an eyeopener, never even occured to me that the DB2 also uses Inverted Flare nuts!
Thank you very much!

Thank you all!

Jake
Belgium

 

[Jake59]

Good morning all,

Having the above information now, I will be replacing the rusted(through) AT 5/16" cooler lines with 8mm soft copper tubing. Drivers therefore:

• Shipping the replacement steel tubing parts for overseas delivery is very expensive, due to dimensions mainly.
• Oil flow capacity with copper tubing will be nearly the same I guess, although copper tubing has a slightly thicker wall and thus meaning a smaller ID (copper 8mm OD has 6mm ID vs. steel 5/16" OD with 0.028"wall has 6.5mm ID); so copper has only 92% cross section ID of steel tube.
• Easy bending and shaping of soft copper tubing
• Corrosion resistance of copper tubing. I will never again twist and shear the AT tubing at the inverted flare nuts on either side, radiator or AT.
• I also hope the copper tubing will provide a tiny little bit of extra ATF oil cooling, as copper is an extremely good heat conductor and thus the under body airflow will hopefully also cool the ATF oil lines somewhat better than the original steel tubing. Will have to install more tube support brackets however, as this is a much softer material.

There is no scientific evidence or proof of any kind for my statement about cooling... maybe just wishful thinking on my behalf... actually I should take temp measurements before and aft, but it's too late now, since the original cooler lines are punctured/defective, so no more measurement comparison is possible.
But copper is an easy to work/shape, corrosion free, alternative, that is cooler ((hopefully)literaly and also -looking) then steel tubing or rubber/braided hose.

Cheers,
Jake