Bastard sized Inverted Flare Nuts

50C8DAN

I wanted to pass on something I found out the hard way on some of the inverted stainless flare fittings on my brake conversion.  I purchased my distribution block from Speedway and it came with two short stainless lines to connect it to the MC.  The lines were already flared with stainless fittings.  When I connected it I only finger tightened the lines so I could adjust them once it was mounted and in place.  This is not as easy as I thought as the fittings on the MC I used were on the right side toward the engine and the brake light switch was in between the two connectors on the right side of the block.  Well as I tried to tighten them I could not get my 3/8" tubing wrench or even open wrench to fit on the nuts!  I thought what the hey here!!  I then realized that the lines were supposedly 3/16" but the fittings were METRIC!  The nuts were 10mm, luckily I had a 10mm tubing wrench, which I had never used for all of probably 30 years. Anyway I went on line and found that others had had issues with other supposedly English sized tubing nuts that turned out to be metric, but were advertised as 3/8 x 24 for 3/16" tubing, also some found oversized ones at 12mm.  So I am guessing these came from China and are bastard mix of English tubing with metric sized nuts on the outside and English 3/8-24 threads.  So be aware this may happen to you!  

cchancel

I've seen this issue on brake cylinders.  The fitting threads are correct, the mounting threads are correct, but the bleed screws are metric heads.  Yes, it is very frustrating!

bob ward

Metric hex sizes are very common on import English thread tube nuts, 10mm hex instead of 9.53mm (3/8") for instance. I don't lose too much sleep over it.

50C8DAN

Inline tube is still all English at least.  

ken1962

That's the trouble when the whole world is metric but not the USA. 

50C8DAN

Well perhaps, but when you are working on a 66 year old car that cannot speak metric it is a problem.