Best estimate: OEM fitting ID = 2.5mm versus 1/8" NPT Brass ID = 5mm, so about 4 times the area. Hydraulic friction varies by the 5th power of the diameter so 1/32nd as much flow resistance per unit length if I recall my 2nd year fluid dynamics correctly.
Here's a pic...
I used a brass bulkhead fitting Greenline Part No. G0808BBH-02-02. It is designed to screw into a tank and provide a 1/8" FNPT cplg thread. Not sure what the female thread was I drilled and tapped into the differential housing to mount the bulkhead fitting but it was a std UNC screw thread I...
Problem Solved! I tapped the breather hole for a larger fitting! Forgot all about that! Thanks ;) Fortunately I just finished taking off the swivels and hadn't pulled the 3rd. Whew!
Yeah i've had that 35-40mph vibe too, then more recently a bit higher speed one. Anyway I'm going to have to pull it and have a look. That washer thing is like semi-spherical, shiny on the inner surface and dull on outside with a small divot attached in the center (if that makes sense). Some...
I think I have a problem. Was in the middle of a knuckle job on an HDJ-81 with 180k. When I drained the diff I discovered some odd shavings on the magnet. I'm used to seeing a few fine shavings from gear wear but this had many small shiny thin flakes, including a thin rounded bit of what looks...