Filling rear end 1923 Hudson Super 6

Does anyone know the purpose of the extra fitting on my differential? I see the plug to fill and the plug to empty but what is the purpose of the other arm and plug.  The only thing I can think of is it is a way to measure the about of fluid you put in not to exceed this level?  Anyone know the answer?
Robert

Comments

  • Geoff
    Geoff Senior Contributor
    It  is actually a sight hole for aligning the mesh of the crown wheel and pinion. 
  • wow I never would have known that.  What do modern cars have to do the same thing?
    Robert
  • Geoff
    Geoff Senior Contributor
    Modern cars are all pre-loaded and  not adjustable the same.  the principle is the same  but the construction totally different.
  • I'm confused.....it has a right angle bend I would think you couldn't see anything?
    Robert
  • Geoff
    Geoff Senior Contributor
    We are talking about the small square plug in the centre of the pinion housing, not the  curved filler fitting.
  • bob ward
    bob ward Senior Contributor
    I'd say the elbow fitting is the filler and the top plug is the sight hole. The top of the elbow would be the limit for the amount of oil that can go in the diff, to drain the diff turn the elbow 180°.
  • The elbow stays where it is. The drain plug is on the bottom of the diff. 
  • Thanks guys for straightening me out. I got it now. No telling what I will find when I drain it. I have the 600 wt steam oil to fill it with.
    Robert