Vent screw on power brake junction box function ?

[Clyde9]

From: tatkin  (Original Message)
Sent: 4/30/2006 5:10 PM

On the rear axle is a junction box, the power brake line splits to feed each rear brake.   On that junction box is a Vent Screw.  I cannot find reference to it's use in the Service Manual.   Anyone know its function    Thanks ...



From: denisondc
Sent: 4/30/2006 6:16 PM

That vent allows the air inside the axle housing to expand with heat, when you are on the highway and the diff. oil gets hot. If the vent is plugged up, the pressure will tend force some of the diff. oil out past the grease seals at the ends of the axle. There is a drain scheme that is part of the hub, so the diff. oil should not get onto the brake shoes - but if the vent is plugged long enough, the drain scheme will begin to clog up from road dust. When I got mine, with 49k miles on it - the vent was plugged, the drain area was clogged with dirt, and differential oil beginning to get on my brake shoes.
I remove that vent bolt for cleaning about each 2 years.



From: tatkin
Sent: 4/30/2006 6:41 PM


Ah I see it now, just a handy hole to serve the axle and hold the junction box ...