I put a 9 inch rear end in my truck and I'm working on routing the brake lines. I ran into a dilemma when I realized that the breather hole on the top of the housing is not threaded. Like an idiot, I had already installed my third member, with the copper crush washers and tack on the gasket. I'm not too keen on drilling and tapping the hole for a breather bolt since I can't make sure that all of the chips would be removed without taking off the third member. I'm not aware of a breather that presses into the housing, but it appears as if that's what came on this rear end. The 9 inch is from a 68 Galaxie. I'm leaning towards buying a flex line with a bracket that fastens to the studs like this one: https://www.currieenterprises.com/bolt-on-rear-brake-hose, then modifying a breather to press into the hole in the housing. Is anyone familiar with the breathers in these rear ends? Would it be better to remove my axles and third member, drill and tap the hole for a 7/16 breather bolt, and use a junction that's held by that bolt instead? Any suggestions would be appreciated.
It was probably one of the short self contained plastic type. It would have no hose on it. You could put one of those back in the hole and used a hose like the one in your link. That's what I would do unless you plan on wading water deeper than your axle.
That hole looks tapped to me, if not check what tap may work. I've heavily applied grease to a tap and held the chips. Unless it's too big, use a 3/8" fine and copper washers under the Y fitting. Your lucky your not working under a car body...
I apologize for the low-quality pictures, but I know for sure that it's not tapped. The diameter is about 3/8", so I'd have to drill to 25/64", then tap 7/16" UNF for a vent bolt. It's the drilling that concerns me because I'd probably have to take everything apart again in order to collect the chips. I almost never choose the easier option because it's easier, but it seems that this may be an exception. You're right about not working under a car and it's not difficult to take the rear end apart, and it would probably be best to do that. I just hate moving backwards when I'm so close to getting this thing back on the road.
Lots of options You could thread the hole by applying grease to the tap and going slowly pulling the tap out and cleaning often you would minimize any metal getting into the housing. Do you have a drain on the diff? Even finding something that fits and either epoxy or jb weld to secure it to the diff will work. There is a s minimal if any pressure in a diff ..... as long as it’s vented! I’ve seen axle seals go on diffs that had the vent plugged with dirt or rusted over There are a lot of press in breathers in industrial equipment , gear boxes etc Also transmissions have press in breathers ZF comes to mind quickly
I did put a drain in the bottom of the housing. Like you said, pressure isn't really an issue. My only concern with a press-in breather, particularly one that is all plastic, is whether it will maintain its integrity when exposed to the elements.
Maybe you already have your solution figured-out. I had the same problem once...untapped hole after all was together on my rearend. I got a rough inside diameter measurement of the hole and then went and found a brass fuel fitting larger than the diameter (I'm thinking it was 1/4" NPT on one end ??) as pictured below. I ground the threaded end to an interference fit of the hole, mixed-up some JB Weld, slapped it on the fitting end and tapped the fitting into the hole. It held very well while I owned the car and I'll bet it's still holding...wherever it is. (after installing it in the housing, attach a short section of hose turned down to prevent water from entering.) Good Luck.
I chose to go with the press-in breather and brake hose that fastens to the third member and everything seems to fit all right.
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