Rubber vent in front knuckle???

[Petzel]

I am currently rebuilding my birfields and i just noticed that there is a rubber "breather" like thing that came out of the top of the knuckle. There is a machined groove for it to go in the top of the knuckle. It looks like it is held there by the spindle. Anyone see this before? I have never seen it, although this is the first time I have taken this trucks front axle apart. I have never seen this on 60 series axles. The truck is a 1991 PZJ77 with the high pinion diff.

 

[Petzel]

Also, while i was cleaning the parts, i noticed that this rubber breather had been filled with blue silicone(rtv?). I am wondering if i should do the same again, or if there is a reason for this breather. Seems wierd to me to have a breather that could possibly feed water/dirt inside the housing directly to the birf. Maybe it is not a breather????!!!?

 

[AlbertoSD]

Greetings,

That is not a breather, but rather the rubber grommet for the electric actuated locking hubs. It seems that the PO either used those knuckles to complete a disc brake conversion, or they simply removed the electric locking hubs in favor of the manual locking hubs and plugged the hole as you have described with RTV.

That connector is where the wires enter the knuckle to provide power to the little electric motors mounted on the hubs.

I've only seen knuckles like that in trucks with electric actuating locking hubs.

Hope this helps,

-Alberto

 

[Petzel]

Of course! The previous owner did change hubs to manual. Ok thanks Alberto for the quick reply, I can continue without worrying!

 

[AlbertoSD]

Of course! The previous owner did change hubs to manual. Ok thanks Alberto for the quick reply, I can continue without worrying!

 

[ForealBoreal]

Yup i ran into this exact same thing. I honestly took a stainless bolt that was the biggest i could fit in the hole and RTV'd the hell out of it to plug it. No issues.