Ford Mustang Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
2,662 Posts
Discussion Starter #1
So I'm changing out a pinion seal that was leaking. I took the differential breather off to check and make sure it wasn't clogged. Thankfully, it's in good working order. However, I noticed that the breather is a one-way check valve. It can relieve the pressure out but does not let any vacuum in once the differential and fluid has cooled.

The only way for the vacuum to be released in the rear end assembly is through the seals then. This does not seem like a very good set up for a road race car that gets extremely hot then cools back down to ambient temperature over and over throughout the weekend. Is there possibly a better set up/system for this?
 

·
Registered
Joined
·
2,662 Posts
Discussion Starter #3
If you have the stock breather (which by your explanation it sounds like you do) then it is in fact a one-way valve. It will let air out (pressure) but not air in (vacuum).

And it definitely creates enough pressure to push fluid out on a weekend of track days. If it is pushing fluid out, it means that once it cools there is a vacuum that needs to be filled.

How mush pressure and/or vacuum I have no idea.

The whole purpose of this thread is that perhaps there is enough to cause the pinion/axle seals to leak and possibly go bad much quicker than normal.
 

·
Registered
Joined
·
302 Posts
I fabricated a catch can with a breather and used a 90 degree hose barb on the axle housing... the hose going from the axle housing runs "up hill" to the catch can. If any gear oil is vented to the catch can it drains back into the axle housing.
 

·
Registered
Joined
·
334 Posts
I think your overthinking it a little, but the sintered breather I posted or one similar will solve that. If your pushing fluid out run a hose to a high point and install the breather. Off road guys do this quite often as the "one way" valve you spoke of lets water in the diff. The vacuum, if any, would only pull past the parts of the seals that weren't submerged under the fluid so the pressure would be more likely to cause the leaks.
 

·
Registered
Joined
·
2,662 Posts
Discussion Starter #6
I fabricated a catch can with a breather and used a 90 degree hose barb on the axle housing... the hose going from the axle housing runs "up hill" to the catch can. If any gear oil is vented to the catch can it drains back into the axle housing.
Possibly have any pics? Do you know what size thread the hose barb is that screws into the axle?
 

·
Registered
Joined
·
302 Posts
https://ibb.co/bUVR5a

https://ibb.co/fTwzQa

I hope those pics work...

IIRC the fitting size on the axle tube is 1/8 npt. Whatever it is the fitting was a little loose. I put Permatex high torque rtv around the fitting before I screwed the fitting into the axle tube. So far, so good...
 

·
Registered
Joined
·
2,662 Posts
Discussion Starter #10
That looks good. I'm trying to find something similar.
 

·
Registered
Joined
·
444 Posts
Here is a catch can/breather by Full tilt boogie for a irs:
FT 1382
It will work the same for any differential set up though.
 

·
Registered
Joined
·
302 Posts
What's the brand of that reservoir?
No particular brand... it is just something I put together. It is actually PVC from Home Depot. I used two pieces that had bosses on them for 1/4 npt thread IIRC, a coupler, some caps, a few fittings and a breather from Advance Auto. It is filled with stainless mesh that I picked up at the grocery store. I probably have $20 in the entire project... I also did something similar for my t5 transmission... it kept blowing fluid up through the shifter so I removed the tailhousing and and drilled and tapped the vent hole for a fitting. I ran a -8 line up the catch in the engine bay... I will try to post up a pic...
 

·
Registered
Joined
·
138 Posts

·
Registered
Joined
·
138 Posts
Is that an optical illusion or is that close to the tailpipe?
It's an optical illusion. It's about 1.5" away at the closest point. The rubber is fuel hose from advanced auto. Do you think that is a concern for heat? I was hoping to use the clear tubing for the whole thing. It's rated at 500F but it kinks to easily.
 

·
Premium Member
Joined
·
2,410 Posts
If you have the stock breather (which by your explanation it sounds like you do) then it is in fact a one-way valve. It will let air out (pressure) but not air in (vacuum).

And it definitely creates enough pressure to push fluid out on a weekend of track days. If it is pushing fluid out, it means that once it cools there is a vacuum that needs to be filled.

How mush pressure and/or vacuum I have no idea.

The whole purpose of this thread is that perhaps there is enough to cause the pinion/axle seals to leak and possibly go bad much quicker than normal.
If there is a vacuum in the rear differential, it would be impossible for oil to leak out. With a lower pressure inside the diff, air would be trying to get in, thus preventing oil from leaking out. Simple physics. This is one of the reasons why I run a vacuum pump on my engine...no oil leaks!
 

·
Registered
Joined
·
662 Posts
It's an optical illusion. It's about 1.5" away at the closest point. The rubber is fuel hose from advanced auto. Do you think that is a concern for heat? I was hoping to use the clear tubing for the whole thing. It's rated at 500F but it kinks to easily.
1.5" is probably ok...if it were my car, I would just keep an eye on it...I don't believe the tailpipes are over 500F that far down the system :grin2:
 
1 - 20 of 21 Posts
Top