Venting rear diff
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Topic author - Posts: 397
- Joined: Sun Jan 06, 2019 2:36 pm
- First Name: Dennis
- Last Name: Prince
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Venting rear diff
I am wondering if you need to add a vent to the rear axle tube when going to a modern pinion bearing setup, they say that one or more of the bearings are sealed and I am thinking that I need to add a vent. This could be a dangerous move but "what do you think?"
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Re: Venting rear diff
Not needed. Don't overthink it.
Scott Conger
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves™
Obsolete carburetor parts manufactured
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves™
Obsolete carburetor parts manufactured
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- First Name: John
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Re: Venting rear diff
I vented the Ruckstell I rebuilt for my speedster. With the sealed pinion and in my case, sealed safety hubs and neoprene grease seals, I feel the axle is pretty much air tight....
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Re: Venting rear diff
I vented the Ruckstell I rebuilt for my speedster. With the sealed pinion and in my case, sealed safety hubs and neoprene grease seals, I feel the axle is pretty much air tight....
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Re: Venting rear diff
If venting an axle or torque tube makes someone sleep better at night, then there is some value in it, I suppose. However, with respect to pressure, there is nothing sealed about a sealed bearing. There is nothing in a Model T drive line that is building pressure that will not leak past a sealed bearing.
Scott Conger
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves™
Obsolete carburetor parts manufactured
Tyranny under the guise of law is still Tyranny
NH Full Flow Float Valves™
Obsolete carburetor parts manufactured
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Re: Venting rear diff
I believe a Ruckstell has a small vent that comes out under the name plate.
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Re: Venting rear diff
Re; I believe a Ruckstell has a small vent that comes out under the name plate.
No it does not.
No it does not.
I know the voices aren't real but damn they have some good ideas!
1925 Cut down pickup
1948 Ford F2 pickup

1925 Cut down pickup
1948 Ford F2 pickup
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Re: Venting rear diff
The carburetor has an air vent under the name plate. That's why you've never heard of anybody having trouble with their carburetor bearings.
The inevitable often happens.
1915 Runabout
1923 Touring
1915 Runabout
1923 Touring
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Re: Venting rear diff
I thought they were vented through the axle shafts? into the brake drums.
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Re: Venting rear diff
Bwahahahaha!Steve Jelf wrote: ↑Wed Feb 20, 2019 2:23 amThe carburetor has an air vent under the name plate. That's why you've never heard of anybody having trouble with their carburetor bearings.

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Re: Venting rear diff
I believe this is a great question. The original Differential design has numerous areas where any expansion or built up
pressure can escape but when you move a few steps into modern design a vent would be desirable. I have the
Sealed Pinion unit, Safety Hubs plus leather seals inboard of the Safety Hubs and a coil “wind back” spring on the axle. I have gone to great lengths To prevent pesky oil leaks but suffer with oil leak from the LH Wheel (typical of driving on the LHS of the road) Modern vehicles have breathers and their sealing devices are similar in effectiveness to what I now have in my T.
I look forward to hearing other experiences that others have with breathers
Alan
pressure can escape but when you move a few steps into modern design a vent would be desirable. I have the
Sealed Pinion unit, Safety Hubs plus leather seals inboard of the Safety Hubs and a coil “wind back” spring on the axle. I have gone to great lengths To prevent pesky oil leaks but suffer with oil leak from the LH Wheel (typical of driving on the LHS of the road) Modern vehicles have breathers and their sealing devices are similar in effectiveness to what I now have in my T.
I look forward to hearing other experiences that others have with breathers
Alan
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Re: Venting rear diff
If the axle is sealed like a new axle, it should be vented. Could help keep grease/oil out of the brakes. Be sure and put a snorkel tube on it if your going to forge any rivers.

24-28 TA race car, 26 Canadian touring, 25 Roadster pickup, 14 Roadster, and 11AB Maxwell runabout
Keep it simple and keep a good junk pile if you want to invent something
Keep it simple and keep a good junk pile if you want to invent something

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Re: Venting rear diff
A Ruckstell housing has no vent under the Ruckstell plate. You must be thinking of a NH carburetor!
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Re: Venting rear diff
Venting is a good idea, but on a T it seems, even with modern sealers, etc. I can't imagine that pressure would not be vented through the torque tube and u-joint ball and/or the engine. 

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Re: Venting rear diff
One of the biggest rough running issues that often goes undiagnosed is a loose carburetor bearing! (Where the throttle shaft passes thru the casting). It is an intake air leak at high vacuum condtions thus causing too rich a mixture at low vacuum and too lean a mixture at high vacuum.Steve Jelf wrote: ↑Wed Feb 20, 2019 2:23 amThe carburetor has an air vent under the name plate. That's why you've never heard of anybody having trouble with their carburetor bearings.
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Re: Venting rear diff
Quite true. Sometimes the hole is worn, sometimes the shaft, and sometimes both.
The inevitable often happens.
1915 Runabout
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Re: Venting rear diff
Very true...even on carbs on much later model cars.Steve Jelf wrote: ↑Wed Feb 20, 2019 12:17 pmQuite true. Sometimes the hole is worn, sometimes the shaft, and sometimes both.
1924 Touring
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Re: Venting rear diff
I've seen many used rear axles with vents in the axle tube. Mine has a vent also. Some people worry about dirt getting in also, Mine has a flip top press in oiler in the dried hole.
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Re: Venting rear diff
I have the modern axle seals & immediately after a long drive I removed the diff: oil plug to check the oil level and heard a puff of air exit. That was enough for me to install a vent.
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Re: Venting rear diff
What about putting a vacuum line into the vent to keep the oil from leaking out?
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Re: Venting rear diff
I had a similar experience as Roy Stone. I saw a small bubble as I was removing the plug. Drilled the plug and installed a vent line that runs up to the frame.
I also had thought of a vacum line when a rear axle seal started to leak but redoing the seal and lowering the fluid level has resolved that problem.
I also had thought of a vacum line when a rear axle seal started to leak but redoing the seal and lowering the fluid level has resolved that problem.