MTFCA Forum

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?"







i

Not needed. Don't overthink it.

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....

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....

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.

I believe a Ruckstell has a small vent that comes out under the name plate.

Re; I believe a Ruckstell has a small vent that comes out under the name plate.
No it does not.

I thought they were vented through the axle shafts? into the brake drums.

Steve Jelf wrote: ↑

Wed Feb 20, 2019 2:23 am

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.

Bwahahahaha! And all this time I thought that muffler bearings were the culprit..............

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

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.

A Ruckstell housing has no vent under the Ruckstell plate. You must be thinking of a NH carburetor!

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.

Steve Jelf wrote: ↑

Wed Feb 20, 2019 2:23 am

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.

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 12:17 pm

Quite true. Sometimes the hole is worn, sometimes the shaft, and sometimes both.

Very true...even on carbs on much later model cars.

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.

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.

What about putting a vacuum line into the vent to keep the oil from leaking out?

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.