Rear End Vent.

[The Master Cylinder]

Is the Model A rear axle vented anywhere? I know the trans in vented, just curious about the rear end.

[abachman3]

In a word "NO." It is not a sealed unit, though, as the torque tube is open to the atmosphere, as are the axles. Thus there is not a need for a vent.

[Tom Endy]

It vents into the torque tube though the pinion bearings.

Tom Endy

[The Master Cylinder]

Thanks Guys. I suppose I should have mentioned I have a Mitchell O/D. So does it vent thru the Mitchell via the torque tube?

[Synchro909]

When I was installing a Mitchell O/D in one of my cars, I wondered the same thing and decided it wouldn't vent so I modified a bolt to allow a vent. It allowed oil to get out, not air so I removed it and went back to the solid bolt. I have 4 Model As, all with a Mitchell. None of them have any special venting and none have such an issue.
If you're concerned about venting the rear end after you install the O/D, don't be. There are who knows how many thousands of them running around and they don't have a reputation for that, mine included!

[redmodelt]

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They are self venting esp if the seals are shot!

[The Master Cylinder]

Originally Posted by Synchro909

When I was installing a Mitchell O/D in one of my cars, I wondered the same thing and decided it wouldn't vent so I modified a bolt to allow a vent. It allowed oil to get out, not air so I removed it and went back to the solid bolt. I have 4 Model As, all with a Mitchell. None of them have any special venting and none have such an issue.
If you're concerned about venting the rear end after you install the O/D, don't be. There are who knows how many thousands of them running around and they don't have a reputation for that, mine included!

Thanks, Synchro. My rear end developed a slight leak where the bell bolts to the center section and I thought it may be because it was building pressure. Small drip, started after I installed the Mitchell. No big deal it is just I chased down and stopped or controlled all the other drivetrain drips from the front engine seal back to the rear end. Pretty dry down there!

Somrthing to keep me busy.

[GPierce]

My Mitchell came with a vent tube you mount to the underside of the car.

[redmodelt]

That vent is for the transmission itself, not the rear end.

[Planojc]

Not on a Model A but when I installed a Mitchell on my 39 Ford, the much shorter torque tube on the Mitchell caused pressure to build up in the banjo and I was leaking oil. I talked to Steve Mitchell and decided to vent the axle housing by drilling a small hole on top, tapped it and used a brass barb fitting and hose just like the one on the Mitchell itself. No more leaks. The TT on a Model A Mitchell is a little longer than the TT on the V8 Mitchell, so venting may not be needed.

[The Master Cylinder]

Thanks for the info Planojc. Gives me something to ponder. I can't think of another reason it would develop a leak "all of the sudden". I put 'The Right Stuff' on all the bolts to ensure the leak was not from one of them.

[redmodelt]

Originally Posted by Planojc

Not on a Model A but when I installed a Mitchell on my 39 Ford, the much shorter torque tube on the Mitchell caused pressure to build up in the banjo and I was leaking oil. I talked to Steve Mitchell and decided to vent the axle housing by drilling a small hole on top, tapped it and used a brass barb fitting and hose just like the one on the Mitchell itself. No more leaks. The TT on a Model A Mitchell is a little longer than the TT on the V8 Mitchell, so venting may not be needed.

I am doing the same with a Model T rear end that has a Laycock overdrive. The outer bearings are safety hubs so will not have the same venting as stock, along with that short tube between the rear end and overdrive. I was going to add vents, the type that look like little balls compressed, at the end of the axle tubes, but decided I did not want water dumping on them.

[jukenut 16]

My '30 coupe leaked at the torque tube plugs and diff center bolts (after fitting o/d). I fitted a breather on one diff axle tube, no more leaks.

[daren007]

As I get older my rear end develops a slight leak and it has always been vented.

[Ruth]

Originally Posted by daren007

As I get older my rear end develops a slight leak and it has always been vented.

Why do old men always think they are funny obsessing over leaking body orifices. In case you have not noticed, this Forum is about 'A's, not a$$es.

[redmodelt]

Originally Posted by Ruth

Why do old men always think they are funny obsessing over leaking body orifices. In case you have not noticed, this Forum is about 'A's, not a$$es.

Oh lighten up man, life is way too short to be that anal. MaHaHa!

[Ruth]

Originally Posted by redmodelt

Oh lighten up man, life is way too short to be that anal. MaHaHa!

I rest my case.

[nkaminar]

I have the Mitchell overdrive with a small leak at the differential and will install the vent that Planojc talked about. The trick will be to keep the chips out of the torque tube. Shop vac? Big magnet?

[redmodelt]

Modify one of the banjo bolts. Drill a hole in one, then braze on a section of barbed fitting for the hose to fit over. No drilling of the housing needed.

[marc silva]

That is a great idea! I’m going to try that. My center section started leaking after I installed a Mitchell also. Thank you for the tip! Marc

[Planojc]

Originally Posted by nkaminar

I have the Mitchell overdrive with a small leak at the differential and will install the vent that Planojc talked about. The trick will be to keep the chips out of the torque tube. Shop vac? Big magnet?

I drilled the top of the axle housing, not the torque tube and used an air hose to blow away chips as I was drilling. This is where Ford vented their cars when they went to open drive shafts.

[The Master Cylinder]

Originally Posted by redmodelt

Modify one of the banjo bolts. Drill a hole in one, then braze on a section of barbed fitting for the hose to fit over. No drilling of the housing needed.

Originally Posted by Planojc

I drilled the top of the axle housing, not the torque tube and used an air hose to blow away chips as I was drilling. This is where Ford vented their cars when they went to open drive shafts.

It's been awhile. I drilled a banjo bolt and silver soldered a piece of tubing on it. I then ran a piece of clear tubing up as high as I could (higher than my Mitchell vent). It pushed oil out.

I then installed a vent on the axle tube. No more leaks.

[Big hammer]

When drilling holes and you want to control the chips use grease on the drill bit !

[The Master Cylinder]

Originally Posted by Big hammer

When drilling holes and you want to control the chips use grease on the drill bit !

Yes sir, that is exactly what I did. A big ol' glob of grease. Greased up the tap also. Then I stuck a magnet thru the hole to check.

[C1Nelson]

I think venting the axle tube is the way to go. Can I tap it and put in a barber fitting?

[The Master Cylinder]

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Originally Posted by C1Nelson

If I drill one of the banjo bolts I do not have the ability to braze the barbed fitting. I suppose I could epoxy the fitting. Thoughts please.

You could but when I vented one of the banjo bolts it pushed oil out the 2' long clear tube I installed. see post #22. Venting the axle tube worked better for me.

I used a vent similar to this; https://www.amazon.com/Alemite-30080...%2C162&sr=8-10

[C1Nelson]

Originally Posted by The Master Cylinder

You could but when I vented one of the banjo bolts it pushed oil out the 2' clear tube I installed. see post #22. Venting the axle tube worked better for me.

I used a vent similar to this; https://www.amazon.com/Alemite-30080...%2C162&sr=8-10

Perfect, thank you for info where you got it. I also saw where you used grease on the drill and probably on the tap as well? How far from the banjo did you put the vent ?

[updraught]

What goes on in the diff
https://www.youtube.com/watch?v=9-yG3D3JBRs

[john in illinois]

I drilled a small hole in top banjo bolt. It leaked like a sieve. Top vent in axle has worked well.


John