VCCA Home Forums TECHNICAL - 1945 AND NEWER 1949-1954 differential oil

While I have the car up waiting on parts for the torque tube I thought I would check the differential oil level. The book says that it should hold 3 1/2 pints. I put way more than in it before it came up to the fill hole.

I have the front of the car on ramps and the rear axle on stands and the car is pretty level. I raised the front of the drive shaft up to where it would be if it were connected.

I some times see an oil spot under the rear axle that looks like it is coming from the breather.

Where did the extra oil go?

The extra oil is headed for the axle seals. That's where it will eventually leak out onto the linings on your brake shoes. I would take out the bottom bolt on your axle cover and drain all the fluid out and then put exactly 3 1/2 pints of oil back in. Filling the oil up to the top of the plug or until you can feel it with your finger is not correct.

Good luck, Mike

A question I probably should know the answer.

How do I check oil level when servicing? How do I know when it is low?

I add oil to the bottom of the fill hole and never had a problem with oil going to the axle. mine is a 52.

Is your fill plug located just above or below halfway up on the differential cover?

Several years ago, I installed my cover wrong, with the plug in the top half section, rather than the bottom half. When I added the book specified amount of oil, it was not enough. So I soon realized I had installed the cover wrong after comparing it with pictures in the service manual or owners guide.

The fill hole is above center. Probably 2/3 up. I haven't had the cover off. I guess the previous owner put it back that way. It looks like someone has put sealer between the cover and the housing.

Thanks. I thought the hole looked high but didn't think of it being on upside down.

That's very good info that most folks would never consider.

So, would this positioning be correct?

Yes.

I'm surprised that the cover can be installed upside down. Would have thought factory would have designed it so that could not happen. I just checked my two 47s and guess what! Have one with plug high and one with plug low. The high one has been that way for 8 years with fluid level up to the plug and no leaks (yet) at axles. Guess I better either turn the car over or change the cover.

Dick

The differential is designed for the axle bearings to get oil only when you go around a bend. Right turn, left gets oil left turn, right gets oil.

The problem with too much gear oil could be oil foaming due to the ring gear being submerged in oil.

You should never have to add oil to the differential. Now and then you may have to drain some off. After the initial filling, the differential gets plenty of oil from the transmission. That transmission oil should be replaced as needed.

While Mike is right on initial filling of the differenital, from then on a curved pinkie just touching the oil will tell you it is full enough,

The transmission should be filled slowlly and stop after the oil creaps to the plug hole,

Some perfer the heavy oil 140 while others perfer the lighter 80 weight. It amounts to whether you think your car likes syrup or molasses.

It is my belief that the lighter the oil that can adequately do the job is preferable over the heaviest oil that can do the job. Engine also.

Wait for it.

Charlie

" After the initial filling, the differential gets plenty of oil from the transmission. That transmission oil should be replaced as needed."

I'm assuming you were kidding around, when you wrote this comment.

Ha. I thought the same thing, Bob. My torque tube is sealed much better than that.

Now you have me curious. I am going out during 1/2 time of the Warriors Cav's game and check them. I know the 46 is okay, because I look at it every day as it is setting on my driveway.

Yes, Wayne, torque tube must be sealed correctly to operate properly.

Transmission fluid and differential fluid should not mix with one another, if torque tube is correctly sealed.

My statement was sound about not having to replenish the differential oil. The only way it would not be is for the car to not be driven much or just having the torque tube seal replaced. Even then the seal will not function for long.

The torque tube is on a slant down toward the differential. Warm oil (even 140) will soon ease by the seal.

You who never drive your cars as you would back in the day, will not be bothered by haveing to check the depth of oil in either the transmission, differential or the engine.

Ask yourself, when was the last time you had to add oil to the differential? When was the last time you had to add oil to the transmission? I rest my case.

A seal, when you are speaking of the torque tube is merely an annoyance to warm transmission oil not a complete blockage. Think about it.

How long does your engine's rear main stay "sealed." Good example.

Now all kidding aside you all, after some truthful reflection, know ol' Charlie is right on. Not always but in this case it's so. I'm talking about torque tube slight seepage here (which is adequate) not a river.

You'all be a checkin' those trannies and rearends now and report the facts of your findings. Let's see how many of you change your opinion.

"Sealed" really? Mine arse!

Charlie

Yep! Charlie is barking up the right tree here when it comes to oil seals and old Chev's. Same goes for valve cover gaskets, side cover gaskets, rear main bearing seals and timing cover gaskets. Trying to keep an old Chev from leaking oil somewhere is as futile as trying to stuff toothpaste back into the tube. The only way to keep a Chev dry is to not drive it.

Hmmmmm, ...... well Charlie, after giving much thought to what you have written ...... and taking the time to re-evaluate the design, I have come to the conclusion the oil from the

transmission should not mix with the oil in the differential, if the torque tube is sealed correctly..

Yes, a poor torque tube seal will allow fluids to go into the wrong neighborhood, but if the seal is good, AS DESIGNED, the fluids will behave themselves, within their own

neighborhoods.

Okay, Bob,

Let's put your theory to a test. We'll jack up a 41 that you have personally installed seal in the torque tube and have run the car for 1k miles.. We will then take the torque tube out and put it on two saw-horses of different hights representing the slant of when it's in the car. Then after wiping away the oil present in the pumpkin place a towell down on the ground and let you lie under the drip zone for one hour with your mouth wide open. (Medic will be standing by)

The above test will prove two things:

a. That you're been weined from oil having acquired a taste for sweeter products such a Dr Pepper.

b. That you will listen to my superior knowledge a little better in the future.

c. That the wonderful mountain air has a diterious effect on your noggin. I'll check with with Chip. I have noted no deteriation in his brain waves. So far.

I can tell you have not thought this instant mattger through. You are, perhaps, going along with other na-sayers just to be with the majority of skeptics.

Best,

Charlie

BTW: The towel is so you don't mess up the ground not for your personal protection.

Yea ..... you must be right Charlie.

Actually you've reminded me tomorrow I have to drain the excess oil from the rear end and reinstall that oil back into the tranny ..... kind of full circle maintenance , right Charlie ?

I hope Charlie and Bob that you realize this post concerns a 54 powerglide transmission. I have never heard of ATF leaking into the rear axle and if it did I certainly would not dump any oil from a rear axle back into the POWERGLIDE transmission.

Steve, I hope you have read this entire post ...... no way do I agree with the Fayetteville member here.

Yes I have read it all and am aware of your opinion. Charlie does from time to time bring up some interesting points and while some may be questionable they are at least entertaining .