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Checking transmission fluid
Posted by: piddler ()
Date: January 23, 2023 12:10PM

On the 4 speed is transmission fluid checked with dip stick or fill transmission to bottom of fill hole. The manual is not very clear on this.

Thanks, Pete

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Re: Checking transmission fluid
Posted by: RobertC ()
Date: January 23, 2023 12:53PM

You can use the dipstick, if so equipped.

There is (should be) a hole between diff and trans, so fluid is "shared".

I have always added fluid just to the diff (my 65) - even with bottom of the plug hole - with no issues.

If both are dry, I would add fluid to both.

Other people probably have other practices.

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Re: Checking transmission fluid
Posted by: piddler ()
Date: January 23, 2023 06:44PM

I changed the backup light switch and inly hadabout a quarter gear oil on hand. I was going to pick up some more oil to finish topping off. I checked axel oil with the dip stick and it was a little over full, I did not know if there is a passage between the two gear boxes.

Thanks, Pete

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Re: Checking transmission fluid
Posted by: piddler ()
Date: January 24, 2023 04:11AM

The gear oil did not come up to the bottom of the fill hole. Please excuse my ignorance but I am new to Corvairs. I don't want to over Fll but I sure don't want to damage the transmission.

So, do I fill to the bottom of the fill hole on the transmission or go by what shows on axle dipstick?

Thanks, Pete

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Re: Checking transmission fluid
Posted by: gbullman ()
Date: January 24, 2023 04:30AM

Note that the dipstick is measuring the oil in the differential, not the transmission. When both are filled to the bottom of the fill hole oil can move between the 2 and stay pretty much at the same level. But when you’ve drained the transmission to change the backup light switch it is empty and must be refilled to the fill hole in the transmission.

Hope that answers your question.


Gary
1966 Corsa Convertible
Northern New Jersey


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Re: Checking transmission fluid
Posted by: Tramp61 ()
Date: January 24, 2023 04:34AM

If you still have the round label on the transmission fill plug it says “Trans fill only”, “Check oil level at axle filler plug”. I would take the time to check at the axle fill plug to determine that your axle dipstick is reading correctly when the axle is filled to just below the axle filler plug. Over the years it may have been changed under previous ownership.

Craig T
Central NY
1961 Tramp (truck with a ramp)

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Re: Checking transmission fluid
Posted by: JimBrandberg ()
Date: January 24, 2023 04:49AM

The level between the 2 is a slow process. It's not like you can fill one and 2 minutes later they are equalized.
If you're a little high in the differential now that excess will find it's way into the transmission and equalize when underway.
Correct me if I'm wrong but I believe if they're low on gear oil the pinion shaft will often be the first thing to fail. I believe available oil is sort of induced into the transmission.
Early axle seals may leak with too much oil. They're sort of a bugger sometimes with axle radial play, "yoke slop" to coin a phrase.
I suppose it is transmission fluid but gear oil is a better term. Harder to find but GL-4 is better for us than GL-5 and 80/90 better for us than 85/90.
Are you sure you lost a quart of oil? If you pour a quart of oil on the floor it's A LOT OF OIL.

Jim Brandberg
Isanti, MN
CorvairRepair.com



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Re: Checking transmission fluid
Posted by: RobertC ()
Date: January 24, 2023 10:10AM

gbullman Wrote:
-------------------------------------------------------
> But when you’ve drained the transmission to change the backup light switch

Why? Do not know 66 - 69; switch is on the side

But, I have changed the backup light switch on my 65 4sp a couple times without significant loss of gear oil.

You do need to make sure you remove the old washer.



Edited 1 time(s). Last edit at 01/24/2023 10:14AM by RobertC.

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Re: Checking transmission fluid
Posted by: piddler ()
Date: January 24, 2023 03:40PM

The switch is on the bottom of the transmission on my car.

I had time today to take a look. I found the fill hole on axle. I removed the fill plug and drained a small amount of gear oil. I replaced the plug and filled the transmission to the bottom of the fill hole. I checked the axle dip stick and it showed a little over fill. I will need to remember this.

Any "new" old car is a learning experience. I learned some things today that are really simple for you guys. Mistakes come from inexperience and experience come from our mistakes.

Thanks, Pete

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Re: Checking transmission fluid
Posted by: Tramp61 ()
Date: January 24, 2023 06:45PM

Glad you figured that all out. Enjoy your car!

Craig T
Central NY
1961 Tramp (truck with a ramp)

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Re: Checking transmission fluid
Posted by: Mike Stillwell ()
Date: January 24, 2023 07:01PM

Do not overfill the transaxle. It will overcome the input shaft seal and ruin your clutch - quickly. I like to run it about a 1/2” below the fill plug on the diff, as measured by my middle finger stuck in it, with the car mildly jacked up on the drivers side.

Mike
YS-117

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