Transmission Output Shaft Seal Replacement

[orbit398]

I have a '74 2.0 liter manual transmission that has a substantial gear oil leak. I believe it is coming from the passenger side output shaft seal. Does anyone have instructions on how to replace this seal? As well as the driver's side? Can this be done with the engine/transmission in the car?




Also, I am assuming it's the output shaft seal. But I wonder if it might be the mating surface area between the tranny output shaft and the half shaft (6 bolts that hold the two together). I have heard there was supposed to be a gasket or silicon used there to seal the surface. I did not put either there. Wonder if gear lube oil in the transmission actually come out through the center of the transmission output shaft and leak out between the two mating surfaces? See attached pic. I figure the only way this gear lube could come out at this area would be a faulty seal on the transmission output shaft.




any info / advice appreciated

[stinkindiesel]

The surface at the red line will have a paper gasket for the original CV joints. Many VW type 1 replacement CV joints weren't cut for the gasket, and are just sealed with your favorite soft sealing compound.

Gary

[Dave at Pelican Parts]

There should be no way for gear oil to get into the middle of the output flange. There will be plenty of CV joint grease there, but that isn't gear oil.

I know professional mechanics who insist that the cardboard-type gasket must be used between the flange and the joint, and others who prefer not to use it.

Replacing the output seals can be done with the engine/trans still in the car. But it's easy to drop the trans off the engine, so consider if working upside down under the car is more of a pain than removing the trans and working on the bench.

Basically you will need to hold the flange still and remove the big bolt in the middle of it. Then pull the flange out, pull the seal out, drive the new seal in, and bolt up the flange again. You will want to make sure everything is clean and free of scratches, too.

--DD

[orbit398]

Dave - dropping the tranny may be the best bet. I can also check the front seal just for the heck of it.
Also, I have a side shift transmission and remember reading about replacing the first gear on the 901 transmission is quite easy. Mine grinds a bit if not careful when shifting and wonder if it's the same easy replacement as on the side shifter transmission? Any tips appreciated.

[Dave at Pelican Parts]

Fixing the 1st-gear synchros on all 901s is basically the same. It is a little easier on the side-shift versions, as you don't have to deal with the main part of the gear selector.

--DD