4 Speed main seal question

[Dave_R]

Hi Guys,

'53 pan with a '57 casting tranny.

I have been fighting against tranny leaks for quite a few years now. It looks that I got most of them plugged. The question I have is regarding the main seal.

I got hold of a Jims dual-lip seal thinking this would be better. Two years ago, following the instructions, I pressed in the seal with a cork behind it, but when trying to get it below the lip of the case by 0.050" I "warped" it inward. I ran it like this for the season, and it dripped a little.

So, last year I pulled it, and pressed in another cork and seal, only this time I was careful not to "warp" it. That seal went just about flush with the case. So I ran that last season. As the season went on, the leak rate increased to where it leaves a softball sized mark now.

So, here I am this year, with it torn down again. The seal's lip is torn off by the little key in the spline. It looks that if I leave the cork out, then the seal will go in below the case by the 0.050" I need.

Why is that cork there in the first place? I was trying to understand why that was there.

Can I leave it out?

Thanks for any advise!!

- Dave

[Bosheff]

I can't see what the cork does so I never use it. As far as countersinking the seal .050", I don't know what that does. Maybe when using a double lip seal this is necessary, but when using the H-D seal this should not be necessary. Have you checked/replaced the main drive gear spacer? If there are grooves worn in the spacer where the seal rides, you'll never get a seal to hold back the oil. As far as the drive gear spacer key tearin up the seal, there is no reason for the key to come in contact with the seal. Always run the key because without it, an oil leak is just about certain. Are you absolutely sure the leak is in fact comin from the seal/spacer?....bosheff

[hplhd]

Special-spacer-with-o-ring-for-the-leaking-tranny-
check this out. he also goes into detail if you do a search on how to make your tranny leak proof.
http://www.caimag.com/forum/showthread. ... drive-gear" onclick="window.open(this.href);return false;

[Bosheff]

Are ya sure the tranny isn't leakin between the mainshaft and the main drive gear?....bosheff

[Dave_R]

Most parts are 2 years or newer, as I went thru it completely in 2008. That includes all of the parts that any seal rides on as well. That is when I installed the seal and pressed it in too hard, which pushed in the face of the seal inward.

I used Andrews where I could. I upgraded to the newer main drive gear with the seal.

I also went so far, since I got a new mainshaft as well, to removing the new bushing inside the MDG and had a new one pressed in and sized.

In 2009 I cleaned up the area after I removed the drive components with brake cleaner, then used talcum powder to dust the area. It wasn't long before I saw the main seal are get damp. Eventually, it started dripping. Since that seal was bent inward, I replaced it again.

This time, I can see a rubber strip "peeled" off of the face of the seal.

The only thing I can see that would do this is if the little key had somehow hit the edge of it.

It drips from between the sprocket and the case.

Thanks Bosheff, I'll put this one on without the cork and see what happens.

Also thanks for the link hplhd!

[RUBONE]

The cork was a seal for the seal! When those gearboxes were designed the stock seals were plain steel on the outside, no plastic coating like modern seals. So to prevent leakage between the case and outer skin of the seal the cork washer was installed. It was thick enough that the inner edge of the seal pressed into it and kept oil from getting into the seal/case interface. With modern plastic covered seals it is redundant and can be left out. I have never used double lip seals or any of the other band-aid approaches to sealing a gearbox. They generally only leak if the breather vent is plugged, or they are over full! And they DO NOT like hypoid gear oil, just use regular motor oil.
Robbie

[indianut]

A Double-Lipped Seal does not seal any better! The Only thing the Second Lip is for is to keep Dust OUT!

[Panshovevo]

A Double-Lipped Seal does not seal any better! The Only thing the Second Lip is for is to keep Dust OUT!

...and water.

[BCOWANWHEELS]

MAKE SURE YOUR TRANS IS VENTED. IF ITS STOPPED UP WHEN IT WARMS UP IT BUILDS UP PRESSURE, IT HAS TO GO SOMEWHERE SO PAST THE SEALS IT GOES. PULL & CLEAN THE VENT BOLT... JMO
BOB

[Robert Luland]

MAKE SURE YOUR TRANS IS VENTED. IF ITS STOPPED UP WHEN IT WARMS UP IT BUILDS UP PRESSURE, IT HAS TO GO SOMEWHERE SO PAST THE SEALS IT GOES. PULL & CLEAN THE VENT BOLT... JMO
BOB

The clogged vent thing is a fallacy. Ever notice how much play you have in the clutch shaft going through the kicker cover. Pressure build up in a big twin tranny. I doubt it. Bob

[George Greer]

Bob, interesting comment about the vent.

On the AH-64 Apache helicopters, the intermediate and tailgearbox's they have vents on them. And these gearbox's are not pressurized like the main transmission. They just change direction and speed, and have one set of gears and various sensors on them.

Once they clog up........the oil/grease it blown out of the seals...and they do it quickly.

Not that this applies to motorcycle transmissions, just a comparison.

George

[Robert Luland]

Let me ask ya something George. If that gear box was as loose as a Harley tranny, would you fly that chopper?

[old1955]

G'day Dave,

Check your sprocket for end float, it may move a lot. There are different thickness retaining washers
now (35131-36) available from 0.005" - 0.020" oversize to adjust the end float.

That seal needs to "bed-in", and needs oil to do that.
Other wise it will just burn out, make sure you put some oil on it when assembling. And check you
box level regularly of course.

In the later seventies The Company eliminated that key you mentioned and removed its corresponding locating
knotch in the main drive spacer. When that sprocket nut is tight, I cant see any reason for that key, it does zip.
I never use it, and there ain't no leaks. One other thing, you may look at is the main race in the box is
correctly seated and the bearing on the other end of the main shaft is seated correctly too. In other words, if its out a poofteenth
and your shaft isn't running perfectly straight it may be causing problems with the seals. Also its a good idea to
run your main shaft in a lathe and check its straight.

Check the opening, the seal is pressed into,.....is it still round?
Carefully check the seal lip or lips, 360 degrees, before installing, you can get bad ones.

OK, I'm out of ideas!

Pete

[George Greer]

Let me ask ya something George. If that gear box was as loose as a Harley tranny, would you fly that chopper?

Not a chance in hell..

George