411 gearbox drive shaft oil seals

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Variantti
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Joined: Tue Nov 10, 2015 11:51 am

411 gearbox drive shaft oil seals

Post by Variantti » Tue Nov 10, 2015 11:57 am

New to 411 and this forum, just got one to revive back to life. Been dormant since 1994.
I see both sides of gear box have sprayed the body with oil, assuming drive shaft seals are leaking. Any advice as to how to change the seals. Do I need to drop the gearbox or can I get to the seals underneath.

Apreciate forum input.

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raygreenwood
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Joined: Wed Jan 22, 2003 3:01 am

Re: 411 gearbox drive shaft oil seals

Post by raygreenwood » Thu Nov 12, 2015 11:57 am

So...is this a manual or automatic? The difference is significant. Drain the final drive gear oil from either type gearbox first.

In short...yes you can do this without removing the transmission....but its easier and safer to just take it out. I ssay this for several reasons.

1. If the side seals are shot on a four speed, the mainshaft seal is the same age. do them together. In reality...the crank seal on the flywheel (four speed) or flex-plate on automatic and the converter seal are also the same age. Its far easier to take the gearbox out and do it all at one time.

2. Its cleaner. You need to get the areas around the seal very, very clean. Your tools need to be very clean. Any grit inside and it is instantly in the bearings.

3. There are two ways to do this (depending on whether you are manual or automatic...one way with automatic...two ways with manual). On the four speed one is hard and you have to be careful...and the other is less hard and you have to be careful. The less hard way applies to the automatic.

It also depends on what year automatic.
There was early and late. The early model is easier.
The early has a five bolts in an aluminum ring around the seal. It has a gasket between that flange ring and the case. That could be leaking as well and needs replacing. There is no snap ring holding the stub axle on. There is an Allen bolt that goes through the center of the stub shaft. DO NOT STRIP OR LOSE THIS BOLT AND USE A TORQUE WRENCH WHILE REPLACING IT. The nut is captive on the inside so dont worry.
Remove the hub....and pull out the shim underneath....do NOT mix it with the other one from the other side. The aluminum five bolt ring with the seal comes out.

take it out...punch out the seal...clean it religiously....press in a new seal....replace. Retrace steps. DO NOT forget the shim.

If the side play of the stub axle was excessive....look to see if the shim or the face of the stub shaft has wear. If so...replace the shim with one that will restore the tolerance. It could be a warning of spider gear thrust washer wear...but on this model of automatic...the risk is very remote. On a four speed.....its a problem that must be addressed.

In the newer automatic and the four speed....you remove the hub by removing the snap ring (have to do this either way even on the four speed.). Then carefully remove with a magnet...the spacer ring that resides between the hub and the face of the bearing. DO not lose or omit this. If its missing...you know why ....other than age...that your seals are shot. that comment goes for the early automatic as well.

If the shim is missing or worn out it will show excessive axial and radial play of the CV hub......which you should measure on any of these transmissions before starting to remove the hub.

On the four speed...remove the plastic or metal anti-rotation locking cover by removing the two Phillips screws.

You then carefully.....using a slide hammer with screw fitting on the end or other small sharp instruments....PROCEED CAREFULLY AND DO NOT GOUGE THE BEARING UNDERNEATH OR PUSH DEBRIS INTO THE CASE......remove the seal. replace the seal carefully.

DO NOT ding up the splined stub shaft sticking out on the four speed. On the automatic...its easier because the splined shaft is attached to the CV hub and pulls out of the way.

Do not gouge the aluminum surrounding adjuster ring on the four speed. Removing and replacing the seal on the four speed is hardest this way.

The easier way....but more tedious and you must be careful....is to remove the seal on the four speed is to place the gearbox on a workbench on its side suspended by a couple of inches so that the spline stub shaft opposite the side you are working on does not contact the workbench.

Either buy or make the suitable spanner to fit the internal 12 point socket of the aluminum adjuster ring holding the seal. Mark the aluminum ring position carefully relative to the case. Remove the aluminum ring. You must count the exact number of turns and partial turns....this is the preload for the differential bearings.

Once you have the ring removed...clean it well...press out the seal and press in a new one. Take this time to inspect the condition of the bearing race. If you see any wear....its time to redo everything. Put a new o-ring on the aluminum adjuster ring.....screw it back in the exact number of turns. Repeat for the other side.

The automatic gearbox in detail can be found in the brown Bentley manual for type 3.

Ray

Variantti
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Joined: Tue Nov 10, 2015 11:51 am

Re: 411 gearbox drive shaft oil seals

Post by Variantti » Thu Nov 12, 2015 12:09 pm

My 411 has a manual gear box. Thanks a lot for your hands-on instructions.

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raygreenwood
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Re: 411 gearbox drive shaft oil seals

Post by raygreenwood » Thu Nov 12, 2015 5:06 pm

Variantti wrote:My 411 has a manual gear box. Thanks a lot for your hands-on instructions.
On the manual trans......if you have the right tools....are patient. ...and careful....and you can get everythjng very clean......you can remkve the CV hub and use o-ring hooks or a very small nail bar to rwmove the seal.

The risk is dingjng up the splines on the stub axle....or damagkng the aluminum adjuster ring the seal is pressed into....or getting debris inside of the case.

Also....read some of my writings on the four speed. If you have a lot of play in the CV hub while the snap ring is still on....and you still have the spacer underneath.....you may have some wear to the differential stub axle thrust washers inside the diff. These are a high wear item on high mileage transmissions.if they wear too far the spyder gears are at risk. Ray

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