Final drive leak....

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harascho
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Final drive leak....

Postby harascho » Tue Mar 03, 2015 11:26 am

Hi folks,

my Toronado restauration is comming to an end but the first test drives showed some troubles here and there. I sorted out most of them but the final drive is causing a headache. When the tranny and final drive were removed I removed the cover and cleaned the the inside. There was a very thick brown "something" inside. It was flowing like hot honey... ok I cleaned it, removed the left and right flange and the left and right oil seal. Also the double oil seal to the tranny on the pinion gear was renewed. The vent in the left flange was cleaned and checked.
The new seals were ordered at Applied airfilters and everything they sent me was fitting as it should. The left and right oil seals were replaced and the corresponding fit on the flanges cleaned and inspected. everything was a straightforward repair.

But... why is there always that "but" ???

After driving the car the left oil seal was leaking badly. I used 90W mineral gear, 4,5 pints = 2,12l as stated in the manual. I checked the level and it was at the lower part of the fill hole.

Last week I decided to work that out, removed the cover again and built a double layer seal with an additional vent path in it, which ends in a small hole near the upper bolt in the cover's flange.
Again filled to the inspection hole with gear oil and...again leaking, even out of the vent hole. I removed a pint of oil ( about 3 pints left in the final drive) and then the leakage was a lot less, the vent hole stayed dry. In my opinion the 4,5 pints and the inspection hole above the axis of the ring gear is quite a lot of oil when modern 90W gear oil is used. I can't remember a differential with such a high fill level. The differentials are splash lubricated and as long as a good third of the ring gear is under oil that works fine and every bearing inside gets its oil.
So are there any ideas out there? In one manual I read about an oil seal with vent holes in it.. they had to be positionerd to the top.. but I guess with our kind of oil that would have resulted in a very bad leak ..;-)

Harald

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harascho
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Re: Final drive leak....

Postby harascho » Tue Mar 03, 2015 11:28 am

Here's the corresponding drawing out of the parts manual..
Attachments
Final_drive.JPG
Final_drive.JPG (163.72 KiB) Viewed 1931 times

bluecab
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Re: Final drive leak....

Postby bluecab » Thu Mar 05, 2015 7:36 am

Hi Harald,
Saw your pics at CO.

Is it the seals where the axles exit the final drive that are leaking?

I was not really sure from the photos.

You think it is a venting problem in the final drive?

I'm interested as I am getting ready to install mine..

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harascho
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Re: Final drive leak....

Postby harascho » Thu Mar 05, 2015 11:45 am

Problems are the axle seals ( No 2, 12) in the view above) Mine is leaking from seal 12.
As I konw how to install an oil seal I am not sure what my problem is. I am tending towards a too high fill level and a venting problem. but that's just guesswork right now. I reduced the oil by one pint and built that two layer vented cover gasket.. still leaking, so maxbe also that seal No 12 is the source of the trouble..

Harald

Aliraza9
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Re: Final drive leak....

Postby Aliraza9 » Fri Apr 03, 2015 12:23 am

Inline tube will use your old ones as patterns if you send them to them.???

bcroe
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Re: Final drive leak....

Postby bcroe » Sat Apr 04, 2015 7:06 am

harascho wrote:Here's the corresponding drawing out of the parts manual..


This may not be it. But the right side cross over shaft on a 66-67 Toro (3.21:1 final
drive) is a smaller dia than on a 68-78 Toro (3.07 or 2.73 final drive). If they sent you
a 68-78 seal, it wouldn't seal at all. Don't know if the left side was different.
Bruce Roe

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harascho
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Re: Final drive leak....

Postby harascho » Sat Apr 04, 2015 10:45 pm

Final drive leak is solved. It was my own problem. All the replacement seals for the left shaft are made for the later venting system, which means they have two small holes in the outside steel ring of the seal. The '66 final drive is vented through a hole in the the left shafts flange securing bolt. In the flange on the outer side there is a checkvalve and the flange itsself has two small holes in it.
Now said hat the newer style oil seal must be installed with the holes in the upper most position, mine were in the lower most position..;-(

I didn't care about the holes , didn't recognize them as what their purpose was and didn't pay any attention to them 'cause I never saw an oil seal with a venting option... and I saw a lot of them.....

I just had a chance to close them with epoxi, didn't even have to remove a single bolt... the Final drive doesn't leak anymore...
Harald

danifer
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Re: Final drive leak....

Postby danifer » Wed Feb 14, 2018 8:46 pm

Can you share the part numbers for both of those seals? I’m having trouble finding them for my 67 Toronado.

Otto Skorzeny
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Re: Final drive leak....

Postby Otto Skorzeny » Wed Feb 14, 2018 10:27 pm

Here are the seals from Applied GMC:

http://www.appliedgmc.com/prod.itml/icOid/1881

danifer
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Re: Final drive leak....

Postby danifer » Fri Feb 23, 2018 12:47 pm

I just went through the ordeal of replacing the final drive seals. Mine is a 1967 Toronado. These are my notes:

2/15/18
Talked to Jim @ appliedgmc.com (510-742-1101)
He's sending:
Left (Driver) OEM 9158S - 45.00
Right (Pass) NP9568 - 15.00

The driver side seal is very difficult to find, and Jim told me that National makes a limited production run specifically for them. Note that the driver side outer seal (9158S) will come with two small vent holes, which are to be installed in the 12 o'clock position. My original equipment seal did not include those vent holes because, as stated above, that side is vented via a small nut in the shaft. I'm going to install mine in the 12 o'clock position which should put them above the fluid fill level. I'll seal them with epoxy if I see any leakage.

The passenger (NP9568) seal is much easier to find. I did note that the original equipment seal has a lip around the outer perimeter that the replacement does not have. I don't think that will impede the function, but it was worth noting. I'm also not planning to reuse the metal shroud that was originally installed on top of this seal.


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