5 speed output shaft seal replacement

[Orange Guzzi]

The output shaft seal is leaking on my 5 speed transmission.  Nothing major, but gets messy after a few hundred miles.  Do need to take the nut off the shaft to replace the seal or can I pull the old seal with a slide hammer and reinstall new seal?  I done this before.  If I remember correctly, I removed the old seal and replaced it with a new one while the nut was installed.  The one I replaced leaks because it was not seated completely.  The outer lip was/is not on the shaft/smooth section of the nut.  I know this because when I replaced the tires, I did some diagnostics.  It was obvious the outer seal lip was not on the nut shaft area.  I attempted to push it in furthers, but it is still leaking today.

The front seal is leaking also.  I may hold out until winter sets in and pull the engine to replace front and rear seals.  Don't tell the wife, but there may be a lighten clutch assembly that goes back in.

[Wayne Orwig]

The transmission output seal rides against the drive gear for the speedometer. Not the nut.
The nut has an o-ring to help seal it against the shaft which can also leak.
If you replace the seal with the speedometer drive in place, and you 'touch' that drive gear, you will easily damage the gear, and have a leak.

[Orange Guzzi]

http://www.thisoldtractor.com/guzzitech.dk/pdf/gearbox-rebuilding-john-noble_print.pdf

Found this nice picture at this old tractor.

Wayne, your description is confusing.  Are you referring to the speedometer gear that the cable attaches to or the speedometer worm drive gear? 

Are you saying that the the stack of narrow washer, o ring, support washer, speedo worm drive and nut should be installed after the seal is installed?  I was going to pull the seal and place a new in its place without removing any of the parts. But then again, if I am going this far, I should go on and  replace the o ring.

I can see how the o ring can leak since it is sandwiched between two washers rather than being against the worm drive gear.  It would seem that the or ring would be between the front washer and the worm drive

[Vasco DG]

Logic dictates that should be where it goes but it doesn't. It goes on the shaft outboard of the bearing but under the washer.

Pete

[Wayne Orwig]

Are you referring to the speedometer gear that the cable attaches to or the speedometer worm drive gear? 

The seal rides against the worm gear on the shaft. I have replaced the seals without touching the worm gear, but it is not easy.
Also, be 100% sure that the bearing inside the transmission isn't failing and letting the shaft move.

[Orange Guzzi]

Thanks.  This Old Tractor is a good source and helped to visualize the procedure.  I can see that it would be wise to replace the o ring while inside the case.  I am looking for a short term fix thru the end of riding season.  I plan on removing the motor and doing other mods thru the cold weather months.  As I said, it was obvious the seal I had installed several year ago was not seated in the case.  The outer lip was not riding on the worm gear when I inspected the other day while changing the tire.  I tried to push it in further, but only made the leak worse.  Front seal is leaking also, I have gear oil coming out of the bell housing. 

[Stevex]

I replaced my input and output seals last winter with the box out.
Took the advise of some guys on this forum to replace originals with Viton seals (brown in colour, as opposed to the blue originals).
This pic of the seal and worm drive before the nut's refitted may help you visualize.
The Viton seal has an outer dust seal lip but the seal doesn't sit low enough for it to make contact with the worm drive.
There's also a small ball bearing in there that you don't want to lose.

[Orange Guzzi]

I replaced my input and output seals last winter with the box out.
Took the advise of some guys on this forum to replace originals with Viton seals (brown in colour, as opposed to the blue originals).
This pic of the seal and worm drive before the nut's refitted may help you visualize.
The Viton seal has an outer dust seal lip but the seal doesn't sit low enough for it to make contact with the worm drive.
There's also a small ball bearing in there that you don't want to lose.

Double lip seal.  So the stock seal is not a double lip seal and the outer lip on the seal does not ride on the speedo worm gear.  That is what I see when I look into the case also.  I suspected that was the cause of my leak and tried to push the seal in further, but you are telling me that the single lip style OEM is correct and should seal.  As Wayne said, the o ring could be leaking.  I will buy both and replace as a set.  The seal that is currently installed is black and a double lip seal.  Probably an EDPM

[Stevex]

The originals I replaced were single lipped; I was ready to chuck the same seals back in but was advised to use Viton seals as they are apparently a lot more durable.
I'm not worried about the dust seal not mating with the worm drive, there shouldn't be much of any dust or crap in there to keep out, so long as the oil seal does it's thing.
The double lip on the input side is a bonus in keeping out clutch dust etc.