Author Topic: Tranny Output Seal Fail  (Read 545 times)

Offline kfz

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Tranny Output Seal Fail
« on: August 04, 2021, 02:11:31 AM »
Hello world.

Ive done loads of Gearbox's and never had had this problem.  Long story short is that the speedo drive worm is not positioned correctly regarding the output seal and the output seal fails.  Ive created a few videos and its easier to show then explain. 

What the hell am i doing wrong, I just want my bike back....

Video 1:  Issue   - https://youtu.be/5aiQ8PQ2kOo
Video2 :  analysis  -  https://youtu.be/320ckfwNdTw

Kev

Offline balvenie

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Re: Tranny Output Seal Fail
« Reply #1 on: August 04, 2021, 04:56:07 AM »
Good luck Kev :grin:
Sorry I can't help.
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Online lucian

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Re: Tranny Output Seal Fail
« Reply #2 on: August 04, 2021, 06:18:17 AM »
Can you mic. the old and new bearings to confirm the thickness?

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #3 on: August 04, 2021, 06:26:06 AM »
Can you mic. the old and new bearings to confirm the thickness?

Yes spot on.  They are identical,  within 0.01mm, which is as good as my veriner is i guess.

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Re: Tranny Output Seal Fail
« Reply #3 on: August 04, 2021, 06:26:06 AM »

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #4 on: August 04, 2021, 06:27:30 AM »
Video 3 - https://youtu.be/Y6AXM2qKXVA


dry run assembly,  Can anyone see what stupid potato brained donkey act I am doing wrong here......   

sorry it so long, set to x2 speed.

Kev

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #5 on: August 04, 2021, 07:51:02 AM »
Have you pushed the sealing to the bottom? Did you mention that the thickness was  7mm? My sealings atre about 8-9mm thick. The sealings has 2 lips, and the upper lip is a dust lip. The major lip is at the bottom.
Rolf

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #6 on: August 04, 2021, 08:05:55 AM »
Have you pushed the sealing to the bottom? Did you mention that the thickness was  7mm? My sealings atre about 8-9mm thick. The sealings has 2 lips, and the upper lip is a dust lip. The major lip is at the bottom.
Rolf

High Rolf,  long time no speak!

A thick seal would make the problem worse since it will overhang the speed drive even more.  I need a thinner seal if anything.  I confirm the sela size with John (Noble) and confirms its correct.

???

Kev

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #7 on: August 04, 2021, 08:46:03 AM »
Thin or thick - does not make a different. The main lip is always at the bottom.

And NEVER use any other tool than a seeger-ring tool, to remove the big drive. Else you would ruin the sealing surface.

Rolf

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #8 on: August 04, 2021, 08:48:03 AM »
And the main question is: have you put the seal in the correct way? It is impossible to see in the film.

Offline Wayne Orwig

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Re: Tranny Output Seal Fail
« Reply #9 on: August 04, 2021, 10:38:57 AM »
Odd. I'll list a few thoughts, but I suspect you covered all of this.

1. Is the seal all the way seated. I ask because maybe that seal driver you have is too big, hitting the metal lip, and not driving the seal deep enough. I think the seal goes a bit below the metal lip.
2. How thick is the output bearing. I'm sure it is right, but I have to ask.
3. Sort of unrelated to the depth issue, is the speedo drive seal surface perfect? I've always worried that it is fragile and would be easy to damage.
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Offline kfz

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Re: Tranny Output Seal Fail
« Reply #10 on: August 04, 2021, 11:23:34 AM »
Odd. I'll list a few thoughts, but I suspect you covered all of this.

1. Is the seal all the way seated. I ask because maybe that seal driver you have is too big, hitting the metal lip, and not driving the seal deep enough. I think the seal goes a bit below the metal lip.
2. How thick is the output bearing. I'm sure it is right, but I have to ask.
3. Sort of unrelated to the depth issue, is the speedo drive seal surface perfect? I've always worried that it is fragile and would be easy to damage.

Hi Wayne,

1. Good point, i will double check.
2.Yes confirmed identical to the pile i have removed in the past.
3. Yes its good.  But again I have few spares so will try some others.

Kev

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #11 on: August 04, 2021, 11:40:48 AM »
You have probably assembled the sealing ring - the wrong way.

Rolf

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #12 on: August 04, 2021, 12:02:50 PM »
You have probably assembled the sealing ring - the wrong way.

Rolf

Rolf, what Sealing ring?  The oil seal?

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #13 on: August 04, 2021, 12:09:27 PM »
Kev

Yes - the oil seal. It has one inside and one outside position. The open end is the inside - and should face the gearbox internal.

Rolf

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #14 on: August 04, 2021, 12:14:07 PM »
Kev

Yes - the oil seal. It has one inside and one outside position. The open end is the inside - and should face the gearbox internal.

Rolf

yep if you look in the video you can see its in correctly.  Also Ive checked per Wayne suggestion that its not fully home. I can confirm it is.


Online acogoff

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Re: Tranny Output Seal Fail
« Reply #15 on: August 04, 2021, 12:27:24 PM »
    If this helps at all,  I just went and measured my spare box with the output seal removed and the shaft securing nut tight. From the end of the output casting to the speedo drive is 9/16 inch plus about a hairs width. And If the o ring forward of 5th gear is not in good shape it can let extra oil migrate up the shaft  towards the out put seal, but not sure it would amount to much as it has to make it past the bearing to the seal.
« Last Edit: August 04, 2021, 12:31:59 PM by acogoff »
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Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #16 on: August 04, 2021, 12:36:56 PM »
Kev

I had some problem seeing the video - but after seeing it in full screen, I see that the seal is in place in the correct way - and deep enough.

But some sealing rings has 2 lips. The lower lip is the original sealing lip, and the upper smaller lip - is a dust lip.

In the video - it looks like you touches the dust lip. The lower lip may me in an OK position.

Check the outer surface of the big wheel - where it seals against the seal.

Rolf

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #17 on: August 04, 2021, 01:42:11 PM »
Kev

I had some problem seeing the video - but after seeing it in full screen, I see that the seal is in place in the correct way - and deep enough.

But some sealing rings has 2 lips. The lower lip is the original sealing lip, and the upper smaller lip - is a dust lip.

In the video - it looks like you touches the dust lip. The lower lip may me in an OK position.

Check the outer surface of the big wheel - where it seals against the seal.

Rolf

Yes I believe the lower part of the seal is in position. But the upper lip is not.  As you say its to keep muck out, not oil in.  Unfortunately cos the lip shreded up on the endge of the speed drive the inner lip then fail. Presumably the seal had lip debris in-between the inner and outer lips.

I think I want the whole seal to be running on the surface.

Im going to order some new seals, see if Its just the design of seal.

Kev

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #18 on: August 04, 2021, 01:56:32 PM »
How about this for a theory.

Im guessing he output seal should be a R21 -- single lip seal, Not a R23 - Twin lip seal.  This is why ive never noticed it before.  ITs the wrong type of seal.

Twin lip R23 isnt really needed as its in a controlled enviroment in side the UJ boot.  Im guessing Guzzi fit the single lip seal, which is fine. 

Previously ive fitted twin lip seal and this had led to failure.

Kev

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #19 on: August 04, 2021, 02:39:34 PM »
single or twin lip - I do not believe it matters. The main lip is in the same position.

Rolf

Offline Stevex

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Re: Tranny Output Seal Fail
« Reply #20 on: August 04, 2021, 02:41:35 PM »
I replaced that same seal during my LM2 refurb.
I used a double lip viton seal in place of the oem blue seal.
As you can see from the pic, the seal is too deep to allow the dust lip part of the seal to contact its mating surface.
The oil seal which you can see as the lower lip on the seal provides a good seal and has done so for several years.
As the upper lip is only a dust seal it didn't worry me too much as there isn't much dust in that area to keep out!

Seal with the double lips visible:





Seal in place, you can see the dust seal lip doesn't quite mate:








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« Last Edit: August 04, 2021, 02:45:52 PM by Stevex »
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Offline kfz

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Re: Tranny Output Seal Fail
« Reply #21 on: August 04, 2021, 02:47:20 PM »
I replaced that same seal during my LM2 refurb.
I used a double lip viton seal in place of the oem blue seal.
As you can see from the pic, the seal is too deep to allow the dust lip part of the seal to contact its mating surface.
The oil seal which you can see as the lower lip on the seal provides a good seal and has done so for several years.
As the upper lip is only a dust seal it didn't worry me too much as there isn't much dust in that area to keep out?

Seal with the double lips visible:





Seal in place, you can see the dust seal lip doesn't quite mate:







Thaks Stevex,  i think this is how i did mine and its cuased it to fail.  The speed drive chewed up the outer lip and left the remenents to to damge the inner lip,  im guessing.

Im going to fit a single lip seal and see how that goes.

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #22 on: August 04, 2021, 02:50:40 PM »
single or twin lip - I do not believe it matters. The main lip is in the same position.

Rolf

Not convinced Rolf,  I think the failing chewed up outer lip may have caused the inner lip to fail.  When i dissembled i found thin rubber string debris all wrapped up in the speedo drive.

I will fit a single lip and see how that goes.

Kev

Offline moto-uno

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Re: Tranny Output Seal Fail
« Reply #23 on: August 04, 2021, 05:18:14 PM »
  The only follow-up to this , is verify that the sleeve the seal rides on is in excellent shape .
  I'd also suggest a viton lipped seal ( some times called high speed seals at supply houses).  Peter

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #24 on: August 05, 2021, 01:24:03 AM »
  The only follow-up to this , is verify that the sleeve the seal rides on is in excellent shape .
  I'd also suggest a viton lipped seal ( some times called high speed seals at supply houses).  Peter

Peter,  Yes of course. I suspect the sharp edge cut into the outer seal seal lip after 10 yrs or so of use.  Ive got a lot of spares ill pick the best.

Offline Rolf Halvorsen

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Re: Tranny Output Seal Fail
« Reply #25 on: August 05, 2021, 02:23:10 AM »
High temperature resistance VITON - is used on the clutch-side, because of heat from the clutch. Standard black/blue material is used on the outgoing side.

Rolf

Offline berniebee

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Re: Tranny Output Seal Fail
« Reply #26 on: August 05, 2021, 07:58:40 AM »
  The only follow-up to this , is verify that the sleeve the seal rides on is in excellent shape .
  I'd also suggest a viton lipped seal ( some times called high speed seals at supply houses).  Peter

I know a bit about seals. (And the following is about the sum total of my seal knowledge  :laugh:)
The advantage of Viton over Buna (Ie: a black seal)  is mainly it's better performance with high temperature applications. Viton is also more resistant to certain chemicals, sunlight and weather. AFAIK, there is no difference in performance with respect to speed. In any case, the output  shaft is spinning at roughly 4,000 rpm  on the highway, not a particularly high speed application. But an advantage that might be important here is that Buna is more tear and abrasion resistant. Since that particular seal is at the "cool" end of the transmission, you might want to stick with a buna seal.

I assembled (my first ) Tonti transmission a few months ago and I recall the seal lips being exactly on the edge of the worm drive, which was a bit concerning, but, you know, Italian engineering.  And as has been mentioned, it's a double lipped seal in an enclosed space, not exposed to road dirt. So I pressed on with my renewing of the bike.

That might just be a malformed seal, could have been because of manufacturing or storage.  In the video it looks like the seal lip may be actually curled outwards? Have you tried pressing the lip area inwards and spinning the o/p shaft to see if it stays in place?




Offline kfz

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Re: Tranny Output Seal Fail
« Reply #27 on: August 05, 2021, 08:55:49 AM »
I know a bit about seals. (And the following is about the sum total of my seal knowledge  :laugh:)
The advantage of Viton over Buna (Ie: a black seal)  is mainly it's better performance with high temperature applications. Viton is also more resistant to certain chemicals, sunlight and weather. AFAIK, there is no difference in performance with respect to speed. In any case, the output  shaft is spinning at roughly 4,000 rpm  on the highway, not a particularly high speed application. But an advantage that might be important here is that Buna is more tear and abrasion resistant. Since that particular seal is at the "cool" end of the transmission, you might want to stick with a buna seal.

I assembled (my first ) Tonti transmission a few months ago and I recall the seal lips being exactly on the edge of the worm drive, which was a bit concerning, but, you know, Italian engineering.  And as has been mentioned, it's a double lipped seal in an enclosed space, not exposed to road dirt. So I pressed on with my renewing of the bike.

That might just be a malformed seal, could have been because of manufacturing or storage.  In the video it looks like the seal lip may be actually curled outwards? Have you tried pressing the lip area inwards and spinning the o/p shaft to see if it stays in place?


Thanks berniebee, 

no i havent as ive ordered a new single lip seal.  Its serving no purpose and its possibility its actually causing problems.  Ok so it takes a long time for it to wrong, but why do it if there is no advantage.

Kev

Offline kfz

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Re: Tranny Output Seal Fail
« Reply #28 on: August 20, 2021, 03:40:34 PM »
Put this one to bed.  All done bike back together. Massive thanks to John Noble.  I owe you an 80 shilling mate.

https://youtu.be/vIvA1vgrp58


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