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Author Topic: Rubber seals in general rebellion  (Read 1455 times)

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Offline gregimotis

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Rubber seals in general rebellion
« on: March 15, 2006, 06:05:48 PM »
'76 Cb750fF


Two hundred miles ago, I stove my crankcase when my chain wrapped the front sprocket.  I fixed this with much care and JB weld, it seems to be holding up except that:

About fifty miles ago the rubber seal behind my front sprocket (very close to the JB-weld repair) slid out of the engine.  I replaced it, but it seems to be slipping again.  I have purchased a new seal reasoning that the old one may have been damaged in the primary disaster, however I have not installed it yet.  Now, the seal behind my shifter is busy making IT'S escape as well.


Does any one have a theory as to why my rubber seals are suddenly jumping ship?
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Offline Bob Wessner

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Re: Rubber seals in general rebellion
« Reply #1 on: March 15, 2006, 06:57:33 PM »
That's a strange one. Are you using some sort of new, exotic oil maybe?
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Offline TwoTired

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Re: Rubber seals in general rebellion
« Reply #2 on: March 15, 2006, 10:10:56 PM »
Theory?  Okay, crankcase pressure?  How is your breather tube/filter thingy?

???
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Offline Jay B

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Re: Rubber seals in general rebellion
« Reply #3 on: March 16, 2006, 04:05:58 AM »
How close did the crack go to the seals? It almost sounds like the recess the seal fits into has sprung open a bit. Did the crack get to the recess?
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Offline gregimotis

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Re: Rubber seals in general rebellion
« Reply #4 on: March 16, 2006, 08:50:26 AM »
Thanks for the reply's.

I am using the cheapest oil I can buy at the moment, as I am changing it a couple times to clean any metal bits, cleaning products,  etc. out of the case.  The 'crack' was actually a half-dollar sized hole with cracks running off in all directions.  While I don't think any cracks actually got all the way to the seal, it's possible that there is some slight warping in the area - that might explain the seal behind the sprocket getting loose... but not the shifter seal.

I will check on the crankcase breather thingy... that should have occured to me.  Assuming that is clear, I plan to apply some RTV silicone (A.K.A. gasket maker) to the new seals as glue - bold or foolish?
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Offline byidesign

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Re: Rubber seals in general rebellion
« Reply #5 on: March 16, 2006, 10:13:38 AM »
RTV [High temp} or permatex gasket sealer will do an acceptable job of holding
   things, be sure that the sealing surfaces are cleaned of all oil or solvent residue.
      Apply a little assembly lube to the shafts ,and shaft seal sections.before
      slipping them on.
          Hope it helps,
                   Bruce
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