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Re: Spark Plugs and other stuff.

Thanks for that info.  
The bearing I changed also used in LTs where, according my information, people had problems with it.  If a bearing happened to be a lemon it still unlikely that it'll fail at a very early life.  My replaced bearing had about 1,000.000 miles of life time (160,000 km), so I could assume that another bearing may be good, let's say, for 50,000 km.  

In the fall I may go for a ride:  Montreal - L.A. - Montreal, and I'd like to do the same trip next spring too.  Two trips to L.A. amounts to about 35,000 km.  I don't want any failure of anything at a place far from home.   If something happens, not to far from my garage, it costs me the towing only (forget the bearing). 

Next year, if I'll be still around at 80, I am planning a trip to L.A. by myself, alone only.  So you understand that no reasonable maintenance is too expensive or is redundant, in my case.  After that trip I may not go for long rides or not only by myself.  In case I still would ride on long trips in subsequent years, I don't mind to change bearing again.

Apart of all the above, you are right in your analysis of life of bearings.
Thanks for your comments
Bob Silas 
  ----- Original Message ----- 
  From: Bob Hadden 
  To: oilheads@xxxxxxxxx 
  Sent: Friday, June 10, 2005 5:31 PM
  Subject: Re: Spark Plugs and other stuff.

  Just one note on bearings and seals.  Ball bearings are rated based on 
  the design life under their designed load.  A typical rating would be 
  the B10 rating, listed in a number of hours where 10% of the bearings 
  would fail.  There is another hour rating at 5% and 1% etc.  The actual 
  numbers aren't important unless you are the design engineer, but the 
  concept is important to us users.

  If a bearing or seal fails at, say, 10000 miles, it was likely one of 
  those 10% (or 5%, or 1% depending on the selection the engineer made) 
  that are just going to fail.  So you replace it and move on.

  If, at 10000 miles (or 120000 miles in Bob Silas's case) you decide to 
  replace a bearing or seal that hasn't failed, you may not have done 
  yourself any favors.  The fact that the original bearing hasn't failed, 
  means it's one of the good ones.  You have no idea if the one you put 
  in is a good one or not.  So it's a crap shoot to some degree.  I have 
  no idea what the design life of the bearings in our bikes is, but it's 
  something to think about when you decide to change out a good bearing.

  This above logic also applies to seals.  If the seal isn't leaking, 
  don't mess with it.  If you take something apart anyway, you should 
  always replace the seal, because you could well have wrecked it when 
  taking apart the item.

  Some of this goes back to the old saying:  If it ain't broke, don't fix 

  Bob,  Don't get me wrong here.  I'm not saying you shouldn't have 
  changed out the parts you did.  After all, 120k is a bunch of miles.

  OK,  Time to go back to riding.

  Bob Hadden '05R12GS, '62R27

  On Jun 10, 2005, at 9:26 AM, Robert Silas wrote:

  > Clive,
  > <snip>
  > The cage which holds the 19 balls in place in the large roller bearing 
  > broke, cut the seal and let the oil escape from the final drive.
  > I had at least 50% more milage at that point and I figured better 
  > change bearing and seal, which I did.  The bearing which I replaced 
  > was in perfect shape.
  > <snip>
  > Regards
  > Bob Silas