Before I defer to the Factory recommendations let me just say that if you
were correct in the residues acting as a lubricant, then there would not be
evidence of galling at the operating and accumulator piston bores.
All those crunches into 1st and reverse end up comingling, as do the brass
bits from the thrust washers/spacers on the laygear and O/D mainshaft. The
designers foresaw this and specified non detergent to separate solids from
liquids.
Seems logical to me.. just saying...
Dave
frogeye@porterscustom.com
Porter Customs 2909 Arno NE
Albuquerque, NM USA 87107
505-352-1378
1954 BN2 1959 AN5
Porter Custom Bicycles
cars:
www.britishcarforum.com/portercustoms.html
gallery:
http://picasaweb.google.com/porterscustombicycles/PorterCustomBicyclesStuff
blog: http://porterbikes.com/
-----Original Message-----
From: Bob Spidell [mailto:bspidell@comcast.net]
Sent: Sunday, November 15, 2009 10:22 AM
To: Dave Porter
Cc: 'Bob Haskell'; healeys@autox.team.net
Subject: Re: [Healeys] Dave Dougan's overdrive part 2
Uh oh ... here comes another 'oils' thread ;)
re: "... non detergent formulation. This formulation allows contaminants
to settle out and not be continually re-circulated, thus hastening
damage..."
Though I defer to Dave's knowledge and experience, this 'theory' never
made sense to me, mostly because a properly cleaned and assembled
gearbox and O/D should not have any contaminants. They are pretty much
sealed and won't suffer any combustion byproducts or other
contamination. When I've changed my gearbox and O/D oil, there was
always a minuscule amount of brass 'shake' suspended in the oil which
sparkled prettily in the sunlight. I guessed this was an amount of
brass about the size of a B-B that had been ground into infinitesimally
small particles. When rubbing the 'shakey' oil between my fingers I
could feel absolutely no grit whatsoever--it felt just like virgin oil.
There was usually a very small amount of ferrous metal on the magnets in
the O/D strainer, even with ashless dispersant-- aka 'detergent' oil, so
the heavier stuff was settling out anyway.
Given that brass is a relatively soft metal, and most high-quality
greases are oil thickened with finely-ground metals--molybdenum,
lithium, etc.--I believe the finely ground brass causes no harm at all
and may, conceivably, be a lubricant and/or protectant in its own
right. I feel the only reason to even change the oil is because the oil
molecules will be sheared over time and may lose some viscosity; though
the fact that modern differentials call for never even changing the oil
may belie that belief.
I have over 165K miles on my gearbox and O/D with one rebuild on the
gearbox only and they both operate quite well.
bs
*******************************************************************
Bob Spidell San Jose, CA bspidell@comcast.net
*******************************************************************
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