[Healeys] Dave Dougan's overdrive part 2

[Dave Porter]

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 at porterscustom.com

Porter Customs   2909 Arno NE
Albuquerque, NM USA 87107
505-352-1378
1954 BN2  1959 AN5
Porter Custom Bicycles

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-----Original Message-----
From: Bob Spidell [mailto:bspidell at comcast.net] 
Sent: Sunday, November 15, 2009 10:22 AM
To: Dave Porter
Cc: 'Bob Haskell'; healeys at 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

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Bob Spidell           San Jose, CA            bspidell at comcast.net

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