Re: [T3] Grease.

["Jim Adney" <jadney@vwtype3.org>]

On 28 Apr 99, at 13:52, oofacts@earthlink.net wrote:

> >Moral: Use clean cam grease here, and clean the cam every time you
> >replace the points.
> 
> Now, where is a body supposed to find cam grease. Muir said wheel bearing
> grease, so I figured thats ok. But now I'm wondering, could it contribute
> to this wear on the rubbing block? Whats the difference between say cam
> grease, wheel bearing grease, multi purp grease, lithium grease and this
> moly grease I hear/read about every now and again?

Wheel bearing grease is probably fine. The important thing is to not 
run them dry and don't run with dirty grease. Dist grease is just a 
little bit tackier.

Okay, grease lesson time.

Grease is a MIXTURE of oil and a soap. While this is not the kind of 
soap you use in the shower, it is cherelated and this is the 
correct term for it. You can have different kinds and viscosities of 
both the soap and oil portions.

The soap portion will be based on one of the alkali metals:calcium, 
sodium, or lithium. Virtually all modern greases are made from 
lithium based soaps. Lithium based greases do better in high temps 
than the older calcium and sodium greases. The oil in most greases is 
petroleum oil, but it is also possible to use silicone or synthetic 
oils to make special greases. 

Grease lubricates by slowly allowing the oil portion to separate out 
and flow into the bearing, or whatever. If you take apart some old 
piece of machinery that has old caked grease in it, that is just the 
soap with all the oil leached away. The speed that the oil separates 
is controlled by the viscosity of the oil portion, while the 
thickness of the grease as a whole is controlled by the viscosity of 
the soap. So you can start to get an idea of the many kinds of 
greases possible.

Beyond this, it is possible to add any number of other substances 
which may affect the properties of the grease. One ot the most 
common, and most useful is molybdenum disulfide. MoS2 is just a solid 
which is an even better solid lubricant than graphite. It is ground 
into extremely fine particles and mixed in with the grease. Under 
high pressure it burnishes into wear surfaces and is an extremely 
high pressure additive.

I use a special MoS2 compound as an anti seize. It works especially 
well on spark plug threads as it is non-conductive. If anyone is 
interested, I have a few small tubes of this (Dow-Corning Molykote G 
Paste) available for  $5 @. The tubes are small, but it is a lifetime 
supply. My own 1 lb. can is nearly 30 years old, I use it everywhere 
in small dabs, and it is still 1/2 full.

Jim
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Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
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