Gearbox/Diff oil has a sulphur-based additive that improves
the ability of the oil to provide lubrication under the compression
and shear loads found at the gear/gear sliding surfaces.
Unfortunately, these same compounds are bad for the bronze
components we find in our gearboxes. Redline and perhaps
others have oils that use alternate means of providing the extreme
pressure performance (redline manual transmission oil supposedly
is saf e for our gearboxes - we don't get it here so I can't say
from direct experience).
FYI, molybdenum (sp?) and zinc additives also provide good extreme
pressure additives. I can't recall the reference, perhaps it was an SAE
publication or a Instute of Mechanical Engineer publication, but I once
trolled through the literature and found a good comparative study.
As a result, I use a good quality oil and some moly additive in the gearbox.
Mike
----- Original Message -----
From "Mike Maclean" <macleans at earthlink.net>
To: "Steven Fooshee" <sfooshee@home.com>
Cc: "spridgets team" <spridgets@autox.team.net>
Sent: Sunday, February 11, 2001 5:42 AM
Subject: Re: Tranny oil
> Probably has additives that protect bronze bushings and handles extreme
pressure better
> than regular 20W-50 Wt oil. I was just reading on the British Sprite and
Midget Club web
> site that the only thing you need for the smooth and ribcase gearbox is 20W-50
wt oil and
> STP. At first I put Redline MT-90 in my just rebuilt smoothcae gearbox and
discovered the
> first motion shaft making a noise like the bearings were not getting any oil.
We thought
> it might be the pilot bushing at first, remember Frank? I put the combo in
that I just
> mentioned and it is very quiet now. Besides, STP is cheap.
> Mike MacLean-60 Sprite
>
> Steven Fooshee wrote:
>
> > While I'm on the subject of motorcycle fluids, has anyone given
consideration
> > to using 20W-50 motorcycle oil for the ribcase? One of the points that the
local
> > motorcycle shop explained to me that I have to pay $2.50 a quart for this
oil is
> > that it's specifically formulated for use in gearboxes (bikes share their
oil
> > Mini-style).
> > --
> > ~
> > '87 RX-7 TII: Fastest F%^!er with Fenders.
> > MCMLXIX Sprite: Retro before retro was cool.
> > '90 GS-500E: Perfect in her simplicity.
> > '87 RX-7 TII: Sad Sack. Partz 4 sail.
> > Do infants enjoy infancy as much as adults enjoy adultery?
> >
> > ~
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