Just a fyi, there is a very real reason for the hypoid description in
gear oil. Has to do with shearing the oil. Hypoid gears put tremendous
sliding loads across the faces of the teeth, tearing oils up. To handle
this tremendous load, the oils are modified with things like Zinc,
Sulphur and such. While these special hypoid additives greatly help the
oil survive, they tend to be corrosive to soft metals like brass and
copper. So you need to be careful which you use. There is a
correlation between the GL specifications and hypoid suitability, but I
don't remember the exacts of it.
As another fyi, the overdrive clutch is perfectly capable of handling
all the power a Spitfire engine can give it. The problem is the
hydraulic pump is driven by the output shaft, and needs to be spun up
enough to build up suitable pressure to properly hold the clutch. The
vehicle speed in 1st and 2nd gear is not high enough to have the output
shaft spinning adequate rpms for building pressure. So the problem
isn't with the power of the engine, it's with the rpms of the output
shaft. There are some modifications that can be done to better build
pressure, allowing 2nd gear usage, as well as external oil pumps to
allow 1st gear usage. But for a Spitfire application, they are rather
silly.
>>> Richard Gosling <richard.gosling@exprogroup.com> 04/05/02 10:14AM
>>>
Gear oil labelled 'Hypoid' (a fairly meaningless term, as this
just refers to gears that are cut at an angle rather than parallel to
the
shaft, so I can't see it's relevance to oil specs) ...
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