Re: [MV] DRILLING CAST IRON - (more on fittings).

Alan Bowes (alan_bowes@phast.com)
Mon, 04 May 1998 20:17:05 -0600

> Dennis wrote:
> >....modify the filler and drain plugs....
> You wouldn't even need to modify them.

This is absolutely true. There are actually many different possible
combinations of fittings that you could use, any of which would screw
into the plug holes in the case.

I had mentioned in my previous posting that you could design this in a
way that would allow you to drain and refill the case without removing
the lines to the pump/filter. One simple way to do this would be to
incorporate a T-fitting with a separate drain plug (lower assembly) or
filler plug (upper assembly).

Do keep in mind that if you add any fittings at the bottom of the case,
they should be kept as close to the case as possible so as not to snag
or bang against things like sticks and stones. You may want to consider
using an elbow of an appropriate angle to prevent the assembly from
extending down too far. Don't have the elbow bend forward, since it can
form a "hook" that can snag things.

Getting back to the initial reason for this, however, is the issue of
heat. These transfer cases do produce a bit of heat, especially when
operated at higher speeds. However, since you don't have to worry about
things like clutch plates and synchronizer rings (which require a
certain amount of "grip"), you can use the slipperiest available oil. A
synthetic gear lube that is NOT approved for use with limited slip
differentials will help minimize friction in the transfer case, which
reduces heat. In addition, their easy-flow characteristics also help to
reduce heat. And, perhaps more importantly, it should also tend to
provide better high-temperature film/shear strength and protection.

Just for the heck of it, you might want to do an experiment. Drive some
particular measured route and note the speed, ambient temperature, etc.,
and then take the oil temperature at the end of the route. Then switch
to a synthetic lube and repeat the process. See what kind of temperature
difference you experience. Try to do it on a day when the ambient
temperature and humidity are about the same. You may decide that you
don't need the pump/cooler/filter after all.

Have fun,

Alan

===
To unsubscribe from the mil-veh mailing list, send the single word
UNSUBSCRIBE in the body of a message to <mil-veh-request@skylee.com>.