At 07:10 PM 7/20/2000 +0100, paul.hunt1@virgin.net wrote:
> the heater motors on both my MGBs exhibit significantly different output
volumes according to which way the supply and ground are connected to the
motor.
The possibility of bad connections aside, do you know if this actually
reverses the direction of the motor?
>.... when I got my V8 as a daily driver I noticed the heater output was
significantly less than that of my roadster. .... I took both motors out
and found them identical but that they rotated in different directions.
Reversing the connections on the V8 brought it up to the same 'performance'.
Does this mean that the direction reversed, or only that it ran faster?
>Can't speak for how the MGA is wound or how it differs from the MGB, have
you tried reversing yours just to see what happens, ....
Yup, many times, and I did that again just before my recent posting just to
be sure. The MGA heater motor always runs the same direction and speed
regardless of polarity. Furthermore, every MGA heater motor I have seen
(quite a few) has two black wires, so there's no way to tell which is which
without opening the motor case. Do the later MGB motors have color coded
wires?
V.B. lists one part number for the heater motor for all MGA and MGB,
including the twin cam (opposite rotational direction) and V8 (shorter
motor case). Big laugh. I bought one of these motors from V.B. a couple
of years ago and promptly returned it. That motor has the same cross
section as my original motor but is a full one inch shorter in the field
coils and armature and outside case. I have been told that this was done
to accomodate a space restriction with the introduction of the V8 in the
BGT. I suspect this motor will not have the same power or blowing capacity
as the larger units. I never powered it up to see which way it runs, and
neither did I notice if it may have had color coded wire leads.
So here is the next reasonable guess. Perhaps the newer replacement motors
are wound differently and designed to change rotation with polarity. This
would solve a sales volume and stocking problem by replacing multiple part
numbers with one common part. I notice that Moss does not have a part
number for the MGA heater motor, but does have two different numbers for
the MGB motors. Oh Kelvin, are you there?
Barney Gaylord
1958 MGA with an attitude
http://www.ntsource.com/~barneymg
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