I'm not sure on the heater; however, the wiper motor is not polarity
sensitive. I have a 67BGT which is the positive ground Mk1. However, it
uses a circular wiper motor similar to the newer negative grounds. Moss
lists a specific model for the earlier positive ground GTs but they
apparently are now no longer available contrary to what their catalog says.
To make matters worse, they have started to sell the newer wiper motors
without the gear assembly and expect you to use your old gear assembly. I
couldn't get an original motor since they were no longer available so I had
to settle for the newer negative ground model which will work in a positive
ground car. However, the gear assembly and the part that connects the wiper
coil to the gear are also not interchangeable (they are smaller in the
newer wiper motors). Fortunately, Jeff Zorn was able to locate these parts
for me, used, and I was able to get my wipers going.
I suspect that VB is slightly ahead of Moss in updating their catalog and
that you will see this trend continue when Moss puts out their next
catalog. My experience above is slightly different than yours but its still
showing the tendency to discontinue parts and consolidate them with similar
parts from later years.
David
At 04:56 PM 9/13/00 -0700, Bullwinkle wrote:
>I checked Vic Brit's catalogs on the MGA and MGB. I have a MGA catalog from
>Moss but not one for for the MGB so I checked their on line catalog. Here's
>what I found.
>
>1) The MGB went from a generator to an alternator in 1968 at chassis
>138401 for
>the roadster and switched to negative ground.
>
>2) Vic Brit lists the same heater motor for the MGA and MGB, Moss
>doesn't. Moss
>changes stock number for the MGB at chassis 138401 for the later cars, Vic
>Brit
>doesn't.
>Vic Brit is also selling the same heater motor for the twin cam. I have a
>twin
>cam
>which uses a heater housing that is a mirror image for those in the standard
>cars. That is, everything is switched arround with the air trunking on the
>left
>side rather than the right. The motor only runs one way regardless of
>polarity. That is why the heater motor
>for the twin cam has a different BMC part number than the one for the standard
>MGA. I have a NEW standard MGA heater motor and it runs the opposite
>direction
>of the twin cam's regardless of the polarity.
>
>3) Vic Brit lists the same rebuilt wiper motor for the MGA and MK I MGB. Moss
>lists two different motors. According to the illustrations from both sources
>and stock numbers, the wiper motor for the MGB changed design at chassis
>138401. From the illustrations, the
>early MGBs used a wiper motor that looks the same as that used in the
>MGA. This
>motor isn't round but is rectangular. The rectangular wiper MOTOR on my twin
>cam rotates only one
>direction regardles of polarity. It doesn't have permanent magnets, but is a
>series wound motor just like the heater motor for the MGA.
>
>MY conclusions:
>
>1) Vic Brit is selling the later MGB heater motor as a replacement for ALL
>MGAs
>and MGBs as it will run either way by switching the leads. Moss is
>selling the
>correct item for each different model.
>
>2) Early MGBs, MK I, with the generator and positive ground use heater and
>wiper
>motors which are NOT polarity sensative.
>
>Blake
|