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#1 Windscreen wipers and polarity.
Posted: Mon Jun 24, 2013 1:17 am
by abowie
In restoring my 3.8 roadster, I'm both converting it to RHD and also to negative earth.
I have read Joe Hardy's excellent guide
http://www.xkedata.com/resources/read/?id=9.
My question in my ignorance is, if I change the earth polarity to negative earth, do I still need to reverse the 2 wires in the wiper motor?
#2
Posted: Mon Jun 24, 2013 8:37 am
by Heuer
#3
Posted: Mon Jun 24, 2013 8:57 am
by abowie
Thanks David. I have read Mike's excellent series of articles, which led me to Joe's posts on Jag Lovers.
Neither touch on the effect of converting to negative earth though, and I am not electrically educated enough to be able to tell.
#4
Posted: Mon Jun 24, 2013 9:12 am
by Heuer
Makes sense you should not have to change the wires over. Why not test it on the bench and simply connect it to both +ve and -ve earth and see what happens?
#5
Posted: Mon Jun 24, 2013 4:51 pm
by PeterCrespin
Without referring specifically to the wiper jobbie, series-wound motors don't care about polarity, they'll always turn the same way. Hence you don't have to swap starters over when altering polarity.
Permanent magnet motors are polarity sensitive and so do need to be switchexover to preserve direction if the car's polarity is reversed. Simple test is if a motor casing grabs your screwdriver it needs reversing.
Pete