Post by jeff on Apr 28, 2020 20:50:27 GMT
Hi all,
Since my front suspension rebuild, I turned my attention to the mysteries of converting the Morris's single speed wiper into 2 speed. I had a unipart GEU 717 spare 2 speed motor so set about it. I spent hours searching the web and eventually came across a post with a similar motor internal arrangement for Triumph TR4, Motor DW3A. Oh the diagram was simple but understanding it was a bad dream. What I couldnt get my head around was how the hell do you get a higher second speed when you switch a resistor into the circuit.
. Eventually the penny dropped but its complicated to explain. Then a bagfull of pennies dropped when I worked out the wiring and switching arrangement.
The motor direct live feed is unswitched when ignition is on and by earthing (on the bench using a battery charger for power) the slow speed wire starts the motor on slow speed. Only when you connect the fast speed wire WITH the low speed wire, do you get high speed. This had me foxed until I read again and again. It's all to do with reducing the magnetic field via the internal resistor wire causing the motor armature to call for more current forcing it to speed up. Now I've got to find a way of switching it and getting the auto park to work.
Everywhere I read, it cant be done with a side and headlamp switch. Well it can. All you need is a Lucas toggle switch which will connect a common (to earth or car body), to a terminal for low speed wire on it's own,and another terminal for the high speed wire, both terminals connected to earth at the same time. Like our sort of side and headlamps,when heads are on side lights remain on.
The auto park had me foxed for a while until I realised the contact in the motor cap keeps the motor earthed and running when switched to off, until the revolving contact reaches a gap in its corresponding contact plate.
So I learned in summary,ignition on gives a live feed direct to the motor on the green wire. The other 2 wires go back to the switch, red/green for fast, and Brown/green for slow and they are only earthed via the switch. The spare black wire connected to E on the motor case and is connected to earth (the car body). So the auto park will work. I hope this is of help to anyone contemplating 2 speed wipers on an early landcrab.
My next task is to find out why the heater blower barely produces a draught. The car was swapped to negative earth years ago. I read a post on this site which goes into some depth. What I want to know is, do you really have to take the heater unit out to get at the motor?? The manual says it can be removed but I dont yet see how. Any offers or advice??
Since my front suspension rebuild, I turned my attention to the mysteries of converting the Morris's single speed wiper into 2 speed. I had a unipart GEU 717 spare 2 speed motor so set about it. I spent hours searching the web and eventually came across a post with a similar motor internal arrangement for Triumph TR4, Motor DW3A. Oh the diagram was simple but understanding it was a bad dream. What I couldnt get my head around was how the hell do you get a higher second speed when you switch a resistor into the circuit.
. Eventually the penny dropped but its complicated to explain. Then a bagfull of pennies dropped when I worked out the wiring and switching arrangement. The motor direct live feed is unswitched when ignition is on and by earthing (on the bench using a battery charger for power) the slow speed wire starts the motor on slow speed. Only when you connect the fast speed wire WITH the low speed wire, do you get high speed. This had me foxed until I read again and again. It's all to do with reducing the magnetic field via the internal resistor wire causing the motor armature to call for more current forcing it to speed up. Now I've got to find a way of switching it and getting the auto park to work.
Everywhere I read, it cant be done with a side and headlamp switch. Well it can. All you need is a Lucas toggle switch which will connect a common (to earth or car body), to a terminal for low speed wire on it's own,and another terminal for the high speed wire, both terminals connected to earth at the same time. Like our sort of side and headlamps,when heads are on side lights remain on.
The auto park had me foxed for a while until I realised the contact in the motor cap keeps the motor earthed and running when switched to off, until the revolving contact reaches a gap in its corresponding contact plate.
So I learned in summary,ignition on gives a live feed direct to the motor on the green wire. The other 2 wires go back to the switch, red/green for fast, and Brown/green for slow and they are only earthed via the switch. The spare black wire connected to E on the motor case and is connected to earth (the car body). So the auto park will work. I hope this is of help to anyone contemplating 2 speed wipers on an early landcrab.
My next task is to find out why the heater blower barely produces a draught. The car was swapped to negative earth years ago. I read a post on this site which goes into some depth. What I want to know is, do you really have to take the heater unit out to get at the motor?? The manual says it can be removed but I dont yet see how. Any offers or advice??
