Hi all,
Those of you who have been around for a few years may remember my neverending
quest for two speed wipers that park in a '67 B. With the help of my brother
the electrical genius, the holy grail is now in my possession. Surprisingly, I
figured out the wiring and he solved the mechanical problem.
So here's the whole story, including some mechanical details that I posted a
while ago. Feel free to include this on any how-to site. This info will only
remain in my hands for as long as the hard drive lasts on this laptop. For
anyone wishing to reproduce this...
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This is the procedure for installing two-speed wipers in a US-spec MGB that
originally came with one-speed wipers (pre-'68).
Parts:
Two-speed wiper motor with electrical connector and mounting bracket, '68 and
later
Toggle headlight switch for '62-'65 MGB, TRF #LU31837, Victoria British #8-414,
Moss #141-230
sheet metal and bolts for custom mounting bracket
assorted wires and connectors
Before mounting the motor, some modifications need to be made to it:
The two-speed motor was used on cars with three wipers. The drive cable for
these motors is shorter than the two wiper cable. The cables are mounted
differently in the two different motors so just the cables should be switched.
With the flat cover removed from the motor, the procedure should be obvious.
While the cover is off and the cable disconnected, the position of the cable on
the gear relative to the position of the park switch needs to be changed. I
gather that the wipers on three-wiper cars park the other direction so the
direction needs to be reversed. To do this, remove the circlip holding the
large (2" diameter) nylon gear to the housing and remove the gear assembly.
You'll see two square bosses on the gear that fit into two square cutouts on the
metal plate. Pry the gear away from the metal plate. When the bosses are clear
of their slots, turn the gear 180 degrees and line up the bosses. Press the
gear back towards the plate and re-install the assembly.
Mounting the motor:
The early wiper motor is mounted to a black bracket with studs that screw into
the upper part of the motor (where the cable goes in). The later motor doesn't
have these threaded holes. It's mounted directly to the fire wall (I assume)
with a strap that goes around the lower, round part of the motor where the
windings are. I made a sheet metal plate (out of a rusty battery cover) that
mounts to the early bracket where the motor studs were and extends down and
to the left (LHD car). The motor is then mounted to the plate with the strap.
Here's an ascii drawing of the plate:
____________________
| |
| () | This is where the early motor was mounted
| () | with big rubber bushings.
| () |
| |
________| |
| |
| |
| |
| o o | The strap holds the motor to the plate here.
| | Packing needs to go under the motor to make the
| | strap tight.
____________________________
This method uses both early and late mounting brackets plus a custom bracket.
It should be possible to mount the later motor the way it was mounted in later
cars using only the strap. I didn't do this because it would require drilling
holes in the firewall. If you choose to do this, you'll notice that the motor
is too far away from the firewall. It should be possible to fix this problem by
bending or replacing the cable sheath between the motor and right side wiper.
Wiring:
The switch logic is:
Position Connects terminals
Off 6-7,1-2
Low 4-6-7
High 4-7-8
The connector to the motor has five wires:
__
1
| |
3 2
| |
5 4
1 is black (B) - ground
2 is brown w/light green (NLG) - park
3 is blue w/light green (ULG) - high speed
4 is green (G) - keyed power in
5 is red w/light green (RLG) - low speed
The wiring harness in my '67 B has three wires at the wiper motor:
green (G) - keyed power in
black w/green (BG) - to the switch
black (B) - ground
The green and black wires from the harness connect to the green and black wires
at the motor. I used the black w/green wire (BG) for the high speed, blue
w/light green (ULG). Additional wires came from a partially burned harness.
At the switch, the wiring is:
4 - green (G)
6 - red w/light green (RLG); jumper wire to terminal 1
8 - blue w/light green (ULG), or if using the harness wire, black w/green (BG)
1 - jumper wire to terminal 6
2 - brown w/light green (NLG)
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Now you know what a rare creature I am. No, not a woman who works on cars, but
a computer geek who documents her work!
Denise Thorpe
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