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MG MGA - Non-Standard Wiper Motor

When I pulled out my non-working wiper motor this afternoon I discovered that it was not a standard A unit. Although the back plate is labeled the same as an A, this unit has 3 wires that exit the housing via a grommet. The grommet is to the right of the “E” in the attached photo.

The wire colors are difficult to decipher, maybe red yellow/black and black. What appears to the red wire (#2 terminal) was connected to A’s green wire and the yellow/black (#1 terminal) was connected to the A’s green/black wire. The ground ring was not connected to the motor body at “E”.

The brushes look fine and the motor turns freely so I am hoping to figure out how to patch in into my harness. Any thoughts on wiring this baby?

John



jjb Backman

Looks like a standard motor with a wiring patch job, but regardless, .... See here: http://mgaguru.com/mgtech/electric/et110.htm

Most likely connect the remaining black wire to the harness black wire and it will work. Black should always be ground. A striped wire should be switched. That leaves the red wire to be power input. Start there and see if it works. If not, then you can switch two wires at a time following the diagnostic descriptions of results on the web page.
Barney Gaylord

Barney,

This wiper motor has three wires, none of which are a ground. I tried wiring it per #1 (Black/Green) and #2 (green), plus ground on the back plate. The wiper switch was in the off position. As soon as I connected the battery it to power I got a short.

A second difference between this unit and a standard A wiper motor is that the wiper drive cable is all most 12” shorter. The PO cut out the guide tube between the wiper wheel boxes and used a wire clamp to add an extension to the wiper drive cable. (Anyone have a spare center guide tube?)

Here is a better picture of the rear plate, grommet and wires. Can anyone identify this beast?

John



jjb Backman

It might be a Lucas DR3A motor as used on the TR4A, AH BJ8 and some Mini's, maybe some Land Rovers too. I think this is a DR3A:

http://cgi.ebay.com/ebaymotors/NOS-LUCAS-B90-75735-WIPER-MOTOR_W0QQcmdZViewItemQQ_trksidZp1638Q2em118Q2el1247QQcategoryZ10076QQihZ023QQitemZ360105302318QQrdZ1QQsspagenameZWD1V

The wire colors don't match your description but there are 3 wires from the body. I think it is a 2 speed so the 3 wires would make sense. I don't know about anything but MGA's so.....
C Schaefer

Ah, yes, it may be 2-speed with 3-wires, but 2-speed normally calls for 4-wires (including a ground connection. MGB about 1967 used 2-speed in the square case before going to the larger round case unit. The 1967 MGB wiring diagram shows 4-wires on the wiper motor (numbered 1,2,4 and 5).
Barney Gaylord

John, on the stamped metal cover to the gearbox, there should be some sort of stamped numbers. Can you photo them or tell us what they are, in order?

Can the cover to the gearbox be rotated?

3 wires, plus ground should control both speeds if it is a 2-speed. Ground could be the threaded terminal in the cast end plate. But we are only guessing.
C Schaefer

Sorry about the slow response, my pc power supply died and took out the motherboard as well. I can’t send a picture yet but here are the numbers in two rows from the gear case:

DR3A (symbol like an upside down Mercedes star) 54071383 (the last four numbers are a larger font)

75568A 12V 8 65

The gear case is similar to the MGA’s and does not rotate. Hopefully I will be able to post a picture in a day or two.

John
jjb Backman

John, no need for a photo. The number listing is enough to go on. FYI, the wiring color identified as the "main color"/"thin stripe color". What you describe as the yellow/black is actually called black/yellow.


DR3A: is the Wiper motor style. It comes in both 1 and 2-speed wipers.

54071383: I think is a part number. Not really sure. it could be just the PN of the tin cover plate.

75568A 12V 8 65: the "75568A" is a wiper motor PN for a specific application. This one has flying leads and is a 2-speed motor. the "12V" is obvious- 12 volts. the "8 65" signifies a manufacturing build of the 8th week of 1965


According to this auction:

http://cgi.ebay.com/ebaymotors/NOS-Lucas-Wiper-M%2FCap-Bentley-Rolls-Shadow-Jaguar-XKE_W0QQitemZ120371030783QQcmdZViewItemQQimsxZ20090130?IMSfp=TL090130154006r9155

this 75568A wiper was used in Bentley Continental and T-Series,Rolls Royce Silver Shadow, Jaguar XKE 3.8, early 4.2, 3.8S, 3.8 and others,Lotus Elan,Saab 96 V-4,and Triumph TR4A.

I'm not 100% sure of this though. I did find the listing in a Lucas/Triumph cross reference here:
http://www.vitessesteve.co.uk/PDF/ST%20Lucas%201969.pdf
Search for "75568A" It does indicate that there should be a ground wire attached to the wiper motor thru a screw terminal.

I also found this wiring schematic of a 3-wire 2-speed application on the TR4A.
http://www.dctra.org/files/Dan_Master_Wiring_Diagrams_TR2-4a.pdf.

Go to page 4, lower RH corner for the wiper motor wiring. It also shows the ground wire to the screw terminal. However it uses different color wires than yours is. How the inside of the wiper switch is wired, I'm not sure.

You could just wire your motor up the way you originally had it. MGA Green (switched power)to wiper red; MGA black/green (wiper switch)to wiper Black/yellow. Without the MGA Black wire going to the "E" screw, my guess is that the wipers would never park, but they should have run and stopped. Of course, your wiper was not working this way to start with.

This is the best I can do without putting my hands on your motor.



C Schaefer

This thread was discussed between 08/02/2009 and 18/02/2009

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