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MG Midget and Sprite Technical - Windscreen Motor

How sung should the windscreen motor be mounted? My motor moves fairly easily in the mount and I'm thinking the rubber is to worn out.
This is '73 midget with the round motor housing.
Jon Saylor

That should say ... windscreen wiper motor.
Jon Saylor

Hi Jon
the rubbers worn out it shouldn't move. When you replace this make sure the earth to the mount/body is good
Cheers Rod
R W Bowers

Hi,

There should be a degree of flexibility as it insulates noise from the body of the car.


Often the rubber pad that the motor sits on gets lost and all that's present is is the metal hoop and its rubber sheath.


No need to worry about earthing as the motor has an earth wire in the 5 way multiplug.
SR Smith 1

The rubber pad on the seat is there and the rubber strip is still on the metal hoop so I guess that the rubber is worn out a bit even though it doesn't look like it. I'll put some inner tube rubber around the motor and see if that helps.
Jon Saylor


FWIW just measured the resistance to earth on the earth wire in the plug .5ohms, earth strap to motor .2 ohms. You can never trust the black earth wires in the loom, even mine which has been completely stripped and re-terminated with spade clips has higher than expected resistive losses due to the long runs back under the dash. Plugs and sockets which can only be cleaned up are another source of loss.
Jon while you've got it off the car you might as well regrease the gearbox and drive cable, can't hurt. The wheel boxes are hard to get at but some heavy oil (not too much as it will drip through and under the dash) can be applied from the top using some duct tape to form a dam (see image) This will make them function better but there is no substitute for pulling them out and servicing them. Cheers Rod



R W Bowers

Hi Rod,

SR Smith is right, the motor is isolated from earth by the rubber pad beneath it and the rubber pad between its hold down strap and the motor yoke can. The rubber pads are not necessarily meant to prevent connection to ground, just to reduce noise transmission, but if there is a connection to ground by that route, it is unexpected.

There is a ground wire in the harness, and it is connected to ground. If you have a resistance in that wire, then that is an electrical problem in your harness that ought to be resolved by cleaning the connections or tracking down the worn portion in the wire. The length of run in a car is not that long to worry about for electrical losses.



Rod, I do agree with you though, in your advice about cleaning and lubricating the wheel boxes and the drive cable. If one has their dash out, those are worth removing, disassembling, cleaning and re-greasing, since they've been in use for 40+ years by now a freshening like that can do wonders.

In fact, you could say that cleaning the electrical connections is just as much a good idea on a 40 year old car as cleaning the wheel boxes in the wiper system!


Norm


Norm Kerr

Correct Norm. But my wipers are at best slow despite all my servicing/greasing etc. Any loss is unacceptable.
I found what I call "black wire syndrome" in some of the earth returns, the copper had turned black and manky, but generally it was at the front of the car in the headlight harness. Cheers Rod

R W Bowers

Rod,
I had the dash out about 4 years ago a did lube the wheel boxes. I did pull out the drive cable and re-greased it last week-end as well as the gearbox.
I think I'll try your idea but some heavy oil in the boxes using the duct tape idea you have. I also added some rubber, about 1/8" thick, on the strap and the bottom rubber pad and the motor is in snugly.
Jon Saylor

This thread was discussed between 14/06/2013 and 17/06/2013

MG Midget and Sprite Technical index

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