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MG TD TF 1500 - wiper motor wiring

I, perhaps stupidly, cut the old lamp wire that the PO installed for the wiper motor (decided I wouldn't drive in the rain and thought it looked cleaner without the motor but now I'm having second thoughts) so I'd like to pull the "looks just like the original" cable that I got from M.

What are the chances I can just unscrew the four screws on the top channel, lift it, and rerun the wire? I'd prefer to do it in situ (fancy Latin for I'm lazy and don't want to take the windscreen off the car again).

Thanks.

Jud
J K Chapin

Good luck with that in situ! I couldn't even get the "M" wire in there and I had the whole windscreen apart! Finally gave up and ran it up side of the glass.
efh Haskell

Doubtful. Its a tight fit regardless and the chances of you getting it by the bracket are slim. Since you cannot take the bracket out without removing the side screws you are out of luck.

On the odd chance you can remove all but the hidden screw under the side support you could possibly rotate it enough to allow you to expose the top two screws for the bracket on the side and then maybe you could extract the bracket. Then you would have to be careful to feed the wire from the side hole and out the top with enough material to reach over to the top hole and out to the wiper motor.
Chris Couper

When I lost the wiring from a short, I seem to remember replacing it without taking the windscreen off the car.... I do remember removing pieces....
gblawson(gordon- TD27667)

I think you've got two chances Jud, Buckleys & none! I'm just about to reassemble my screen (without the puny audio wire from M or AS & using the original black & green automotive wires in grey heat shrink). I've reassembled the screen with just the glass (which was tailor made for my screen sporting the original date correct Triplex logo!) & no rubber, to ensure that all of the screws were well clear of the glass. There was no way I could feed the cable through. I'm now installing the cable into the frame, then the rubber with silicon release agent to lubricate things & then the glass. I've cut the wire under the dash & fitted a pair of connectors so that I can offer up the assembled screen with the cable fitted, ensuring that the grommet is on the cable & that the connectors fit through the hole in the scuttle. Sometimes it's better to take two steps back in order to go one step forward. Cheers
Peter TD 5801
P Hehir

Thanks all for saving me the frustration of trying a dumb idea and failing. Referring to another thread - 62 days and counting. After that I'll have time (between Honey-dos) to take the windscreen off the car (I've alreaady done tht once) and do a proper job. I think I'll also toss the M audio wire and make up a cable with proper conductors in grey heat-shrink ala Peter.

Peter, what size conductor do you recommend? Seems like #14 or even #16 would be sufficient and #16 might be easier to get through the channel.

Jud
J K Chapin

Jud, even 16 gauge is overkill. The wiper motor draws very little current. You could readily get away with 18 gauge. Heat shrink tubing is very rigid. You'd be much better off finding a more flexible gray cable. Just use the colored heat shrink for the pieces sticking out of the gray tubing. Needless to say, the above is MHO. Bud
Bud Krueger

I used the gray auto cable and twisted the two wires together to act as one. Then I used the windshield frame as the second wire with an earthing connection under the dash.
Sandy
ss sanders

SS, I like that, one dedicated conductor to get the little electrons there and the grounded windscreen to get the little buggers back to home base. I think I'll try that method. I can do a prototype without even getting into the issue of getting the wire through the channels in the frame. I'll let you know how it works out.

Jud
J K Chapin

Hold on a second, Jud. I'm not sure how Sandy did what he did, but the wiper motor is not electrically connected to the windscreen. I suppose that one could connect one of the two power input connectors to a screw on the windscreen. Before doing this I would suggest taking an ohmmeter and measure the resistance from a screw on the windscreen near the wiper motor to earth ground at terminal E of the Control Box (Regulator). Bud
Bud Krueger

Bud, exactly my plan. I thought I'd attach one lead (I don't think the motor is polarity sensitive so I guess it doesn't matter which one) to the nearest screw that holds the clip for the wiper wire and test how good the ground return path is. If it's not good (pretty close to 0 ohms) I'd figure out a non-otrusive place to hook another wire between the frame and a known good earth.

Jud
J K Chapin

Bud, exactly my plan. I thought I'd attach one lead (I don't think the motor is polarity sensitive so I guess it doesn't matter which one) to the nearest screw that holds the clip for the wiper wire and test how good the ground return path is. If it's not good (pretty close to 0 ohms) I'd figure out a non-obtrusive place to hook another wire between the frame and a known good earth.

Jud
J K Chapin

I put the earth wire around the closest mounting stud and windshield frame., That way you can barely see it as about one inch is apparent.Under the dash I installed an earthing wire to one of the hoop mounting bolts. It worked for the 18 years that I had it.
Sandy
ss sanders

I just connected my old analog ohm meter between the windscreen frame and the POS post on my battery. It read about 2 ohms. I did the same with my new $7 digital ohm meter which read 2.2 ohms with the leads firmly touching each other. Windscreen to frame reads 3.3 ohms so I guess that means the added resistance is 1.1 ohms (precision does not necessarily imply accuracy and being old school I'm inclined to trust analog things over digital stuff). In either event, 1.1 ohms or 2 ohms, I think the return to earth path is good enough. Thoughts?

Thanks.

Jud
J K Chapin

Jud "old school here to " and would say just go ahead

Gerard
Gerard Hengeveld

I'm a wee bit unclear, Jud. Are you saying that the resistance from the grounding point near to the wiper motor to your battery ground terminal is about 5 ohms? That's too much, IMHO. The normal ground return path for the wiper motor black wire is to the E terminal of the Control Box. It might be worth your while to clean up your battery to ground connection as well as the E terminal to ground. I seem to recall that Dave DuBois has some good scoop on earth grounds on his website. If I were grounding the windscreen I'd do it at the mounting screws on the left side of the frame rather than the right side. Bud
Bud Krueger

The resistance is between 1.2 and 2 ohms. I thought about grounding to the E terminal (that's where the original wiring was grounded) but because I plan on using the screw holding the clip nearest motor (center mounted motor) as a ground point I thought measuring the resistance all the way back to the battery post (however the electricity finds its way there) would be more important.

Your idea of using the left motor mounting screw has shorter-wire appeal so I'll check to see how well that screw is grounded and let you know. I don't remember for sure but I seem to recall that the motor mounting screws are electrically isolated from the windscreen frame. Maybe (hopefully) they're just isolated from the motor.

Jud
J K Chapin

Last night I checked the resistance from the wiper motor mounting screw to earth and found it quite a bit higher than the resistance directly from the windscreen frame to earth so I'll stick with the plan to connect the earth lead from the motor to the screw holding the wire clip nearest the motor.

Jud
J K Chapin

Good day:

Just a query regarding the windscreen wire(s).

I seem to recall reading, somewhere, that the original wiper motor wires were encased in a loom made of black, cotton material.

And, furthermore; I faintly remember a grey coloured, PVC or like material item, covering the two wires and appearing quite flat in appearance, offered and reported by some past parts firm, as being an original feature.

Can someone, just for my satisfaction, clear up this conundrum for me ?

Being unqualified and unknowledgeable, in all things proper regarding restoration, when I put the windscreen together, many years ago, I just used a red and black wire taping them together at various positions along the feed.

By-the-by:
My hat is off, to any and all who have accomplished the wizardly feat of rewiring, within the frames, without knocking the windscreen down. HURRAH ! Well played !

Emdall, TC6768/TD3191, Halfmoon Bay, British Columbia, Canada


kernow

This thread was discussed between 30/03/2014 and 02/04/2014

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