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Bench testing a Lucas wiper motor


Colin Lindsay

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The Herald single speed variety. I've melted two wiring looms over the years wiring these up wrong (in one case, to be a smart ass, and the other, forgetting what I had done originally and melting the replacement loom)

If I want to test a few of these with a 12v battery, which wires to what for simple, non-thermal testing?

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Hello Colin,

The set-up is a 12v supply with an earth return through the wiper switch. That means the number 1 on the wiper motor is the earth return and number 2 is the supply B+ 12 Volts. There is also an earth connection on the wiper case for the parking switch. The 1200 Herald the live 12v is White (Green in the Vitesse photo) and the earth return is Black/Green.

May the smoke not be with you!

Dave

Vitesse.JPG

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I looked up in my free to download online workshop manual for the Vitesse which also has the single speed wipers and theres a 12v+ve supply to the green wire while the black/green wire goes off to the switch which earths when operated. Using these two connections will make the motor run and connecting the third, black wire, to -ve as well will test the wiper parking control as the motor should run on a bit after disconnecting the black/green wire. This should always be done with a correctly fused supply to avoid thermal testing....

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So.... just terminals 1 and 2 (earth and live respectively) - mine isn't fitted so I have no cables to guide.

NEVER EVER believe that you should wire it back to front in order to overcome a worn drive gear... this was bandied about in the early 1990s and of course I tried it, and melted the loom. I bought a new loom and connected it up, using the old and incorrectly marked loom as a reference... oops. Lots of smoke from under the dash. I think when I refit mine there'll be an inline fuse too.

Given the price of replacement motors I didn't want to fry those too, so thought I'd ask. Thanks!

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Sound like a very early type, the two speeder had just cable as well. If you have a multi-meter that can read very low ohms then the lowest reading obtained between the case and one of the leads will be the earth return lead. The supply lead should be very slightly higher  in reading. That is the resistance of the motor coil.

The other way is to have an inline fuse, 5 amps, on the + lead and try leads in turn. Hmm - plus a bag of fuses!

I agree back to front will just short the supply to earth! You have to change the wiring inside the motor.

Dave

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Colin, I done some more digging and I see what you mean about some of the early Herald wiper motors. The picture I have shows the white lead on the right hand terminal. But the best way is too take the back off the motor and one of the bush terminals should have an internal lead connected to it. This goes to the alto-stop. The bush terminal without this lead is the 12v + Supply feed.

Dave

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If the motor is off the car, resting on an insulated mat, then you can connect the battery either way round without problems. You may actually need to do so before conducting Dave's multimeter test, because what you're looking for with that is the earth return from the self-parking switch, which is present only when not parked. It's also that earth return through the parking switch (connects terminal 1 to terminal E) that causes the smoke.

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  • 4 weeks later...

Ok so Hurricane Whore-Gay (George to you and me) is raging away and I'm bored so I started on the wiper motor. Never saw so much black grease in my life; in fact there were odd bits stuck in it when I removed the cover. Have a look at the top of the photo of the gearwheel... no idea how long that's been there, but there's another one in the correct place!

So: Dave: if the red wire coming from the bottom right goes to the park then it's connected to terminal 2; this means that the terminal for the power is terminal 1? Terminal 2 had a cut-out for a spade terminal with a lug on top, so it can only fit one way when on the car and it takes the white cable which I would have thought was the ignition circuit? I've ordered new brushes as these are worn almost completely away so will wait for those before trying a battery across the terminals.

1F3331CD-584D-4D63-A6D3-86576F0C52BC_1_105_c.jpg.85f4fe43d3336474d863a7969ffad6c5.jpg  1058143D-2C22-4B75-A954-7ADFA9DBBFE2_1_105_c.jpg.6a9b192451676211e1520261021a855a.jpg

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Morning all. It came to me last night, in a dream... not Abu-ben Adhem, awakening from a great dream of peace to see an angel holding a Haynes manual, but it just occurred to me - if the system is live, and the switch earths it then power to 2, earth to 1 and that's it. Ignore the case earth and the extra earth at the washer bottle holder. Exactly as Dave said way back. Sorry guys, sometimes it doesn't sink in first go.

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I've just rebuilt the Herald Estate motor, single speed (and two brushes) but when it came to the park system, I'd forgotten the order of the bits. I can't find the exact Herald motor but have found a few breakdown diagrams of other versions; there's a flat washer under the connecting rod, but when we have the self-park, none on top.That refreshes the memory regarding that.  However I've just realised where the large washer that was left over is meant to go...!

I've got a two-speed motor from a GT6, same body as the Herald version but different connectors and different gear / rod assembly. I'm wondering if you could make a Herald two-speed out of this, using an old Herald mounting / gear assembly?

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1 hour ago, Colin Lindsay said:

NOW: anyone up to the challenge of a two-speed GT6 MK1 wiper motor? It's got three connectors...

The GT6 14W is not too bad. The three brushes are for the two speeds.

The three wires go into the park switch where it becomes 5 wires.

The park switch can go dicky if the operating pin wears down.   I've just made a non-contact switch for mine.

The park switch operates a single pole change over contacts. One side drives the motor the other side stops the motor dead - Regen braking. 

I understand that different cars switch the motor in different ways.

 

Roger

 

 

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I had a huge box of them a few years ago but gave them to a mate to rebuild two good ones from the pile of parts; sadly he passed on and I never got them back...

I found a second tin box of bodies yesterday, some Herald, one GT6 and others probably Mini, but at the price of reconditioned ones it's worth a bit of practice to see how many I can get to operate. New brushes with the corrugations: do they go up and down, or side to side across the face of the rotor? 

 

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Correct me if I'm wrong the supply & wiring to the single speed DR3 wiper motor is different to the later 2 speed unit.

In the case of the single speed eg GT6 Mk1 the motor is wired in series with the switch at the end of the circuit earthing the supply and switching the motor on. whereas the 2 speed motor GT6 Mk2 has the circuit supply going first to the switch then finally the motor and motor earth switching the motor on.

I came across the attached 2 speed conversion for the DR3A Single Speed Wiper Motor, unfortunately I don't know the source, I've  intended to follow it and modify my Mk2 Vitesse but haven't been able to understand (mental block) or source  the necessary switch, or modify the later GT6 style 4 connection Lucas rotary switch with inbuilt electric push wiper washer switch, which I want to keep.

Unfortunately the tome with explanations is 9 pages long.

Hope its of use, or creates comment on an alternative method.

Peter T

 

 

Lucas Wiper Motor 2 Speed Conversion pg1.jpg

Wiper pg2.jpg

Wiper pg3.jpg

Wiper pg4.jpg

Wiper pg5.jpg

Wiper pg6.jpg

Wiper pg7.jpg

Wiper pg8.jpg

Wiper pg9.jpg

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Thanks Peter,

that is an excellent write up of the motors.

The third from last page is very important. You must use the correct switch. For example within the TR cars the switch is from Moss BHA4578

It is often commented why does the wiper motor turn ON in the fast mode.  It doesn't have to.  The switch is quite complicated but a slow turn on can be done.

But as mentioned it need both earth wires to be grounded (GN & GR)

 

Also the resistance overwind wire is not part of the armature windings and can be replaced with a 10R x 5W resistor

Roger 

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Thanks Peter and Roger; that's very informative. Interesting to note that reducing the current actually causes it to speed up.

The original wiper motor on my Mk1 has very faded wiring and I was worried about wiring it incorrectly after the first restoration - it's three identical bullet connectors - so I had to open the body to expose unfaded wiring and trace each cable in turn. It's still running well, probably due a regrease now after twenty years.

This second motor is in a box of spares, I dismantled it years ago (probably as an alternative to the original) so whilst I can rebuild it I've lost the parking arm cover so it may not be immediately useable. I just hate things lying in pieces so in the last few days have rebuilt two complete Herald motors and one smaller which I think is Mini-related, but have now run out of replacement brushes (available online)

Re my last question in my earlier post - the brushes are corrugated at the ends, in order to allow them to quickly wear to the shape of the rotor, but do the corrugations go up and down ie parallel to rotation, or across the windings? I had thought across, but have seen them fitted vertically... so now not sure.

brush.jpg.47d93892a0d9ab8333b8522af60167cb.jpg

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  • 1 month later...
On 05/03/2020 at 12:43, RogerH said:

Hi Colin,

to me 90 degrees to the armature slots sounds good.

That way and slot depressions will not cause clicking etc.

 

Roger

Thanks again Roger; you're very helpful. I replaced the wiper motor; in fact I had one professionally rebuilt out of two, it was returned to me yesterday and looks amazing so it's now connected and amazingly, the GT6 has started up with no fuses blowing (although I rewired the stereo and all of the column wiring so it could have been anything) 

All I need to do now is set the park... which is what started this all off in the first place. Interesting to note that the GT6 wiper motor which I've had rebuild has a 140 degree gear and the other has a 130 degree, which actually leaves it short on the passenger side.

So thanks to lockdown and some good advice here I've now refurbished three Herald motors, two TR2/3 DR2 motors, one MK1 GT6 2-speed motor and gained a spare, and used my entire stock of replacement brushes and most of my grease. 

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Excellent. Very productive.

During the lockdown on the TR4A  I have fitted a new dash top crash pad,. a new righthand lower pad and re=covered the left hand grab handle.

Tidied up the rats nest of wires behind the dash, And made new centre console out of Manogamy as the replacement ones are not special.

And I have dug all the flower borders in the garden.

This virus is very tiring.

Roger

 

DSC_4787a.jpg

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That looks superb! What's the centre (silver) panel - two small switches and one rocker? (Just being nosey...) 

Your CD player reminds me that whilst my replacement JVC unit is working fine, it won't play USB sticks, just iPods or phones which I only found out when it was all installed, and which is not what  I wanted at all. I wanted a dedicated USB stick of maybe 40 CDs to be kept in the slot, and be there when I took the GT6 out. Now I have to run a cable and have another player with me, which totally defeats the purpose of having no cables or bulky CDs lying about.

I don't have anywhere near as many switches, though ... :)

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