2 speed wiper motor issues

[keith1948]

Two issues.

First one is wiper motor running very slow on slow speed but ok on fast speed. I have fiddled around trying to line up commutator with floating bearings each end and also cleaned out all old grease that had gone hard. Problem can be seen with motor on the bench. Brushes and commutator look ok. Any ideas?

Second problem is that the 3 wires are now 50 years old and need replacing. What size wires are recommended - 8 amp, 10 amp, 15 amp? I can get correct colour coded wires once I know what ampage I need.

Keith

[keith1948]

I think I have solved slow running on the bench.

For fast speed connect green wire to battery + and brown/green to earth

For slow speed connect green wire to battery + as before. Then connect both brown/green AND red/green to earth and hey presto I got slow or normal speed. I was mistakenly connecting just the red/green to earth.

See this link for an explanation

 

http://www.britishcarforum.com/bcf/content.php?156-Lucas-DR3A-Two-Speed-Wiper-motors

 

So now the motor seems to be functioning ok but still not sure about wire size (amps). Article in the link mentions 12A start up so does that mean I need wires capable of carrying 12 amp?

Keith

[RogerH]

Hi Keith,

Vehicle Wiring Products thin wall cable is very good 16Amp is physically small yet with good capacity

http://www.vehicle-wiring-products.eu/product.php/973/16-5-amp-1mm-sq-32-0-20

 

Roger

[keith1948]

Thanks Roger

I haven't come across this company before but just what I need. I was thinking 15 amp would be the ones to go for. Not entirely sure why old wiper motor kept slowing down on way home from Wales. Drove most of the way home with it switched off and only using it when absolutely needed. Just about to investigate the switch to see if that has a fault or loose connections. Poor earthing is often a cause of TR electrical problems. Wheel boxes seem free enough so don't think it is them.

Keith

[AlanT]

Its hard enough to wire these field coils with 8A wire.

 

The normal running current is about 3A.

If you are taking 8A then your rack wire is too stiff and the motor will get really hot.

 

They get pretty warm at 3A actually.

 

This 8A wire from VWP wont go through the bullets used originally. I normally drill them out so it does.

 

Edited May 5, 2016 by AlanT

[AlanT]

Another thing to watch for is that Lucas lubricated these very poorly.

 

 

This one has been well used but you can see that the two dollops of grease are as they were placed and never lubricated anything. The grease used is almost totally immobile.

 

The gear-wheels can get pretty stiff in the Bronze bush and can seize solid, if any water gets in. It always does of course.

 

This is how I do them:

 

 

 

I even fill the interstices between the nylon-gear and the crank-plate because if water gets in here and the shaft rusts it can split the nylon-gear.

 

This is K99 water-proof stern-gland grease.

Edited May 5, 2016 by AlanT

[keith1948]

Just in case anyone should decide to go to Halfords to buy wiper motor cable. The other day I had 2 assistants telling me that I needed 27amp cable. I said I had measured running amps at about 2 amp. I did this by connecting an ammeter between earth wire from switch and earth on car. Assistants told me that current (amps) should be measured on supply lead because it would be much more there. I said current was same where-ever it was measured because ammeter was in series. I was then asked whether I had positive or negative earth. I said it didn't make any difference. I said voltage would vary depending on where you measured it (0-12volt) but current depended on load being drawn by wiper motor. I left them still insisting that current would vary along the wires. I only went in to see what cable they had - shouldn't have wasted my time.

Keith

[Lebro]

What fun !!

 

Bob.