1950 MM Horn Ground on Steering Column Problem

for those with Series MM sidevalve cars produced between September 1948 and February 1953
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dschwartz1957
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1950 MM Horn Ground on Steering Column Problem

Post by dschwartz1957 »

I own a 1950 US export model Tourer. One of my winter projects was to refurbish the wiper motor, wheel boxes, and wiper rack. In removing and replacing the wiper parts some bullet connectors became separated. All that is resolved, but there is now a problem with the horn. I assumed that too was due to a loose bullet connector, but it turned out to be a dirty fuse holder under the bonnet. The horn worked fine when I put the car away for the winter.

As part of trouble shooting, I removed the horn ground pieces from the steering column support bracket. I knew these parts were a problem from previous experience, and the insulator is squashed flat and rather useless. When I reassembled the ground pieces, the horn blew continually. No amount for reordering the parts, or substituting rubber washers or grommets for the worn insulator made a difference.

The only information I have found regarding these parts is on plate D in the Morris Minor Service Parts list. Attached are photos from the parts list and from my car.

I replaced the parts in the order shown in the diagram, and tried placing the wiring harness connector in several different locations. The diameter of the connector is huge, and I also tried a size that is just large enough to fit over the bolt. Nothing makes a difference and the horn blows continually.

What is the correct order of parts, including the wiring harness connector?
Are replacements for any of these parts available? If not, what do people substitute for the originals?

Thank you,

David Schwartz
Framingham, Massachusetts
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1950 Morris Minor Tourer
1968 Morris Mini Traveller
1962 MGA 1600 Mk2
Mick Lynch
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Re: 1950 MM Horn Ground on Steering Column Problem

Post by Mick Lynch »

I think the problem is the top-hat shaped insulator (part 59) which has just turned into a flat rubber washer on your installation. I’m betting that part 57 is contacting bolt 60 or washer 71, completing the circuit and leading to a constant ’on’ condition.

You need to insulate the nut and bolt from the brass part and the ring terminal. That being said the ring terminal must contact 57.

Suggest you try to find a plastic nut and bolt if you can’t get the correct insulator. They are common in plumbing where you screw things to chinaware.
alanworland
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Re: 1950 MM Horn Ground on Steering Column Problem

Post by alanworland »

Had trouble with my horn once , would work sometimes depending on position of steering wheel, problem was due to the brass slip ring - it had worn right through!

Alan
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geoberni
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Re: 1950 MM Horn Ground on Steering Column Problem

Post by geoberni »

I agree with Mick, there should be a definite Top Hat shape to the insulator...item 59.
Basil the 1955 series II

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dschwartz1957
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Re: 1950 MM Horn Ground on Steering Column Problem

Post by dschwartz1957 »

I did some trouble shooting yesterday with a multi-meter, and the problem is due to the insulator (59) not being able to prevent the ring connector from touching the threads on the bolt. I tried using rubber grommets in place of 59, but the diameter is either too small or too large. I will try to find a substitute insulator at an auto parts, plumbing supply, or hardware store, or even substitute a plastic nut and bolt. Failing all of those, I will solder a wire to the "Brush-contact" (57). The contact is worn down, as is the steering column ring.

Thanks for the suggestions,

David
1950 Morris Minor Tourer
1968 Morris Mini Traveller
1962 MGA 1600 Mk2
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