High horn contact wear : MGB & GT Forum : The MG Experience

High horn contact wear #1
KenAdkison Ken Adkison Shelton, WA, USA Sign in to contact 1975 MG MGB	Topic Creator (OP) Apr 9, 2024 10:38 PM Top Contributor Joined 15 years ago 393 Posts

My '75 MGB horn contact refuses to slide easily on the steering wheel ring. It leaves film powered bronze (or whatever yellow metal it is) all over the inside of the plastic covers.
Previously, it would squeal when turning. It is like the metals have too much friction.

I have had this car apart so regularly, that I have had a chance to readjust the contact spring pressure and its angle to try to solve the problems to avail. I am on my second contact with no real improvement.

What do you all think about dielectric grease here? Maybe I should scrub the ring with a graphite pencil?
Any better ideas.

1975 MGB restored in 2009 to near stock with 9.8:1 compression and mild cam.
Bespoke closed loop, sequential, port fuel injection system with crank triggered ignition.
Hand made intake, wiring and other parts.

https://www.youtube.com/channel/UCcdmkAGSliRgRzpdyuSaMrA

Edited 1 time(s). Last edit at 2024-04-09 10:39 PM by KenAdkison.

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Re: High horn contact wear #2
Not-Anumber Chris S Southend, South east UK, UK Sign in to contact 1979 MG MGB GT	Apr 10, 2024 07:05 AM Top Contributor Joined 12 years ago 1,009 Posts

Is it switching the horn directly or have you added a horn relay to reduce the amount of sparking and arcing the horn switch contacts are exposed to ?

Edited 1 time(s). Last edit at 2024-04-10 07:05 AM by Not-Anumber.

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Re: High horn contact wear #3
smokey w Juri P Toronto, ON, Canada Sign in to contact 2023 Volkswagen GTI	Apr 10, 2024 07:06 AM Top Contributor Joined 5 years ago 2,511 Posts

In my experience, the squeal comes from a worn brass button on the contact spring. I did a termporary fix by building up the button with solder, and have a new contact ready to install when I next remove the steering column plastic cowling. The pics show how it works on my '71 NA. Moss sells the contact : PN 141-804.

Turn signal switch bracket.jpg 43.6 KB

IMG_0391.JPG 40.9 KB

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Re: High horn contact wear #4
KenAdkison Ken Adkison Shelton, WA, USA Sign in to contact 1975 MG MGB	Topic Creator (OP) Apr 10, 2024 09:35 AM Top Contributor Joined 15 years ago 393 Posts

I have a horn relay. I was thinking about taking the idea Smokey has a bit further and making a new contact out of A better/different material. IT is like the replacement contact and the ring are of too similar metals and one won't slide well on the other. My thought was a carbon brush from an electric motor would work better.

I should not be the only one with this trouble. It may be time to pull the covers and measure the contact pressure and photograph the alignment.

1975 MGB restored in 2009 to near stock with 9.8:1 compression and mild cam.
Bespoke closed loop, sequential, port fuel injection system with crank triggered ignition.
Hand made intake, wiring and other parts.

https://www.youtube.com/channel/UCcdmkAGSliRgRzpdyuSaMrA

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Re: High horn contact wear #5
BH Davis Grosvenordale, CT &, Warren, VT, USA Sign in to contact 1968 MG MGB GT "Primrose" 1973 MG MGB	Apr 11, 2024 05:09 PM Top Contributor Joined 19 years ago 4,913 Posts

Just use dielectric grease as you suggested.
BH

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Re: High horn contact wear #6
GlennMGB Glenn G Fort Worth, TX, USA Sign in to contact 1965 Triumph TR4A 1967 MG MGB GT "Rose"	Apr 12, 2024 09:56 PM Top Contributor Joined 12 years ago 2,036 Posts

I use a dab of conductive grease here. Kopr-Shield seems very expensive these days, so maybe try MG Chemicals 846 or 8463A.

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Re: High horn contact wear #7
smokey w Juri P Toronto, ON, Canada Sign in to contact 2023 Volkswagen GTI	Apr 13, 2024 06:33 AM Top Contributor Joined 5 years ago 2,511 Posts

I first tried the grease, and it worked for a while, but the squeal came back. The squeal is caused by the hard spring-type brush making direct contact with the ring, leading to a resonance. The solder blob has worked for a couple of years, but will obviously wear out, so I have a new brush ready to go when I'm in there again to replace the turn signal and wiper switches.

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Re: High horn contact wear #8
BH Davis Grosvenordale, CT &, Warren, VT, USA Sign in to contact 1968 MG MGB GT "Primrose" 1973 MG MGB	Apr 13, 2024 06:45 AM Top Contributor Joined 19 years ago 4,913 Posts

Might as well put a new brass ring in as well for the spring loaded stub to rub against.

BH

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Re: High horn contact wear #9
smokey w Juri P Toronto, ON, Canada Sign in to contact 2023 Volkswagen GTI	Apr 13, 2024 08:46 AM Top Contributor Joined 5 years ago 2,511 Posts

Thanks, didn't realize it was available. I'll order one and put it on the shelf.

In reply to # 4784451 by BH Davis Might as well put a new brass ring in as well for the spring loaded stub to rub against.

BH

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