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Ungrounded horn problem

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emmett1010

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Since my TR3 is in limbo, waiting for body work, I've been sprucing up my 74 MGB, and have a wierd problem with the horns.
Except for Tony, I think the brainpower is much higher on the Triumph forum.
The horn button grounds on the steering wheel housing/shaft, and should blow the horn. My doesn't! You can ground the horn wire to the chassis and it blows great. You can ground the steering shaft under the hood with a wire and the button will work. If fact, I've tried to clamp a wire to the shaft to provide a ground but of course the wire twist when you turn, and this is not a perfect solution.
Any thoughts on what can be wrong?
Thanks, Emmett1010
 
Does the MGB have a horn brush similar to the TRs? It would be a plastic cylindrical shaped, 1/4" diameter and 2 1/2" length with metal contacts at each end and sprung in the middle. If so, this was suspect on my car.
 
https://www.britishcarforum.com/bcforum/ubbthreads.php/topics/478189/1

I'll try not to take offense at the lack of brainpower over on the MG forums! :p

In short... ground the steering rack. A test wire on alligator clips should let you check whether this is going to be effective.

And maybe think about installing a horn relay (although the luminaries are split on that last point.)
 
No the rack itself is grounded, but not the shaft.It seems like the shaft should ground through the rack, but that doesn't seem to be the case. My steering is somewhat hard, and I discovered, no oil in the rack during restoration, so I suspect a new rack might be needed.
It just seems weird, and I was hoping there might be a simplier solution, one that wouldn't be so costly--this tr3 resto is bankrupting me-
Thanks, Emmett
 
Some TRs use rubber couplings in the steering column, which need to have little braided jumpers to carry the ground across the coupling. If your MG is similar, might be a broken, missing or improperly installed jumper.

Or, it might be that the rack is so rusty or gunked up inside that it actually doesn't carry the ground from the pinion to the housing. I'd try fastening the test ground at different points to try to isolate the problem.
 
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