2500M: horn-push for the electronically challenged

[Renaldo]

Guys, I've been looking at the Mountney (all metal) billet horn push I bought for my new wood steering wheel (photo of the back, attached)

Forgive my electronic ignorance, but I'm unsured how the circuit completes itself?

I'll offer this as my possibly misguided guess: when all is connected, you push the button which somehow grounds to the boss adapter for the steering wheel?

Am I out in left field without a glove?

Please free to get out the chalk board to correct me.

Ron

[RCK974X]

Not completely clear from the photo, but a lot of horns from various cars had their earth return via the case of the unit, so that 12V connected to the spade is enough, because horn always mounts to a steel bodied (earthed) vehicle.

For a fibreglass body, TVR, kit car, etc, put a eyelet connector on one of the mounting bolts....

The same principle applies to horn pushes on older steering columns - the design probably assumes that the body of the push is earthed via the column. You may have to add a wire to the column mounting bracket.


Does that all make sense ?

Edited by RCK974X on Monday 27th January 01:12

[Renaldo]

Andy, I think I'm getting you. So with this Mountney piece, it connects to the horn brush via its spade terminal. (wire goes from the horn brush to the spade terminal on the back of the horn-push)

Do I understands correctly that it's automatically grounded by being in contact with the steering wheel boss (hub)?

Excuse my ignorance, but where I get confused is how pushing that button achieves any connection? Is it all occurring out of sight, inside the workings of the horn push itself?

Ron

[GadgeS3C]

Ron, it's not clear from the picture but it looks like the plastic bit with the connector in the centre is the bit that moves when the horn push is pushed. If so then I believe that rectangular strip (could be brass from the colour) that is screwed to the boss needs to be rotated so the centre bit connects to it when the horn is pushed. That should then make the earth connection to operate the horn.

Picture below might make it clearer

[Adrian@]

On the M series/Vixen that DO NOT have wash wipe (I saw a Vixen last week WITH a late column) on the column the steering boss needs to have a sprung loaded link between the central bolt and the slip ring under the boss.
The picture shows you the Triumph version of the connector, TVR used a simpler version as it is pressed into the rear of the boss and a sprung connector and link wire with an eyelet then allows you to connect to the central bolt.



IMHO you then need to ensure that the earth works down AND through each UJ AND then a link across from the rack to the chassis (IF you are using rubber mounts) AND the steering column locking ring and bronze bush assembly on the chassis is set correctly (this stops the modulation of the twin UJ's and the resultant rise and fall of the steering wheel in relation to the outer column).
Adrian@

Edited by Adrian@ on Monday 27th January 09:00

[heightswitch]

Or you could just get a horn push with 2 wire conections?
N

[Renaldo]

Thanks Gary, Adrian and all.

I definitely have the spring loaded horn brush that slots through the boss, leading from a "slip" ring (if that's the correct term)on the steering column.

It makes sense to me Gary, that the metal tab you illustrated would need to line up as you indicated.

Oh, to understand auto electrics much better than I do! It seriously baffles me.

Any plain-language books out there (for Dummies) that explain classic auto electrics?

Ron

[thegamekeeper]

If you are struggling understanding the wiring for a horn push may I suggest "The AA Book of the Car" 1970, probably the finest tome ever written for a beginners understanding of cars and
how they work and very much appropriate for our types of car. Once you have mastered that "Haynes Electrical and electronic systems manual".

If everyone had a copy of the AA book half the questions on here would never be asked. Its the silver one available on ebay from 99p.

Edited by thegamekeeper on Monday 27th January 17:11

[Adrian@]

Where it all started for me and still used on the odd occasion...lol



Adrian@

[Renaldo]

Beautiful! On to E-Bay I go!

Ron

[oliverb205]

Hear hear for the "AA book of the car". I used to study my Dad's copy when I had my Vixen, and then purloined my Grandfather's copy when we were clearing out his stuff after his death. Invaluable.

Oliver.

[RCK974X]

Doh !! Of course, I totally forgot about the spring loaded 'push pin' in the old Triumph columns as per Vixens.

I remembered a type which was all incorporated in one unit, from a ....er...... [memory fail].

Sorry about that.

[Cerberus90]

I've got one of those AA books, given to me by my Grandad, along with an RAC one in a blue plastic folder too, and another one similar to the AA one which name escapes me.

[prideaux]

thegamekeeper said:

If you are struggling understanding the wiring for a horn push may I suggest "The AA Book of the Car" 1970, probably the finest tome ever written for a beginners understanding of cars and
how they work and very much appropriate for our types of car. Once you have mastered that "Haynes Electrical and electronic systems manual".

If everyone had a copy of the AA book half the questions on here would never be asked. Its the silver one available on ebay from 99p.

Edited by thegamekeeper on Monday 27th January 17:11

Thanks Steve
99p spent as no one else listened to you so i will either ask less Questions or even answer a few once i learn to read
A

[Grantura MKI]

prideaux said:

thegamekeeper said:

If you are struggling understanding the wiring for a horn push may I suggest "The AA Book of the Car" 1970, probably the finest tome ever written for a beginners understanding of cars and
how they work and very much appropriate for our types of car. Once you have mastered that "Haynes Electrical and electronic systems manual".

If everyone had a copy of the AA book half the questions on here would never be asked. Its the silver one available on ebay from 99p.

Edited by thegamekeeper on Monday 27th January 17:11

Thanks Steve
99p spent as no one else listened to you so i will either ask less Questions or even answer a few once i learn to read
A

Good for you, A. This is what the forum is meant. Happy reading!
Regards,
D.