Does anyone have schematics or can point me towards some help in refurbishing or tweaking lucas horns for the XK150?
I have two supposedly refurbished original lucas horns, and one has gone almost silent.
Of course we have checked to make sure it is getting juice (it is) and when it is squeezed slightly it seems to make a louder sound.
How do these work, and what can be done to tweak them?

thank you!

greg arnold
JCNA
'58 Xk150, 66 E type, 61 Mk IX

Submitted by greg@nofatmusic.com on Sat, 11/09/2013 - 23:31

GOOD LUCAS HORN INFO IN CASE YOU DIDNT KNOW!

Follow up - Otto suggesting contacting Lawrie Rhoads (info above) regarding Lucas horn adjustments. He was enormously kind and helpful, and pointed me to the slotted screw next to the horn terminals.
A very simple adjustment that corrects or changes the distance between the electrical points, provided they are not corroded.
That was my problem, and my simple solution. A few twists of this screw (DONT REMOVE IT! I was warned or the points fall away inside the horn) - but a few twists and VOILA! my horn sounds fab, consistently beeps, and is in perfect harmony with the other one in the car.
So nice when the rare easy fix actually works!!
greg Arnold NYC

Submitted by greg@nofatmusic.com on Tue, 10/01/2013 - 11:13

hi Otto - thanks for the help and the contact. Horns are getting juice and after some googling I found that the center brass nut can be tightened (or loosened) to adjust volume performance. Pretty basic but who knew from looking at them?!
I've tightened the horn nut and Voila! it has increased the volume - so I'm guessing it's still in good shape. Perhaps this basic tweak of a Lucas horn will be useful to the group - or maybe it's so obvious and common that I look foolish! Either way - I was happy to discover it - and find a simple turn of the nut solved the problem. How seldom does that occur with an XK?!
Cheers
Greg

Submitted by NE08-63766 on Mon, 09/30/2013 - 03:50

Hi Greg,
There are 2 holes where the wires are connected, one is constant 12V, GREEN wire from fuse A4, the other is GRD., GREEN/BLACK wire, coming from the horn button. Leave the HOT wire in & remove the GR/BK wire, connect a good solid GRD. to that hole & if the horn sounds normal, you have to back trace that GREEN/BK wire & find where the fault lies. If the horn still sounds crappy, find out where it was refurbished & send it back. Or you can contact:

E. Lawrie Rhoads
7 Knollwood Road
Medfield, MA 02052-2703
USA

Telephone: (508) 359-2077