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Robbie's How To Guide – Stebel Nautilus Horn Fitting
How To Guide – Stebel Nautilus Horn Fitting
This how to guide covers the fitting of the Stebel Nautilus Horn, which is a step change in volume and urgency compared to the rather limp OEM offering. This thing is loud and pulls a fair current when operating. The guide focuses on DIY fitment using regular parts and techniques but given the current the Stebel requires care must be taken. Be methodical, use the correct wiring; install a suitable relay, an inline fuse and decent connections. I have tried to aim the guide at the beginner and have included tips on crimping. There are many ways to skin a cat and this guide is just one way to fit this horn, so if you are more experienced feel free to wire it your way. If I have missed out some detail please point it out or ask questions and I will go back and edit this guide. As ever, if in doubt consult a proper auto electrician!
1. The horn was from Nippy Norman’s and is a rugged design suitable for bikes and Land Rovers. The instructions are non-existent but it does come with a relay but no brackets, wiring or connections.
2. Once free of the packaging it pays to test it before fitting. Learning from others I tested mine with ear defenders on! Mine worked fine but the relay was a little sticky. After a few cycles it worked fine but something I intend to keep an eye on as the relay provided is not the best quality.
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3. Do not be daunted by your car’s wiring; it is simple by design with everything connected via a common ground – the car’s bodywork. It is always worth checking the OEM diagrams to see the colour coding and the specifications of the various looms. The D3 horn is wired via a relay that is built into the junction box in the passenger footwell. For my installation I am leaving everything as LR intended and picking the horn signal from one of the original horns (one of mine is dead) to trigger the relay to allow the current to flow from the battery and make a heck of a din.
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4. The relay is just a switch that keeps the high current required for the horn away from the original horn wiring. Simplified the wiring will look like this:
5. So park the car in a suitable place for DIY, unlock all the doors, open the driver’s window and remove the key. The car needs to go to sleep before removing battery power; the window and door unlocking is a precaution to make sure you are not stranded on the outside of a locked car if something goes wrong. It takes 2-3mins before the handbrake symbol goes out, indicating the car is asleep. Whilst you wait you can assemble the tools:
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6. When the car is asleep disconnect the negative terminal – the order matters and is for your safety. The D3 still draws some current when asleep and draws more when reconnected. As a result try and make it a clean break to avoid sparks. As the negative terminal is a little tight under the plate stick something non-conductive between the lead and the battery terminal to avoid it springing back – I used a white plastic bottle cap.
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7. Now remove any trim or parts required to gain access to where you want to mount the Stebel horn. The horn may be compact for a dual air horn but it is still pretty hefty. As I wanted to keep the wiring simple and as my LHS horn is dying I decided to mount on the LHS strut (ie to the right of this picture, leaving the RHS horn intact). All I had to remove at this stage was the front grill and LHS headlight unit.
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8. Having offered up the horn I selected a location and marked the strut with a punch.
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9. Drill a pilot hole into the soft aluminium.
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10. Then drill to full size for the bolt (8mm in my case).
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11. Out of habit I painted the hole.
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12. Then a check-fit.
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13. Relays are very simple devices that use one voltage source to switch another on and off. They are reasonably rugged but prefer to be mounted somewhere a bit sheltered and with terminals hanging underneath. When used in confined spaces I quite often copy the terminal numbers onto the side to aid in wiring.
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14. Having decided on where the horn was going to be mounted finding a place for the relay and wiring is easy. With the LHS headlight removed there is plenty access for wires from the battery and back to one of the 3 earth studs forward of the battery compartment. The relay is going to be mounted to the left of the coolant bottle, above the original LHS horn.
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15. Original horn as viewed from the side.
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16. Unhooking the rubber shield from the grill side exposes the back of the horn. I used the horn mounting-nut itself and added a small bracket to mount the relay a little higher. In this position it is sheltered from the elements. You can also see that I have marked the terminal numbers in felt pen – keeping it simple helps to avoid errors.
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17. Now for the wiring. Plan out what you need, think about how much is required and how it is going to be terminated. If you are using heatshrink, remember to put it on before crimping away. I recommend adding some additional unshrunk lengths to the wire that can be shrunk as required to reinforce anywhere it may rub. If it is not needed then it does no harm left on the wire.
Please use proper cable designed for automotive use; 17 amp in this case. Quality automatic wire strippers really can help when working on cars (or aircraft!) as there is typically little spare wiring. I like these Knipex strippers as they strip from the end of the pliers rather then the sides. Side strippers are ok on the bench but stripping end on helps in tight places. For 6.4mm crimp terminals a 6mm / 0.25in strip is required, so dial that in on your strippers / calibrated eye.
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18. Give the exposed wires a little twist to keep them together.
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19. Load a 6.4mm blue terminal crimp into the correct jaw. Ratchet crimps are a must in my view, as cheap crimpers do not provide the quality required for safe and reliable wiring.
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20. Insert the exposed wire until it stops and give the ratchet crimper a firm squeeze…
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21. Until the crimper unlocks again…
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22. For a good quality crimp.
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23. Again, only expect misery with the crimp function on the strippers on the left. I’m using cheap pre-insulated crimps in this guide but feel free to use higher quality un-insulated crimps and use heatshrink or (even better) crimps with heatshrink and glue pre-packaged for waterproof and robust connections.
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24. I did cheat and use a heatshrunk crimp for some of my loom where I though there may may be some strain.
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25. Loom forming, complete with in-line fuseholder.
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26. Don’t forget the fuse.
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27. Having crimped one side of the loom it’s time to start threading it around the car before adding the terminals to the other end. I picked the live from the battery, routed it in the gap between the battery box and the body, before running it under the FBH to the relay by the grill. As a precaution I used automotive conduit to protect the wires from heat of the FBH; although routing the new wires under existing wires does hold everything clear of the hot stuff.
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28. The conduit and wires popping out behind the coolant bottle and through to the grill. Near the strut you can see the relay and its markings. I have marked the ground with green heatshrink and the live with red.
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29. Then route the female fully insulated crimp to the respective terminals on the relay.
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30. Insert the final ends on to the horn itself and once everything is connected tighten up the mounting bolt.
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31. If you have a DMM and are as cautious as me, now is a good time to run some continuity checks. If you have a bad joint then locate the poor crimp, snip and replace. Mine were all good.
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32. Having double-checked everything, reconnect the negative lead to the battery.
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33. Ask the Wife to stand here whilst you test the horns:
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34. Never gets old, does it!!!
Feel free to comment, add your own top tips or ask questions from the true forum gurus (which I am not, I hasten to add!).
Edited to add:
35. I was wondering about the orientation of the horn vs the compressor's sealed lubrication. After consulting the www it seems that the horn can fail prematurely if not near the vertical. So grabbed a suitable handful of washers to pack-out the recess on the back of the strut. Not having a suitable length of M8 bolt with a square head I had to trim a longer one with a grinder.
So it now looks like this:
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36. But it according to Stebel it does not have to be perfectly level; shame that these instructions did not come with the horn:
Anyway, lets hope it helps the reliability as compressor horns are not famed for their longevity!
Regards to all.
Robbie
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 22 Nov 2008
Location: Cumbria
Posts: 4401
Great write-up. I am not DIY so paid dealer to do this -
SOLD - 23my Range Rover Sport D300 Dynamic SE
21st May 2012 9:28 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Hi DJ,
You probably don't want to hear this but your horn draws more amps that the 1.0D wire currently connected to it can handle. What is less clear is the max rating of the original horn relay built into the Central Junction Box so there is a chance that this may get damaged too.
Slightly surprised that a dealer would fit it in the manner they have done unless they were truly unaware of the current draw of the Stebel (I had to do some thinking and investigation before fitting mine but one would hope that it would be second nature for an auto-sparky).
Never easy to pass on such news...Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 22 Nov 2008
Location: Cumbria
Posts: 4401
Ok thanks for spotting that. I sold the D3 several months ago so that's not my problem but it worked fine for 2 years. SOLD - 23my Range Rover Sport D300 Dynamic SE
You probably don't want to hear this but your horn draws more amps that the 1.0D wire currently connected to it can handle. What is less clear is the max rating of the original horn relay built into the Central Junction Box so there is a chance that this may get damaged too.
Oh dear!
Help please:-
What wire should I be using in lieu of the 1.0D wire? Can I simply run an additional one in parallel?
What relay should I use to replace the original horn relay?
NJSSAm I Gammon or Woke ? - I neither know nor care.
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23rd May 2012 6:56 pm
Disco_Mikey
Member Since: 29 May 2007
Location: Dundee, Scotland
Posts: 20802
Makes my How-To's look like sh*t
Good write up, clear instructions. Must spend more time on my next guide My D3 Build Thread
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