Maximus BMW Sports Horn

Maximus BMW Sports Horn - Universal 12V Twin Snail Horn Set, Mega Blast Series

This is a pair of black 12V snail horns from the Maximus Mega Blast series, tuned to give the sporty two-tone sound you hear from a BMW. It is a universal horn. BMW had no part in making it, and it fits any 12V car, SUV or pickup with room behind the grille, from a Cultus to a Fortuner. The horns are made in China. People usually buy a set when the factory horn has gone weak, or when they want something that sounds sportier than the thin beep a small hatchback leaves the showroom with.

Inside each horn is a wire coil and a thin steel diaphragm. Switch the coil on and it pulls the diaphragm in, which breaks a contact and cuts the current. A spring pushes the diaphragm back, the contact closes, and the cycle repeats 400 to 500 times a second. That repetition is the note you hear. The curled shell around it is a trumpet wound up to fit a small space. Sound has to travel round the spiral before it leaves, so it moves far more air than a flat disc horn would.

What the box claims, and what that means in practice

Look at the stamp on each bracket and you will find H or L next to the frequency. The H horn sits around 500 Hz and the L around 400 Hz, and both are wired to sound at once. The gap of roughly 100 Hz between them makes the notes clash slightly, and the ear hears that as louder and more urgent than one note alone. The printed claims on the carton line up with the supplier's figures like this.

Here is the thing you only learn after fitting a few sets. Point the horn openings down or sideways, never up. IP65 covers splashes and jets, but it does not cover water that sits still. A horn mounted face-up behind the grille fills its spiral with rain during the Lahore monsoon, and water left sitting against the diaphragm turns a loud horn croaky within a month.

What it cannot do and where it does not fit

• It is not an air horn. There is no compressor. If you want bus-and-truck volume, you need a compressor horn kit, and those are restricted on city roads.
• It is not a BMW part. "BMW Sports" in the name describes the sound. There is no BMW part number, so anyone restoring a BMW to factory spec should buy the genuine horn.
• It is 12V only. Trucks, tractors and most buses run 24V, and a 12V coil burns out quickly on a 24V supply.
• This horn is deep, so measure first. Each unit is about 81mm tall and 97mm deep front to back, which is noticeably deeper than our Mercedes Benz horn. You need roughly 100mm of clear space behind the grille. On a Mehran or an older Alto you may end up with one horn behind the grille and the other lower down near the bumper beam. If there is no room at all, a slim disc horn is the better choice.
• It needs a steel mounting point. At 0.66 kg per horn, a plastic clip or a thin tab from a lighter horn will crack with the vibration.

How to fit it

1. Take the negative lead off the battery. On most cars sold here that is one 10mm nut.
2. Find the old horn. On Suzuki, Toyota and Honda models it usually sits behind the front bumper, bolted to a small bracket on the slam panel.
3. Unbolt it. Each new horn has its own 1.8mm steel bracket with an 8.5mm hole, which takes a standard M8 bolt. Bolt it to solid steel with the opening pointing down.
4. Keep the two horns apart, and away from plastic trim. A horn leaning on something loses part of its sound into it.
5. Each horn has two spade terminals, one for the positive feed and one for earth. The bracket does not carry the earth, so run that wire to bare metal on the chassis. Painted or undersealed metal is the usual reason one horn stays silent.
6. Wire the pair through a relay, with the relay's power coming straight from the battery through a fuse and the car's original horn wire used only to trigger it.
7. Reconnect the battery and test both horns.

The most common mistake is wiring both horns onto the original horn wire because the old single horn never needed a relay. Each of these draws up to 4A, so the pair pulls close to 8A. The contacts behind the steering-wheel horn pad were never meant for that, and when they burn, the repair costs far more than the relay would have.

Specifications

Who buys this

Most buyers drive a City, Civic, Corolla, Cultus or Swift and want the horn to sound as if it belongs on a sportier car. Another steady group are drivers whose factory horn has faded after years of heat and rain, and who decide to upgrade instead of buying the same weak part again.

Highway drivers on the motorway and GT Road fit a twin set for a practical reason. A single factory horn does not reach a truck driver through a closed cab at night. Two horns do.

If you are choosing between this and the Maximus Mercedes Benz Horn, the ratings are the same and the difference is the sound and the shape. The Mercedes set is about 14mm shallower, so it is the easier fit on a car with a cramped front end. Ask at the branch to hear both. If you want real air-horn volume, neither one is the right product.

Where to buy

The Maximus BMW Sports Horn is stocked at Sehgal Motors branches in Lahore, Faisalabad, Sialkot and Multan, and on sehgalmotors.pk with delivery across Pakistan. Call 0311-1222357 before you come in and the branch will keep a set aside. The staff can also tell you, for your car, whether both horns fit behind the grille or one has to go lower on the bumper beam.