Big sound

| February 01, 2006

Air horns are crowd pleasers and easy to install.

One of the sights that makes a trucker smile on the road is a young child peering out a car window and making the famous gesture – a pumping motion with his arm that means, “I wanna hear the air horn!”

Fitting air blasters onto your rig is surprisingly easy. Even if you’re a company driver, the installation is simple enough that your fleet is likely to let you put them on their rig. You can use the brake system air to provide the power, greatly simplifying installation and reducing the chance of trouble, as compared with installing these fun devices on your pickup or family sedan. Just be careful about things like air hose length and routing, and the system will work just fine.

We consulted with two of the major air horn manufacturers and got their advice on installation.

Grover Air Horns
One of Grover’s largest distributors is Gabbert Equipment Company, and we got the help and advice of Jason Gabbert there, along with receiving a set of instructions directly from Grover Product’s sales manager, Bill Marting.

Gabbert says the first thing you need to do is to make sure you buy one of the kits designed for a complete installation, not one designed to provide only a replacement horn. This includes an air valve and some air fittings you will need. Also, get a sealer designed for high pressure air fittings. Gabbert suggests the familiar Permatex, but you might want to ask your truck dealer for what they recommend. You’ll also need a sealer designed to go around piping that’s passing through walls – something that will allow you to seal between a nipple in the kit and roof, where the nipple passes into the cab.

  1. Find the air system junction box. Contact your truck dealer or the factory service representative to help you if you can’t locate it on the vehicle.

  2. Decide where you want to mount the horns. The standard spot is right on top of the cab. It’s smart to have them out in the open, not behind anything else that may be mounted there, like an air shield. Make sure the location allows you to install the horns as close as possible to the electric air solenoid valve, if you plan to install one. With a manual valve, the kind you pull open with a lanyard, this valve (called a “1630 valve”) will be connected directly to the rear of a single air horn. Make sure the rear of the single horn is located in a spot you can reach comfortably from the driver’s seat. With dual horns, there will be a central fitting – a tee – with a nipple connecting it to the valve.
  3. Carefully mark the mounting holes for your horns with a horn in position on the roof. If installing a single horn, make sure to mark the hole for the nipple so it will be properly aligned when the horn is mounted. Drill the holes for the horn mounting bolts with a 5/16-inch drill. If installing a single horn, drill the single hole for the nipple with a 1/2-inch drill. Since a 1/2-inch hole is so large, you might want to go in stages, doing an initial drilling with the smaller drill first.
  4. If installing a single horn, apply air pressure sealer and then screw the 1/8-inch NPT close nipple in the kit into the bottom of the horn. The easiest way to turn the nipple tight is with a pipe wrench. This way, when you mount the horn, you can insert the nipple through the roof of the cab. You then won’t have to engage the threads from the driver’s seat. Then mount the horn or horns on top of the cab with the 1/4-inch bolts, putting a waterproof sealer on them. For single horn installations, now skip to Step 9.
  5. If installing multiple horns, first use the two mounting holes to install the 1630 air valve with bolts. Put a waterproof sealer on the threads. The company suggests locating it on the left/upper side of the cab, in front of the driver, over the windshield. You may also wish to put it above the window on the left side door. Just make sure the driver will be able to reach the control handle. Don’t snug the bolts up all the way – you’re just putting the valve in place momentarily so you can figure out where to drill the hole for the nipple through the roof.
  6. Once you have test-mounted the valve, carefully mark the position of the hole through the roof. You’ll need to drill a 1/2-inch hole directly above the connection on top of the valve. This needs be done so that the nipple can be screwed into the valve and will pass through the roof when the valve is mounted. You might want to start the hole with the 5/16-inch drill to make the job easier.
  7. Apply air pressure sealer and then screw the 1/8-inch NPT close nipple into the top of the valve, tightening with a pipe wrench. Now, install and tighten the valve mounting bolts. Once the valve is mounted, apply a waterproof sealer to the seam between the roof and nipple.
  8. Apply the air pressure sealer to the threads on top of the nipple, and then screw the tee onto it and snug it up. Make sure to cut your 1/4-inch tubing to the appropriate length for the horn that is farther away from the tee. Then duplicate that length for the other tube. Securely connect the tubes to the fittings on either end of the tee and on the bottoms of the horns.
  9. With single horn installations, now apply air pressure sealer to the threads on the bottom of the nipple and install the valve onto the nipple. Turn the valve so it is snug, but the control-handle also points toward the front of the cab.
  10. Connect another length of tubing to the air supply fitting at the rear of the valve. With dual size 10 horns, the 5/16-inch tubing supplied with Kit #1098 should be used here. Run the other end of this tubing to the brake junction box, and connect it to the box with the fittings supplied in the kit.
  11. Tie a chain or strap to the control lever of the valve and you should be in business. The horns require 60 psi to operate properly, so they should work any time the air brake system pressure has not leaked down too much.

You can also install these air horns on a pickup truck. You’ll need to add a compressor and air tank, installed under the hood, with a line running from air tank to the horn. The compressor supplies the tank via tubing between its outlet and the tank inlet. A good mounting position for the horn might be the fender, since you can then route the air line that runs from the tank to the horn through the fender itself. You’ll also need to mount a solenoid near the horn, in this case, in series between the storage tank and horn, possibly in the engine compartment right near the horn. Wire the air compressor and solenoid as shown, and the air horn will sound when you push your regular horn button. The closer the solenoid is to the horn, the more quickly it will respond.

Hadley Products
Hadley products also provides air horn kits, and Mark DeBoar of their engineering department helped us with instructions and illustrations.

Hadley makes Model 981, the simpler kit, which uses a simple air valve that you pull with a lanyard. You can also purchase Model 2009D, which is similar except that you then use a solenoid valve. You will need to wire the solenoid to the existing horn circuit for this type. The straight air type is a little simpler to install, and in addition to the macho factor of yanking down on a lanyard to sound the horn, will allow you to continue to use your regular horn alone when in cities and towns where you might want to avoid making too much noise. Get some pipe dope-type sealer to seal all the threaded air connections.

The company recommends that you check into noise ordinances before indiscriminately operating that horn.

To install:

  1. Choose your horn mounting locations, which should be on the front of the cab and pointing just slightly downward for maximum sound.

  2. Remove the roof inner trim panel to make mounting the horns easier.
  3. The horns come with mounting gaskets with holes corresponding to the mounting bolt locations. Use the gasket as a template, and drill 1/2-inch and 9/32-inch holes aligned with the holes in the gasket for each horn. The 1/2-inch hole is for the mounting stem that carries the air. Put each horn in position, test mount the front support for each, and drill the 9/32-inch holes for each of its two mounts.
  4. Locate the horns on the roof with the mounting gaskets squarely under the horn and support bases. For each horn, assemble the bolts, nuts and lock washers through the two mounting holes on the horn at the rear and the two holes on the mounting support at the front. Then install each tension washer, jam nut, mounting stem and brass elbow through each horn’s mounting base for the air supply.
  5. Cut tubing of equal length to run between the tee and each horn. Then connect the tubing between the tee linking the two horns and the elbow at the base of each horn. Coat threads with sealer and tighten the fittings gently and carefully until just snug. They don’t need to be extremely tight.
  6. For Model 981, find a location where the driver can reach the manual air valve inside the cab. Use the angle bracket supplied as a template, and drill two 3/16-inch holes. Install the valve into the bracket with the two jam nuts supplied, and attach the assembly to the cab with the two sheet metal screws. Coat fittings with sealer, and then connect the tubing between the valve’s top and the tee that supplies the horns with air. Make sure you look at the arrow that indicates flow and have this air line connected at the valve’s outlet. Then gently snug up the fittings.
  7. For Model 2009D, mount the solenoid valve where tubing and wiring will reach. Coat threads with sealer and then connect tubing between the valve and tee that supplies air to the horns. Then tighten the fittings gently until just snug.
  8. On Model 981, coat all threads with sealer. You’ll next connect the air line between a fitting on the vehicle’s air junction box and the inlet on the side of the manual valve (nearer the back end of the arrow indicating flow). First, slip the line into the nut on the side of the air valve and gently tighten the nut. To make the connection to the vehicle air supply, first coat threads with sealer and then install the male connector into a female fitting in the junction box. Then install the insert through the nut so its collar rests inside the nut. Force the other end snugly into the air line. Then install the sleeve inside the male connector at the junction box, and finally, coat threads with sealer and install and gently tighten the fastening nut.
  9. On 2009D models, connect the tubing to the air junction box as in the step above for the 981. Then install the insert into the nut so the collar will be retained. Force the insert into that end of the tubing so it is tight. Coat the threads with sealer and then screw the 1/8 NPT connector into the side of the solenoid and snug it up. Finally, install the sleeve, coat the threads with sealer, and then screw on and tighten the nut.
  10. On the 981, punch a hole in the trim panel for the valve lanyard. Route the lanyard through the panel, replace the panel and fasten the outer end of the lanyard to a convenient trim panel screw.
  11. On the 2009D, wire the solenoid to the existing horn circuit as shown in the diagram. This means finding the existing wire that runs from the horn relay to the horns and connecting into it, or to the relay terminal it’s connected to. Then connect the other end of the wire, using the terminal, to the solenoid. The solenoid is grounded to the vehicle via its mounting bolts.

For further information, please contact the following:
Grover Air Horns
www.groverproducts.com
(323) 263-9981

Gabbert Equipment, Inc.
www.groverairhorns.com
(956) 682-1421

Hadley
www.hadley-products.com
(616) 530-1717

75 Chrome Shop
www.75chromeshop.com
(866) 255-6206


Correction: The contact number given for TruckWeight in our December issue was incorrect. Please call (877) 757-7888. The company’s web address is www.truckweight.com. We are happy to set the record straight.

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