How To Install Speakers in Car Trunk? A Step-by-Step Guide


Installing new speakers in your car trunk is an excellent and inexpensive way to improve your car’s audio system.

It is also not too difficult and it does not consume too much time. But how to install car speakers in the trunk, so you can enjoy better audio in no time? Let’s find out.

In general, to install speakers in a car trunk, disconnect your car’s battery, remove any necessary panels and mounting screws, and replace the old speakers with the new ones. When installing a subwoofer in the trunk, place an enclosure in a stable position close to the amplifier, and run the speaker wires between the amplifier’s and subwoofer’s terminals.

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Tip: Although you need just a few screws for speakers installation, it is worth mounting speakers to the car body with speaker baffles and foam gaskets. They are available on Amazon, so if you want to install baffles in your car, click the above links and check the latest price.

Baffles not only protect the back of the speakers from mechanical damage or potential water but also create an enclosure effect and will strengthen sound waves coming out of the speakers.

On the other hand, Gaskets significantly reduce any potential vibrations transferred from the speakers to the car body panels.

While installing new speakers in your car trunk is generally an easy task, there are a few things you need to avoid. In this article, I will show you clear instructions on installing new speakers and warn you of dangers worth avoiding.

What Tools Do I Need to Install Speakers in Car Trunk?

The tools you’ll need to install your new speaker system will probably include most of the following. I listed tools that I use, and I am happy with their quality.

Screwdrivers

  • Torx drivers are also called star screwdrivers. They’re used in some speakers and are widely used by electronics manufacturers.
  • Magnetic screwdrivers form a magnetic connection with the screw. If you want to avoid dropping a necessary screw into your car’s body, this set of magnetized Phillips, flathead, and Torx screwdrivers can replace both above standard alternatives.
  • Offset screwdrivers have the bit at a 90-degree angle to the handle, allowing you to rotate screws in obstructed areas a straight screwdriver can’t reach.

Wrenches 

Panels are often held in place by Allen bolts. The TEKTON Hex Key Wrench Set has long, and short Allen wrenches in 15 sizes ranging from 0.028 to 10mm (0.001 to 0.39cm).

If your panel bolts need socket wrenches, the EPAuto Set with Ratchet Wrench will help you loosen them and put them back tightly when finished.

Panel and Trim Removal Kit

These polyethylene/nylon tools help you pry loose panels and dashboards without scraping or marring the metal or tearing foam.

In addition, the Amorka Trim Removal Kit will help you expose your speakers and put things back in place when you finish.

Power Drill  

A drill can help you tighten or loosen screws and bolts. It can also create new mounting holes if the holes on your new speaker are placed differently than on your old one.

WAKYME Cordless Drill Driver Kit offers many bits that will help you install your new speakers by drilling new holes or tightening a screw or bolt. 

Hobby Knife

You may need to cut through foam or sealant around your factory speakers’ edges. This DIYSelf Exacto Knife includes 40 extra blades for scrapbooking, art, or car speaker installation. Trim speaker edges carefully, as you don’t want to cut wires or yourself.  

How to Hook up Speakers in Car Trunk?

Carpenters often say, “measure twice, cut once.” It’s easier to get the job done right once than to fix botched work. The more you know about your system and your speakers, old and new, the better your chances of having a smooth and easy installation. Let’s start with a step by step guide:

Check Your Amplifier’s Power Rating and Channels

If you’re upgrading your factory system, check your automobile’s instruction manual. Car Manuals Online has manuals available for most makes and models if you misplaced yours.

Most car manufacturers offer various audio tiers, so check to see if your model comes with the stock system or with one of the upgrades.

If you’re working with a factory system and are only upgrading your speakers, you should replace them with speakers that have similar or identical power and resistance ratings.

For example, your current amplifier may be able to handle your 50-watt 4-ohm speakers just fine but struggle to keep up with 200-watt 2-ohm replacements. 

The most important statistic is the ohm rating. Most, but not all, car speakers measure at 4 ohms. An ohm is a unit of resistance. Lower ohmage means the speaker will draw more current from the amplifier. If the current draw gets too high, your amplifier may go into protection mode and shuts down.

But you should also pay attention to your new speakers’ wattage ratings. For example, replacing a 30-watt 4-ohm speaker with a 100-watt 4-ohm will probably be fine. However, replacing 30-watt speakers with low impedance behemoths like JBL GTO939 might be more than your factory radio can handle. 

More power isn’t always better, and it’ll undoubtedly be more costly and inconvenient. Also, current-guzzling new speakers might require higher-gauge wiring and a new (or even a second) amplifier.

The vast majority of aftermarket speakers with comparable power ratings will outperform your stock speakers and bring better sound from your amplifier without overtaxing it.

Check the Size and Shape of Your Old and New Speakers

Car speakers come in various shapes and sizes. If you have a 5x7in (12.7×17.78cm) oval installed in your rear deck, replacing it with a 5x7in (12.7×17.78cm) aftermarket speaker should be relatively simple. 

However, putting a 6x9in (15.24×22.86cm) speaker in its place might require enlarging the speaker hole, while getting a 4x6in (10.16×15.24cm) speaker to fit could involve installing mounting brackets or building one from MDF.

Many rear deck speakers can only be disconnected and reconnected through the trunk, so it is worth cleaning out your trunk and remove any clutter that might interfere with your access.

If you’re planning to install a subwoofer, trunk installations are popular. But first, you have to measure available space and determine what options you have available. 

If you’re installing new rear deck speakers because one or both old speakers were cutting out, make sure the problem lies with your speakers and not with your amplifier.

When you remove your old speakers or want to measure your system, use a multimeter like my favorite AstroAl 6000 Digital Multimeter to check the ohm resistance rating.

If the excessive volume or a power surge overloaded your old speaker, it might have a broken voice coil.

A broken voice coil is an open circuit and will measure as infinite resistance. For example, a 4-ohm speaker typically reads between 2 and 3.5 ohms. A partially broken voice coil will pass much less current, and it may measure 35 to 100 ohms or even higher.

If the coil becomes hot enough to fuse, it can form a short circuit. A short circuit provides a direct connection back to the original generator.

Short circuits result in rapid heating and can cause fires or even explosions. Your amplifier responds to this by shutting down to avoid damage. A multimeter will measure a short circuit at near-zero resistance.

If you’re replacing your speakers because of rattling, popping noises, you may be dealing with a torn speaker cone. If the cone rip is small, you may only hear rattling at higher volumes. But cone tears only get bigger, and ultimately they may destroy the speaker and even your amplifier.

Disconnect Grund Wire from Your Car Battery

Before starting any work on your speakers, or any other electrical system in your car, disconnect your battery’s negative (-) or black terminal. Disconnecting the negative terminal opens the circuit and stops electrical current flowing from the battery through your car’s wiring. 

Ensure the negative cable isn’t near the negative terminal, and under no circumstances should it touch the positive cable or terminal.

A short circuit will not only damage your battery, but it’ll also likely make it catch fire and explode after taking out most of your vehicle’s electronics. A bit of caution can save you from expensive repairs and acid burns.

Pry the Panels off With a Trim Removal Tool

Before you can take out your old rear speakers, you’ll need to remove the back panel covering the rear deck. Use your trim removal tool to slowly and gently pry the panel up. If you’re fortunate, this will expose your speakers. 

Plastic or metal clips hold your panel in place. Bolts or screws may also fasten them in one or more areas. Remove those carefully and take your time. Exerting too much force won’t loosen a bolted panel; it’ll damage it.

Depending on your car’s make and model, you may need to remove the rear seat to access your rear deck speakers. You’ll need to explore the trunk to find the wires that connect your rear speakers to the system in many cases. 

After you finally get access to your speakers, make sure you save every bolt and clip removed. Put them aside in a sandwich bag, an empty fishing tackle box, or some other place where they’ll be easily visible and kept in one place.

Removing panels and seats is only half the battle. You still have to put everything back together.

Many speakers are covered by a protective grill which you must remove. To do this, follow the steps below:

  1. Loosen any bolts or screws holding the grill. 
  2. Pry the grill loose with your trim removal tool. If necessary, use your hobby knife to cut away any foam or sealant that holds the grill in place. 
  3. Put the speaker bolts and screws in a safe place, separate from the panel clips and connectors. 

Unplug the Speaker and Pull Out the Blade Connectors

Gently remove the factory speaker. Your speaker connects to the main wiring via a plug attached to a wiring harness. You don’t want to rip wires by taking them out too roughly.

If you have difficulty removing your old speaker, check for any small bolts you might have missed or for any adhesive foam or glue still holding the speaker in place.

Your speaker connects to the wiring harness with a plug or through blade connectors attached to the speaker. Lift the plug gently out of the harness or carefully pull out the blade connectors, then set your old speaker aside. Repeat this process with the other speaker. 

Connect Your New Speaker’s Wiring Harness

If all has gone well, you need to attach your new speaker’s wiring harness to the car’s wiring harness or to the speaker wires from the amplifier.

But things may not be that simple. For example, the old speaker connector may be damaged, or your old speakers may use a different wiring scheme. 

The simplest solution for this problem is a replacement speaker connector harness. HSTECH Car Speaker Connector Harnesses will connect new rear speakers in any car. First, check your car’s make, model, and year and determine which connector fits your automobile’s harness.

Most new car speakers attach to their connector harness via blade connectors. Push the connector into the receptacle until it fits snugly. Make sure you match the polarity.

The speaker’s positive terminal is generally larger and marked with a + or a small dot (Your new connector will likely take care of that issue for you. The blades are differently sized, and the positive and negative wires will only fit on the appropriate terminal). 

The best way to connect wires is to solder them together and then to cover the solder joint with a heat-shrink sleeve. 

While soldering isn’t difficult, there’s a learning curve and a chance of blisters. But even if you don’t feel comfortable with a soldering iron, you don’t have to rely on duct tape. Instead, a better and more reliable solution is to connect wires with Posi-Products Posi Twist Connectors.

Turn on the Stereo & Test Your New Speakers

Now that you have connected your speakers, you should make sure they work before putting everything back together.

Reconnect your battery, and then turn on your stereo. You should hear music coming out of your new speakers.

If one of your new rear speakers doesn’t produce sound, try it on the other channel. If it works on that side, there’s likely a problem with your connection.

If it doesn’t work, there’s likely an issue with your new speaker. If both your new rear speakers work, your connections, and speakers have passed with flying colors. 

Secure Your New Speaker Snugly With Screws

Now that you know your new speakers are correctly connected and in good working order, you can mount them in your rear deck.

Your new speakers will fit perfectly in an ideal situation, and all you need to do is affix them in the old screw holes. But things are not always perfect.

If your old speaker’s mounting holes don’t line up with the new speaker, you’ll need to use your drill to create holes in the proper place. Make sure first that you’re not drilling into wires, electronics, or any other vulnerable tubes or equipment.

Use a marker or pencil to trace the mounting holes on your new speaker, then drill them.

The speaker must fit snugly and securely into its space. If your speaker doesn’t fit properly, it may require a mounting bracket. These are often included with the speaker or can be purchased separately. 

Your speaker’s innards may be exposed beneath its mounting. You’ll get better sound and better equipment longevity by using foam baffles. Foam baffles create a tight mounting seal around the speaker and reduce distortion caused by road noise and panel resonance. They also protect the voice coil and connectors from dirt and grime.

If you want better sound and longer-lasting speakers (and who doesn’t?), you can find on Amazon RDBS Car Door Speaker Foam Baffle Kit in various sizes.

Replace All Panels and Speaker Grilles

Reattach the speaker grills and reassemble your rear deck panel or anything else you removed during the installation.

You’ll need to replace any lost bolts, screws, or clips. A missing connector can lead to speaker rattling and buzzing or cause your panel to fall off. Replacements should be available at any auto parts store.

Make sure your connections are tight, and your speakers and panels are both well secured. Once you’ve done that, you’ve completed your rear speaker replacement.

This short video shows a replacement and an install of new aftermarket speakers in the rear deck. Check it out:

Final Thoughts

Congratulations! You’ve just installed new rear speakers. Your new rear speakers will give you a more realistic soundstage throughout the car and significantly improve your passengers’ listening experience in the back seat. 

Once you’ve upgraded your rear speakers, you’ll probably want to upgrade your front speakers as well. You may also find you need to install or upgrade your subwoofer. There are many ways you can improve your automobile’s speaker system in the future. 

Sources

Martin

Welcome to ImproveCarAudio! I am Martin, and I love to write about everything related to car sound systems. I strive to provide the most accurate and helpful information about car audio through extensive research, as well as my experience with car audio installations.

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