Installing an AutoSound Challenger Speaker Bar in a C3 Corvette

If there's one area in which C3 Corvettes fall short, is audio. And if you haven't already swapped the most likely dry-rotted factory dash speakers for better-sounding modern units, I am sure your Vette's radio sounds horrible.

However, it doesn't need to be that way.

A few years ago, I bought a speaker box I found at AutoZone. It was cheap and it came with speakers and tweeters. I think I paid around $30 for it (it was on sale), so for that price, I'm sure the components were of low quality, even though the box was well made.

It sounded ok for the most part, but eventually, I added a subwoofer and that made all the difference.



I think I have to mention that even though I love music and a great-sounding stereo, I am not a true audiophile, and on top of that, I am a cheapskate when it comes to my car audio equipment.

My car's radio, a Dual XR4120, also came from a big-box retailer and it was cheap. I wanted to upgrade from the gigantic AM/FM factory radio the Vette came with, and this unit was all I needed.

My only "requirement" was that it had an auxiliary port so I could listen to the songs I have on my phone. A Bluetooth radio would've been nice, but let's not forget the cheapskate part.

I did splurge on a Kenwood KSC-SW11 150 Watt Compact Subwoofer and a pair of PolkAudio DB461P speakers for the dashboard.



And even though everything was well with my current setup, the problem was losing the ability to store the T-tops in the storage area behind the seats, even though I rarely take them off.

Having the subwoofer on top of the jack storage compartment door does not help either, but I ran long wiring when I installed it, so it can be moved around a bit.

So in order to regain the ability to stow the T-tops inside the Vette, the AutoSound speaker bar was an affordable solution to the problem. I paid $120 plus tax and free shipping from Speedway Motors.

Installation is straightforward since the soundbar is a "pressure fit," so there's no drilling required. And it fits 1968 through 1982 C3 Corvettes (coupe models only). 

If you already have rear speaker wires in place, then the install will be a lot easier. However, you have to remove one of the seats and the T-top above it to make the process easier and prevent damage.


With all the soundbar components inventoried, the next step is to read the instruction sheet. I had inadvertently left a small bag of hex set screws needed for the assembly in the box.



The set screws (four of them, shown below), are used to secure the spanner bars to the speaker panels. This allows you to maneuver the soundbar as one unit and stretch it to fit snuggly in place. The hex or Allen key is included.

In order to install and tighten the set screws, you must remove the speaker boxes' pressure-fit trim end covers by prying them carefully with a flathead screwdriver.



The second photo below shows where the set screws go (yellow arrows). Snug them up so you can pre-set the assembly to the approximate width of the storage compartment and move it safely into place without the speaker boxes falling out.

It is cumbersome, but once you get into place the process becomes a lot simpler.



I measured the approximate width of the area where the soundbar would be located, and that dimension is roughly 52 inches. I also made a mark on each of the spanner bars centers so they would be tightened equidistantly. The mark allowed me to visually position them in relation to the whole 52-inch span.


The picture below shows the assembly in place after sliding the speaker boxes into place.

I must note that I did not want the soundbar to tilt forward when I drove the car and hit the brakes, something that was likely to occur. So I devised a simple solution by wrapping a piece of wire around the top spanner bar and securing it with the carpet clip as shown in the photo below (see yellow arrow).


You could, alternatively, drill a couple of holes and secure it more permanently to the tub, but that would make removing the assembly too much of a chore should you need to do so.


The next step is to measure the span of the middle section where the spanner bars are exposed in order to cut the middle filler panel, something that can be easily done with a sharp utility knife. 

As you've probably heard many times, the "measure twice, cut once" rule applies in this case as you only get one shot at this.


The end result may not look pretty but that's okay as the speaker box end trim caps will cover a portion of the filler pad hiding any rough edges.


I also had to trim some of the excess vinyl that kept the pad from fitting over the spanner bars. And even after that, it was a tight fit.


Installation of the speakers is very straightforward, especially if you already have rear speaker wires in place. The soundbar woofer, mid-range, and tweeter are pre-wired internally, so all you have to do is connect them to the speaker wiring.

And with that, the installation is complete.


I am very pleased with how "factory" the soundbar looks, and I regained the room necessary for stowing the T-tops when necessary.

The soundbar rests about 4 inches above the floor of the storage compartment giving you plenty of space for the T-tops or anything else.

Since I kept the Kenwood subwoofer, I cannot tell you how the soundbar sounds by itself, but I think a subwoofer is mandatory if you want a rich sound in your vehicle. 

For a detailed video of the soundbar installation, please click the image below.

There are several vendors that offer the Custom Autosound Challenger Soundbar, but as I mentioned earlier, I purchased mine from Speedway Motors on eBay. I am not sponsored by them. I am just a happy customer.

Thank you for following my 76vette Blog!


Product Links... (#sponsored)


• Dual DC206BT Single-DIN Car Stereo | Bluetooth, CD/MP3 Player
• Dual XRM59BT Single-DIN In-Dash Media Receiver with Bluetooth