You'll probably have to ring it out unless you are using a shallow sub. You'll probably need to make new screw holes to match the pattern of your replacement sub. You'll have to fill in a hole on the back side of the box. There is bolt that goes through the back of the box into the magnet area of the speaker cage so once you remove the stock sub you're left with a big hole. You'll probably have to remove the plastic grille that says Pioneer from the back panel and install an aftermarket grille unless you want your replacement sub getting damaged and sounding like crap from rubbing on the stock grille.

 

I agree. If I had it to do over again I would have just left the factory sub alone and went straight to a box. I had to experiment though seeing as how I was one of the first on the site to swap out the sub not too long after the HHRs launch. So at the time when I did it there wasn't any info on here about swapping it nor were there pics posted anywhere. What I found out is that the factory box is too small and odd shaped to provide satisfactory bass even when you've done everything you can such as completely sealing it, putting the sub on it's own separate amp, and polyfilling the box. I hardly ever hook up the 8" anymore. I might have hooked it up twice last year. The only time I will use it is if I'm forced to remove my box with two 12"s because I need the room to transport a large item with the seats down. Then I'll hook the 8" back up and re-tune the amp so I at least have some bass in the absence of my box.

 

That is why I put a separate amp on my 8". That way if for some reason I have to take my box out I don't have to worry about hooking it up and retuning the amp. I usually just throw my mat in the back over the box if I need to carry anything big though

 

Can you install any bigger of a sub than 8" in the stock location? Is there enough room behind that panel to build your own box?

 

That's not a bad idea. But for the amount of times per year I take my box out it's probably not worth it for me. Although re-tuning twice can be a PITA.

 

I have been working on that. After enlarging the hole in the plastic panal, you have to cut out some of the metal from a piece that goes across the top of the panal. I got a standard depth 10 inch to fit, and used foam tape around it to seal the speaker. For strength, I cut a hole in a piece of plywood, then cut it in half in order to fit it into the cavity. Then, I secured each half with 2 screws through the plastic panal. Finally, I screwed the sub into the plastic/wood combination. Behind, I put Dynamat Extreme on every area of surface I could, and filled in the forward most and back (by the access panal for the lights) with foam.

I know this is not a perfect airtight seal, but the bass was pretty good. I am still experimenting in settings, and comparing it to a matching sub that I have installed in a tube. I have spade connectors in parallel, so together they are 2 ohm and separate 4 ohm each. Since my amp is stable down to 2 ohms, I can use either sub or both together.

My goal is to get solid bass from the built in sub without the need for the tube, and just use it for car shows and special occassions.

Unfortunately, they both appear to be blown right now-horrible distortion. They were purchased with a Blaupunk amp that was supposed to be a good match, so I am going to call Crutchfield tomorrow and see what to do.

 

Hey guys and galls...I just bought an '08 HHR yesterday and I didn't get the factory sub. My question is...could you enlarge the hole for the factory sub to fit a 10", and mount it with the magnet facing out? It's done all the time. (called reversing the phase) I guess my question is how big is the factory sub box (cubic). The magnet and voice coils on the outside would give more room in the box, AND the magnet would be off the floor so you could still place items (bags, books, etc) under it with out hitting your sub. thnx

 

I dont know about reversing the speaker, but I gave up on my idea of the factory location. I actually did enlarge the hole. But, due to the shape of the panal, the speaker did not fit exactly flush to make an airtight seal, so I cut out a piece of plywood and sealed it do the panal then screwed the sub to it. I used fiberglass insulation and about a hundred dollars worth of Dynamat Extreme to soundproof the area, and even tried using wood pieces to reduce the air space. I tried a variety of speakers, including one that is supposed to be 'Freeair'. NOTHING sounded to good. FInally, I gave up. I attached a door I made of plywood with hinges, and now use the old sup hole as storage. As for sound, I built a .75 cu ft box for my Infinity Kappa ten inch, and it sounds great. Thumps the car, seats rumble, doors vibrate, etc. All from one speaker in a well built/sealed box with a 400 Watt Alpine amp.

The enclosure attaches to the drivers side seat with a piece of plywood that has 2 holes in it for the head rest posts to go through. It is shallow enough that the storage compartment still opens. And, when I fold the seat forward, the speaker stays attached and I can use the small storage bin under it.

 

The factory sub box is about .3 cubic feet while most 10" subs require at least .75 in a sealed box.
Some people have removed the factory box and installed a custom box that is slightly larger due to relocating the amp. There are also shallow mount 10" subs now that would fit in the conventional mounting direction.

 

I would guess that even an 8 inch sub, like the factory one, needs more than .3 cubic feet. My Infinity advertises that they are designed to use a small enclosure, at .75. What was the factory thinking with their miniscule box? Also, the advertised wattage of the 'premium' sound system is grossly overrated. And check out the size of the factory amp! Teeny-tiny.