I decided to switch out the stock speakers with aftermarket Jehnert Flatlines, These include two 8" subs, two 4" mids and two 1" tweeters in a 3way component set, with two sets of crossovers.
For the first part, I will go over the process for the subwoofer upgrade.
Tools you will need:
Socket wrench with a 10mm socket (may need this)
T10, T20 and T50 torx keys or bits
Trim removal tool
Pick and hook
Optionally:
Spade clips male and female
Solder
I didn't have all these tools on hand, but I made it work.
Now to begin we need to start by removing the bolts to the front seats. There are four total and they are removed using the T50 torx key. Here is where the key is preferable to a bit, unless you are using it with a drill, as turning these by hand on a screwdriver would require a lot of force. Even so, a key would fit more conveniently.
Tip: for the front bolts, push the seat all the way back and down if you have power seats; for the rears, go forward and up for better clearance. I opted not to remove the seats from the car and just tilted them back against the rear seat. You will have the sub grill in sight. It is held in place by four torx screws. Use your t20 key to remove them.
Now the sub is exposed.
Before I go any further, note that whatever you do, do not remove the trim piece on the door sill. It is a royal pain in the ass to put back on and you can get by without it. Trust me... I spent 30 minutes reattaching this thing.
Pull the foam carpet trim from around the speaker and from under the door sill trim piece. You will see yet another set of 4 torx screws holding down the sub enclosure.
Remove these with your t10 torx key.
This is optional, as you could replace the sub from here, but I chose to remove the enclosure. If you do not remove the enclosure, go down to the section about removing the sub from the enclosure after removing the white connector from the stock sub. If I were to do it again, I would leave the sub enclosure in place.
Now grab your socket/ratchet and pull back the carpet toward the far end of the enclosure to reveal two bolts you will need to remove.
Before you pull the enclosure, there is a loom of wire running the length of the side of the enclosure and the connector that need to be removed. For the wire loom, use a trim removal tool to pop up the two tie down bits holding it to the enclosure. These are tough to remove as they want to come straight up or not at all.
The connector is toward you and you can use a flathead to push in the pin and pull it out.
Now the more carpet you push away, the easier it will be to remove the enclosure. I found starting from the side with the two large bolts worked best for me.
Once you have enclosure out, you can remove the sub. Use your pick tool and insert it into the outer edges of the sub, curl it underneath and pull up to lift the sub out. You can see the seams along the connector terminal piece, where there is a gray seal strip underneath. Do not pry up the metal part held down by clips, but the edge just outside of that. (You can see the stock sub is 2ohms)
Some pics of the new sub...
The Jehnerts came with a spacer made of acrylic or Lexan which goes into the enclosure first, with the recessed wedge facing down to allow wires to pass underneath which will connect to the speaker leads.
For this install I chose to use the stock connector mated to the new sub spade terminals. The subs use a large and small male spade connector for negative and positive, but the bmw connector has two mini spade female connectors requiring half sized spade male connectors.
I had to mess around with the wiring to get it right. If you look at the stock sub, you can see it has an inverted design, so the polarity is backwards from what I expected. I would recommend wiring up one sub and listening before doing the second. The stock sub will tell you how to wire the replacement. It was pretty obvious I had positive and negative reversed when bass response was weak. I flipped the connections and everything sounded louder.
Anyway, lastly if you removed the enclosure, you will want to pop the white, rubber cushion back onto the enclosure. Pull this off the floor of the car, and clip it to the bottom of the enclosure.
Screw the sub and spacer into place, and wedge the enclosure with the new sub on the floor space where it was pulled from. Clip the connections in and do a listening test before wrapping things up.:party0030:
