BMW 325CI Stereo Project - PeachParts Mercedes-Benz Forum

G-Benz · #1 07-26-2013, 05:32 PM

Things have changed a bit since I last posted pics on the stereo system I installed in my daughter's 98 Mustang.

She is now in college and the stereo is still going strong. This summer I will be reupholstering her interior and adding tweeter pods (pics to come later when I start on that project).

Anyway, I bought a 2001 BMW 325ci last summer. Car was in decent shape but for some reason, the previous owner REALLY abused the modest factory stereo and literally blew every midrange/woofer in the system.

That is a lot of gear to replace, so I had to accumulate stuff over several months.

The time has now come to install everything.

G-Benz · #2 07-26-2013, 05:36 PM

This is what I'm starting with in the trunk area:

Plenty of room and fold-down seats, soon to be filled with a large cabinet containing two 12" Polk Audio subwoofers.

The cabinet fits perfectly, but the raised areas on each side of the trunk don't allow the cabinet to sit flush in the trunk...time to perform surgery on a perfectly good (and expensive) structure...

G-Benz · #3 07-26-2013, 05:38 PM

This thing weighs 80 pounds, so I removed everything during the cutting and fitting phase. A significant chunk of MDF is now absent from the bottom of the cabinet:

G-Benz · #4 07-26-2013, 05:40 PM

I added more MDF to the cut-out area where the void exists to keep the cabinet sealed:

Here are the woofers that were installed, now sitting on my desk:

This is what the cabinet looks like with all of the trim pieces installed (minus woofers)

G-Benz · #5 07-26-2013, 05:43 PM

The system power will be provided by this 4.1 channel amp. Bought it several years ago for my daughter's system, but ended up using the amp from an older setup.

The BMW system has built-in crossovers in the factory amp and sends the signals to the drivers individually...therefore I am using passive crossovers for my amp setup:

And the capacitor left over from the W124 system I did years ago:

G-Benz · #6 07-29-2013, 10:29 AM

Test-fitted the cabinet with the woofers in place...

G-Benz · #7 07-29-2013, 10:33 AM

Bought some MDF board, trimmed it to fit, and laid down some adhesive shelf paper before securely mounting the equipment...

...then test fitted it in the car. This is the rear of the car with the seats folded down. I can easily tweak the amp from here without crawling around in the trunk.

The stray wires were left over from the previous owner's attempt to add a sub to the factory system. I will be cleaning those wires up when I get ready to mount things permanently.

G-Benz · #8 08-08-2013, 03:48 PM

Decided that it wasn't worth the effort to manipulate the factory head unit to accommodate the aftermarket gear...especially with all of the inexpensive head units available with far newer technology.

I picked up a Kenwood and a Metra faceplate. The OEM head unit is the one one the bottom:

Also got a Metra interface plug to make the wiring tasks a whole lot easier:

G-Benz · #9 08-08-2013, 03:53 PM

I haven't updated this thread in awhile due to my daughter's car projects. I'm in the process of replacing seats:

Also got my carbon fiber wrap. Decided to replace the heat-stressed pillar cloth on the bimmer that has peeled over time from the hot Texas summers:

G-Benz · #10 08-08-2013, 04:20 PM

This was undoubtedly the most difficult head unit install I have ever done! An installer friend of mine warned me about the tight confines of the area behind the cavity with these early Bimmers! It took me two hours to manage to get enough wiring out of the way to shoe-horn the deck into the dash!

Nevertheless, it doesn't impact the overall look of the dash too much:

G-Benz · #11 08-08-2013, 04:23 PM

Amp board wiring is almost complete. Need to hook up to the factory speaker wiring:

Once everything is calibrated, I will go over the cosmetics and tighten everything up. The subwoofer is operational and so far, the known issues are rattle isolation throughout the trunk and rear deck, and possibly rewiring the subs to an 8-ohm load. The amp kicks into protection mode if I turn up the gain past mid-level.

G-Benz · #12 08-13-2013, 11:32 AM

Once again, I"m derailed.

Daughter is heading for college this week, so I had to scramble to complete her car seats:

Driver's seat before:

Driver's seat after:

And now the seats are in:

G-Benz · #13 08-29-2013, 10:35 AM

Had to make an emergency trip to the university last weekend to swap out the battery and alternator on the daughter's car. Again, no time to work on mine (sigh).

However, I had enough frustration with the software glitches and electronic problems with the current head unit, so I swapped it out.

Dropped down from the Kenwood BT655U to the BT555U...didn't need all of that functionality anyway...

G-Benz · #14 08-29-2013, 10:41 AM

The previous install was a total pain due to the limited room behind the chassis...wonder if all Bimmers suffer from this?

Anyway, I learned a bit from all of that, and sorted out wiring a bit differently this time.

The six RCA outs require a lot of real estate, and wire routing is critical. Tried to ensure that the wiring isn't too stressed, as I believe I had a lost channel the last time due to kinked wiring.

I'm not using any of the speaker-level wires, so I went ahead and clipped them off...so that's eight wires that don't need to clutter the wire harness.

I wrapped the harness in electrical tape, and the bumps are where the wire ties reside. Metra connector at the end of the wire harness is a direct fit to the factory BMW connector.

G-Benz · #15 08-29-2013, 10:47 AM

The RCA cables route to the left side of the dash, while the power harness goes to the right. Power and signal wires need to intersect at 90 degrees whenever they cross.

I chose Monster Cable for interconnects...used them for every install I have ever done.

I don't really know if they are audibly noticeable over cheaper brands, but the cable quality ensures fuss-free installs...I swear by them!