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  • 1981 B7 turbo

Two down, two to go (pandemic progress)

The shelter-in-place, as described briefly in the last post, gave me time to tear into several projects on the B7. Since I was getting the seats reupholstered, the interior was more accessible and in pieces. Taking the center console apart to fix the sticky fan switch got me close to the stereo and taking the rear seat out expose the amps and cross-over powering the sound: it was 1990s state of the art audio equipment but now more like a mess of boat anchors mess. So, reupholstering begat two more projects – the fan switch repair and the stereo upgrade.

The fan switch refused to turn. With two hands and a lot of brute force, I could get it to barely turn. I went to the e12 on-line forum and learned this wasn’t too uncommon; indeed, there was even an FAQ about how to fix it (https://www.firstfives.org/faq/heater_controls/heater_controls_repair.html). After reading the FAQ, I bought a second heater control unit off eBay and dove into rebuilding that one to learn so that I would be expert by the time I tried to fix mine. I won’t recite the rebuilding details; it’s adequately described in the FAQ. But the switch goes south because it has a weird design where the contacts move up and down depending on the position of the switch. Over time the lubricant fails and the friction makes it impossible to turn. The solution is to take the whole assembly apart, clean off the failed lubricant and free the stuck contacts with a liberal amount of lubricant, which hopefully will last another 30 or so years. Electronics have evolved and this design shows why.


It’s a messy and tedious job.






The old lubricant is (ironically) sticky and must be cleaned off all surfaces.




As I was putting it all back together, I noticed the microswitch for the A/C was broken – on both the spare heater control unit I bought and the original! Of course, that might be why it wasn’t working, but I wasn’t in there to fix the air condition so we’ll just have to wait and see on that. The BMW parts catalogue lists the microswitch but when I tried to order it, it was NLA. Turns out, though, that it is a standard size and a modern microswitch fits fine.



Drill out the rivets securing the old miocroswitch.

Bolt in the new microswitch.




The reinstalled the heater control unit and the fan works great (haven’t tried the A/C yet as the car is on jack stands and didn’t feel like starting the engine while it’s up in the air). One project done.

Up next was the stereo, which was a mess. A 1990s Alpine that looked out of place and worse was the two big amps and cross-over under the rear seats. It looked like a rat’s nest of wires.



Worst was the speakers; the ones in the doors were completely blown.

The old speakers in the door.


I didn’t even want speakers in the doors, but the decision cut holes in them was made long ago. I looked for new door panels, couldn’t find any. So, the blown speakers needed to be replace. The mid-range speaker was standard 5.25 inch, an easy to find standard size. The tweeter, though, was in a rather large housing, fit into hole in the door panel almost as big as the mid-range speaker. So I looked for a speaker set with an appropriately sized mid-range and a tweeter that would cover the upper holes in the door. That proved impossible. I decided to look for a black plastic disc that would cover the holes yet the tweeter would fit in the center. I looked for discs on Amazon, google, and eBay. The best I could find were on eBay: big enough to cover the tweeter holes and hole cut to fit the tweeter. I used my Dremel tool to cut out a hole in the center big enough for the tweeter. It didn’t look beautiful and wasn’t quite turning lemons into lemonade, but it certainly was less bitter than what was in there before. Even dirty from the install and greasy hands, it was a visual improvement and sounded even better.




The mid-range speakers were simply plug and play. I used the existing wiring but it tracing them back to the amps was hard (more on that later).







The new speakers in the door.


Picking the speakers for the doors was easy; I simply got the best reasonably priced speakers that would fit. The head-unit and amp were harder, with the former taking hours of time on-line and talking with folks. I wanted something that looked somewhat period appropriate and could play music from my iphone. First I thought about the vintage Blaupunkt Bavaria I had stashed in my garage, but it was a mono unit with no inputs for my phone and no pre-amp out; there are a few shops out there that replace the innards of vintage radios with modern components but I wanted to consider all options. So, I posted a couple of places asking for suggestions; the replies basically fell into one of three categories: vintage Blaupunkt; vintage Blaupunkt or Becker with modern innards; and modern head-unit designed to look vintage. For first suggestion, a vintage Blau, didn’t satisfy my criteria, so that idea was discarded.

Some specific shops were suggested for the second approach and I called, emailed, and scoured web sites to wrap my mind around that option. This route, it seemed, was probably ideal for the hardcore restoration. It offered the best period look with decent sound but boy was it expensive! Several folks made specific suggestions in the third category, a modern unit made to look vintage. The most common suggestion was a new Blaupunkt SRQ 46 DAB, a remake by Blaupunkt of the mid-1980s classic, with modern features. It didn’t look like what would have come in the e12 circa 1981, but have the appearance of someone that would have put in a few years later. It also had everything else I wanted: the phone input and four pre-amp outputs. All this and less than half the price of a vintage Blaupunkt modified to my spec. I found one on eBay from England and it “only” took a month and half to get to Northern California!


Selecting the amp was easy. It was going under the rear seat, so looks were unimportant; only performance and price mattered. A nice JL Audio 4 channel amp would do.

Pulling apart the existing stereo was easy work but figuring out how the speakers were wired up required a bit of effort. I didn’t want to put new wires in, especially for the doors – that would require taking off the door panels, which seemed a bridge too far considering there were (presumably) perfectly good wire going to the previous speakers. So, I dug around; in doing that I found a pair of dormant speakers that were hidden in the front kick panel. Those wired directly to the head unit, which made no sense since all the other speakers were powered by the two big-ass; amps in under the rear seat. Plus, those speakers were blown and couldn’t make a decent sound. This added further mystery to the crazy stereo installs. The (formerly) hidden speakers were removed and the wires terminated. The wires for the speakers in the passenger side door were easy to trace back to the old amps, but not so for the driver’s side. The wiring between the amps, cross-overs, and the head unit was simple enough and all just removed and replaced with new wiring.


All wired up.


The cross-overs about to get wired-up.

The new amp and cross-overs installed, I wired up the speakers as best I could. Without installing it (in case there were problems wiring everything up), I connected the head unit and powered it up. Everything got juice and some sound came out, but there were troubles with the speaker wiring. The driver’s door didn’t work at all and the tweeter on the passenger door did, but not the mid-range. More tracing and I was able to find another set of wires coming from the driver’s door and once attached, the speakers in that door worked fine. As for the passenger door speakers, the wires for tweeter and mid-range were reversed; once they were transposed, that all worked great. The rear speakers (which were not replaced) worked great.


Head unit semi-installed for testing the system.


With the system working, the process of buttoning it up begins.



With the console put back together, the interior was complete other than the seats that were getting reupholstered.

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