A Seat in First Class
One of the coolest things about the BMW Coupe are the seats. From all that chrome greeting you when you enter the car to the stunning design of the headrest supports. They are just beautiful to look at.
But we are building a daily driver. Something that we can comfortably drive on a regular basis. In that respect the factory seats are greatly lacking in these ways:
They sit extremely high. At 6’3” I have to slouch down or recline the seat into the lap of my kids to keep my head from rubbing the ceiling.
They don’t hold you in. While they were “sport seats” for their day they hardly hold you in the way a modern sport seat does today, especially in spirited driving. Make a hard left turn and you’ll find yourself sitting in the passenger seat.
The Seatbelt is subpar for everyday use. Being a pillar-less coupe, the shoulder belt attaches way back near the rear seat. (For those not familiar, most cars have a solid vertical pillar that runs from where your door latches to the roof of the car. This is where you grab for your shoulder belt). In later models this attachment point was relocated to the roof (as the above photo shows). This point is too high and too forward to provide proper restraint. None of this was a problem at all for our ancestors who didn’t use the safety belts to begin with.
In order to drive the car every day I really wanted to solve all three of these issues with new seats. After researching all options (and there are plenty) I landed on seats from a BMW E93 (2004-2013) M3 Convertible. This particular variation solves all of these issues along with a couple of bonuses:
They will adjust so low that I would need to sit on a phone book to see over the dash. I can also raise the seat higher than the original seats.
The M3 version of these seats have gobs of lateral support, adjustable lumbar and thigh support and so on as you would expect.
The convertible version of these seats is designed with the shoulder belt retracting from the top of the backrest itself. I reach no further than my actual shoulder to grab the belt. This also makes it incredibly convenient when my kids hop in the back seat. Finally, the retracting and restraint mechanism is far smoother and far safer than the 45 year old unit.
Bonus 1 - These seats are electric and gazillion-way adjustable with driver seat memory settings. Don’t roll your eyes, remember daily driver…
Bonus 2 - These seats are heated, so those frigid 55 degree Southern California mornings we see in February won’t feel nearly so bad. I don’t know if I will bother implementing this, but it would be fun to add the control to the touch screen.
I searched for a just the right pair of nice condition used seats for several months. Eventually I found an entire 2011 M3 Convertible interior (all 4 seats, door panels, carpet, console) for less money than I had been tracking for just good front seats. Because of this I will experiment with modifying and using the M3 rear seats as well. The look, feel and leather would match and they are much lighter in weight. I have seen a lot of restorations where Recarros or other modern seats are installed into the fronts, and the stock rears look terribly mismatched.
First we had to remove the factory seat bases. Unlike most modern seats, the coupe has the front-to-rear adjustment mechanism as part of a tall base which is welded into the floor of the car. We removed this whole base to expose a flat clean floor.
We then needed to create a new mounting solution for the new seats. This seems simple enough as the new seats just bolt to a flat floor. Keep in mind our new seats have the seatbelts integrated. The mounts don’t just need to hold the seat down to the floor - they need to securely hold the seat and a human down in a collision.
To accomplish this, we fabricated steel plates to run along a long section of the floor under the car. These greatly distribute the mounting points providing more than enough strength. To do this we performed some ship building techniques to flatten areas of the pan.
After all was done we now have a pair of comfortable, convenient seats with integrated modern safety belts. Not nearly as elegant as the factory seats, but they fit perfectly into our design standard for the project: Update Everything you Touch. I couldn’t be happier with the fit, and the feel when sitting in the car.