BMW E92 06/2007 lumbar-support retrofit install for Sport seat (non-electric)

BMW sport seats seem to fit some backs better than others . In contrary to most quality car seats, the

BMW:s seats curve backwards heavily at the lower back, causing problems to some drivers. One significant

reason for back pain is the lack of proper lumbar support in the seats. This DIY will help you install lumbar

support as a retrofit install, using original BMW parts. No part numbers are mentioned, but you can look

them up yourself, depending on your car model at for example. www.realoem.com

What is needed for the install?

- New seat bottom harness (retrofit harness includes connector for 4-way switch)

- New seat backrest harness (includes connector for both pressure valves)

- 4-way switch (installs in seat side-cover)

- Lordosis pad (lumbar pad, goes into backrest)

- Lordosis pad pump and pressure valves (one part, goes into backrest)

- New replacement clips (2 pcs) for backrest backplate reinstallation.

INSTALLATION

It is more or less necessary to completely remove the seat from the car. The operation can be done with

the seat in the car, but this will be very difficult and time-consuming.

First:

* Remove ground from battery (not absolutely necessary, but recommendable, at least make sure power is

switched off and the ignition key is removed)

* Unscrew the 4 torx-screws holding the seat to the floor

* Remove wiring from seatbottom yellow connector

* Lift seat out carefully not to scratch the interior

PART 1, seat-bottom

* Start disassembling the seat-bottom

* Remove the 2 seat adjuster handles from the side

* There are clips on the backside of the handles you need to lift up before pulling them out

* Handles removed:

* Remove rear side cover

* Remove remaining large side plastic cover

* First unscrew torx screw (easier with the backrest pushed all way back)

* Second, pry up the clips in order to pull the cover out (careful not to break them)

* Remove the wiring from the 2-way side-bolster switch and remove the switch from the side-cover.

* Now, make a hole in the side-cover for the lumbar support 4-way switch.

It is quite easy, as you can first drill a large hole in the middle of the 4-way switch area and then carefully

grind the hole down to the inner edge of the circle already visible in the cover. Alternatively you can buy a

new side-cover from your dealer, with the hole already made. Try fitting the switch at an early stage of

grinding making sure you don’t grind away too much of the material. Keep grinding until the switch fits

flush with the hole.

* Start fitting the seat bottom harness.

* Remove the old harness by unclipping it from the backrest wiring at the top right of the seat (see picture),

the yellow main socket and black switchbox. There is really no need to mark the connections / wiring,

because they only go back one way.

New seat-bottom wiring:

* Detach old wiring from these:

* Disassembling the yellow main socket is easy, just pry up the small clips and it comes apart:

* Take out the grey parts and old black harness connector, install the new black harness connector and put

the grey parts back in.

* Black switchbox, just plug an play one connector.

* Connector to seat backrest. Don’t plug this yet to the the new harness, as it will also be replaced by the

new backrest wiring.

* Finally run the new 4-way switch wire to the side of the seat.

* Make sure the new harness is run thru the seat bottom the same way as the old one, using the old

attachments so that it is firmly secured.

* Install the 2-way and 4-way switch onto the side-cover and connect the wiring. Slap the side-cover on and

screw it securely to the seat with the torx screw. Install the rear cover and handles in reverse order to

removal.

PART 2, seat backrest

* Remove the 2 plastic clips from the bottom of the backrest (demolish the heads and remove stubs when

back of seat is off). Remove the seat back by pulling it down and twisting it slightly. Remove broken clip

stubs.

* Remove the old wiring by unplugging it from all visible parts. This requires slight disassembly of the

upholstery as well as slight pulling and pushing of the seat padding.

* Remove the old pump and pressure valve as well as airhoses. Attention! When removing the side bolster

dual airhose from the old pressure valve, be careful not to break the connector as it will be connected to

the new pressure valve!

* Then, run the new wiring from the bottom of the backrest to the seat-bottom. This is tricky and requires a

bit of patience to get the wire running exactly as the original. (make sure it fits, or it will break in time due

to excessive wear). Plug it to the seat-bottom harness when you are satisfied and refit the upholstery.

*Install the lordosis-pad. It takes a bit of fiddling around, but finally you should end up with the pad like in

the picture below. Then install the new pump and pressure valves as in the following picture.

* The pump directly replaces the old pump and installs in the same position. The new pressure valves also

install in a similar way as the old valve and the airhoses are run as in the picture. Make sure there are no

sharp bends in the airhoses, especially in the ones from the lordosis valve to the lordosis pad.

* Plug the new wiring harness to the new pump and valves and you are finished!

Don’t reinstall the seat backrest cover just yet, or at least do not install the two black clips yet that secure

the cover to the seat, as I may be necessary to adjust the lordosis pad later on. The clips may be installed

even with the seat is back in the car.

* Install the seat back into the car in reverse order to removal.

Start the car and try adjusting the lumbar support. Pushing forward on the 4-way switch should inflate both

the lower and the upper pad and you should clearly feel a difference. Pushing down inflates only the lower

pad and up only the upper. Pushing backwards deflates both pads. Drive around for a few days to find the

correct setting and only after verifying everything works as it should can you install the 2 plastic clips that

hold the seat back-plate in place. The back-plate will stay in place even without the clips.

There, you are done!

As a final note I can attest, that installing lumbar-support made a significant difference to the feel of the

seat and relieved some of the back pain caused by the (in my view) awkward design of the seat. In addition

to the lumbar support I have added more padding to the seat-bottom (thick canvas under the seat springs)

in order to raise the seat bottom a bit as well as adding more padding to the lower part of the seat backrest

in order to straighten the backrest out and relieving stress in the lower back area.

Just have a look at any other brand performace car seats and you will see the difference in seat backrest

curvature especially in the lower back area. (heavy backward curvature in BMW seat as opposed to virtually

none in other brand cars).

I do not know why BMW has opted for such a solution, but I know it most definitely does not suit my back

and I was almost ready to give up and switch back to Audi. With these modifications I am fairly happy with

my seat and my back-pains are also gone!