Power windows

For a little bit of a modern touch to the Mini, I wanted some power windows installed. When I started this project years go, I purchased a SPAL power window kit and it was now time to fit the motors. With one end of the motor mechanism attached to the window winder, the other end would fit nicely in the door skin opening and not interfere with the window glass or mechanism as the motor would sit directly below the 1/4 window in the door.

The kit comes with a set of rings and adapters for various cars so it was a simple case of choosing the matching adapters for the square profile Mini windows winder shaft.

This left a gap between the door and the adapter, so the adapter could slide back & forth over the window handle shaft so I machined a spacer/bush from some HDPE plastic rod for the adapter to slip on top of.


The kit (like most universal power windows kits) came with triangular mounting brackets to hold the motor/rings in place. These brackets are normally just mounted to the door with self tapping screws but I wanted something neater and rigid.

I made a pair of brackets for each end of the motor assembly with captive nuts and some spacers welded to the brackets.

I used the rusty white door in the photos above for test fitting but once I had the bracket designs confirmed (with no cutting of the doors required), I installed some rivnuts to the good doors for the brackets. The motors are actually hidden within the door cavity.

While I was working on the doors I also fixed a the previous dodgy patch (right hand door in the photo above) where someone had welded a piece of steel straight over a hole that had been hacked out (I assume to get access to the side mirror mounts)

Once everything was screwed together I connected each of the motors to a car battery and tested them. The window mechanisms move relatively quickly but once the glass, channel and seals are installed I hope they will slow down slightly with some weight and friction.

One important thing to know about the wiring for power windows is that you shouldn't use fuses for the power supply. Auto-resetting circuit breakers are often used in place of fuses in window circuits as they serve two purposes - they not only protect the circuit from a short circuit, but also stops an overload when the window seats into the window frame (or the base of its travel) and the up/down button is still being pressed. For each window motor, I will be using a 20A auto-reset circuit breaker.

Also, the reverse polarity switches that were supplied with the kit are rated so that no additional relays are required for each door/window. I previously made room for mounting four relays next to the main fuse box but this relay mount will now be deleted.