Alfa Romeo 939 Spider Roof Flap Motor

Alfa Romeo 939 Spider Roof Flap Motor

The convertible roof flap motors on the 939 Spiders are a common failure point of the convertible system. Their construction uses a plastic chassis, a plastic geartrain inside that is driven plastic worm drive connected via a motor. Whilst I’m not doubting the use of plastic mechanisms in certain parts of a car, the usage of a high-torque gearset that lifts an object with a lot of inertia which relies on plastic isn’t the smartest idea that someone has ever had.

Remanufactured gears are fairly easy to get a hold of ones; some are nylon, others are made from aluminium or brass. The motor isn’t too difficult to find replacements for either, as it’s a simple 12V brushed stepper motor.

So why go through the effort if you can get parts?

It’s nigh-on impossible to find complete units which people aren’t charging through the roof for (looking at you £450 for a pair on eBay). It doesn’t help that no other vehicle manufactured by FCA during the Spider production years had the same kind of convertible roof mechanism that was a soft-top so you can’t really go looking for parts off another manufacturer when they don’t exist.

During one of my searches online into what actually makes the roof flap motor signal back to the hood ECU, I found a copy of the Brera/Spider eLearn workshop manual. Thankfully within this there are the roof operating procedures and what each part of the roof does in relation to the cycle, namely the roof flap motors;

  • Being provided with a 12VDC supply for the motor to move the flaps
  • Being provided with a 5V signalling supply
  • A return from the signalling supply as to what position the flap motors are in.

So off I went to see what was needed for the car and if I could get a hold of them for less than £225 for one – and I found a way to get similar-enough units that with a little modification can be used as OEM roof flap motors.

I only have one at the moment for testing purposes, however am willing to lend this out on a return basis with a surcharge.

October 2021

Following some minor changes in development of this; I’ve opted to replace the potentiometer within the flap motors entirely. There will be a digitally controlled output to the car to inform it of the flap position, so no more having to strip the motors apart to clean the potentiometer out! First revisions should be available within a month if suppliers are able to deliver on time.

  • Plug & Play
  • Return Basis
  • Pre-Release
  • <1 Hour Installation Time

Clientele: Alfa Romeo 939 Series

Compatible Engines: Entire Engine Range

Compatible Cars: Alfa Romeo Spider (939)

Release Date: January 17, 2021