March 21, 2010 blog

Door games…

From researching on forums and asking questions of other drivers in last years racing one of the simplest ways of loosing some weight from the car was to have ‘Aluminium’ doors, these doors were fitted to some M3’s at around the 1995/1996 model years, and from whats been said, they are the lightest you can get that are original BMW equipment, as we are not allowed to run composite doors, like carbon fibre or fibreglass.

I started to search for a pair of these doors last year, about November time, but most places had not heard of them, or if they had they wanted some serious money for a pair, it seams its not just racers that like them, people with later road cars like the doors also.

It took me till February this year to locate the doors, I got a drivers one in December of last year, but the passenger was harder to locate (without paying silly money)

I decided to do some experiments with the weight to see how much (if any) I would save, below are the figures

  • Standard door (glass, impact bar but no electric motor for the window, as I had sold it) – 28kg
  • Standard door (as above but with the interior stripped, and cut back) – 25kg
  • Standard door (as above but no side impact bar) – 22kg
  • Aluminium door (glass, impact bar, no electric motor) 16kg

So having them just fitted as they are I would aim to be saving about 15kg, as my drivers door still has the side impact bar in, this should take my weight down to 1140kg ish in race prep.

The door glass by its self weighed 4kg, and from what its been said about plastic windows, this could be cut down to 2.5kg (they state 40% weight saving), at present I think I may keep the glass in the doors, as it does not move around when racing, and i can if needed fit the electric motors and have windows that move, unlike now when they are fixed in position.

All I have to do now is get the doors sprayed white, as currently one is black (the original primer from the factory) and the other is a nice shade of blue.

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