At least they're recessed, not further out. That can be fixed with some appropriate spacers. I'll get some wheels for the next set of tyres I fit. I'm getting close to needing a new set anyway. I checked my tyre pressures earlier and Mercedes had helpfully dropped them to 30psi at the last service and I'd not checked them in the intervening 6 weeks! I'm back up to 40psi now.
Coincidentally, my wife has just walked in the door with a nice new round steel tray from Ikea. £7. Some measuring will be going on later.
A puller will be useful, so I'll get one anyway. I bought some cheap wipers on Ebay and the passenger one is rubbish. The only thing it does is stop the arm scratching the screen - I won't miss it!
As far as the diffuser goes, my theory was that it'd minimise the size of the wake by reducing the vertical surface area of the rear. It's all guesswork at the moment. If nothing else, it'll finish off the undertray that stops before the engine. I have a spare carbon boot floor that's going on the Mini at some point and it almost got fitted to the underside of the Roadster this afternoon! I think a few sharp creases on the car may help its looks, especially if I can combine them with smaller wheel arch bulges. One thing I learned today was how simple it is to mould Perspex with a little heat from the oven.
You can't see it very well, but that's the point! Also I moved the number plate up a bit. On a roadster I don't think it makes much difference anyway.
I wasn't able to get the deflectors above the windscreen off, they are very stubborn. I'll try to heat it up with a hairdryer at the weekend and try again.
You really can't see the grille block from the photos - good job! I may follow your lead with the number plate - it's a good solution, I think. I found the best way to get the deflectors off was to push them with my thumb so I could get a flat bladed screwdriver underneath, then gently lever up until they're off. It took less than a minute but then I had to spend 15 minutes scratching off the adhesive with my fingernail.
I've done a frontal area comparison in GIMP of the Roadster with and without wing mirrors. The difference with a double wing mirror deletion is ~2.3%, which should gain me ~1mpg. We'll see the real world results when I have done a few tanks of fuel.
Got it! Pixels is fine since you're able to get an accurate % difference.
I'm going to remove the passengers side first; not sure if I want to remove the driver's side (eventhough I think I use the passengers more when changing lanes).
Also as well as decreasing the frontal area, I'm pretty sure it will improve the cd as well, since the mirrors are aerodynamicaly very dirty and they are in an area of high pressure.
Is there anything else we can remove? :-)
I must work out the frontal area reduction in lowering my car 25mm. Got new springs partially for looks, partially since they all seem to break and also for a slight aerodynamic improvement!
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Last edited by damo; 10-08-2009 at 01:24 PM..
Reason: spelling, grammar
There's too many inaccuracies to take this as gospel but it looks to be ~3%, although I don't know if you're supposed to use the area under the car when calculating the benefits of lowering. I did this time, although I didn't when calculating the benefit of removing the mirrors.
I'm very seriously considering putting my passenger mirror back on. I don't feel comfortable with my reduced vision. I keep noticing cars moving into my blind spot, which is now much larger!
I don’t think you count the area under the car, just the tyres frontal.
Area of 2 205 width tyres lowered by 25mm.
205 x 25 = 5125 mm sq x2 = 10250 mm sq
20.5 x 2.5 = 51.25 cm sq x 2 = 102.5 cm sq
0.205 x 0.025 = 0.005125 m sq x 2 = 0.01025 m sq
Total frontal area is 1.93m sq
% of original frontal area being removed:
0.01025m sq / 1.93m sq = 0.00531 * 100 = 0.531%
I’m not sure if that’s correct, but I suppose there are other advantages to lowering (less air under the car, smaller wheel arch gaps).
If you feel not having the pass mirror is a safety issue then put it back on, it's just not worth the risk of an accident.
That'd make sense, really. Of course, the narrower your tyres, the lesser the effect. I'm on 185 width tyres and considering a move to 135! As for the mirror, I'm going to fit one inside the car and see if that's good enough, if not, I have a reversing camera to fit and my last resort is to reinstate the mirror.
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