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      10-25-2011, 03:10 AM   #223
swamp2
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Drives: E92 M3
Join Date: Sep 2006
Location: San Diego, CA USA

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Quote:
Originally Posted by lukester View Post
Great thread. But the issue with removing weight from the M3 is that it changes the car.
If you go through it like I did - basically the stuff which makes sense - only removes weight from the rear of the car which changes the handling.

I did:
Full Akrapovic Exhaust (~23kg/50lbs)
rear seat delete & remove all unnecessary parts and insulation from the trunk (~28kg/61lbs)
55Ah Battery (~11kg/ 24lbs)
Recaro Pole Position seats driver and passenger (~29kg/ 64lbs)
OZ Ultraleggera Wheels with Michelin Pilot Cup tires (~7kg/ 15lbs)

All mods make sense for me as I love track days and would have done it even if it doesn't make the car lighter (e.g. the seats, wheels, tires, ...)

My M3 should be +/- 216 lbs (98kg) lighter than stock at the moment.

But....the car switched from a slightly oversteering M3 to an more understeering M3. There's no power steering available any more as it just
pushes over the front wheels.
(you can still drift it but you have to force it)

It's logical. A lot of the stuff has been removed from the rear or the center of the car.
Nothing from the front or under the hood. So the weight balance moved away from were it should be.

Will weight my car within the next weeks and I'm really interested to see the final results.

What can be done against this new handling?
I'm gonna try some 265/35-19 Michelin Pilot Cup on the front, too. At the moment the setup is 235 and 265 which is not perfect if you like an oversteering M3.
The seats and tires will shed weight fairly evenly across the wheels. That leaves about 120 lb removed from the cars rear. That is about 3%. I would be quite surprised if that turned a car from over to understeer. As well, from the factory, the car will understeer, not oversteer, that is more or less a legal obligation for safety and to prevent lawsuits. Also the car should not change its basic handling tendencies with out without rear luggage or a passenger whose weight these changes are comparable to

Quote:
Originally Posted by lukester View Post
But I'm missing ideas what to do with the front.

A carbon hood will only help with ~4kg/ 8.8lbs. Not really worth it.

What I saw ... but I'm not sure if it's a good idea. Replace the big underfloor plate (it's directly under the engine) with a more lightweight part as this thing is really massive (and we do have good streets in germany so there's no need for such a engine protection).
Adjust your tires pressures, despite being very skeptical about the changes you have observed tire pressures can make a decent sized effect. Despite how good your roads are I would NOT remove that plate. Why risk an 18000 euro engine for a few pounds? It isn't a race car...