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      09-18-2011, 08:34 PM   #221
RPM8300
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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.

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).
Luke, I have an E92 M3 and I run 265x35 Dunlop Star Specs all around on 18x9s - it works very well and helps with understeer. You have to be careful what you ask for because when you are at the limit on a track and the rear gives, it will not be as forgiving as a staggered setup. This is fine for me and I like it very much - your throttle control and counter steering just has to be a little bit more quick to respond to what the car is doing. I do much more autorcross than track events so weight loss is big for me, and steering with the throttle is big as well.

One idea that I had which the experts that read this can comment on, is stripping out everything you want and then possibly adding a little weight to the rear to balance the f/r weight distribution. My rough estimates are the same as what has been stated in plenty of times - after I take out the back seat, strip the trunk, and switch out the front seats I would not be suprised if track ready weight of the car (1/2 tank) was right around or even below 3500. I have already thrown the lightest 18x9 rims I could find at a descent price and I run Dunlops which are about the same weight as PS2s. The issue I see is that at that point the f/r distro will be more like 53/47. I had an E82 135i for a couple years before this and as everyone knows, it understeers like crazy. That was mostly due to suspension geometry but the f/r weight distro didnt help, which was also about 53/47.

That brings me to the idea - I heard the 135 has extra weight in the rear to help the f/r distro - I know it will have a marginal effect but I wonder how the M3 would feel if you stripped it down but then added just enough to the very rear of the car to keep about 50.7/49.3 f/r. Experts give us your opinions.
Tom
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