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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Tracking, Autocrossing, Dragstrip, Driving Techniques > 6MT question



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      12-05-2011, 10:51 AM   #23
GaryS
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There are several posts from people who tried lightweight flywheels and said it solved this problem for them. I remember posts from FormerBoostedIS, for example, but there were others too. You might be able to get an idea of the difference by driving a 1M and 135i. The 1M flywheel is five or six pounds lighter.
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      08-10-2012, 08:54 AM   #24
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Sorry to ressurect such an old thread, but I too was having problems shifting at redline.

I think I have cracked it however, thanks to one of my friends who races in Spec Miata.

1st, don't bother with the 1-2 shift for a start. The gear spacing is bigger than on the other gears, so it takes more time for the revs to drop.

I calculated the target RPMs if you're shifting to the next gear at 7000:
1-2 = 4195
2-3 = 4875
3-4 = 5376
4-5 = 6000

Sooo... practice on shifting 2-3, that seems to be the simplest. Now, the biggest trick I was taught was to NOT LET GO OF THE GAS COMPLETELY! It would be interesting to know if someone can confirm this, but it seems like the revs drop faster if you position your gas pedal where you want them?

So, instead of clutch in - completely off the gas, you back off some (this takes practice). Then, release the clutch with the gas in the same state/press it to the floor. If you get it right, you will feel nothing, i.e. only constant acceleration. Out of the 25 or so tries I had, I only managed to do this once, but I'm a newb. Other times, I could feel the CDV jerk (small), the tranny jerk (small to big) or wheels spin.

So, do you need the CDV delete, clutch stops, etc.? No. If you time it right, you can shift perfectly with our stock setup, at whatever revs. Howver, it will probably be easier to do it consistently without the CDV and with a clutch stop.

That's all.
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