Quote:
|
Originally Posted by Rick F.
AriuSen,
Looks like you had a fun and exciting time!
Your car was obviously a handful, and I think much of that was attributable to rear springs that were too stiff compared to the fronts. You were getting a lot of oversteer, even with throttle-neutral cornering--that is, not induced by strong acceleration.
I don't know what spring rates are best for a Z4M, but I'd guess that the 150 lb differential between front and rear was considerably too much. The back end was having to do more than its fair share of total roll resistance, which was loading up the outside rear tire a lot more than the outside front.
I also noticed, especially in your earlier laps, that you were getting a lot of oversteer when you let the clutch out after downshifting as you entered the turns. Absent a heel-and-toe downshift, to match the engine rev's with the axle speed, the driveline has to pull the engine speed up to match, and that creates quite a braking effect. Enough that it was throwing the weight forward, lightening the rear end, and forcing the tail of your car out. You did well to catch it!
In friction circle terms, the deceleration force on the rear tires caused by the engine, plus the cornering force from entry into the turn, added up to quite a bit more than the tires could handle. Thus the rear tire breakaway.
Anyway, it all looked like a lot of fun. Compared to your fastest lap, however, when you completed your downshifts before turning in, your earlier laps with all the tail-wagging really killed your lap times. Heel-and-toe downshifting requires some contortion, and sensitive application of both the brake and the accelerator with just your right foot, but I think you'd find it enormously helpful in smoothing out your laps and increasing speed. It might not be quite as much fun, however! 
I suspect you already know all of this, but I thought I'd provide my 2 cents, just in case. Good luck with the new springs, and have a great time.
Rick F. |
Yea thanks a lot for your feedback! Tips and criticism are always welcome!
I actually do heel n toe. However, I feel like my heel n toe wasn't enough in normal throttle mode....its way too lazy the gas pedal so I don't think it was revving high enough.... I tried to drive on sport, but it's absolutely impossible to drive..... I wish there was a medium option like the e92. I guess I have to get used the normal mode and maybe go on gas more than usual to match Rev.
But yea... Some of the turns I messed up heel n toe and caused the weight to move to the front.... But overall, this track day was one of days that I had the most fun and also it was an awesome school for me... I used to spin a lot before even with e92. And now I know why..... The e92 chassi is so good and so easy to control that you kinda get lazy at times.... The z4 makes me concentrate so much and be very alarmed to oversteer, that my reactions became faster.... I love z4m! Lol. It really teaches me to be a better driver