Combating Wheelspin

[ZStig]

Originally Posted by The HACK

Throw 2 50 lbs sandbags in the trunk of the car. If they fit.

Traction is merely a function of weight over the rear axle vs the friction coefficient of the tires. More weight = more traction.

That's why it's pointless to equip a Lotus Exige S with more than 300 HP when the car only weighs 2,400 lbs. Even with R-Comps standard (Exige comes with Yokohama Advan AD-08 I think) the Exige S will easily break rear traction because, well, the car's freakin' light. With a measly 240HP.

Sometimes cars with too stiff springs all around will exhibit this behavior too. Problem may be alleviated by stiffening up rebound in the rear (odd, I know...But sometimes stiff rebound promotes weight transfer).

A viper isn't much heavier than a supercharged Z4M, but puts the power down really well on 335mm wide michelin PS2s. You think its because of the rear suspension setup + more weight over the rears? Going by this logical idea, putting on light weight exhaust in the back of the car will hurt more than benefit acceleration. 1999 Viper has 1770lbs over the rear tires, and Z4M has ...

I've heard that tire width doesn't affect straightline grip because theoretically the contact patch would be the same size, but experience tells a different story.

I know compound and tire pressure is a huge factor with our limited tire size options in the stock fenders, as is the alignment.

As George has experienced in real life, a wide 285mm tire fits the bill for over 400rwhp on this platform. I think a 335mm tire on an 18" wheel would be enough traction to run full throttle in second gear on 500rwhp. Thats my eventual goal with my car

[pokeybritches]

I confirmed my LSD is still operating correctly. Guess I will try changing the RTABs.

[beta]

What about racelogic traction control? That is assuming CA Automotive can get a tune for z4.

[exdos]

Originally Posted by pokeybritches

I confirmed my LSD is still operating correctly. Guess I will try changing the RTABs.

Whilst you are at it, I would suggest that you also install a RTAB Limiter kit:

http://www.turnermotorsport.com/p-96...-shim-kit.aspx These restrict lateral movement of the trailing arms without having to use polyurethane bushes. I've fitted them and they make the handling far more positive.

[ZStig]

Originally Posted by beta

What about racelogic traction control? That is assuming CA Automotive can get a tune for z4.

would definitely have to tuned for the finicky throttle and ecu relation

[nekky]

Originally Posted by gmd2003

Hankook Ventus TD 265/35/18 front , 285/30 rear ( stock fenders , lowered on KW V3's , -3 front camber -2 rear . Traction is not an issue lol . Best tire available period right now . This set lasted 8 Advanced group track days and 3,000 street miles while delivering near Hoosier levels of grip on track . They are even reasonable down into 40 degree temps , which has not been my experience with other DOT R comps.

What's your ride height? Mine was originally set up higher in the rear than the front. I have yet to measure, but you have a very similar setup to me other than that I have clubsports instead of V3s, and Stoptech instead of PFC