Zcp ride too hard

[-=Hot|Ice=-]

Originally Posted by chriszeh

i wish i had that issue. stiff is good usually.

[1MOREMOD]

that being said i run comfort on the track. seems to give me better control since Pacific Raceways is fairly rough and with it stiffer i unsettle the car more.

[Nine]

Considering the car is new, I think one poster already hit this thing on the head. It's probably the factory bumpstops for when these cars are delivered.

If you think the ride is harsh or too hard, you are not experience M3 settings...expecially not in comfort mode.

[Radiation Joe]

Originally Posted by 4sevens.com

Of course a certain amount of sidewall flex is needed - but the question is HOW MUCH? There is an optimum slip angle for max grip which depends on ALOT of things. The type of tires you're running (slicks, r-comps, streets have VERY different optimum slip angles). Also your alignment, weight, suspension, geometry will all matter. Just because you threw out a race car example doesn't make much of a point.

I have first-hand clinical results - running 18's versus 19's back to the back on the same car, same day with same alignment and same rubber I was able to shave off almost 4 seconds at road atlanta - thats what I have to report from experience from MY car - I don't speak for all.

If you attribute the difference between 18s and 19s for a 4 second gain per lap, you've lost all credibility. Even if 19s were a better performance option (they aren't), they would never gain 4 seconds a lap in an apples to apples comparison. I'd be damned impressed if the stock 19s gained 1 second over the stock 18s. And it would almost certainly be attributable to differences in hot tire pressures.

[quads]

Originally Posted by Radiation Joe

If you attribute the difference between 18s and 19s for a 4 second gain per lap, you've lost all credibility. Even if 19s were a better performance option (they aren't), they would never gain 4 seconds a lap in an apples to apples comparison. I'd be damned impressed if the stock 19s gained 1 second over the stock 18s. And it would almost certainly be attributable to differences in hot tire pressures.

If you read the thread I referenced it had all the details - not just the wheel size. 18's were 275/35/18 fronts, 285/35/18 rears. 19's were 275/30/19 fronts, 295/30/19 rears. I'd been running with the 18's on two other tracks beforehand and I ran them hard, pushing to the limits, learning the optimum temps that they liked. Then I switched to the 19's for the first time and rocked my lap time. I myself was shocked to say the least. The car felt very different. The wheel size of the 18's were 18x10 all around and they weighed 20 pounds each. The 19's were zcp's that were 19x9 fronts and 19x10 rears that weighed about 26 pounds each. Sure the wheels are a bit smaler for the rubber used on the 19's but gave the car so much more grip. I noticed on the PSS's the 19 rubbers sat much more square than the 18's which actually had a lot more stretch to them.

As you said there are lots of variables to consider but bottom line I was able to turn faster times at road atlanta with 19's even with greater rotation mass.

[Prince_of_Persia]

Its sad to see M cars ARE becoming status cars!

[1MOREMOD]

Originally Posted by Prince_of_Persia

Its sad to see M cars ARE becoming status cars!

they are? i thought they were track stars.

[Radiation Joe]

Originally Posted by Prince_of_Persia

Its sad to see M cars ARE becoming status cars!

Originally Posted by chriszeh

they are? i thought they were track stars.

I believe they are Black Tars. Crack-Jars? Mack-Cars?

[ASENNA]

Went to the dealer yesterday and the salesperson said his first thought was that it could be the shipping blocks. Over came the technical guys who quickly dismissed that idea, insisting someone would have noticed when preparing the car for delivery. The technical manager then drove the car with me around town and remarked that it was "normal". Never mind extra panty cushion, this guy thought I needed huggies and a bib. He then checked tire pressures and informed me that the fronts had been inflated past recommended maximum, and this was the likely cause of vibration. He lowered all pressures to minimum. I remained dubious until I did my daily drive, which was much better. It's still not ideal, I may end up tinkering with things, but am much happier. Thanks to Ateam and others for your suggestions. The most irritating thing now is having to obey the speed limit.

[Rshane]

Originally Posted by ASENNA

Went to the dealer yesterday and the salesperson said his first thought was that it could be the shipping blocks. Over came the technical guys who quickly dismissed that idea, insisting someone would have noticed when preparing the car for delivery. The technical manager then drove the car with me around town and remarked that it was "normal". Never mind extra panty cushion, this guy thought I needed huggies and a bib. He then checked tire pressures and informed me that the fronts had been inflated past recommended maximum, and this was the likely cause of vibration. He lowered all pressures to minimum. I remained dubious until I did my daily drive, which was much better. It's still not ideal, I may end up tinkering with things, but am much happier. Thanks to Ateam and others for your suggestions. The most irritating thing now is having to obey the speed limit.

Well, hopefully the ride won't be so bad now and the vibrations will stop. Good luck with the speed limit thing...I don't have that problem withe the autobahn

BTW, let's try to keep this thread on topic. It's about the performance relationship between 18 and 19 inch tires now...or whatever it is everyone is arguing about.

[ASENNA]

Originally Posted by Rshane

Well, hopefully the ride won't be so bad now and the vibrations will stop. Good luck with the speed limit thing...I don't have that problem withe the autobahn

BTW, let's try to keep this thread on topic. It's about the performance relationship between 18 and 19 inch tires now...or whatever it is everyone is arguing about.