Gents,
I can reveal that, at least for my car, there was a surprisingly simple solution for the hopeless tramlining: 15mm rear spacers, one at each side.
My car during the test had:
OEM 18/19" combo
OEM Pirelli AR
AW intermediate spacers(but now uprated to race for more camber)
1mm toe in on each side
I have not tried car without AW spacers, had them installed before I picked up the car. Even with these, tramlining was close to intolerable.
After installation, nothing else changed, it was more or less gone, by that I mean it was feeling like a normal sports car, tendency, but far from intolerable. On top of that, I did not notice downsides at trackday, possibly better handling, something that surprised me. So for now, no downsides, and I have been running it for 3-4000km. I also have fellow 4C owner with 17/18" who did it, and it was better, but difference maybe not as huge as mine.
Have thought long and hard why, not that it matters since result is good, but my hypothesis is:
Outside of rear rubber is now approx 10mm outside front. This mean that front used to be 10mm outside. On a uneven road, this will cause front wheels to start climbing before rear, and by that steering will be self amplifying.
But this should be tested by more owners before we can say that it's a general fix.
EDIT:
I tested and ran mostly of the 3-4000km with Pirelli AR (OEM) tires.
Recently I changed to Michelin Pilot Sport 4, hoped for a further improvement. Actually I did not notice a big improvement in tramlining, but they are better and more comfortable.
I can reveal that, at least for my car, there was a surprisingly simple solution for the hopeless tramlining: 15mm rear spacers, one at each side.
My car during the test had:
OEM 18/19" combo
OEM Pirelli AR
AW intermediate spacers(but now uprated to race for more camber)
1mm toe in on each side
I have not tried car without AW spacers, had them installed before I picked up the car. Even with these, tramlining was close to intolerable.
After installation, nothing else changed, it was more or less gone, by that I mean it was feeling like a normal sports car, tendency, but far from intolerable. On top of that, I did not notice downsides at trackday, possibly better handling, something that surprised me. So for now, no downsides, and I have been running it for 3-4000km. I also have fellow 4C owner with 17/18" who did it, and it was better, but difference maybe not as huge as mine.
Have thought long and hard why, not that it matters since result is good, but my hypothesis is:
Outside of rear rubber is now approx 10mm outside front. This mean that front used to be 10mm outside. On a uneven road, this will cause front wheels to start climbing before rear, and by that steering will be self amplifying.
But this should be tested by more owners before we can say that it's a general fix.
EDIT:
I tested and ran mostly of the 3-4000km with Pirelli AR (OEM) tires.
Recently I changed to Michelin Pilot Sport 4, hoped for a further improvement. Actually I did not notice a big improvement in tramlining, but they are better and more comfortable.