Quote:
Originally Posted by slcook54
Thanks again for the starting the thread Alex. I'm also hoping we can use this thread to talk through modifications and troubleshoot, given the CS differences compared to base and competition F80s.
This thread is confirming that something is off with my car. I picked up my CS a couple weeks ago and started my build journal here. I track my E92 1x per month and was excited to see what the CS offered out of the gate. I drove the car back from Seattle home to San Francisco and was honestly shocked how floaty the front-end felt. Texting with Alex, I believe this has something to do with the Dinan HAS kit that the previous owner installed. This is a generic F80 kit, not specific to the CS. Link here.
The description of the kit specifies that it increases the front stiffness by 50% and the rear by only 10%. Aside from the front-end being jarring over bumps, even in Comfort, I'm thinking this adjustment also messed with the F/R balance of the suspension. Taking corners even at 6/10th's, the traction light is going crazy, there is no front-end presence or connection to the road. The front-end is lifting significantly under throttle and inducing understeer.
The car came with mismatched tires, 255 PSS on the front and 285 Hankook Ventus Evo2 on the rear. The tread life looks fine. After reading some of the initial posts in this thread and better understanding that several of the systems were developed around the Cup2, I'll likely move to that tire to best replicate the factory intentions.
We also decided to remove the front splitter for the drive back, which could be contributing to a bit of missing down force. My plan will be to have my shop reinstall the lip, balance the wheels, align the car and reinstall the stock springs and see what is feels like after that. |
The CS suspension tuning was all about SOFTENING the front relative to the rear (through the sway bars) to reduce understeer. So the spring rates you mention would definitely increase the level of push.
I had the MP-HAS on my M4cs and just tinkering with the front and rear ride height also helped tune the balance of the car. I had originally set the front to a lower ride height, which reduce corner exit traction. Raising the front a tad eliminated the problem I had.
Suspension tuning is a fine art that is very difficult to master. It is so much easier to make things worse instead of improving them.