Re: Cayman 2.7 PASM6 Sport Chrono 230km perspectives
caySman;242413 said:
Hey Shaun, since you're here ...
All my life I've been taught that, dampers CANNOT be a setup crutch, it's for finetune only.
True to some degree that they can't be a crutch, but no different from anything else. What other setup parameters can be a crutch? As for finetune.. maybe finetune ride characteristics, but definitely not handling. Shocks have a huge effect handling.
I've tried that with the W203 C200 and C32, went to hell and back with loads of dampers and still it wallows in understeer, me and my bro tried it on a Renault Coupe turbo and it's proven to me again and again.
If you are referring to steady state (large enough turn radius and turn angle for the car to take a set) understeer on listed cars, then yes, non active shocks can't help that because final roll stiffness distribution is determined by springs and bars. It is only transients (entries and exits) that non active shocks affect, and not just finely, but in a big way. Sometimes with a poor enough weight distribution, inherent handling problems can't be fixed without an ungodly amount of time and money.
I can see how on listed cars the shock effects may have been small versus other changes, but it is tough to compare changes in different areas, especially when of different quantities that themselves can hardly be referenced. How does 2 degrees of camber change relate to 50 lbs more force from a shock at 7 inches/sec shaft speed, etc.?
Basically, dampers don't do SHIT.
I wonder where this comes from because on certain road courses, an extremely good driver reporting an already quick comfortable car can drop around 2 seconds on an approx. 73 second lap, due alone to external damper setting changes - shims untouched.
Of course we never tried any dynamic dampers like the PASM system before. What I'm surprised is how much difference dynamic dampers do to the handling in the case of the Cayman, and more recently, I found that the new Mercedes C-Class active damper system actually made it drive like ... a super sporty car. It's incredible especially in the case of the C-Class. The handling of the C-Class without the active dampers is SOFT and WALLOWS IN MUD. With the active dampers it's a champ!
I haven't read much about the Mercedes system, but from what little I understand of PASM, the body is still going to settle at the same roll angle in a turn, provided the turn is long enough. It is only the transients that are made sharper. The valves can close off to effectively turn the shock solid and limit the roll angle, but I don't know if the system has that degree of control, and even if it does, it is almost certainly not a full active system that reads surfaces and immediately reacts to them, so if there were to be a mid corner bump, with crazy high wheel rates, the car is going to be severely upset. The only way I can see it totally limiting body roll is by having a valve that blows open beyond a certain force. With known peak loads at maximum lateral and longitudinal acclerations on typical road surfaces as references, and bump forces yielding forces considerably above the reference, the blow open point can be set. The downside is that once you encounter a large enough bump mid corner and the valve blows open to save the car, the remainder of the corner is going to be very different with lots of roll. So I see it best applied for roll control on good roads or ride control (this with hardly any compromise) depending on whether the control valves work to control both bound and rebound independently.
If there were systems that involved changing spring preload and/or heights, it would increase the range of situations the system could work under without compromise, but still be limited. Full active is still too expensive for production cars, though I wonder why some supercar company hasn't applied it yet. It probably takes too much money for what little edge it gives - an edge not required on street cars, and on race cars the sanctioning bodies are all about cost control.
Is this new? Is the rule that `dampers are for finetuning only' now invalid in your racing circles also?
I really don't think dampers for finetuning only, was ever a rule in racing. I haven't heard anyone ever say that, or read it anywhere.
