Quote:
Originally Posted by PetieD 7
If that's the case….money well wasted then. BTW, are you SME in terms of automotive suspension systems? Or, this is based on your experience and/or opinion using sport spring kit?
|
For the look it's money well wasted, that's after all the main objective of most people looking at lowering springs... Hell that's the objective of most people who buy coilovers, it's to adjust ride height
If that's the goal then no harm no foul, if that's worth 1000 dollars to you, good for you, if that's worth 2000 good for you.
In regards to comfort and ride control and handling though, these are far more objective measures.
While a claim of "I love that slammed look" is unassailable in that it is something that is pure opinion, a claim of "this suspension rises better" can be measured.
No matter how much a person may think or claim to prefer the feel of one setup up another, qualities like whether a setup is under or over damped are objective realities. Whether a spring rate is too high to maintain adhesion over rough surfaces is an objective quantity.
Increasing spring rates must necessarily hurt your ride (comfort and compliance) because there is simply less room/time in which the suspension can dissipate energy from road irregularities (bumps)
This is assuming you had matched damping rates with the higher spring rates, if you have an under damped system it must be necessarily worse. It may not be MUCH worse if the spring rate difference isn't great but if you think the stock setup is perfectly damped, simply raising spring rates must necessarily make the new setup under damped.
As for spring rates and roll stiffness, the common sense argument is usually that "harder" suspension and greater resistance to roll (not the same thing) is better for handling and grip. This is usually backed up by looking at race cars and motor sports and seeing how they all have much stiffer suspension than road cars and correlating that extra performance with the harder suspension / roll stiffness.
It's surprising to most that this isn't actually the case, a suspension's job is to keep the tires on the road, if your tires are on the air, you don't have control, harder springs makes this more difficult. You generally want to run as soft a setup as you can get away with after taking other factors into consideration.
If you have a high aero car, you need harder springs because otherwise you'll bottom out under high aero load (limit is suspension travel)
If you have grippier tires, you need more roll stiffness otherwise in high G load corners you'll start riding on your bump stops. This is bad because a quick dynamic change in roll stiffness that results is "upsetting" the balance (the fronts and the rears don't tend to hit the stops at the same time). The geometry of the suspension can lead to some other undesirable effects at the extremes as well (loss of camber control or some dynamic change of toe that's undesirable for example).
In bumpy street circuits you'll very often step down in spring rates relative to a smooth circuit that has similar aero and cornering speeds, compensating for the roll stiffness by running harder anti roll bars (which don't have dedicated damping usually)
People tend to think body roll is in and off itself bad, it isn't. Load transfer that is due to body roll is surprisingly little compared to load transfer that happens simply because you're turning (even in a car with a completely rigid suspension on a perfectly smooth surface you'll have almost as much load transfer between the left and rear axles in a corner as a car with a real suspension). The load transfer solely due to roll is from the center of mass moving to a different location, this tends to be very very very small. The main downside to body roll is that having more of it necessarily means the car takes longer to get settled in transitional phases, something that makes it harder to push since the grip in transient situations keeps changing.
Now with that said, it's there any benefits to roll? Mainly in communicating to the driver how close to the limit or how hard they're actually cornering. If you're a super super keen experienced driver you don't need this as much but for a novice, body roll tells you in a very visual/tactile/obvious way how hard you are cornering.
The simple takeaways are this:
If your roads are shit, don't run as stiff suspension as if your roads are mirror flat.
If you don't have grippy tires, don't run a stiffer suspension, you're giving up suspension travel for no reason.
If you want extra roll stiffness, a stiffer set of anti roll bars often gets you a lot of bang for the buck and doesn't negatively affect bump performance much. You can't derive all or even a majority of your roll stiffness from ARBs but most factory setups come really really weak and a set of aftermarket bars give you both more stiffness and often more adjustability to tune cornering balance.
As for my credentials, not that it matters what they are if there is nothing wrong with what I've stated above but I did FSAE for a decent while when I was in uni and have spent ungodly amounts of money on car mods over 15 years and realized that a lot of them were crap. The most crap items were usually from companies telling you how it's all amazing with no drawbacks whereas the best items were the ones that were upfront and told you "hey, you'll get an improvement here but what you're going to lose out on is there, make sure you're OK with that". There is ALWAYS a drawback somewhere. Gone are the days of really shitty engineering where changing an intake would release 20hp.
Honesty in running a business and in treating your customers usually correlates quite well with good engineering (at least not bad engineering).