What makes a coilover GOOD? And the magic of setting up a car with good coilovers....
Jul 13, 2009, 07:37 PM
#17
From what I've been reading..... the Ohlin DFV's are about as compliant as you are going to get while still providing outstanding track performance.
I've also read that stock suspension with springs and bars is fine for a decent size street tire but once you run R-compounds it gets overwhelmed.
I'm not sure everyone needs bushings and roll center kits. Many evo's do just fine with just 10k springs and decent alignment.
I've also read that stock suspension with springs and bars is fine for a decent size street tire but once you run R-compounds it gets overwhelmed.
I'm not sure everyone needs bushings and roll center kits. Many evo's do just fine with just 10k springs and decent alignment.
Jul 13, 2009, 07:51 PM
#18
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This thread is a little misleading in that it makes readers/posters throw up brand name parts/coilovers. The reality is that suspension is a multidimensional component. It depends on the driving style, track, surface, etc. Setting up a a car is comparable to tuning a car. Small miscalculations can be the diffence of slight over/understeer or flying off the road.
Jul 15, 2009, 02:22 PM
#19
...back after the break. We like our siestas here in New Mexico. :-p
They have a damper that works. That's it. There's no magic fairy dust that turns your car into the spirit of a rocket ship. If you boil it all down, you want a damper that provides a linear force curve over the speed ranges found in body motion, then a highly digressive curve above that.
What forces do you want? Something between 30%-75% critical depending on what your goal is for a non-aero car. I'll refer everyone Dixon's Shock Absorber Handbook for the reasons why. It's the pretty standard text on damper design from the SAE.
The first thing you have to figure out is what your goal is. "I want maximum handling, the softest ride, and a cheap price." That's not a goal, it's a pipe dream. That's why I say not to bother if you aren't ready to pony up some real cash. If you're not in the position to spend what's really necessary, then you probably aren't in a position to really be doing a setup overhaul in the first place. I dunno. It's just my opinion.
Back on topic, pick your goal. For us, that's almost always a performance increase for autocross or sprint races / track duty. Rally guys will have different requirements.
To me, the setup procedure seems straight forward.
0) Choose goal. Decide if you really want to be doing this.
1) Pick you're tire. It's the biggest variable in the system and has the most effect on _everything_.
2) Pick the springrates that are reasonable for tire you want on the surface you are targeting. Once choice doesn't work everywhere. Are you willing to switch springs between sessions if it starts to rain? As grip levels go up, so does the discrepancy between dry grip and wet grip.
3) Pick shocks / valvings that control those ^^^ springs. Adjustable shocks are handy if you switch springs, but don't adjust a car from a 'street' car to 'race' car with the turn of a knob.
4) Align the car to give the balance that you want, along with the stability that you need.
5) Drive and adjust.
more?
MEANWHILE....the "higher end" coilovers are seen as magical dampers with pixie dust in the shock oil that literally make you breakfast as you drive. Really though, they are amazing works of engineering art and are every bit as good as they're made out to be. But how do they do it? What do they do that low end, or even mid-range coilovers can't do well?
What forces do you want? Something between 30%-75% critical depending on what your goal is for a non-aero car. I'll refer everyone Dixon's Shock Absorber Handbook for the reasons why. It's the pretty standard text on damper design from the SAE.
And what about the set-up process? A suspension guru puts the car on an alignment rack + scales, waves a magic wand and there you go, camber dialed exactly to match your tire choice and roll resistance, a perfect corner weight, etc. What's actually happening and what's the difference between a decent set-up process and a damn good one?
Back on topic, pick your goal. For us, that's almost always a performance increase for autocross or sprint races / track duty. Rally guys will have different requirements.
To me, the setup procedure seems straight forward.
0) Choose goal. Decide if you really want to be doing this.
1) Pick you're tire. It's the biggest variable in the system and has the most effect on _everything_.
2) Pick the springrates that are reasonable for tire you want on the surface you are targeting. Once choice doesn't work everywhere. Are you willing to switch springs between sessions if it starts to rain? As grip levels go up, so does the discrepancy between dry grip and wet grip.
3) Pick shocks / valvings that control those ^^^ springs. Adjustable shocks are handy if you switch springs, but don't adjust a car from a 'street' car to 'race' car with the turn of a knob.
4) Align the car to give the balance that you want, along with the stability that you need.
5) Drive and adjust.
more?
Jul 15, 2009, 06:35 PM
#20
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Ah more setup talk. Subjective as others have suggested. Thats why people call it a black art. It's not. Suspension tuning and design is considered to be this way because the tuner/engineer/guy-who-calls-himself-a-guru has to synthesize lots of variables with often incomplete information.
In my opinion, what makes a suspension great is support. The people that can support the product tend to be able to design/mfg/produce the product. Great people, great shocks, great performance. It's important for your suspension manufactuerer to make you the right part and help you use it. Same as any other technical product. That extends from working with someone who has little knowledge all the way to someone that asks you for a curve and a response characteristic and you satisfy it.
Adjustment range makes life easier too. Especially in changing conditions.
All the mathematical work can go out the window when organizing bodies try to cut costs or maintain parity. This can lead to unconventional damping.
In my opinion, what makes a suspension great is support. The people that can support the product tend to be able to design/mfg/produce the product. Great people, great shocks, great performance. It's important for your suspension manufactuerer to make you the right part and help you use it. Same as any other technical product. That extends from working with someone who has little knowledge all the way to someone that asks you for a curve and a response characteristic and you satisfy it.
Adjustment range makes life easier too. Especially in changing conditions.
All the mathematical work can go out the window when organizing bodies try to cut costs or maintain parity. This can lead to unconventional damping.
Jul 15, 2009, 08:16 PM
#21
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So now that we have the attention of some knowledgeable folks, let me ask this ... if I wanted to, for example, build a time attack Evo VIII with real aerodynamics, what kind of damper/spring combo would I be looking for?
The JRZ 3-way, for example states that:
What is considered a moderate to large aerodynamic load? If my initial goal were 500 lbs of downforce @ 100mph on a ~3000 lb chassis. Is that moderate? If so, what is considered a high aerodynamic load?
l8r)
The JRZ 3-way, for example states that:
To customize track to track setups and tailor the chassis to the JRZ Triple Adjustable has an adjustment range able to provide damping to spring configurations ranging from 1.5-4Hz on vehicle with moderate to large aerodynamic loads.
l8r)
Jul 15, 2009, 09:40 PM
#22
In addition it's harder to get substantial ground effect than it is on a car that you can drop very low (e.g. double a-armed flat bottom sports car). The low pressure area created by the ground effect is sensitive to ground to panel distance. In which case you might want to keep the car within a small window of ride height -- even to the detriment of low speed mechanical grip.
d
Last edited by donour; Jul 15, 2009 at 09:43 PM.
Jul 16, 2009, 08:32 AM
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A moderate to high aerodynamic load is generally something with a negative coefficient of lift in the range of -0.5 to -2.0 That being said, the triples are used extensively on "non aero" cars. We've damped cars all the way across the range.
Tradeoffs certainly exist in passive suspension design when working with cars that have ride height dependence and higher aerodynamic loads. Its just the nature of the beast. You do your best to satisfy both and pursue the road that yields the best laptime and/or tire wear depending on the series.
A note on aero in the unlimited time trial leagues. Nobody has come close to making real downforce yet. Nobody.
Tradeoffs certainly exist in passive suspension design when working with cars that have ride height dependence and higher aerodynamic loads. Its just the nature of the beast. You do your best to satisfy both and pursue the road that yields the best laptime and/or tire wear depending on the series.
A note on aero in the unlimited time trial leagues. Nobody has come close to making real downforce yet. Nobody.
Jul 16, 2009, 09:25 AM
#25
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l8r)
Jul 16, 2009, 11:42 AM
#28
I have a good aero book, and looking at a lot of the body kits, wings, splitters, etc. out there, it's just hilarious how bad some are.
- andrew
Jul 16, 2009, 11:53 AM
#29
I would tend to believe some parts such as Voltex do fairly well since I have seen wind tunnel testing on them. I suppose how they are used on the car in conjunction with other parts is what would translate into a decent amount of downforce though. People that put the tallest whale wing on they can find...not so much.
Jul 16, 2009, 01:42 PM
#30
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Wow this thread is so far OT but already looking to be so full of win.
I was wondering why there seems to be hints that KWs are not as good as they are touted, yet no one comes out and says in fact they are not.
With my year experience with them I think they are better then alot of others however definitely not the best.
I know we cant go bashing but what are the problem(s) that those that have dyno'd them or seen with the damper.
I am currently looking to build a set of Konis for myself in the future with the help of a friend in town. Now questioning myself whether it is worth the trouble of changing from Robi's V3s.
I was wondering why there seems to be hints that KWs are not as good as they are touted, yet no one comes out and says in fact they are not.
With my year experience with them I think they are better then alot of others however definitely not the best.
I know we cant go bashing but what are the problem(s) that those that have dyno'd them or seen with the damper.
I am currently looking to build a set of Konis for myself in the future with the help of a friend in town. Now questioning myself whether it is worth the trouble of changing from Robi's V3s.