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MartinNoHo

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Re: the sway bars, I think you're still good getting the front one. If you can front and rear adjustable you can fine tune the balance afterward. Generally I am not a fan of the big rear bar at all, but given your comparable soft rear spring, it might be warranted.

Generally the COG lower is good, but not at the expense of the roll center. Most suspension manufacturers won't tell you - that once you lower the car your suspension geometry changes. Many times that it isn't good. And of course most of them won't. They're trying to sell parts. Most folks that are just lowering the car for looks won't notice because they're not pushing their car hard enough. Some will notice they're getting bumpsteer issues when before there wasn't any. The bumpsteer also changes when you lower the ride height. Both problems can be fixed by the aftermarket if you so choose.

Yeah, I think raising it back up is a win-win. You get more suspension travel for bumps and improves your geometry some.
If it isn't a bother can you explain/summarize to me how spring rates might affect handling dynamics in layman's terms, I'm curious how you came to the idea that my car is front biased and what does this mean.
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MartinNoHo

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No, the opposite.
Do you have a recommended read for me to better understand suspension dynamics? Cause now i'm confused as to how sway bars, springs rates, etc work together and affect vehicle dynamics, because I understand them far to simplistically. I learn from engineering explained videos on youtube, and I think its simple mainly because it's for general audience.
 
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Bluemustang

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If it isn't a bother can you explain/summarize to me how spring rates might affect handling dynamics in layman's terms, I'm curious how you came to the idea that my car is front biased and what does this mean.
I'll let those more technically oriented answer that question as I might not use the correct terms. Again it's hard to know for sure because I don't know exactly what it is happening with the progressive rate.
But assume you have a linear front and rear spring - just from the numbers you listed (in lb/in) it indicates a higher front ride frequency vs. the rear. There's a spreadsheet floating around that lists all the known S550 spring rates, wheel rates and corresponding ride frequencies of the different springs out there.

Ride frequency is extremely important to vehicle dynamics and resulting handling balance, as well as the overall ride quality. Basically what I'm talking about is stiffness, roll resistance front to rear. Changing this relationship alters the handling balance and vehicle dynamics.

Understanding the result of a change to one end of the car or the other, you have to first understand the suspension system/how it functions. There are many general norms with respect to tuning handling balance. Some may be applicable to you, some may not.

I suggest reading some articles about tuning handling balance and ride frequencies. Also, understand the car you are working with - heavier front weight distribution, RWD and big power. MacPherson front suspension, multi-link IRS. Therefore, some general norms of tuning handling balance may not apply if you're basing it on suggestions off a another platform. A good car to look at with similar suspension system is the BMW M3. They also use MacPherson struts and a similar IRS. Also, RWD, big power and similar weight.

You'll notice a lot of M3 guys will upgrade to a larger front sway bar. Why? To combat the poor camber control of the MacPherson strut. Front camber and front roll stiffness is your friend. The reason why the bigger rear bar doesn't work as well on this car is because 1) the IRS has a much better camber gain than the front suspension does, so it doesn't need it as much, and 2) the stiff rear bar also has drawbacks (as do all sway bars), one of which is sacrificing wheel independence. Look at it this way, you're trying to put power down to the rear wheels - the rear sway links both sides of the suspension together. Your suspension is now less independent. If you go extremely stiff you are almost turning your IRS into a straight axle. It can make the rear end more twitchy. It ultimately reduces rear grip which hurts you trying to put power down out of the corner.

Typically, the general norm on stiffer front sway bars is that it can make the car understeer. And yes it still can. But used in the right away on this car (with enough camber and good tires), it can actually reduce understeer by combating the weakness in the MacPherson strut. The MacPherson doesn't have a way to keep the outside tire from curling into positive camber when it's pushed too far in cornering. This is why the autocross guys will run a stiffer front bar to keep that from happening. It helps to stabilize the dynamic camber angle.
 

TeeLew

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_Tune to Win_ isn't correct about everything, but it's so damned good for the late 1970's, that it might as well be. Beyond that, Carroll was just a guy that liked to make things go fast. His books are the standard by which every other car-tech book is measured.
 

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That's very informative thanks, I always thought the lower the COG the better, but I always thought it can't be that simple.
"Lower" only makes a car look more race car-ish. That's not the same thing as it actually driving more like a race car. People manage to reach improper conclusions based on what they see because of such visual associations.

The time delay to when the car takes a set is a function of the sprung mass frequency in roll. Roll takes time to happen, and there isn't much you can do about this in a lowered street-driven car other than stiffen the suspension some more. Don't ignore the shocks & struts here, and not just because stiffer springs and stiffer bars need more damping to control them. Damper forces peak before roll has fully developed and can make the car feel closer to its set before it gets all the way to a geometric definition of 'set' if they're high enough (don't go too far, though). Composure coming from appropriate levels of damping go a long way toward making the car easy to drive.


Big heavy cars are inherently more 'deliberate' in their response to steering inputs, so you can't exactly drive them like you could a track-tuned Miata. I don't know what your corner sequence looks like, but I suspect what you're going to have to teach yourself is to have a little more patience as far as the car's inertial response times are concerned. Go back to a speed that you can comfortably stay at while focusing on the right line through those turns. Consider that you might have to write the first turn off as a "throw-away" in order to be set up properly for the second.

I'm afraid I can't tell you how well figuring this part out as you go in only street driving is going to play out (let alone in the absence of knowledgeable instruction). Not unless you're willing to put what could amount to (literally) decades into paying close attention - all the time and at lower speeds - to what works well and what doesn't work so well. Even then, it's kind of a 'feel' or a 'rhythm' thing that different people have different aptitudes for sensing.


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Emilbadal

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For faster weight transfer feel, thicker sway bars front and rear will help. Cradle lock out kit will help getting some vagueness out of your car handling feel. If you choose to put chassis braces on, they will help with predictability and you will feel the road more.

As many here pointed out, public roads no matter what time of day and where it is, it’s not a good place to learn what your car’s capabilities are. It’s a disaster waiting to happen.
 

Ecoboosted

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I'll let those more technically oriented answer that question as I might not use the correct terms. Again it's hard to know for sure because I don't know exactly what it is happening with the progressive rate.
But assume you have a linear front and rear spring - just from the numbers you listed (in lb/in) it indicates a higher front ride frequency vs. the rear. There's a spreadsheet floating around that lists all the known S550 spring rates, wheel rates and corresponding ride frequencies of the different springs out there.

Ride frequency is extremely important to vehicle dynamics and resulting handling balance, as well as the overall ride quality. Basically what I'm talking about is stiffness, roll resistance front to rear. Changing this relationship alters the handling balance and vehicle dynamics.

Understanding the result of a change to one end of the car or the other, you have to first understand the suspension system/how it functions. There are many general norms with respect to tuning handling balance. Some may be applicable to you, some may not.

I suggest reading some articles about tuning handling balance and ride frequencies. Also, understand the car you are working with - heavier front weight distribution, RWD and big power. MacPherson front suspension, multi-link IRS. Therefore, some general norms of tuning handling balance may not apply if you're basing it on suggestions off a another platform. A good car to look at with similar suspension system is the BMW M3. They also use MacPherson struts and a similar IRS. Also, RWD, big power and similar weight.

You'll notice a lot of M3 guys will upgrade to a larger front sway bar. Why? To combat the poor camber control of the MacPherson strut. Front camber and front roll stiffness is your friend. The reason why the bigger rear bar doesn't work as well on this car is because 1) the IRS has a much better camber gain than the front suspension does, so it doesn't need it as much, and 2) the stiff rear bar also has drawbacks (as do all sway bars), one of which is sacrificing wheel independence. Look at it this way, you're trying to put power down to the rear wheels - the rear sway links both sides of the suspension together. Your suspension is now less independent. If you go extremely stiff you are almost turning your IRS into a straight axle. It can make the rear end more twitchy. It ultimately reduces rear grip which hurts you trying to put power down out of the corner.

Typically, the general norm on stiffer front sway bars is that it can make the car understeer. And yes it still can. But used in the right away on this car (with enough camber and good tires), it can actually reduce understeer by combating the weakness in the MacPherson strut. The MacPherson doesn't have a way to keep the outside tire from curling into positive camber when it's pushed too far in cornering. This is why the autocross guys will run a stiffer front bar to keep that from happening. It helps to stabilize the dynamic camber angle.
I have Steeda front and rear sway bars. I have the front set to the 2nd to stiffest setting out of 4 adjustable holes and rear to the softest setting out of 3 adjustable holes. Does that sound right or should I set them differently?
 

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I have Steeda front and rear sway bars. I have the front set to the 2nd to stiffest setting out of 4 adjustable holes and rear to the softest setting out of 3 adjustable holes. Does that sound right or should I set them differently?
I would start off with the softest setting front and rear and tune from there.

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Ecoboosted

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I would start off with the softest setting front and rear and tune from there.

Steeda Tech
I’ve tried all settings front and back except the front at the stiffest settings because I have the magnaride suspension.

When I had the front set to the 3rd stiffest and rear to the stiffest setting after a while I heard some creaking and the car seemed twitchy on high speed back roads. I adjusted the front to 2nd softest setting and rear to middle setting. For a long time but after reading Bluemustang’s post I set the rear to the softest setting to see if it will be more compliant on the same back roads vs the settings I just had them on. Will see if it rides better.
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