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Which rear sway bar?

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I have a Roush front lip which protrudes a little further that the oem lip and is supported by the front bumper, but it's no big downforce. But i'll confess..... I have a huge rear wing (pitch adjustable). Hey, I like the look, what can I say. I'll work on a more aggressive splitter next year, but even then, rules say it cannot protrude further than 2" ahead of the front bumper line.

With the rear wing and proper rake you can avoid some of the pitch sensitivity. Your aerodynamic balance will shift forward when the front pitches up and vise versa when the front pitches down. To control that you would want moderately stiff springs or 2-2.5hz ride rates and enough rebound damping to tie the car down.
 
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Bulgaria
With the rear wing and proper rake you can avoid some of the pitch sensitivity. Your aerodynamic balance will shift forward when the front pitches up and vise versa when the front pitches down. To control that you would want moderately stiff springs or 2-2.5hz ride rates and enough rebound damping to tie the car down.

Much convenient to skip my post can you say how much Downforce a Roush front lip make :?
 
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I have a Roush front lip which protrudes a little further that the oem lip and is supported by the front bumper, but it's no big downforce. But i'll confess..... I have a huge rear wing (pitch adjustable). Hey, I like the look, what can I say. I'll work on a more aggressive splitter next year, but even then, rules say it cannot protrude further than 2" ahead of the front bumper line.

For rear wing you need to be sure how much downforce it makes and at what speed and you need to increase your rear spring in order to not bottom out the car when the max downforce happen.
 
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Much convenient to skip my post can you say how much Downforce a Roush front lip make :?
I am not going to argue with you over the internet. You are interested in trading anecdotal evidence and being more righter-er. If you want to have a discussion, happy to do that. Rather than addressing my original point you just ignored it and argued for the sake of arguing. If you want to crusade about how wrong you think I am, then I do not care to participate.



For rear wing you need to be sure how much downforce it makes and at what speed and you need to increase your rear spring in order to not bottom out the car when the max downforce happen.

For instance this is correct, spring rates at both ends of the car would need to be addressed based on how much aero is being made. To answer your question about how much aero each wing is making;
The front lip of his I assume to be smaller than the rear wing, especially if it is a GT4 wing;

The downforce exerted by a wing is usually expressed as a function of its lift coefficient:

tmstng.PNG
where:

  • D is downforce (SI unit: newtons)
  • W is wingspan (SI unit: meters)
  • H is the chord of the wing (SI unit: meters) if F is wing area basis, or the thickness of the wing if using frontal area basis
  • F is the lift coefficient
  • ρ is air density (SI unit: kg/m3)
  • v is velocity (SI unit: m/s)
If the wing is not rectangular, aspect ratio is written AR=b2/s, where AR=aspect ratio, b=span, and s=wing area.

1 N = 0.2248089431 lbf


So the question should be: how much downforce, at what speed?
 

TMSBOSS

Spending my pension on car parts and track fees.
6,352
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5-10 Years
Illinois
Rather than addressing my original point you just ignored it and argued for the sake of arguing. If you want to crusade about how wrong you think I am, then I do not care to participate.
You did notice the gentleman with a different opinion then yours also speaks a different language then most of us...Right? Taking offense to how he words his opinion is somewhat petty considering he likely speaks our language as a second, third or perhaps fourth language. Lets not even get into cultural differences. Being petty and showing your fourth point of contact is not becoming. Although with your under 3 years experience/expertise, listed under your signature, I guess you should feel free to continue to talk down to a newer member. Nice job!!:confused:
 
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You did notice the gentleman with a different opinion then yours also speaks a different language then most of us...Right? Taking offense to how he words his opinion is somewhat petty considering he likely speaks our language as a second, third or perhaps fourth language. Lets not even get into cultural differences. Being petty and showing your fourth point of contact is not becoming. Although with your under 3 years experience/expertise, listed under your signature, I guess you should feel free to continue to talk down to a newer member. Nice job!!:confused:

I don't judge him based on his mastery of english. What culture makes it ok to be argumentative? Who here has talked down? I think that's a bit of projection on your part. As for me I'm no expert, never claimed to be, and I don't have to argue or justify myself with anyone. I'd rather have a productive conversation instead of who is most right.
 
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Bulgaria
I am not going to argue with you over the internet. You are interested in trading anecdotal evidence and being more righter-er. If you want to have a discussion, happy to do that. Rather than addressing my original point you just ignored it and argued for the sake of arguing. If you want to crusade about how wrong you think I am, then I do not care to participate.

How a video prove of more front end grip is anecdotal evidence ? From what I can tell you are doing anecdotal arguments based on math and formulas that don't apply to the S550 Mustang at all. I'm sure you are happy with your OEM PP suspension then and the car don't need suspension mods based on your math at all Ford figured out the car from the factory right ?

Did you even looked in both videos that clearly showed more front bar = more front spring rate (as you can consider the sway bar like 3rd spring) added more grip (btw the sway bar rate is 520 lbs) ?

Also what is your initial point that spring rate up to the limit of mechanical grip is beneficial ? Or that more spring rate mean less mechanical grip ?

It does but did you answer why the Auto X guys run 450-500 lbs springs ?

Or is just convenient to ignore that more front spring is helping with turn in response ? Also less mechanical grip where during brake in, turn in, mid corner, corner exit or acceleration ?

For the downforce question I don't want to argue about math I want to ask you do you know how much as a number is the downforce on the Roush lip or PP2 lip because I could argue that 20 kg if that much on 1700 kg car is not important at all for spring rate. Sure if you are running big wing that may have some impact of adding 180-200 kg of downforce to an 800 kg rear end is big enough of a difference to consider more spring.

Ether way I'm not saying you are wrong but so far I didn't any prove from you that the S550 on track don't need more front spring and I show you video of why it does more spring especially if you are planning to run stickier tires.
 
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TX
How a video prove of more front end grip is anecdotal evidence ? From what I can tell you are doing anecdotal arguments based on math and formulas that don't apply to the S550 Mustang at all. I'm sure you are happy with your OEM PP suspension then and the car don't need suspension mods based on your math at all Ford figured out the car from the factory right ?

I have a GT350, I do not know the difference between the FRPP and the GT magnaride (shocks) As for the springs their selection is arbitrary since both vehicles are under-sprung because they are passenger cars. The math to create a baseline for any chassis is not anecdotal, math is math. What works for you and your driving; is anecdotal. I even admitted as much, which is why I think that simply claiming a SINGULAR change to ONE component is not the best advise to give. Since we can agree people drive differently, have different cars, and or are racing in different series. I believe there needs to be suspension modification(s) if you are going to race a non factory race car s550. See here;


Did you even looked in both videos that clearly showed more front bar = more front spring rate (as you can consider the sway bar like 3rd spring) added more grip (btw the sway bar rate is 520 lbs) ?

Your video does not address anything meaningful. Does the car need a change in ARB settings when you change springs? Yes. What that change is goes beyond more = better. Your admission of tire and alignment changes prove at least that much.

Also what is your initial point that spring rate up to the limit of mechanical grip is beneficial ? Or that more spring rate mean less mechanical grip ?

Less spring rate = mechanical grip. Simply stating more spring in front = better is not the whole picture. There are lots of things to consider, how much downforce if any?, what tire? what alignment? what ARB, what shock forces, what if any bump rubber? etc etc

It does but did you answer why the Auto X guys run 450-500 lbs springs ?

AutoX guys are not the only group who will use as little spring as possible. They will run less spring since they do not typically reach speeds where aero begins to dominate the grip profile.


Or is just convenient to ignore that more front spring is helping with turn in response ? Also less mechanical grip where during brake in, turn in, mid corner, corner exit or acceleration ?

Not sure what you want clarification on here?

For the downforce question I don't want to argue about math I want to ask you do you know how much as a number is the downforce on the Roush lip or PP2 lip because I could argue that 20 kg if that much on 1700 kg car is not important at all for spring rate. Sure if you are running big wing that may have some impact of adding 180-200 kg of downforce to an 800 kg rear end is big enough of a difference to consider more spring.

Your original question is "how much downforce?" The answer depends on the size of the wing and the speed the vehicle is traveling. If you are generating more than 100-200lbs of downforce then you might want to pay more attention to the spring rates. The more aero you generate the more pitch sensitive the system is as a matter of fact which means that ride rates / spring rates become even more critical. The rate you select reveals what you care about most in regards to chassis configuration.

Ether way I'm not saying you are wrong but so far I didn't any prove from you that the S550 on track don't need more front spring and I show you video of why it does more spring especially if you are planning to run stickier tires.

When you assume / make the claim I do not understand, that would be akin to saying I am wrong. However to address your need for proof; what level of proof is acceptable for you? Are we talking about a bone stock OE s550 (non GT4 car?) if so then yes it needs more spring. If you are talking about a factory GT4 car, what series are we in? The soft springs available as a package is already higher than a factory street car. When I give you information you hand wave it away as presumably worthless theory.
 
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Bulgaria
Your video does not address anything meaningful. Does the car need a change in ARB settings when you change springs? Yes. What that change is goes beyond more = better. Your admission of tire and alignment changes prove at least that much.

Less spring rate = mechanical grip. Simply stating more spring in front = better is not the whole picture. There are lots of things to consider, how much downforce if any?, what tire? what alignment? what ARB, what shock forces, what if any bump rubber? etc etc

When you assume / make the claim I do not understand, that would be akin to saying I am wrong. However to address your need for proof; what level of proof is acceptable for you? Are we talking about a bone stock OE s550 (non GT4 car?) if so then yes it needs more spring. If you are talking about a factory GT4 car, what series are we in? The soft springs available as a package is already higher than a factory street car. When I give you information you hand wave it away as presumably worthless theory.

My two videos show A car with same tires, and just different bar and camber (not by much) alignment was almost exactly the same just more camber in the second video. What you can see is how the inner tire move during mid corner and having less move mean more contact with road = more mechanical grip.

I read through your tread I can tell you what will happen if you put 400/750 Coilover springs on a Mustang you will not be able to control the car in midcorner and corner exit because the rear will slide a lot we are talking 400 lbs front with 1500 lbs rear here in OEM location sure you will not have understeer but you will have tons of Oversteer. Even if your "math" is correct this is a lot against your philosophy of as little spring as possible. The rear don't need much to be controlled actually especially not 1500 lbs which almost 600 lbs more than what your GT350 is coming from the factory with.

Based on what I have read from you sure you did read a lot of material on the subject of car dynamics sure the math is sound if you are building an S Class not so sound if you are building a race car. Here in the forum there is a lot of very nice build race cars just hear what the people that race/ track week in / week out do. Don't try to invent something that don't exists.

It is worthless theory because it just doesn't work like that in the Mustang as I told you when someone present me with the concept of more front spring / bar mean better turn in I was surprised as this is against what I know math wise regarding car dynamics. But unlike you I decided to give it a shot. And it worked. Also someone present me with the idea of not upgrading rear bar as you need the rear to be soft so you can have traction on corner exit.
 
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HPDE
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Under 3 Years
TX
My two videos show A car with same tires, and just different bar and camber (not by much) alignment was almost exactly the same just more camber in the second video. What you can see is how the inner tire move during mid corner and having less move mean more contact with road = more mechanical grip.

I read through your tread I can tell you what will happen if you put 400/750 Coilover springs on a Mustang you will not be able to control the car in midcorner and corner exit because the rear will slide a lot we are talking 400 lbs front with 1500 lbs rear here in OEM location sure you will not have understeer but you will have tons of Oversteer. Even if your "math" is correct this is a lot against your philosophy of as little spring as possible. The rear don't need much to be controlled actually especially not 1500 lbs which almost 600 lbs more than what your GT350 is coming from the factory with.

Based on what I have read from you sure you did read a lot of material on the subject of car dynamics sure the math is sound if you are building an S Class not so sound if you are building a race car. Here in the forum there is a lot of very nice build race cars just hear what the people that race/ track week in / week out do. Don't try to invent something that don't exists.

It is worthless theory because it just doesn't work like that in the Mustang as I told you when someone present me with the concept of more front spring / bar mean better turn in I was surprised as this is against what I know math wise regarding car dynamics. But unlike you I decided to give it a shot. And it worked. Also someone present me with the idea of not upgrading rear bar as you need the rear to be soft so you can have traction on corner exit.

You are not being very clear where are you getting 1500lbs from? Also mid corner for a car is usually a steady state where the springs and shocks are not doing a whole lot and your sway bars start doing more of the work.

Now onto philosophy... You certainly can run a car with a lot of pitch. You need to be aware of what that does and the rest of your setup should be planned around the amount pitch you have.

You can also run flat ride of which there is plenty of evidence that it does work just fine. Optimum G, Jim Kaszperzak (FSAE), Milliken-Milliken, QA-1, and even dirt track racers will all tell you flat ride is a completely viable option. Granted it is not the only option, and as I have said before driver skill has a lot to do with the results. The fact that you continue to confidentiality claim info from experience beyond you or me is either gospel or worthless is very unfortunate.

By the way, anecdotal:
(of an account) not necessarily true or reliable, because based on personal accounts rather than facts or research.

Your videos only factually show that you raced and the times changed. There is no way to factually prove what changes you made vs what your driving was like change to change. Obviously you raced and made video and your times changed but that's all you can prove.

I see you DM'd me. I'm happy to take the conversation offline.
 
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Raleigh, NC
For a race car with coilovers. I hear lots of people are using the stock rear sway bar? But which one? Regular GT? Perf pack? Other?

Thanks
So Chuck, did you figure it out yet? :)
My $.02....as long as they are adjustable to at least 3 places and you are going with the usual suspects (BMR, Steeda) you will be fine. Our cars don’t need crazy-firm rear ASBs unless you are full race car and then ignore me because I’m not at that level. But you do need to experiment on-track with front/back ASB relationship. I’ve got mine really firm in front, middle of the road in back. I came to that after several adjustments during 2 days at the track. I have no aero. Call the guys at Steeda or Vorschlag, they’ll get you taken care of.

One thing we’ve all got to remember....we all have different driving styles so there is no perfect answer. Unless your answer for the greatest band ever is not Led Zep. Then you are wrong. 🤣
 
So Chuck, did you figure it out yet? :)
My $.02....as long as they are adjustable to at least 3 places and you are going with the usual suspects (BMR, Steeda) you will be fine. Our cars don’t need crazy-firm rear ASBs unless you are full race car and then ignore me because I’m not at that level. But you do need to experiment on-track with front/back ASB relationship. I’ve got mine really firm in front, middle of the road in back. I came to that after several adjustments during 2 days at the track. I have no aero. Call the guys at Steeda or Vorschlag, they’ll get you taken care of.

One thing we’ve all got to remember....we all have different driving styles so there is no perfect answer. Unless your answer for the greatest band ever is not Led Zep. Then you are wrong. 🤣

HAHAHA Almost!

I have the Ford performance adjustable rear sway, but the softest adjustment is not accessible since the link touches the spring (coilover). Am I the only one with this issue?
 
I have the Ford performance adjustable rear sway, but the softest adjustment is not accessible since the link touches the spring (coilover). Am I the only one with this issue?


Hey Chuck I just started another thread about this, but just saw this post of yours. Installing my MCS coilovers and have this problem as well. I saw from a pic in your build thread you had stock endlinks, is that still the case? Did you get this sorted out? If so what was your solution?

I think whiteline endlinks will clear, but also found these from Drake (but not sure of the rod end quality) that look to be quite slim.

 
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Bulgaria
Hey Chuck I just started another thread about this, but just saw this post of yours. Installing my MCS coilovers and have this problem as well. I saw from a pic in your build thread you had stock endlinks, is that still the case? Did you get this sorted out? If so what was your solution?

I think whiteline endlinks will clear, but also found these from Drake (but not sure of the rod end quality) that look to be quite slim.

I think when you lower your car you need adjustable endlinks in order to ensure proper roll bar fitment. I plan to go with steeda for mine as they are easier to source in Europe but any ajustable endlinks will do.
 
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3-5 Years
FL
I think when you lower your car you need adjustable endlinks in order to ensure proper roll bar fitment. I plan to go with steeda for mine as they are easier to source in Europe but any ajustable endlinks will do.
Sorry this is an old post but a very interesting discussion. Not the bickering part, but the behavior of Bnight's GT when he added a much stiffer front roll bar and reduced the understeer. The problem I have is .... I believe you, ... so what gives??

When you stated that a stiffer front roll bar improved your understeer condition, that just hurt my head for a few days until I found a possible physical reason for that.

Well I suspect your front lower control arm angle is near horizontal and any body/chassis roll would put you in a situation of positive camber gain under cornering which would reduced front grip (and maybe significantly enough to push badly). So when you stiffened the front bar, you reduced your body roll to a point where the positive camber gain was less and this produced more favorable front grip. So even though you increased your roll couple to add bias to the front which fundamentally transfer more load to the front outside tire, it was a net benefit in the front grip (hence less push) because the contact patch was "more happy" or "less upset".

So Bnight, something for you to check if you want, 15 mins and $35 angle gauge on the LCA and you will know if this is a contributor.

I'm very far from a suspension expert and basically don't know much, but I'm trying to learn and the folks on the Forum are a major plus. So thanks to all for the education, past and future. Cheers.
 
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Time Attack
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Under 3 Years
Bulgaria
Sorry this is an old post but a very interesting discussion. Not the bickering part, but the behavior of Bnight's GT when he added a much stiffer front roll bar and reduced the understeer. The problem I have is .... I believe you, ... so what gives??

When you stated that a stiffer front roll bar improved your understeer condition, that just hurt my head for a few days until I found a possible physical reason for that.

Well I suspect your front lower control arm angle is near horizontal and any body/chassis roll would put you in a situation of positive camber gain under cornering which would reduced front grip (and maybe significantly enough to push badly). So when you stiffened the front bar, you reduced your body roll to a point where the positive camber gain was less and this produced more favorable front grip. So even though you increased your roll couple to add bias to the front which fundamentally transfer more load to the front outside tire, it was a net benefit in the front grip (hence less push) because the contact patch was "more happy" or "less upset".
That's the technical explanation yeah. the Front Lower Control Arm and the toe link are parallel in order to give correct roll center but the Mustang is under sprung from factory because after all is a street car. So when I add a front roll bar I'm effectively increasing the front spring rate making the car dive less and stop the camber to go positive even though I also have -2.3 degrees of camber. You will see that in this forum a lot of people are running -3 and more degrees of camber even with stiffer springs. This is because even with Steeda Dual-Rate or GT350R rates is still not enough spring rate to tame a 3800 lbs chassis body roll. So the only good option for suspension if you want to drive on track is coil overs where the rates on the front are much higher than even the GT350. Surely when you put such high rates you also need to change the rear rates otherwise the car is going to start to push but you also need to find the softer possible rear rate because otherwise you will start to slide on corner exit. Finding that balance of a good track car is what makes this sport a magic and why we are spending so much time reading anything in order to understand our cars better and improve them for the track.
 

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