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S550 GT350 suspension change affect my aero?

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18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
I've changed my 2020 Gt350 to BMR handling springs giving me higher rates front & rear.
Will the stiffer springs affect the swing/spoiler downforce in the rear and in turn the front aero?
 
23
4
Exp. Type
HPDE
Exp. Level
Under 3 Years
Lubbock
The only thing suspension can do to alter aero (disregarding exposed suspension cars), is rake and underbody aero. Regardless, I doubt either would be significant on a stock car.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
The only thing suspension can do to alter aero (disregarding exposed suspension cars), is rake and underbody aero. Regardless, I doubt either would be significant on a stock car.
I was thinking more along the lines of the rear swing downforce on the new BMR stiffer rear springs. The 2020 had softer rear OEM springs to absorb the downforce and deliver it to the PSC2's, if I am correct. They handle great on the street but this is a dedicated track car.
 
501
550
Exp. Type
W2W Racing
Exp. Level
20+ Years
Snowy North
Call Kelly @ BMR. One of the co-owners and a highly experienced resource. He will answer/settle any questions.

He is really approachable.
 
1,246
1,243
In the V6L
... The 2020 had softer rear OEM springs to absorb the downforce and deliver it to the PSC2's, if I am correct...
Springs don't alter downforce except for a brief moment when they're compressing or stretching from one length to another. Stiffer springs don't move as far, so they actually deliver forces quicker than a softer spring.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
Springs don't alter downforce except for a brief moment when they're compressing or stretching from one length to another. Stiffer springs don't move as far, so they actually deliver forces quicker than a softer spring.
Would the "R" spoiler be more appropriate then?
 
AJ Hartman recently did some wind tunnel work oh his gt350 and the rear wing more or less cancelled out the lift the car experiences at speed. Your OEM wing is not producing enough df to overload either the stock or your new springs. You need a GT wing to even get close to that territory.
 
189
290
Exp. Type
Time Attack
Exp. Level
10-20 Years
75024
I have the bmr springs on my '18, they lower the car slightly but also take out the rear high rake. It is pretty much level. On paper, the lower ride height will help the front spoiler/splitter a little bit, and reduce the angle on the rear swing/gurney, which will reduce the downforce. So the aero balance could shift forward. In practice, the most notable change is the stiffer, flatter, platfrom which gives you more confidence, and helps tire wear. Can't feel any aero difference.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
I have the bmr springs on my '18, they lower the car slightly but also take out the rear high rake. It is pretty much level. On paper, the lower ride height will help the front spoiler/splitter a little bit, and reduce the angle on the rear swing/gurney, which will reduce the downforce. So the aero balance could shift forward. In practice, the most notable change is the stiffer, flatter, platfrom which gives you more confidence, and helps tire wear. Can't feel any aero difference.
Yes, I am extremely happy with the lower setup now with the flatter platform. Track day shake down last week and the thing stuck like super glue to the track. Also had added -3.5 camber. Road America coming up next week, excited to feel any difference.
 
23
4
Exp. Type
HPDE
Exp. Level
Under 3 Years
Lubbock
Yes, I am extremely happy with the lower setup now with the flatter platform. Track day shake down last week and the thing stuck like super glue to the track. Also had added -3.5 camber. Road America coming up next week, excited to feel any difference.
I think you guys are mixing up weight distribution with aero balance.

They only way suspension will alter your AERO balance is if there’s a change in ride height difference (front to back). Adding rake (larger drop at the front vs rear) will increase the weight over the front wheels and make the car more “pointy” or oversteery. The increased drag or downforce from the slightly higher angle of attack will honestly be negligible. Ride height, dampening and sway bars will be way more apparent when setting up a car like the gt350.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
I think you guys are mixing up weight distribution with aero balance.

They only way suspension will alter your AERO balance is if there’s a change in ride height difference (front to back). Adding rake (larger drop at the front vs rear) will increase the weight over the front wheels and make the car more “pointy” or oversteery. The increased drag or downforce from the slightly higher angle of attack will honestly be negligible. Ride height, dampening and sway bars will be way more apparent when setting up a car like the gt350.
I believe that's what I did, stiffer lower springs, stiffer front sway bar.
 
6,361
8,183
From what I've experienced, rake is a massive deal for aero, both in Porsche Cup and GT4, The angle of attack makes all kinds of strange things happen, In P cup it was common to run negative rake to cancel out some of the rear wing to get down the straights.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
From what I've experienced, rake is a massive deal for aero, both in Porsche Cup and GT4, The angle of attack makes all kinds of strange things happen, In P cup it was common to run negative rake to cancel out some of the rear wing to get down the straights.
So, since I've eliminated the angle of attack, and added the stiffer handling springs/suspension mods, and the "R" front splitter, do you thing the swing w/Gurney flap has much of an effect?
 
6,361
8,183
So, since I've eliminated the angle of attack, and added the stiffer handling springs/suspension mods, and the "R" front splitter, do you thing the swing w/Gurney flap has much of an effect?
I'm not a fan of wickerbills, I think they reside in the area of " demon tweaks", one of the things that we did at Daytona on @flyhalf 's car was pull the wicker off to dump some of drag at Daytona. If I were you, I would completely mimic the aero on the Gt4 car. Ford spends tons of money in wind tunnels to get a balance, then we go out experimenting and messing it up. IMO adjust the cars suspension, then tidy it up with the aero.
Wickerbills are a huge drag inducer, but if you get you where you need to be, then go for it.
 
18
12
Exp. Type
HPDE
Exp. Level
3-5 Years
Illinois
I'm not a fan of wickerbills, I think they reside in the area of " demon tweaks", one of the things that we did at Daytona on @flyhalf 's car was pull the wicker off to dump some of drag at Daytona. If I were you, I would completely mimic the aero on the Gt4 car. Ford spends tons of money in wind tunnels to get a balance, then we go out experimenting and messing it up. IMO adjust the cars suspension, then tidy it up with the aero.
Wickerbills are a huge drag inducer, but if you get you where you need to be, then go for it.
There where I was when i started this thread, was the wicker bill causing to much drag or not the desired effect at all, and would the "R" wing be better, or as you suggested the GT4 setup.
 

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