Boss 302 Springs Worth it?

Discussion in 'Mustang Chit Chat' started by vxr500, Jun 30, 2021.

  1. vxr500

    vxr500 forum member

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    I have an opportunity to pick up some low miles fr/rr boss 302 springs for a cheap price. My car is a 2010 Track pack with about 95k on the original springs.

    I know they don’t lower the car much(about 1/2 inch up front, less in rear), but I don’t really want to lower it. I just want something that’ll keep the car a little flatter in turns. I currently have Koni orange SRTs, and a boss 302 rear sway bar. Other than gt500 strut mounts and new stock bushings here and there, the rest of the suspension is stock.

    Will I notice any improvement? How long are original stock springs good for?
     
  2. Forty61

    Forty61 forum member

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    No clue if the track pack springs are a different rate to the 302 ones, I’m sure someone will chime in with that specific info. If you want less roll in turns what about a stiffer front sway bar? You mentioned the rear but no front.
     
  3. vxr500

    vxr500 forum member

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    I’m pretty sure on a rate table I saw somewhere that they are stiffer. Also I think the front sway bar I have is the same one as the Boss 302. And from what I’ve read the boss is pretty much the best handling S197. So you can see what I’m aiming it here. lol
     
  4. LarryJM

    LarryJM forum member

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    I do have the table someplace. All the springs run between 130 to about 190 lbs. I really don't think its worth the trouble changing when Nascars have between 500 and 1000 lbs springs and your trying to decide between 167 lbs or 175 lbs springs.
     
    Last edited: Jun 30, 2021
  5. LarryJM

    LarryJM forum member

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    Although I think I will install the Boss Rear Sway Bar.

    DSC_0053.JPG

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  6. LarryJM

    LarryJM forum member

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    Here is that list.

    DSC_0162.JPG
     
  7. vxr500

    vxr500 forum member

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    Yup. That’s the one, thanks.

    Well, let’s be real here. I’m not expecting track car levels of difference. Just a little less pogo in the twisties. Which is something I’m sure the boss 302 was better at than the track pack.

    Plus I’m assuming mine are a little tired at 95k
     
    GlassTop09 likes this.
  8. LarryJM

    LarryJM forum member

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    Yes any new springs are better then tired springs. Now what the feel difference between a 142 lbs rear standard spring and a 186 lbs rear Boss spring is anyone's guess when people are installing 500 lbs springs for the track.
     
  9. 07 Boss

    07 Boss Senior Member

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  10. LarryJM

    LarryJM forum member

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    Exactly the reason there is no real difference between a standard Rear Sway Bar and a Boss Rear Sway Bar.
     
  11. Norm Peterson

    Norm Peterson corner barstool sitter

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    How much of the amount of roll you're noticing do you think might be based on the amounts of roll you're experiencing in your normal street driving? What I'm getting at here is that your perception is going to be based on much lower cornering g's.

    Are you throwing it into the turns or smoothly adding steering lock?

    How much might be from "overshoot" permitted by the Oranges?


    Here's a quick and dirty edit of a picture of my car at about 0.9g on base GT springs (yup, those 136/142 pieces). But I do have the Koni yellows, and as of that picture, Sam Strano's 35 mm front / 22 mm rear stabars (numbers I have show 547 lb/in for the Strano front vs 385 lb/in for the Ford, about 136 lb/in for the Strano rear vs 96 lb/in for the Ford). Not much difference in slope between the contact patches and between the body points above the exhaust tips.

    T2 between entry and apex showing roll angles.jpg


    Norm
     
    Last edited: Jul 1, 2021
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  12. Maczs007

    Maczs007 Junior Member

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    I put Boss 302 springs on my 2013 GT a year after I bought it new. It did firm it up. The only thing I did not like was the fact that the rear sat higher. I tried to correct this by only changing the rear springs. I now have Steeda Sports on the rear which leveled it out nicely but they seem to bounce around more than the Boss 302 springs. The rear Boss 302 springs have a different design, slightly canted and wound differently.
     
  13. Norm Peterson

    Norm Peterson corner barstool sitter

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    The Steeda rear springs are slightly softer than the Boss rear springs. The same amounts of force coming from either driver steering/braking/throttle inputs or road unevenness will make the rear move around a little more than before.

    You've also affected the car's natural 'flat ride' behavior.

    Probably none of that is enough to see from the outside, but apparently enough for you to feel.


    Norm
     
  14. brembo12

    brembo12 Junior Member

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    Mustang GT (2011+) Stock: Ft 122 lbs/in Rr 154 lbs/in *
    Brembo Stock: Ft 131 Rr167 lbs/in
    Boss Stock: Ft 148 Rr 185 lbs/in
    Boss LS Stock: Ft 137 Rr 191 lbs/in
    Eiback Pro-Kit: Ft 159 Rr 193 lbs/in *
    M- 5300-K rate: Ft 173-248 lbs/in – Rears 195-236 lbs/in
    Steeda Competition: Ft 225 Rr 185 lbs/in
    Steeda Sports: Ft 200 Rr 175 lbs/in
    Steeda Boss Springs Ft 225 Rr 195 lbs/in
    Steeda Ultra-lite (pn 555-8206) 1.25/1.5 front: 195lb/in / rear: 175lb/in

    Per Maximum Motorsports. I had a list from Ford that was on the old BBP Brembo 5.0 website. No idea where it went.
     
  15. LarryJM

    LarryJM forum member

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    Well I do have a Boss rear sway bar that I have not installed. It's 25mm vs 24 and the LS is 26mm. My installer has been booked for over a month and the nearest Ford Dealer is so booked, they could not install a Ford Motorcraft battery for 2 weeks. Besides the sway bar needs one time bolts and I still have not ordered them. Not sure with 500lbs springs around, any of the stock type spring really seems not to make much of a difference.

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  16. Norm Peterson

    Norm Peterson corner barstool sitter

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    Bigger for the straight line stuff, yeah. But that isn't always better when you're tuning for the corners. Too much rear bar = too oversteerish = makes you too slow because of your natural instinct for self-preservation.


    Norm
     
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  17. Norm Peterson

    Norm Peterson corner barstool sitter

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    For a street-driven car up to a semi-serious effort at building a dual-purpose street/HPDE car, the best first step toward handling composure is going to be the shocks and struts.

    I eventually moved up to BMR's handling springs for the GT500 (260f/220r), and the forward shift in spring rate/wheel rate bias from OE had me calling for a bit more rear bar. The handling was OK with Sam's smaller 22 mm bar, but just felt "heavy". 260/220 might represent a decent compromise, at least if you can adjust the shocks and struts for rebound damping to let you find your best ride-handling compromise.

    Oh yeah, the BMR springs only dropped my 4.6 about half an inch up front, but a little over a whole inch out back, which had me fabbing up some spacers to restore the ride height back closer to stock.


    Norm
     
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  18. LarryJM

    LarryJM forum member

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    I actually like the way it handles on the street as is now and reluctant to make any more changes including Brembo Wheels and Achilles 254 45 19 Tires. The wheels and tires cost me $500 total at Christmas time. That's $200 for 4 wheels and $300 for the 4 tires. I think I might sell them including the Boss 25mm sway bar. The tires alone now are $450. Everything else is up big time in price since Christmas.
     
  19. jmustang

    jmustang Junior Member

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    What shock/strut would you recommend pairing with those springs? I’m eyeing them myself as my car is supercharged and Ive run a few hpde this year.


    Sent from my iPhone using Tapatalk
     
  20. Norm Peterson

    Norm Peterson corner barstool sitter

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    My experience is that those rates are within the useful range of Koni yellows. Bilstein may have a comparably firm alternative, but probably non-adjustable.

    Steeda has a brand-new package tuned for NA S197s (with extensive help from Billy Johnson - a talented Ford W2W racer/development driver/driver coach) that appears to have much the same handling balance as mine. My BMR springe are about 30% firmer than the Steedas, which would soften the ride a bit and require a little less damping than what I'd use on the track (think "more headroom" remaining) Though I think with your supercharger you'd want more front spring than the 200 lb/in that ships with this package (200f/175r).

    Steeda 555-2356 Mustang Sport Handling Package (11-14)

    I think starting with a call to Steeda and see if they agree that with the exception of front springs that that could be a viable option. Maybe they could substitute their 555-8241 springs instead (225/185).


    Norm
     
    Last edited: Jul 21, 2021
    jmustang likes this.
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