Steeda's New Dual Rate Ultimate Handling Springs - (Track Proven Winner!!!)

[Norm Peterson]

Dual rate springs. These are easy to spot because, as the image shows, they have tightly spaced coils at one end and wider, equally spaced coils at the other end. Usually, the spring rates for dual rate springs are listed as 250/425lb/in, meaning the top part is 250lb/in. and the bottom is 425lb/in.

I hope what you're getting at is that the spring is a 250 lb/in spring whenever none of the closely would coils are actually closed up, and that the 425 rate is when the close coils are all bound up (inactive) and only the widely spaced coils are active.

What I'm saying in other words is that the closely-spaced top portion makes the spring (in its entirety, spring seat to spring seat) become a 250. Not that the top portion is a 250 all by itself. And that varying the number of active coils by letting some of them bottom out against each other as the spring is compressed is how the spring can have more than one rate.


Norm

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[Norm Peterson]

When you are cornering, the part of the car on the outside of the curve rolls over the edge, while the inside edge rolls or lifts up. As the car rolls over, it moves into the higher spring rate, which greatly reduces roll.

Be careful here. What's being reduced is spring compression, which is only half the story when it comes to roll angle.

On the other side, the car lifts less because it's pushed up by the lighter spring rate.

I don't think so. The independent variable here is spring load (not the amount of roll), which on the inboard side is being reduced by load transfer due to lateral acceleration. Without a sta-bar, the amount of load taken off the inboard spring essentially matches the amount added to the outboard spring. But since you're now in the soft range of the inboard spring it's going to have to extend further before you get a force equilibrium. IOW, 1" compression on the outboard suspension could take 1.75" extension on the inboard suspension, and the amount of roll would be based on 2.75" across the track dimension instead of 2".

I understand that the presence of a sta-bar would minimize the above asymmetry (and complicate the math). But it wouldn't totally eliminate the above more-extension-than-compression effect unless it was firm enough to keep the inboard spring working at the firm rate under however much extension happened.

The Dual Rate Spring combines a relatively low initial spring rate, designed to absorb minor undulations and increase grip with a precise transition point and transition range to a secondary higher spring rate to improve roll control during cornering.

This is why I was asking earlier about whether any coils were in contact with each other at static ride height. Where the rate changes matters because the behavior will be different in roll vs ride.


Norm

 

[NightmareMoon]

Norm, although the Steeda guy's explaination was sort of terrible, hes not entirely wrong.

The weaker coils are compressed at static ride height, glorified helper springs, and since they're never under tension, always some degree of compression, the soft top rates should contribute marginally less to roll vs a linear heavy spring of the same ride height.

You go high enough with the spring rates with coilovers and you need a helper spring to deal with stock suspension travel. Same thing here just in a format compatible with stock shock perches.

 

[SteedaTech]

Be careful here. What's being reduced is spring compression, which is only half the story when it comes to roll angle.



I don't think so. The independent variable here is spring load (not the amount of roll), which on the inboard side is being reduced by load transfer due to lateral acceleration. Without a sta-bar, the amount of load taken off the inboard spring essentially matches the amount added to the outboard spring. But since you're now in the soft range of the inboard spring it's going to have to extend further before you get a force equilibrium. IOW, 1" compression on the outboard suspension could take 1.75" extension on the inboard suspension, and the amount of roll would be based on 2.75" across the track dimension instead of 2".

I understand that the presence of a sta-bar would minimize the above asymmetry (and complicate the math). But it wouldn't totally eliminate the above more-extension-than-compression effect unless it was firm enough to keep the inboard spring working at the firm rate under however much extension happened.



This is why I was asking earlier about whether any coils were in contact with each other at static ride height. Where the rate changes matters because the behavior will be different in roll vs ride.


Norm

Norm, although I respect you on other matters, I disagree with you on this one.
It's all about Newton's Law.

These springs were designed by a top Winston cup engineer that has been designing springs for the last 30 years. Dual Rate springs are a hot ticket in Handling,change is good!
Maybe we are miss interpolating our communication.
Norm, if you like we can discuss in person over the phone with one of our coil spring engineers after the Holidays.
Happy New Year!
Mike D @ 954-960-0774 or you can pm your contact info to discuss

Steeda Tech.

 

[SteedaTech]

Norm, although the Steeda guy's explaination was sort of terrible, hes not entirely wrong.

The weaker coils are compressed at static ride height, glorified helper springs, and since they're never under tension, always some degree of compression, the soft top rates should contribute marginally less to roll vs a linear heavy spring of the same ride height.

You go high enough with the spring rates with coilovers and you need a helper spring to deal with stock suspension travel. Same thing here just in a format compatible with stock shock perches.

The desigin of the Steeda Dual rate spring cannot be accomplished with a traditional coilover setup. Helper or tender spring it is not.

Gentlemen, if you need any technical info on Steeda products please call, I would love to discuss this with you.

Happy New Year!

Thanks,

Mike D @ 954-960-0774

 

[Norm Peterson]

Maybe we are miss interpolating our communication.

Probably true.

I suspect it has to do with what we're calling the independent variable, or what the root cause of spring compression and extension is. Deflections - roll in this case - is only the visible evidence that some amount of load transfer is happening in a flexible system. Not the other way around where some amount of deflection (roll) is driving the amount of load transfer.

The ability to make spring rate variable over the range of compression encountered by varying the coil spacing isn't PhD-level thinking. Even though setting the detail specs to put the right rates at the right amounts of spring compression would take greater understanding and experience than just selecting free length for linear-rate springs of some specified rate to fit between a given set of perch heights.

Incidentally, I used the term 'variable' intentionally, given that dual-rate springs are really just a unique case of progressive (I try to keep up with the progressive spring thread as well).


You might not be able to match your 250/425 dual-rate spring with existing coilover springs and make it fit between the Mustang's spring perches, but isn't that mostly a function of helper vs main spring availabilities and - especially in the case of the rear springs - the need to guarantee spring stability? IOW, I'm sure that c/o designs could be worked up that virtually duplicate that 250/425. And equally sure that it hasn't been worth anybody's trouble to do so even for only occasional production.


I may take you up on your offer after the holidays.


Norm

 

[Norm Peterson]

The weaker coils are compressed at static ride height, glorified helper springs, and since they're never under tension, always some degree of compression, the soft top rates should contribute marginally less to roll vs a linear heavy spring of the same ride height.

You go high enough with the spring rates with coilovers and you need a helper spring to deal with stock suspension travel. Same thing here just in a format compatible with stock shock perches.

I'm quite familiar with all that, both from an engineering perspective and a little practical experience.

I agree with your use of the term 'helper spring'. It's also common for people to consider the term 'tender springs' to mean the same thing (they aren't the same, exactly).


Norm

 

[wildcatgoal]

Anyone in this most recent debate actually run Steeda's Dual Rate Comp springs on their car? Welp... I have been for something like 5 track days and on the street and will continue to do so until I can afford (and understand how to utilize) snazzy coilovers. My car has never felt flatter, I can induce fuel cut off at AMP with 3/4 a tank because I'm going so fast through the last few turns (and yes, I've had my fuel system checked... it's just Ford's a shit design and G-forces), and I've been dropping times this past year at AMP and Road Atlanta. At AMP, I've broken into sticky-tire times on Conti Sport street tires. At Road Atlanta, I reduced my time by 5-7 seconds (granted, the prior time was my first time there, but the second time was only my second time there with more traffic, a notable number of which were Challengers that could drag me on the straights but would slow me down in corners). I was able to avoid three accidents at Gridlife at Road Atlanta because my car did not become drastically upset when I had to make emergency moves at the worst time. Frankly these things are humbling, because I've had someone who is a Spec Iron Mustang race car driver take my car around AMP and he ticked off a 2 seconds lower time than I'm personally capable of (on Nitto NT01s) on the one and only session he drove my car and only the second time he's driven an S550 platform car on track... and came back impressed.

Theory, theory, theory. Steeda's proven these work as described on their own cars. Call Mike D, he might clue you in on a few things they don't go blabbing about on forums. There's a few GT and GT350 drivers out there (some on this forum) who've been beaten (time wise) by a Steeda-equipped Ecoboost. It's great to debate theory. I was apprehensive about such a stiff spring and progressive/dual rate designs (vs easier to grasp linear rate options)... but I'm glad I have these things. Frankly, they've saved me a lot of money - I would have dumped thousands on coilovers by now chasing driver skill with parts. I got to make a change, the car feels great, and I can, with the driver confidence I wanted in hand, learn how to drive... hopefully, haha.

 

[Barrel]

Yeah I'm kinda with wildcat here. I love the engineering talk but driving on these springs will give you an appreciation for how good they are. Very excited to finally drive my car in anger next month and see how squat/dive and launch have changed.

 

[wildcatgoal]

Yeah I'm kinda with wildcat here. I love the engineering talk but driving on these springs will give you an appreciation for how good they are. Very excited to finally drive my car in anger next month and see how squat/dive and launch have changed.

Haha... "drive your car in anger." Sounds like my daily commute...

 

[Norm Peterson]

Yeah I'm kinda with wildcat here. I love the engineering talk but driving on these springs will give you an appreciation for how good they are. Very excited to finally drive my car in anger next month and see how squat/dive and launch have changed.

The engineering talk usually has ramifications beyond the specific discussion. It's one thing to hear that some particular modification works well, but a fuller understanding of why is at least as valuable. Perhaps some insight concerning sta-bar or damper settings when dual-rate springs are present could come out of this one, and if only one trial and error iteration with either of those was avoided by knowing it, I'd call it worth it. The knowledge would be portable to any other car that anybody might choose to fit with similar springs.


Norm

 

[wildcatgoal]

I have done some experimenting with my sway bars with these. I can run full soft and I get less body roll than higher settings with previous springs. I need better seats bad now... turbo have gotten faster and I’m about to go out the window, haha.

 

[TennTex]

While I appreciate the technical discussion as an engineer, I have to admit that my on-track driving is mostly by feel. I've been slowly expanding my "envelope" over the years, and I believe all these Steeda parts I've added have definitely increased the car's envelope. So, this gives me something to go chase for a while!

The setup with these springs, adjustables, and soft roll-bar settings result in a much flatter car than the stock GT-PP setup. In the last year or so, I went to MSR in these steps: a. Brand-new, bone-stock, b. New wheels/tires 18" w/ NT-01's, c. Addition of all the Steeda suspension parts.

No surprise, I took about 4 sec/lap with just better tires. The suspension changes have contributed to another 1~2 sec/lap. Of course, some of it is getting used to the new car (6 spd. vs. S197 5 spd), and all the other variables that come into play.

Happy 2018 to all!

 

[Gurjit]

What are your guy's thoughts on adding GT350R sway bars front and back to my GT with these dual rate springs?
I will be getting adjustable shocks this season hopefully.

 

[SteedaTech]

Steeda Set up

On our 2016 we have the front bar set at full soft with the rear bar set at he middle hole location.

Dampers are set 1 turn off soft front and 3/4 off soft rear

Running 3.0 neg camber front 1.8 neg camber rear 0 toe

Remember, Suspension tuning is very subjective to Driving style,tires,temperature,wheel selection,tire pressure, alignment settings,track conditions, etc.

That's why Steeda offers Adjustable sway bars and dampers for this application so you can dial in your S550 for your particular objectives.

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