Spring Rates for Track Use

[Ewheels]

I apologize in advance for a disorganized post here, a bit of a thought-vomit.

I'm getting more and more into track life recently and while I'm still learning to drive the stock suspension fast, I am looking into upgrading in the somewhat near future. (I like to have a plan of attack ahead of time.) My initial research into suspension eventually resulted in the tried-and-true setup of Ford Track shocks and BMR handling springs (250 lbs/in front rate). I know plenty of people running this setup successfully and have heard nothing but praise for it.

Diving in a bit deeper, I see the really hardcore track guys running 300, 400, even 600 lbs/in rates in the front. Not saying that I am anywhere close to the skill level that would require such rates, but it has me thinking that maybe the 250 lbs/in rate of the BMR springs is insufficient or that with practice and skill advancement over time, I would out grow the BMR springs.

I find it interesting that your typical off-the-shelf front springs (Eibach, BMR, Steeda, ect) for the S550 are all 250 lbs/in rate or lower. Are these all targeting street cars or your average consumer?

My car is not my daily but it is still a street car and will remain a street car. However, I do not mind sacrificing street comfort for greater track performance. In that case, should I skip the BMR springs and look for maybe a 300-400 rate spring for the front? (I'm only using the front rates for the sake of reference and comparison between brands. I know rear rates are another topic.)

Throwing a hail Mary here, but is there any Socal member here with aftermarket springs who wouldn't mind giving me a ride to get a feel for spring rates?

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[BmacIL]

The higher rate springs offer better geometric control, which generally improves grip overall, and quicker turn in. The key is to have a damper setup that can control the higher rates. This comes with big $$$. Having the stiffer front rate means that you have to drive it more late-apex, and do the turn in late and quick to then use the power. Midcorner momentum: sacrifice.

Do you have the BMR springs installed? Do you feel that they are limiting you? With the geometry correction arms, front BMR bar and rear LCA bearings, I do not find that the spring rates have limited the car's performance. Feedback from those who have driven mine on track and autocross is: balanced, controlled, flat. It could use a little tighter damper control for quick transitions (like autocross slaloms), but it's hard to find much to complain about.

 

[SteedaTech]

The Steeda Dual Rate Competition Springs have outstanding results in competition and track events!
https://www.steeda.com/Steeda-S550-...dling-Lowering-Springs-2015-2020_p_11538.html

 

[BmacIL]

I apologize in advance for a disorganized post here, a bit of a thought-vomit.

I'm getting more and more into track life recently and while I'm still learning to drive the stock suspension fast, I am looking into upgrading in the somewhat near future. (I like to have a plan of attack ahead of time.) My initial research into suspension eventually resulted in the tried-and-true setup of Ford Track shocks and BMR handling springs (250 lbs/in front rate). I know plenty of people running this setup successfully and have heard nothing but praise for it.

Diving in a bit deeper, I see the really hardcore track guys running 300, 400, even 600 lbs/in rates in the front. Not saying that I am anywhere close to the skill level that would require such rates, but it has me thinking that maybe the 250 lbs/in rate of the BMR springs is insufficient or that with practice and skill advancement over time, I would out grow the BMR springs.

I find it interesting that your typical off-the-shelf front springs (Eibach, BMR, Steeda, ect) for the S550 are all 250 lbs/in rate or lower. Are these all targeting street cars or your average consumer?

My car is not my daily but it is still a street car and will remain a street car. However, I do not mind sacrificing street comfort for greater track performance. In that case, should I skip the BMR springs and look for maybe a 300-400 rate spring for the front? (I'm only using the front rates for the sake of reference and comparison between brands. I know rear rates are another topic.)

Throwing a hail Mary here, but is there any Socal member here with aftermarket springs who wouldn't mind giving me a ride to get a feel for spring rates?

@Flyhalf has them with the FP dampers and has been winning time trial events in SoCal.

 

[thelostotter]

The Steeda Dual Rate Competition Springs have outstanding results in competition and track events!
https://www.steeda.com/Steeda-S550-...dling-Lowering-Springs-2015-2020_p_11538.html

Will these springs pair well with the FP Track dampers? I already have these shocks/struts new in the box and am looking for spring options.

 

[Norm Peterson]

I'm getting more and more into track life recently and while I'm still learning to drive the stock suspension fast, I am looking into upgrading in the somewhat near future. (I like to have a plan of attack ahead of time.) My initial research into suspension eventually resulted in the tried-and-true setup of Ford Track shocks and BMR handling springs (250 lbs/in front rate). I know plenty of people running this setup successfully and have heard nothing but praise for it.

Diving in a bit deeper, I see the really hardcore track guys running 300, 400, even 600 lbs/in rates in the front. Not saying that I am anywhere close to the skill level that would require such rates, but it has me thinking that maybe the 250 lbs/in rate of the BMR springs is insufficient or that with practice and skill advancement over time, I would out grow the BMR springs.

I don't see any major improvements happening with an increase in spring rates from 250-ish to 300, meaning that roll and pitch aren't going to be reduced by all that much (less than an 0.2° reduction in roll would be my guess). 400 and up is almost certainly going to be too much rate for conventional shocks and struts, which are going to be best matched to 250 and under.

While you do gain grip as you improve the cambers that your tires are actually operating at through higher spring and bar rates, you're also reducing mechanical grip slightly because the car becomes more sensitive to changes in vertical load caused by pavement roughness. Not much of a problem on a nice smooth track, maybe not so nice over bumps or you start using the curbs and running out onto the gators at track out.

I find it interesting that your typical off-the-shelf front springs (Eibach, BMR, Steeda, ect) for the S550 are all 250 lbs/in rate or lower. Are these all targeting street cars or your average consumer?

Generally yes to both. Keep in mind that your average consumer chooses to do spring swaps strictly for appearance reasons. It's probably why for advertising purposes most "big spring" kits are collectively grouped under the heading "lowering springs".

Springs up around 225 - 250 lb/in wheel rate (wheel rate being only a few % lower than the listed rate for front springs in a strut-suspended car) are specifically targeted toward people who are interested in handling seriously enough to accept a firm ride all the time but not to the point where they're ready to consider shopping for dampers at the $2000+ level. 250-ish is about where the GT350R rates have been, maybe a little softer than where the heavier 2020 GT500's rates are supposed to be.​

My car is not my daily but it is still a street car and will remain a street car. However, I do not mind sacrificing street comfort for greater track performance. In that case, should I skip the BMR springs and look for maybe a 300-400 rate spring for the front? (I'm only using the front rates for the sake of reference and comparison between brands. I know rear rates are another topic.)

I don't think I'd look past 250 until I'd at least moved up to 11" wide wheels and wider sub-200-treadwear tires. It seems to be at least possible to stiffen the suspension past what the tires can actually use, sort of related to what "shocking the tires" means to a drag racer.

In somewhat different wording from what Bmac asked above . . . what have you actually noticed about your car's behavior that makes you think that you need 300 lb/in or higher spring rates? Your own thoughts here, not "because other people run springs that stiff maybe I need to as well".


Norm

 

[SteedaTech]

Will these springs pair well with the FP Track dampers? I already have these shocks/struts new in the box and am looking for spring options.

Yes,they will work just fine. You will be impressed on the ride quality as well on the street.

 

[BmacIL]

I don't see any major improvements happening with an increase in spring rates from 250-ish to 300, meaning that roll and pitch aren't going to be reduced by all that much (less than an 0.2° reduction in roll would be my guess). 400 and up is almost certainly going to be too much rate for conventional shocks and struts, which are going to be best matched to 250 and under.

While you do gain grip as you improve the cambers that your tires are actually operating at through higher spring and bar rates, you're also reducing mechanical grip slightly because the car becomes more sensitive to changes in vertical load caused by pavement roughness. Not much of a problem on a nice smooth track, maybe not so nice over bumps or you start using the curbs and running out onto the gators at track out.

Generally yes to both. Keep in mind that your average consumer chooses to do spring swaps strictly for appearance reasons. It's probably why for advertising purposes most "big spring" kits are collectively grouped under the heading "lowering springs".

Springs up around 225 - 250 lb/in wheel rate (wheel rate being only a few % lower than the listed rate for front springs in a strut-suspended car) are specifically targeted toward people who are interested in handling seriously enough to accept a firm ride all the time but not to the point where they're ready to consider shopping for dampers at the $2000+ level. 250-ish is about where the GT350R rates have been, maybe a little softer than where the heavier 2020 GT500's rates are supposed to be.​

I don't think I'd look past 250 until I'd at least moved up to 11" wide wheels and wider sub-200-treadwear tires. It seems to be at least possible to stiffen the suspension past what the tires can actually use, sort of related to what "shocking the tires" means to a drag racer.

In somewhat different wording from what Bmac asked above . . . what have you actually noticed about your car's behavior that makes you think that you need 300 lb/in or higher spring rates? Your own thoughts here, not "because other people run springs that stiff maybe I need to as well".


Norm

All this...thanks as always for adding on Norm.

I have to remind myself often that perfect is the enemy of great. The ~230-240 wheel rate all around is an extremely good dual use car. It's competent on the track (much more so than stock rates) but not punishing on the street.

 

[Ewheels]

balanced, controlled, flat. It could use a little tighter damper control for quick transitions (like autocross slaloms), but it's hard to find much to complain about.

This is exactly what I hear from everyone about the Ford shock/BMR spring combo and exactly why this was my plan forward. But it had me thinking if these 250 rate springs are flat and balanced, then why would racers need spring rates 3 times that? I would love to personally feel these BMR springs for myself before purchase if possible.

 

[BmacIL]

This is exactly what I hear from everyone about the Ford shock/BMR spring combo and exactly why this was my plan forward. But it had me thinking if these 250 rate springs are flat and balanced, then why would racers need spring rates 3 times that? I would love to personally feel these BMR springs for myself before purchase if possible.

If you're running significant aero, or slicks, the higher rates become more necessary or advantageous to account for the downforce and also to maintain ride height. For a track only car, I definitely see the desire to go there. For a mixed street car, they can be a bit much. For autocross, they can be an advantage because the time between corners is less and you need the sharp response for the best run. Once again, you'll need to spend $2500+ to get dampers that can properly control those springs. They will be better on track, but not necessarily better for your goals overall.

The FP/BMR combo fills the dual purpose requirement very, very well. It's not by accident that it was developed. See the spring rate sticky, page 9-10 .

 

[Flyhalf]

The FP with the bmr handling springs work awesome. I paired them after 3 months with Bmr front sway bar. Medium.
I went 1second faster at Buttonwillow,CA.
i personally believe that it must be a combo between spring rate and sway bar.
Of course all connected with a good amount of camber(-3 front)
My car is very precise in turn entry and with the bmr sway bar I do have a better stability also in heavy fast Change direction.
The 250/980.linear combo seems to perform great wkth FP struts.
Alessandro View attachment 411091

 

[ModularKid21]

I end up (maybe as the op has) in the black hole that is suspension threads, wondering if/when I should upgrade springs and dampers. And I emerge thinking I should upgrade springs and dampers without any real info to back it up. But my car is a street car as most others, so the Steeda ultralites and FP dampers combo works great. As stated previously, I decided I should get a set of 11” wheels and sticky tires, and get into some more events until I “outdrive” my suspension, then I’ll upgrade

 

[Norm Peterson]

But it had me thinking if these 250 rate springs are flat and balanced, then why would racers need spring rates 3 times that?

Racers have a real need for - and the ability to consistently realize - gains that lie deeper into the realm of diminishing returns. For them, a half second drop in lap time would be significant.

For an HPDE driver whose lap times might be scattered over a two or maybe three second range even for laps when there isn't any traffic, a half second isn't nearly as meaningful. If you could even separate the effect of the mod out from the normal amount of lap time scatter.


Norm

 

[BmacIL]

The FP with the bmr handling springs work awesome. I paired them after 3 months with Bmr front sway bar. Medium.
I went 1second faster at Buttonwillow,CA.
i personally believe that it must be a combo between spring rate and sway bar.
Of course all connected with a good amount of camber(-3 front)
My car is very precise in turn entry and with the bmr sway bar I do have a better stability also in heavy fast Change direction.
The 250/980.linear combo seems to perform great wkth FP struts.
Alessandro View attachment 411091

Completely agree on the front bar. It was a huge improvement to front end grip and overall balance vs the stock bar.

 

[Bluemustang]

@Flyhalf - thanks for your contribution. It's nice some actual gain attributable to the stiffer front sway bar. I have myself been debating the usefulness of the medium setting vs. just the soft setting.

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