Springs for the street

[Stig_v5.0]

As the title suggests, I'm looking for advice on what springs to use for my '14 GT.

This car is 99.9% street car. It currently has a Koni STR.T kit on it best as I can tell and to me it rides hard and is a little bit too low for our local roads, speed bumps, and my driveway if I'm not careful. I believe the drop is 1" front, 1.5" rear.

I wouldn't mind coming up a little bit from the current height in order to regain some ride quality, but I don't want the thing to scrape its door handles on curvy roads either.

I've read about P springs being mild drop but being a marked improvement? Comments on this?

 

[venom52]

On the wife's car i run SR springs with stock struts and suspension and she loves it. She's driven to and from ohio like it. Mine i have Koni yellows with sportlines and it's a little firmer than stock on the soft setting. Looks like the kit comes with proline springs so the P or comparable spring would hopefully soften it up for you.

 

[Stig_v5.0]

It looks like both the SR springs and the Sportlines advertise even more drop (1.5 front) than the what I currently have which is advertised as 1" front.

Now that I've looked at it a little closer, I think my only option might be to go P spring just because I have ground clearance issues as it is and I think another half inch would really crank that up to 11.

 

[venom52]

Very true and a lot of people on here have used the P springs with no issues.

 

[Stig_v5.0]

What is this I'm reading about P springs needing different strut mounts?

Im assuming these springs work with the koni orange struts as long as I change to GT500 mounts as well. Not sure exactly what the difference is vs stock. Also wondering if it's something the previous owner may have already done?

Damn used, previously modified cars... haha

 

[venom52]

I would to see what you have already. Should be able to see either by looking up there from under or just pop the hood and see from the top.

 

[Stig_v5.0]

Sounds like a great idea now I just need to know what I'm looking that'll tell me which ones are on there lol

 

[VoodooBoss]

The P springs have worked well for many of us. If you want to go a bit lower in the back look at the FP Boss lowering springs. @302 Hi Pro had them on his car.

 

[venom52]

lol yeah that would the way unless you feel like taking a strut out and looking. I would say it's either stock or GT500 mounts.

 

[Stig_v5.0]

The P springs have worked well for many of us. If you want to go a bit lower in the back look at the FP Boss lowering springs. @302 Hi Pro had them on his car.

How do the Boss lowering springs compare to the P springs in terms of springrate? I'm more concerned with ride quality on junk Chicagoland roads.

 

[302 Hi Pro]

Hi Stig_5.0

Is it possible to remove a front and rear wheel and post a few pics? Often springs have Part Numbers printed on every other coil, so so. Also what color springs do you have? Might help to ID the spring manufacturer.

IIRC Ford springs like the P's & K's lower the car same amounts both front and rear. Except the T springs which lowere the car just under 1/2" front and just under 1.5" in rear.

Many Aftermarket spring sets have staggered (front/rear) lowering heights, like you mentioned above.

For a great ride look at the Steeda Boss 302 specific lowering springs.

Last, when you lower the car too much, other work must be done to compensate. As a rule, I wouldn't lower the front of my car more than 1/2". Sticking with 1/2" or less keeps your steering and front end geometry in good order.

Keep us posted on your finding of what you currently have. That is a must for a starting point.

Good luck,
302 Hi Pro

 

[2012-Boss]

Out of all the springs mentioned, I prefer the Steeda Boss springs. They maintain the front ride height within .25" of the OEM front boss spring and have about a .75" rear drop compared to the OEM Boss springs. The Steeda spring rates are 225 F / 195 rear.

Unless I am mistaken, the P springs lower the car a little more and have a slightly lower spring rate. The P springs would be my second choice, but many have had great success with these springs.

I would not be surprised if part of your ride quality issue is bottoming the rear end on the bump stops. When you lower the rear, especially 1.5", you need to increase the spring rate to keep off the bump stops. Its is a little counter intuitive, but in this case a higher rate can yield a better ride.

If your primary concern is ride quality and ground clearance, I would just install a set of OEM Boss springs.

 

[Stig_v5.0]

I might be able to get a wheel off at some point in the near future but this is currently my only car so I'm driving it a lot and don't have a garage and it's cold outside lol.

From having it sit next to known stock mustangs with the same wheels, it seems like it most likely has the pro line springs that come with the koni kit which would make it 1"front and 1.5" rear lower than stock GT height.

I'll have to look into the factory boss springs as well. It appears the boss sits roughly a half inch lower in the front that a GT and only slightly lower in the rear? Unsure.

The P springs advertise 1" drop all around which would effectively raise the rear of my car a half inch, so either would help my potential bottoming issue.

I think I might have to narrow it down between the factory boss spring and the P spring because I'm going to lose a little bit of ride height with a shorter wheel/tire combo when I go 285/35-18 vs 255/40-19 so I have to consider that as well.

 

[Stig_v5.0]

Anyone have part numbers or a known source for OEM boss springs?

Apparently the internet is finicky about showing me anything but aftermarket things today .

 

[byronj]

This might help you out. As for the Boss spring PN I would have to did out my springs. If my parts come in today maybe I can get to them.

https://performanceparts.ford.com/mustang/

 

[Stig_v5.0]

This might help you out. As for the Boss spring PN I would have to did out my springs. If my parts come in today maybe I can get to them.

https://performanceparts.ford.com/mustang/

Thanks. I've actually since sourced the part numbers and figured out I can get a set of OEM boss springs for around $100. I might go that route just out of sheer frugality.

 

[VoodooBoss]

Don't bother with factory Boss springs. Get the P's instead.

 

[Stig_v5.0]

@VoodooBoss I'm seeing a bunch of conflicting information about the P springs as they relate to 2011+ S197's. American Muscle says you need the GT500 strut mounts for those springs on a 2011+, but I'm also seeing people saying they've installed the P springs on factory equipment.

My understanding is that theres a shock shaft diameter difference between 05-10 and 11-14 but if all I'm doing is changing the spring I don't need to change anything. Does that sound correct?

Is there an easy way for me to tell by looking at them from under the hood which ones are currently installed? I'd like to replace them while I have it all apart regardless.

 

[Stig_v5.0]

Alright, well now I'm really curious to know what in god's name is on this car because while it definitely has Koni STR.T shocks and struts, it most definitely does not have Eibach springs. I couldn't ID the front springs because I dont have a way to lift the car to unload the front suspension at home but I was able to weasel my head under the rear.

While I could not ID the front springs, they are the exact same blue color as the rear springs which are marked "hyperco". I can't see a part number with the suspension loaded. What I CAN see is that there's only about an inch of travel space between the chassis and the Ford branded bump stops and, judging by the markings on the chassis, it's very very familiar with them. This car really needs to move up a bit.

I haven't been able to find much about hyperco springs, other than BMR sells some on their website for the rear, either 175 or 225 lb rate. They also look suspiciously the same color as SR springs that American Muscle sells. So I'm think thing theres a good chance that's what they might be.

Also it's come to my attention that Koni STR.T's are only available in 05-09 style and therefore this car must already have GT500 strut mounts. At least one problem solved here.

REGARDLESS;
I'm about ready to just buy the P springs and a new set of mounts and chop it up this weekend.

 

[VoodooBoss]

I'm not sure about the mounts but I don't think they will need to be replaced if you're just changing springs. The mounts can change when you install different struts. @302 Hi Pro or @Grant 302 or @ArizonaBOSS will know.