Springs for the street

[Stig_v5.0]

@VoodooBoss Yeah I'm aware they're likely not worn out or really in need of replacement, but if I'm going to have the whole thing apart anyway, for $100 I might as well replace them. I've heard horror stories of them coming apart upon disassembly and people chasing ball bearings around the floor afterwards.

FRPP also recommends their jounce bumper kit and I can't confirm or deny if the car already has it, so I'll buy it and if I then later confirm it already has them, I'll return them.

The way I usually do things is over-buy and return unused things if I have to because I only have one car and I'd just rather not risk it on a car that absolutely positively has to roll every single day. Once I have it apart, it has to go back together by the end of the day or I'm walking to work. LOL

 

[VoodooBoss]

Pull the wheels on one side and post photos of it. We'll be able to ID most of the parts.

 

[Stig_v5.0]

@VoodooBoss Unfortunately I have no way to get the car off the ground at home other than ramps and thats not gonna help me get wheels off. The soonest I'd be able to get them off would probably be Saturday at work.

Here's what I know with 100% certainty so far.

The car has Koni STR.T struts and shocks. We know these struts require GT500 mounts to be mounted to my car. It has some rear spring with a Hyperco logo on it that matches color with the spring in the front that can't be ID'd at the moment. It has Ford marked bump stops in the rear that could theoretically be stock. The whole setup in the rear sits about 1" off the stops when loaded parked in my relatively flat parking lot and it rides really harsh in the back.

Also the other mods that are on it, LCAs/brackets, adj UCA, adj panhard bar.

What else I know for certain is that regardless of what springs those are, they're coming off. In the interest of time, I've just ordered a set of P springs and new strut mounts and the recommended Ford jounce bumper kit that will be delivered Friday. I'm gonna tear the thing apart Saturday morning at work. Should it turn out that I not need the mounts or the jounce bumpers, I'll send them back. Either way, we'll have a real good idea what's on there once they're laying on my shop floor at work LOL

 

[ArizonaBOSS]

I can't remember what the deal was with the strut mounts being different for certain--I believe this only impacted users if you were also installing aftermarket camber plates at the same time--in which case the upper mount needed to be a certain year range to butt up properly to the camber plate.

 

[Stig_v5.0]

@ArizonaBOSS From what I've been able to gather, the 05-10 strut design has a different dimension in the way which it mounts to the strut mount.

Apparently, when the Coyote engine came out in 2011, there was a change ford made in the dimension to the front struts and a mount change and for a long time the aftermarket didn't pick up the change. They just kept producing 05-10 style struts as you could use an 05-10 GT500 mount (or aftermarket camber plates) with them and install them right into an 11+.

The difference between the two mounts is in the attached file here. The GT500 mount being the one on the left, the 11+ mount being on the right. It's fairly obvious which ones you have once you know what you're looking for under the hood, which took me a while, as any 11-14 style mount will have the final installed strut stud being nearly flush with the tower and a conversion will be protruding out of the tower due to the mounting surface being raised. My car does has the GT500 mounts, and therefore I know the STR.T struts on mine are the 05-10 style.

 

[302 Hi Pro]

Installed the FP Boss 302 T springs with 2012 OEM Boss / Mustang GT camber plates. When it came time to update my camber plated I went with the Steeda HD Adjustables. No need for me to pull 2.7-3.0 degrees of negitive camber.

So I never had to consider camber plate differences.

Grant will tell us for sure but, IIRC struts and camber plates have to be compatible.

302 Hi Pro

 

[Stig_v5.0]

@302 Hi Pro It sounds pretty reasonable that mounts and camber plates should have to be compatible but I can't speak on that for certain. I'm not exactly even concerned with running aftermarket camber plates because this is a daily driver and will be primarily a street car for the foreseeable future. Even in the event that I get a second or third car and park the mustang, I still can't see it ever being a dedicated track car because my schedule as a truck driver makes it almost impossible to make it to most track days. The easiest thing for me to do regularly is non-competitive autocross.

That all being said, I've ordered P springs and replacement GT500 mounts and bump stops, they should be here Friday. Hopefully this solves my street driving woes. After that I'll focus on wheels and tires.

 

[Mad Hatter]

I had P springs a while back and I thought they were ok..... until I changed to cortex coilovers. On the Street the cortex Koni race setup was nicer and more controlled then the P springs. Something I would have never guessed, I think maybe the P spring was too stiff for the stock Boss shocks?. And that was with a 600#/350# spring setup. With something like 450#/250# and the Cortex street setup , my bet the ride would be great. Just goes to show how important the shock setup (valves etc) is. I regret the money I spent on the P springs after the cortex enlightenment. My friend switched from Koni/P spring combo to Cortex Koni race and found the same results, more controlled on the street.

 

[Stig_v5.0]

@Mad Hatter
Coil-overs might be something I'm willing to investigate in the future, I've browsed the cortex selection many times and I could go bankrupt on their page haha

Also, UPDATE:

So, after tearing apart the car today, I was able to finally ID the springs. They're Steeda Sport linear springs. The front are marked steeda with a part number but the tears are marked Hyperco, which is apparently who actually makes the springs. American muscle has them listed as 1" front 1.25" rear drop. 200lb fr 175lb rear.

I also found out this car still had the factory bump stops installed, which likely added a ton to how harsh the rear was.

Anyhow, after installing the p springs and the Ford jounce bumper kit, the car rides worlds better. The front came up maybe an 1/8" and the rear came up about 1/2" but I expect it to settle a bit.

Overall, way glad I switched them. Those linear rate rears slapping off factory bump stops were a nightmare.

 

[VoodooBoss]

I'm glad the P springs worked out for you. They are a good starting point for most.

 

[302 Hi Pro]

Stig_5.0

Nice to read the P's are installed and all is well.
2HP

 

[Stig_v5.0]

Thanks @VoodooBoss @302 Hi Pro , I'm liking them a lot so far. While they may not be the best for performance, paired with the proper bump stops and the koni STR.T dampers I feel like they ride really well for my daily driving duties. Might have to invest in a watts link now just to see how much that changes everything! haha

 

[venom52]

Glad everything worked out and you now have the ride you wanted.

 

[Stig_v5.0]

@Mad302 thanks yeah I'm really happy with it and it should serve me well for the time being until turn into a full track rat and end up changing it all again lol

 

[Senna1]

I know this is a few months old, but do you have any driving impressions after having the P springs on for a while?

I know Sam Strano advocates for the STR.T/Steeda Sport (linear version) combo as a daily driver setup, but you obviously weren't too happy with it. Did the P's make a significant difference? Their listed rates you commonly find for them are very similar to the Steeda sports, at 204/175, but they're also advertised as progressives with slightly less rear lowering.

I'm looking to mildly drop my '13 w/ Brembos too, and deciding how far down the hole to go. By the maths, the STR.Ts are a good match for springs in the OE (131 lb/in) to ~230 lb/in range, but most seem to choose something with higher damping rates (Koni sport or Bilstein).

 

[Stig_v5.0]

@Senna1

Yeah, i feel the car is much more bearable on the street for me personally now. Thevrear came up a half inch vs what was on it and it mostly stays off the bump stops which helped the most I would imagine.

As far as track work, I can’t really say. I had it out on Sunday for the first time and was unable to really test it much because carbotech has sent me the wrong style rear pads and I was forced to run the street rears which quickly gave up the ghost whenever I’d pick up the pace. I wasn’t even really able to find out how the tires were as every time I’d start to pick up the pace the rears would fade.

That all being said, it seems pretty stable once it’s loaded up and planted, but it’s soft in transitions.

 

[Opolis]

I've got Koni SRT.T with Steeda Sports and think it feels pretty good. Experience first time on the track was similar to Stig_v5.0, street pads and couldn't push it too hard, overall stable once loaded up. I originally did not plan on tracking this car but now that I did it once, I wish I got the adjustable Koni's. I hear that the SRT.T's are like yellows on the softest setting. I wish I could firm them up a few clicks! I have no other suspension mods except for adjustable panhard bar and C/C plates.

 

[byronj]

I've got Koni SRT.T with Steeda Sports and think it feels pretty good. Experience first time on the track was similar to Stig_v5.0, street pads and couldn't push it too hard, overall stable once loaded up. I originally did not plan on tracking this car but now that I did it once, I wish I got the adjustable Koni's. I hear that the SRT.T's are like yellows on the softest setting. I wish I could firm them up a few clicks! I have no other suspension mods except for adjustable panhard bar and C/C plates.

I have a like new set of MM CC plates with BNIB GT500 upper strut mounts you might be interested in. If so PM me