FRPP Dynamic Suspension with K-Springs Question?

Vader Stang

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I am a forum newbie. Picked up a 2014 mustang gt this winter. It is pretty much bone stock at the moment. I picked up a set of ford racing shocks, struts(non-adjustable) and K Springs. I am also going to throw on an adjustable panhard bar and the gt500 bump stops. I like the lowered look the k springs give.

My question is, do i need to upgrade my stock front and rear sway bars? I see AM wants close to 450 bucks for the pair. Seems a bit expensive and it looks like they are only 1mm thicker. I might track the car once a year for fun. But basically it is going to be 99% street.

Any advice will be much appreciated.

Thanks
 

Norm Peterson

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There's no need to do anything with the bars right away, and it might well be better not to. Give yourself a chance to find out if you like the car's new understeer/oversteer handling balance, and if not - which direction you want to shift it in. Nothing says you need to swap the bars at both ends of the car if changing only one might do it for you. Worst case if swapping only one doesn't, you can still get the other one. Get adjustable bars, whether it's one or two.


Norm
 

Sky Render

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What are you planning to do with the car?

I'd you just want a lower ride height, you don't need to do anything else.
 

Vader Stang

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Well, I do like the look the K springs will give me. I have a 90 fox body with koni coil overs, tubular k member, control arms beefed up engine and all the goodies, its pretty much made for the track. Only thing is I never get to the track:) One reason is the roads here in CNY about kill me to drive on more than an hour or so with the suspension in the fox body.

So I guess with the new stang I am looking for the best handling car for the twisties that still has moderate comfort on Central New York roads. Which it is getting harder to find smooth patches of pavement here. I joined a mustang club which goes to Watkins Glen(2.5 hours from my town) once a year and they also have a private track they hit once a year. I guess I should mention it is not my daily driver and will be stored during winter. But I will put a lot of miles on it in the summer.

I picked up the FRPP shocks and struts with the K springs cheap, they came assembled so I will be putting them on myself. I noticed that AM sells the ford suspension kit that included front and rear sway bars. Was hoping to skip them for now as my funds are running low. The fox body suspension was already installed when I bought it so I am looking forward to installing the new parts on the new stang and learning a little.

Norms advice seemed to make sense. I should put the car through its paces and get a feel for it with the new shocks and springs then go from there.

I am kind of chomping at the bit here because I bought the car in December and have only the ride back from the dealership. It has literally snowed like three times a week here since. I will be heading down to North Carolina to see my sister next week so I will get some more miles on the stock setup before installing the new springs and shocks when I get back.
 

oldVOR

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Ask the club you're a member of to see if anyone has modified their suspension and ask for a ride along one day to see how it feels. It will help to make your decision where you want to go with your own suspension by sampling the setup of others.

I will agree with Sky Render in that K springs are stiff and you'll feel every imperfection on the road. A good adjustable shock will help to mitigate this to a small degree.
 

Vader Stang

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Thanks for the info guys. Maybe if the K's are to stiff I can try the P's. When searching the forums I found mixed reviews with the K springs for ride quality. Seems like most of the ones complaining were using the stock dampers. Hopefully with the ford racing dampers my fillings won't fall out:)
 

travelers

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Thanks for the info guys. Maybe if the K's are to stiff I can try the P's. When searching the forums I found mixed reviews with the K springs for ride quality. Seems like most of the ones complaining were using the stock dampers. Hopefully with the ford racing dampers my fillings won't fall out:)

I might be selling that exact setup in the near future. I've had them on the car for 2 years and it's not a daily driver. In fact I think I have only 7K in that time frame.
 

Vader Stang

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I might be selling that exact setup in the near future. I've had them on the car for 2 years and it's not a daily driver. In fact I think I have only 7K in that time frame.
Are you running the K or P springs? How harsh was the setup on the road? I already have the shocks, struts and K springs.
 

RocketcarX

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I ran the original American Muscle SR Performance springs (K spring knock off) with new factory take off struts and shocks using GT500 strut mounts, the ride was great. Handled well and was still plenty complaint. The key is NEW struts and shocks, OEM was a great deal at something like #30 shipped for the rear pair and $70 for the front pair from eBay.
 

travelers

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Are you running the K or P springs? How harsh was the setup on the road? I already have the shocks, struts and K springs.

Sorry, I have the P springs with the Tokico/Ford Racing adjustable shocks and struts with J&M caster camber plates. The ride isn't really harsh but with the adjustable shocks and struts, it depends on your setting.
 

mrfatride

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i could be mistaken here but with lowered cars aside from a new panhard bar you might be better off with replacing the lower control arms and using LCA relocation brackets. will help with wheel hop and keep the rear more planted.
 

stevbd

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Vader, the FRPP dampers and K spring combo was discussed here last fall:

http://www.s197forum.com/threads/frpp-m-18000-c-vs-koni-yellows.133193/

IMO shocks generally make a bigger difference to ride than springs.

I use the P spring/Bilstein kit put together by Vorshlag with their CC plates and I feel the ride is better than stock. It's firmer but more supple if that makes sense, the abrupt impacts are actually less harsh and because the rear axle is so much more settled the ride actually feels better. It has far less of that flopping around skittering sensation from the back. Search Bilstein digressive valving to understand the tech behind this. Good luck!

EDIT: Also, you can see all the various common spring rates in that post above. You'll see the P and K springs have very similar spring rates, but with the K spring being shorter and I believe progressive rate, the real world difference could be more significant. I have no experience with the K. I wish my P springs sat a little lower but I have no complaints about the ride.
 
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Sky Render

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The Bilsteins are a popular choice for handling and comfort.

I'm still running Koni Yellows. They handle pretty damn good, but I would not call the ride comfortable.
 

frank s

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Is there a specific model Bilstein shock/strut that is popular? Is it the "B6" version, which is what Bilstein offers up on their site?
 

Norm Peterson

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I'm still running Koni Yellows. They handle pretty damn good, but I would not call the ride comfortable.

I have them as well and totally Agreed
I agree that the Koni yellows don't cope with short, sharp bumps (such as the joints between slabs on concrete roads) as well as they perhaps could, but are you guys dialing them back for street duty? Far enough?


Off-topic - multi-quoting here is a PITA. Not intuitive at all.


Norm
 
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Pentalab

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The Bilsteins that Vorslag sells will make the car sit 1/2" higher. IE: the P springs + normal Bilsteins will result in a 1" drop. (K springs will result in a 1.5" drop). The Vorshlag bilsteins + P springs = 1/2" drop. (1" with K springs).
I'm tempted to try the normal Bilstein front struts with my Roush front springs, since the Roush front springs only provide for a 1/2" drop. Roush front struts have the spring perch a 1/2" lower than oem, which is where they get the remaining 1/2".. for a total of a 1" front drop.

Roush front struts are rock hard, fine for smooth roads and hwy, but a real rough ride on any surface less than perfect. My pass side roush strut sheared after 4 years, so went back to oem struts on both fronts. Now it sits 1/2" higher + softer ride on front, too soft, too bouncy. I bottom out quite often, even though the car sits 1/2" higher. I think Bilsteins would provide for a firmer ride, without being too harsh. 1/2" front drop is ample for my application, since I have LT's and a 2.1" deeper auto tranny pan. I also lowered the eng 1/4".

Somebody posted the compression / rebound curves, for various loads for Bilstein, OEM, then koni yellows (twice, full soft, then full hard). The Bilsteins had a softer rebound than OEM, (and also koni set a full soft /hard) for the 1st portion of the curve, then the Bilsteins all of a sudden have a much harder rebound than oem. That probably explains why the Bilsteins feel smoother on minor road imperfections.
 
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Sky Render

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I agree that the Koni yellows don't cope with short, sharp bumps (such as the joints between slabs on concrete roads) as well as they perhaps could, but are you guys dialing them back for street duty? Far enough?


Off-topic - multi-quoting here is a PITA. Not intuitive at all.


Norm

The adjustment only affects rebound, not bump, so changing the adjustment for street use has no discernable affect on ride quality. At least, that was my experience.
 

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