Eibach Sportline springs question

[Jwh]

2018 GT Non PP with 255 wheels up front and 285 wheels on the rear. I also have upgraded my stock Shocks to the PP shocks.

My question is for my stock non PP struts....how big of a deal is it that I upgrade these before I put the eibach sportlines on? Are the stock struts good enough? I know and felt how terrible the stock shocks were and thats why i changed them. Anyways, any advice would be great.

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[Bluemustang]

IMO you would do well to get better dampers all around to be honest. Even the PP dampers may not be enough for those springs. But to answer your question it depends. I like my struts and shocks to match. Some people run mismatched struts and shocks and it works provided you know what you're doing. The Non-PP struts IMO are not good enough for those springs.

 

[Jwh]

@Bluemustang the springs you got....isnt that advertised as like a .5 inch drop in the rear? Yet every time i see a picture it looks closer to the wheel then i would imagine.

Would the springs you are using be too harsh on my dampers as well?

 

[Bluemustang]

@Bluemustang the springs you got....isnt that advertised as like a .5 inch drop in the rear? Yet every time i see a picture it looks closer to the wheel then i would imagine.

Would the springs you are using be too harsh on my dampers as well?

The SP083s were revised - the rear drop is now 0.75, Front 0.88. Likely, yes. In fact almost surely. There are people who have run PP dampers on them, but it won't have the control of the FP dampers or the other adjustables (Koni, Steeda). FP dampers are a good match for me.

What is your intended purpose? Lowering springs for looks more so or handling?

 

[Jwh]

@Bluemustang looks. I dont track the car or anything.

 

[Bluemustang]

@Bluemustang looks. I dont track the car or anything.

Ahh ok that's fine. I haven't tracked mine either although I will eventually. The Non-PP dampers really suck LOL. You'd do well to at least do PP struts or you could upgrade all four to Ford Performance.

Many folks with stock PPs have complained about the PP dampers. I haven't driven them so I don't know, but knowing that the PP dampers are barely enough on stock cars I think you'd do well with the Ford Performance dampers all around. More control in the dampers generally leads to a better ride even if that means increased responsiveness. It's going to ride stiffer and more responsive because of the lower COG and the higher spring rates of the Sportlines. But if its well controlled by the dampers it will ride better.

 

[Jwh]

Thanks for the info. When i had the non pp shocks pulled off I pushed down on it and i was stunned that it sunk in so easy compared toe the PP one. Was a night and day difference.

Honestly i'd love to get the koni adjustables all around and do the springs and call it a day.

I appreciate your info thank you.

 

[Jwh]

@Bluemustang if i was stubborn and went with the the sportlines before i went with the updated dampers what could i expect? Obvious more wear but how much more? Anything else that would happen?

Edit - also on eibachs website it claims the sportline springs are tested with the non performance package dampers. What do you make of that?

 

[Bluemustang]

@Bluemustang if i was stubborn and went with the the sportlines before i went with the updated dampers what could i expect? Obvious more wear but how much more? Anything else that would happen?

Yeah, the wear and it would be less controlled. It would most likely feel floaty and probably wouldn't inspire much confidence at highway speeds. I don't think any damage could come from it other than the obvious wear. It would likely just handle poorly.

The Sportlines also have a big drop. The lower COG is good but the even lower roll center is not good. The handling dynamics of the stock car will be changed in a negative way because the stock suspension geometry is now compromised to a degree, some might say a large degree. You may already be aware of this and that's okay. You're after looks and not so much handling. But add to that your dampers are not up to snuff, it won't be what you want. But you can probably drive it that way for awhile and it will be fine. Try it and see how it feels.

Although for cost reasons it might make sense to do springs and dampers at the same time unless you're installing yourself.

 

[Jwh]

@Bluemustang did you see my edit about how on their site they say they test it on the factory dampers and not on the performance package. Yet everywhere i read no one really recommends doing them on factory.

 

[Bluemustang]

@Bluemustang if i was stubborn and went with the the sportlines before i went with the updated dampers what could i expect? Obvious more wear but how much more? Anything else that would happen?

Edit - also on eibachs website it claims the sportline springs are tested with the non performance package dampers. What do you make of that?

Umm. well I'd believe what they say if they say it. I mean hey you could try it? It wouldn't cost that much to add dampers later if you decide.

Take a look at this. https://docs.google.com/spreadsheet...d-W1tL2arQSOM9Bd-TagA8py64/edit#gid=188571511

Above is a spreadsheet of all the spring rates for the popular springs out there.

Look at the change in rate from the GTPP. Sportlines are 217-331 Front, 879-994 Rear. Those are pretty high rates although most of the time it will be closer to 217F and 879R than 331F and 994R because the springs won't be fully compressed unless under full load. Still, it's a pretty big departure from 165 Front and 728 Rear in the GTPP. Higher rates tell me it needs more damping to be controlled.

Even though looks seem to be your primary factor, I reckon it'd smart for you to do some research on drops and spring rates and match your dampers to suit. That way you can have an approach that makes sense and do it once. Don't be like me and go through 2 spring/damper combinations lol. I learned the hard way. And even if you don't care about ride and handling now, chances are you will later even if you never track the car. You want a good road handling car. It makes it more fun and rewarding to drive.

Check out this spreadsheet too that @BmacIL did. https://docs.google.com/spreadsheets/d/1qExrjc7BqL7y8j1XQGotlHd9L3hT41aTpKySDTfhvCE/edit?usp=sharing
For some reason the Eibach Sportlines don't appear to be on here though.

The relationship of ride frequency from front to rear is important in how the car rides. If the ride frequency ratio is favorable, stiffer springs can still ride good. 1.10 is a good general ratio for a controlled ride for most cars. In our cars it might be closer to 1.05ish. Generally a slightly higher rear bias is good because when the car encounters a bump the front hits first obviously, but the car has not had time to settle before the rear hits it and thus you need a higher rear spring rate to control it.

Pick your choice of springs first is my recommendation and then match the dampers to the spring rates. Our cars don't like being lowered too much b/c it messes with the geometry too much and you get some negatives with that. Bumpsteer, body roll, reduced steering response, etc. Higher spring rates can compensate to a degree but not totally. It's good to stay at 1" or less on the drop or even 7/8". The rear suspension geometry is more susceptible to the geometry changing with lowering, however, the front experiences this as well and because the front steers the car it is also important IMO. Excessive bumpsteer and things like that aren't fun.

Anyway whatever you decide just some things to think about!

 

[Jwh]

Pretty much considering at this point to go for coilovers but then i got thinking with all the mods you have done, what stopped you from doing coilover kit @Bluemustang

 

[Roadway 5.0]

Sportlines have an aggressive 2” drop and progressive rate. You need to upgrade to adjustable twin tube dampers like Koni or Steeda. The twin tube design will give you the much need extra stroke (vs monotube) and give a slightly more plush ride. The rebound adjustment will help you control the bouncieness that you’ll surely get with those springs.

I caution street drivers on purchasing coilovers. Really study the spring rates you’ll be getting...if you’re not careful you may get a setup so stiff your car won’t be enjoyable to drive.

 

[Jwh]

@Roadway 5.0 i was considering getting the peddlers coilover kit

 

[Roadway 5.0]

@Roadway 5.0 i was considering getting the peddlers coilover kit

Those seem calm enough for a good ride at:

• Spring Rate: Front - 391 lb./in.; Rear - 782 lb./in.

To note: this is the lowest rear rate relative to the front I’ve seen for the S550; I’d be concerned of some handling imbalance. Turn-in should be outstanding though.

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