Need advice on my suspension

[krishelnino]

Yeah right, my concern is if I'd be having too much bar front and rear after doing the SP083 springs, hence i was thinking about swapping them out. The FP rear one is also 25mm compared to GT350 and OEM PP at 22mm.

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[shogun32]

7) Add Steeda diff bushings - the red ones

unless you're just wed to keeping the factory rubbers hanging around I suggest the Whiteline replacements instead. The diff doesn't sing unlike with the 'sandwich' solutions.

 

[krishelnino]

unless you're just wed to keeping the factory rubbers hanging around I suggest the Whiteline replacements instead. The diff doesn't sing unlike with the 'sandwich' solutions.

Thanks, i'll take a look at those. Since i'd be swapping the diff, might be easier to do them at the same time

 

[Bluemustang]

Yeah right, my concern is if I'd be having too much bar front and rear after doing the SP083 springs, hence i was thinking about swapping them out. The FP rear one is also 25mm compared to GT350 and OEM PP at 22mm.

IMO the big rear bar is not great for this car. I don't see a need for it. You can use it as a tuning aid, but as you go bigger you lose ultimate grip potential. And it seems to be contrary to the car's attributes being front heavy (and heavy overall), RWD and big power. Rear traction is at a premium. You can make the car oversteer if you provoke it enough anyways. Getting the most power down coming out of corners is critical.

The sway bar plays the role of increasing roll resistance but it does so with a byproduct of making your independent suspension less "independent".

Also, consider tires in your equation. As you increase roll resistance either by springs or bars, (or combination thereof) your tires will become the weak link. A more responsive and grippy tire will actually make use of that upgraded suspension.

 

[Bluemustang]

I say keep the FP rear bar once you upgrade to the SP083s. Try it out. I think you'll see what I'm talking about it. Later on you could still try the PP bar and then you'll feel the change, understanding what it does.

 

[Bluemustang]

The FP track front spring is pretty much the same rate as the BMR front. It's about 240 lb/in if I recall. Not enough for him to even feel.

I don't know the exact specs of the FP track rear spring, but I know it is a dual rate. I believe the high rate portion is 914 lb/in. Based on my experience and the change in balance after swapping to the SP083 980 lb/in rear spring, I'm pretty sure the initial rate portion of the FP has to be pretty soft. This could explain why this works on the Ford Performance track kit, which has the larger rear bar.

It's also important to realize the Ford Performance track is OEM basically, so the intent had to be increased performance over stock, as well to be marketed to a wide range of individuals. And whoever designed it also injected their preferences. And it also doesn't have subframe lockouts or other rear suspension mods many owners do. It had to be a good package right out of the box, and it is. But that doesn't mean it can't be improved upon for the enthusiastic user who wants a bit more.

 

[krishelnino]

IMO the big rear bar is not great for this car. I don't see a need for it. You can use it as a tuning aid, but as you go bigger you lose ultimate grip potential. And it seems to be contrary to the car's attributes being front heavy (and heavy overall), RWD and big power. Rear traction is at a premium. You can make the car oversteer if you provoke it enough anyways. Getting the most power down coming out of corners is critical.

The sway bar plays the role of increasing roll resistance but it does so with a byproduct of making your independent suspension less "independent".

Also, consider tires in your equation. As you increase roll resistance either by springs or bars, (or combination thereof) your tires will become the weak link. A more responsive and grippy tire will actually make use of that upgraded suspension.

Wider wheels/tires are next on my list. i'm already way over my budget for this year ;) Since i'm doing the diff swap and shifter, i thought it would be best to take care of the suspension at the same time since it would save a lot on labor costs and down time (mine is a DD). I'm planning on getting a 2nd set of wider square wheel setup 19x11 and 305 summer tires next year. I'll have that set dedicated for track days and summer weekends

 

[krishelnino]

The FP track front spring is pretty much the same rate as the BMR front. It's about 240 lb/in if I recall. Not enough for him to even feel.

I don't know the exact specs of the FP track rear spring, but I know it is a dual rate. I believe the high rate portion is 914 lb/in. Based on my experience and the change in balance after swapping to the SP083 980 lb/in rear spring, I'm pretty sure the initial rate portion of the FP has to be pretty soft. This could explain why this works on the Ford Performance track kit, which has the larger rear bar.

It's also important to realize the Ford Performance track is OEM basically, so the intent had to be increased performance over stock, as well to be marketed to a wide range of individuals. And whoever designed it also injected their preferences. And it also doesn't have subframe lockouts or other rear suspension mods many owners do. It had to be a good package right out of the box, and it is. But that doesn't mean it can't be improved upon for the enthusiastic user who wants a bit more.

I wish i could experiment a little bit. However since this is my only car and due to my work schedule plus the shop being closed on weekends, i'd like to avoid the hassle of going back and forth. I'm not comfortable working on the suspension by myself so i always have a shop do it. Hence i'm just considering the combinations that worked well for you, BMacIL and many others.

Even if the FP front springs are identical in rates compared to BMR SP083, but they're still progressive and not linear right ?

The FP bars are unknown commodity, i've searched around but couldn't find any bar stiffness rates to compare against. If they were available i could compare against the BMR to see what difference they could make.

I've found this nice chart made by Brian
https://www.mustang6g.com/forums/threads/sway-bars.119344/page-3#post-2503192

 

[Bluemustang]

Wider wheels/tires are next on my list. i'm already way over my budget for this year ;) Since i'm doing the diff swap and shifter, i thought it would be best to take care of the suspension at the same time since it would save a lot on labor costs and down time (mine is a DD). I'm planning on getting a 2nd set of wider square wheel setup 19x11 and 305 summer tires next year. I'll have that set dedicated for track days and summer weekends

Good idea. Yeah, it gets expensive man lol. I hear ya. Just got a set like that for myself.

I wish i could experiment a little bit. However since this is my only car and due to my work schedule plus the shop being closed on weekends, i'd like to avoid the hassle of going back and forth. I'm not comfortable working on the suspension by myself so i always have a shop do it. Hence i'm just considering the combinations that worked well for you, BMacIL and many others.

Even if the FP front springs are identical in rates compared to BMR SP083, but they're still progressive and not linear right ?

The FP bars are unknown commodity, i've searched around but couldn't find any bar stiffness rates to compare against. If they were available i could compare against the BMR to see what difference they could make.

I've found this nice chart made by Brian
https://www.mustang6g.com/forums/threads/sway-bars.119344/page-3#post-2503192

Front spring is linear. Rear is a progressive dual rate. The main differences to the SP083 is you're getting a stiffer, linear rate rear spring. And also they will reduce your ride height drop is a little bit, which is good IMO.

In the event that you can't test or don't want to mess with it again, using the FP front bar and PP rear is your best bet to a balanced car. A pretty good bet IMO.

 

[krishelnino]

Good idea. Yeah, it gets expensive man lol. I hear ya. Just got a set like that for myself.



Front spring is linear. Rear is a progressive dual rate. The main differences to the SP083 is you're getting a stiffer, linear rate rear spring. And also they will reduce your ride height drop is a little bit, which is good IMO.

In the event that you can't test or don't want to mess with it again, using the FP front bar and PP rear is your best bet to a balanced car. A pretty good bet IMO.

So this thought popped up in my mind after reading your last post. If the FP front spring rate is indeed linear, then i could probably keep it as is and just swap the rear springs to SP083R? This way i don't have to mess anything at the front of the car. The rear i'll just thrown on the OEM PP/GT350 swaybar to keep the balance.

 

[Bluemustang]

So this thought popped up in my mind after reading your last post. If the FP front spring rate is indeed linear, then i could probably keep it as is and just swap the rear springs to SP083R? This way i don't have to mess anything at the front of the car. The rear i'll just thrown on the OEM PP/GT350 swaybar to keep the balance.

You could. The FP front spring will ride lower, increasing your rake at least another 1/8 or 1/4".

 

[krishelnino]

You could. The FP front spring will ride lower, increasing your rake at least another 1/8 or 1/4".

Probably a bad idea, i realized i forgot about the ride height. The SP083 springs have the ride height optimized for geometry.

 

[TeeLew]

You could. The FP front spring will ride lower, increasing your rake at least another 1/8 or 1/4".

What's the consensus on the S550 rake sensitivity? In theory, lowering the front and/or raising the rear should reduce understeer. Do people find this to be the case in practice? What else do they find?

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