Suspension mods to plant the car at higher speeds

[TheReaper]

OK, I apologize if I came up a little trollish, definitely not intended. I have a sense of humor that I forget some people don't like too much.

Turning humor knob down...

It's either springs or tires. My 14 GT stays well planted at 150 on stock suspension so I would expect the s550 do be even better.

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[Performance nut]

It's either springs or tires. My 14 GT stays well planted at 150 on stock suspension so I would expect the s550 do be even better.

Maybe the S550 is different. I got the same feeling when I opened mine up, like it was "floating" and mine was stock at that time. Last time I had that feeling on another car, it was damping that solved it for me (not enough of it).

Aerodynamics as in components that create downforce on the car, may also be considered. Not saying it is needed, just something to consider if you plan on going hella fast (more than what a stock S550 can take you). Usually you have to get going pretty damn fast to generate sufficient downforce (unless you have a really aggressive setting). The rest of the time, it just causes you to have crappy fuel efficiency.

 

[EFI]

100+ is pretty high to me.

Have you ever been in an airboat? It feels very little like that. When you turn the steering a little is not very responsive, like there is a tiny delay. Hard to explain, the car feels more like it is floating rather than on rails like I want it.

I come from a G37s and that car was planted at all times, it gave me a lot of confidence to drive it at high speeds. The Mustang feels like at any moment I could lose control. Kind of like driving a big Pickup truck at high speeds. Not nice at all and the Mustang isn't nearly as heavy as PU. I would like to fix this issue.

Have you actually lost control or seen any specific issues with the high speed handling? It seems you "feel" the car is like that but you don't have any actual examples. And just basing this on "feel" is a poor way to do it. You may feel like it's about to come loose, but in reality it's not.

I can't imagine that a G37 feels like it's on rails but a GTPP feels loose (unless the G37 was modded extensively). I had a 2012 G37 Sport and it does not even come close to the handling and stability of the GT I have currently. Makes me think your feel meter is off and that's why I asked if you had any actual experience rather than just feel.

If everything checks out, as in you don't have any damaged suspension parts, I would say it's mostly in your head.

 

[avocet]

I've had similar, but I had adjustable shocks set too soft.
When loaded up, and with passenger, the ride at speed (100)
Felt unstable, floating ( at the front) I was making minute adjustments on steering wheel as I was driving to keep it straight.I adjusted my suspension stiffer, fitted steeda sway bars,now it feels safe and I have the confidence to open her up.I think because they were set soft, if you had extra weight in the car,it made it light in the front, making it feel loose.

 

[jbailer]

Have you tried clocking the bushings? If you didn't have a problem before the springs were installed and you're confident in the alignment, this is the only thing I can think of.

 

[G-Rell]

I just did sportlines this weekend... been fine to 80 (without the alignment). It handles differently for sure... but no "floating"

 

[fcarpio]

Have you actually lost control or seen any specific issues with the high speed handling? It seems you "feel" the car is like that but you don't have any actual examples. And just basing this on "feel" is a poor way to do it. You may feel like it's about to come loose, but in reality it's not.

I can't imagine that a G37 feels like it's on rails but a GTPP feels loose (unless the G37 was modded extensively). I had a 2012 G37 Sport and it does not even come close to the handling and stability of the GT I have currently. Makes me think your feel meter is off and that's why I asked if you had any actual experience rather than just feel.

If everything checks out, as in you don't have any damaged suspension parts, I would say it's mostly in your head.

There is another thread I created for a similar issue. The car actually lets loose when accelerating and changing lanes. I have to correct to not spin out. Like I mentioned earlier, the new springs (eiback sportlines) made it worse. I'll keep reading here and try the things that some of you have already suggested.

 

[BmacIL]

There is another thread I created for a similar issue. The car actually lets loose when accelerating and changing lanes. I have to correct to not spin out. Like I mentioned earlier, the new springs (eiback sportlines) made it worse. I'll keep reading here and try the things that some of you have already suggested.

Well, you put springs on that are far higher rate than your stock ones and put the car's geometry way out of whack compared to stock. So, lack of weight transfer control and possibly poor contact patch and suspension geometry.

 

[fcarpio]

Have you tried clocking the bushings? If you didn't have a problem before the springs were installed and you're confident in the alignment, this is the only thing I can think of.

did not do that and they mention the floating feeling. This is validation for me, now I know I am not imagining things...

 

[fcarpio]

I just did sportlines this weekend... been fine to 80 (without the alignment). It handles differently for sure... but no "floating"

Take it up to 100 and SAFELY change lanes. Let me know how it goes.

 

[fcarpio]

Well, you put springs on that are far higher rate than your stock ones and put the car's geometry way out of whack compared to stock. So, lack of weight transfer control and possibly poor contact patch and suspension geometry.

Yep, I did it!

 

[s550v6]

The symptom I am trying to fix is the feel of instability at higher speeds. The car does not give me confidence at all. The only suspension mods so far are Eibach SportLine springs. The car felt much better before the springs. At high speeds it feels as it sways a little from side to side. It does not feel stable at all. I have been told that this is just the way the car is, but that is not good enough.

What can I do to make the car feel more stable?

You may need to do shocks and struts to get the feeling youre looking for. I did BMR's SP080 springs and Steeda's pro action fixed shocks/sturts and my car feels planted at 125+ on less than ideal surfaces. Clocking the bushings helped with the bounce a little but also adding spherical bearings where the struts and shocks meet the car made a huge difference in stability. BMR's CP001 caster camber plates and Steedas billet rear shock mounts went on at the same time, but after the whole suspension went in, and they made a very noticeable difference in just how stable the car feels. Its way more planted than floating over the road on pillows-for-bushings.

 

[Bluemustang]

Well, you put springs on that are far higher rate than your stock ones and put the car's geometry way out of whack compared to stock. So, lack of weight transfer control and possibly poor contact patch and suspension geometry.

[MENTION=10281]BmacIL[/MENTION] - I know that front suspension geometry is "fixable" in terms of caster / camber plates and bumpsteer kit if necessary, but I assume the rear geometry is not changeable (other than camber) without significant chassis modifications. Is that right? So in other words, if you lower the rear too much you will get a lot of geometry change?

 

[BmacIL]

[MENTION=10281]BmacIL[/MENTION] - I know that front suspension geometry is "fixable" in terms of caster / camber plates and bumpsteer kit if necessary, but I assume the rear geometry is not changeable (other than camber) without significant chassis modifications. Is that right? So in other words, if you lower the rear too much you will get a lot of geometry change?

Yes the roll and pitch centers, camber gain, plus bump steer all change with lowering. The motion ratio is also not a straight line and changes some with displacement. I'd personally not go significantly further than 0.5" in the rear based on my conversations with those in the know.

This is on a performance basis alone and not factoring in looks, which is a big reason many springs are 1" drop.

 

[Bluemustang]

Yes the roll and pitch centers, camber gain, plus bump steer all change with lowering. The motion ratio is also not a straight line and changes some with displacement. I'd personally not go significantly further than 0.5" in the rear based on my conversations with those in the know.

This is on a performance basis alone and not factoring in looks, which is a big reason many springs are 1" drop.

I wonder why Ford Racing would engineer their track package to lower the car and inch on all 4 corners when the bumpsteer is already bad in this car, and the lowered ride height increases both camber and caster. The Mustang came with a caster of 7. Mine is about nearing 8 possibly more now that I'm lowered.

I read on Steeda's website - they say that most race cars have a caster of 6 to 8 and the Mustang comes from the factory with a caster of 7. They noted that if you go over 8 on the caster that it will put the camber out of its good range. I assume they mean dynamic camber, or the additional lean during cornering?

What irks me is that companies claim to sell you on lowering springs and similar items which will give you "race-car like handling" but they fail to mention that it messes up the geometry of the car and they don't include anything to remedy it. So the customer is left with a good looking car that can't handle for shit and is all over the road because of bumpsteer and alignment is off.

The average consumer doesn't know these things. I'm not a technical suspension engineer. I can't re-design the Mustang's suspension like I would need to to make a lot of these products actually effective.

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