Suspension newbie trying to stabilize car

fsvec · Aug 13, 2017

I’ll be going into suspension next as I feel the car is in dire need of it. First time doing suspension work as it’s the first time I feel the car needs it. I’ve browsed enough to feel like I know how to tackle it but any input would be a plus.

For a while now, the car has felt loose with steering and unstable at 70mph+ on the highway.

I took the car to the dealership twice as the feeling was enough for me to question if there was something wrong or broken. Both times they said the car is good and that feeling the road is part of the mustang experience :doh: .At first, I thought it was just one thing but after doing research it looks like the suspension for the s550 hugely benefits from a few parts to secure it down.

The two problems I’m trying to solve now are:

*Car feels floatly and unstable while going 70mph+

*Steering feels loose. Even at the track going straight it feels loose enough that any undulation on the road could easily steer it in the wrong direction or make me lose control. On normal roads, this is amplified as they’re not as nice as drag strips. I’m able to turn (more like wiggle) the steering wheel to both sides while parked on a level pavement, so it’s not really reflecting the changes in wheel direction. Steering problem has gotten progressively worse, before you could only feel it on the highway going 70+ which made me think it was related to the other problem. Now, unless driving on a straight and freshly paved road, it's loose city over here.

Both those problems combined makes me feel very insecure about the car, much less think about spirited driving. It’s gotten to the point where I’m not comfortable switching lanes “suddenly” or making turns without completely slowing down first. I have to grip the steering wheel when the roads curve a little because it feels like I’ll oversteer or lose control otherwise. I haven't lost control or anything of that sort yet, but I feel its imminent at this pace.

These are the parts I think I need to tackle this:
1. Steeda strut tower brace
2. BMR K brace (CB006)
3. BMR cradle lockout (CB005)
4. Steeda bumpsteer kit
5. Koni orange struts and shocks
6. Steeda billet rear shock mounts
7. BMR differential bushings (BK051)
8. GTPP front long arms
9. BMR front sway bar (SB004)

1 was installed, did tighten front end but mostly helpful for going over train tracks
I’ll be installing 2-4 this following weekend, the rest I’ll get down the line.
7-9 I’m sure will help, but not sure if necessary

Input, advice or reviews would be helpful. Thanks in advance!

Brian V · Aug 13, 2017

Man you must be driving on some really effed up roads to think that you have that severe of a problem with the suspension . Every one has stated about that floating feeling doing 70 on a highway . The rear dampers give you the bouncies because of the pavement is segmented for expansion . ( Expansion joints )

Dampers and a rear sway should get you started .
I drive with the steering set to sport for a better feel of how the steering performs .

BmacIL · Aug 13, 2017

fsvec said:
I’ll be going into suspension next as I feel the car is in dire need of it. First time doing suspension work as it’s the first time I feel the car needs it. I’ve browsed enough to feel like I know how to tackle it but any input would be a plus.

For a while now, the car has felt loose with steering and unstable at 70mph+ on the highway.

I took the car to the dealership twice as the feeling was enough for me to question if there was something wrong or broken. Both times they said the car is good and that feeling the road is part of the mustang experience :doh: .At first, I thought it was just one thing but after doing research it looks like the suspension for the s550 hugely benefits from a few parts to secure it down.

The two problems I’m trying to solve now are:

*Car feels floatly and unstable while going 70mph+

*Steering feels loose. Even at the track going straight it feels loose enough that any undulation on the road could easily steer it in the wrong direction or make me lose control. On normal roads, this is amplified as they’re not as nice as drag strips. I’m able to turn (more like wiggle) the steering wheel to both sides while parked on a level pavement, so it’s not really reflecting the changes in wheel direction. Steering problem has gotten progressively worse, before you could only feel it on the highway going 70+ which made me think it was related to the other problem. Now, unless driving on a straight and freshly paved road, it's loose city over here.

Both those problems combined makes me feel very insecure about the car, much less think about spirited driving. It’s gotten to the point where I’m not comfortable switching lanes “suddenly” or making turns without completely slowing down first. I have to grip the steering wheel when the roads curve a little because it feels like I’ll oversteer or lose control otherwise. I haven't lost control or anything of that sort yet, but I feel its imminent at this pace.

These are the parts I think I need to tackle this:
1. Steeda strut tower brace
2. BMR K brace (CB006)
3. BMR cradle lockout (CB005)
4. Steeda bumpsteer kit
5. Koni orange struts and shocks
6. Steeda billet rear shock mounts
7. BMR differential bushings (BK051)
8. GTPP front long arms
9. BMR front sway bar (SB004)

1 was installed, did tighten front end but mostly helpful for going over train tracks
I’ll be installing 2-4 this following weekend, the rest I’ll get down the line.
7-9 I’m sure will help, but not sure if necessary

Input, advice or reviews would be helpful. Thanks in advance!

I wouldn't bother with 4 unless you're significantly lowered (more than 1" from stock). 3 will make the rear of the car actually feel connected to the body and improve confidence when cornering and putting power down. 5 will take care of most of your floaty feeling. 6 will remove any bounce left that the shocks did not help with. 7 isn't necessary for most people and does absolutely nothing for your issues.

I would wait to do 8 or 9 until after you do 2, 3, 5, and 6. It will be a dramatic improvement with just those.

fsvec · Aug 13, 2017

BmacIL said:
I wouldn't bother with 4 unless you're significantly lowered (more than 1" from stock). 3 will make the rear of the car actually feel connected to the body and improve confidence when cornering and putting power down. 5 will take care of most of your floaty feeling. 6 will remove any bounce left that the shocks did not help with. 7 isn't necessary for most people and does absolutely nothing for your issues.

I would wait to do 8 or 9 until after you do 2, 3, 5, and 6. It will be a dramatic improvement with just those.

If not doing the bump steer kit then do what to tighten steering? I don't expect the steering to be static, but while going in a straight line I wouldn't expect it to feel like it wants to steer in either direction.

It's not the chassis moving, so it's gotta be something to help in this area, would it not?

BmacIL · Aug 13, 2017

That's not what a bumpsteer kit is for. It's for correcting geometry when you lower/raise a car.

A lot of what you're feeling is actually the lack of damping and an unsettled/disconnected chassis. What you perceive as the steering being loose is actually the entire car and unsprung mass moving around in ways it's not supposed to. Do the lockout kit, dampers and shocks mounts. Big improvements will come from those. Believe me I understand. My non PP car did this kinda stuff too.

Stuntman · Aug 13, 2017

What tires are you running and what pressure?

fsvec · Aug 13, 2017

Stuntman said:
What tires are you running and what pressure?

Bridgestone Turanza serenity plus, 32psi

Getting firestone indy 500's next

Stuntman · Aug 13, 2017

fsvec said:
Bridgestone Turanza serenity plus, 32psi

Getting firestone indy 500's next

Those all season tires are probably a big contributing factor to your issue. Try 40psi and report back if that makes it any better..

BmacIL · Aug 13, 2017

Stuntman said:
Those all season tires are probably a big contributing factor to your issue. Try 40psi and report back if that makes it any better..

I really wouldn't recommend this...

Yes all seasons are going to be much softer but regularly running elevated pressures isn't good for wear patterns or traction. Indy 500s will be a nice improvement though.

Stuntman · Aug 14, 2017

BmacIL said:
I really wouldn't recommend this...

Yes all seasons are going to be much softer but regularly running elevated pressures isn't good for wear patterns or traction. Indy 500s will be a nice improvement though.

I ran 40-44psi on my Pirelli PZero Nero all seasons for over a year. The added pressure increases the cornering stiffness of the super soft sidewalls so you mostly feel the tread flex rather than a complete lack of response from tread flexing on top of soft sidewalls (from low pressures).

Some people recommend mid 40s hot pressures on track. I do not, because of the lack of grip from running that high, however you're not going to burn out the center of the tire significantly running that pressure on the street and if you're on a crappy all-season tire, and having the steering response problems that fsvec is having, increasing pressures to 40psi will help.

0.02

BmacIL · Aug 14, 2017

Stuntman said:
I ran 40-44psi on my Pirelli PZero Nero all seasons for over a year. The added pressure increases the cornering stiffness of the super soft sidewalls so you mostly feel the tread flex rather than a complete lack of response from tread flexing on top of soft sidewalls (from low pressures).

Some people recommend mid 40s hot pressures on track. I do not, because of the lack of grip from running that high, however you're not going to burn out the center of the tire significantly running that pressure on the street and if you're on a crappy all-season tire, and having the steering response problems that fsvec is having, increasing pressures to 40psi will help.

0.02

I ran around 38-39 when autocrossing those tires to increase cornering stiffness. That's not what his issue is though.

Stuntman · Aug 14, 2017

BmacIL said:
I ran around 38-39 when autocrossing those tires to increase cornering stiffness. That's not what his issue is though.

His issue sounded like the description of a lower inflated all-season tire, which my suspicion turned out to be true. Let him try out higher pressures and let's see his feedback.

All-season tires are terrible and don't do anything well. There's likely nothing wrong with his car and he doesn't need to buy parts to "fix" it, other than putting on tires that aren't total crap.

BmacIL · Aug 14, 2017

Stuntman said:
His issue sounded like the description of a lower inflated all-season tire, which my suspicion turned out to be true. Let him try out higher pressures and let's see his feedback.

All-season tires are terrible and don't do anything well. There's likely nothing wrong with his car and he doesn't need to buy parts to "fix" it, other than putting on tires that aren't total crap.

Ehhh, the base suspension is pretty much crap. It's pretty compliant and comfortable, but it floats, is unresponsive and horribly damped. Upgrading dampers and doing the cradle lockout is a good thing for every S550 owner that drives the car at more than 3/10ths.

I did not find the P-zero Nero to be awful for responsiveness. Is it as good as a max performance summer? Of course not, but it wasn't terrible.

Stuntman · Aug 14, 2017

BmacIL said:
Ehhh, the base suspension is pretty much crap. It's pretty compliant and comfortable, but it floats, is unresponsive and horribly damped. Upgrading dampers and doing the cradle lockout is a good thing for every S550 owner that drives the car at more than 3/10ths.

I did not find the P-zero Nero to be awful for responsiveness. Is it as good as a max performance summer? Of course not, but it wasn't terrible.

The base suspension makes the Mustang outperform a E90 M3 on track do it must be crap.

There's a big difference from the Nero and the Nero All-season, which greatly benefits from higher pressures.. Same for Dave's crappy Turanza All-Seasons.

Suspension newbie trying to stabilize car

fsvec

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Brian V

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fsvec

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