S650 steering and handling is night and day difference compared to S550 Mustang says Chief Engineer Ed Krenz

[BoostRabbitGT]

I guess my next question would be...what parts of handling and steering feel are subjective, and which parts are based on factual data? (For reference, I daily drive my EcoBoost with Sport steering. I tried driving on Normal a few days ago and it felt too light in my mind taking a sharp turn.)

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[Hack]

The thing about steering feel as I understand it is you feel through the wheel when the tires are losing grip. So it doesn't really apply to driving around on the street. Possibly with really good feel you can notice a difference as the front end becomes more loaded due to cornering forces. But still during 99% of street driving a Mustang is not cornering hard enough to feel an appreciable load.

I think steering feel is one of those things that possibly driving professionals notice more easily but most of us aren't going to be able to tell. I believe I sense with my inner ear more than my hands when the front of the car is losing grip. Also modern heavy cars have really large heavy wheels and tires. The wheels and tires have so much rotational inertia that they damp out any feelings from being transmitted to the steering.

Definitely having a really tight harness will help a person to focus on things like steering feel rather than working hard just to keep in position behind the wheel when on track. I've noticed a big difference on track when using a harness and being relaxed in the corners rather than having every muscle in my body tense trying not to slide around thereby losing control of the car.

Steering feel in a modern car might just be an urban legend more than an actual thing, due to the big, heavy tires and wheels that have so much grip plus electrically power assisted steering. I think with a much lighter car that has less power and tiny wheels you will feel the tires let go, but when you get to a 4,000 lb monstrosity with 300+ section width tires, it's less likely.

 

[saleen367]

Rest assured Krenz is referring to the current base GT (as a comparison), which for all intents and purposes, is not marketed as a track focused car.

Every manufacturer has to build in compromises. Ford has (per Krenz) taken some of those compromises (to a degree) out of the S650 to appeal to the more spirited driving buyer. Most of those compromises consist of NVH mitigating, I.E. bushings, sound deadening, insulating materials. No one wants to drive a car as a daily with solid bushings.

The majority of Mustang buyers (as a %) are still the average Joe/Jane that drive the cars to/from work or for weekend road trips. We, the critics here, are really the exception, not the norm.

 

[Charlemagne]

Model for model guys. GT vs. SS. PP VS 1LE. Ecoboost vs whatever the base Camaro is.
No cherry picking.

Except they are fully comparable, Mach 1/PP2 vs 1SS 1LE. 1LE has 285/30 tires front, 305/30 rear and other chassis improvements meant for track. Endurance (coolers) aside, their handling is definitely comparable, as Randy Probst showed.

 

[OppoLock]

The thing about steering feel as I understand it is you feel through the wheel when the tires are losing grip. So it doesn't really apply to driving around on the street. Possibly with really good feel you can notice a difference as the front end becomes more loaded due to cornering forces. But still during 99% of street driving a Mustang is not cornering hard enough to feel an appreciable load.

I think steering feel is one of those things that possibly driving professionals notice more easily but most of us aren't going to be able to tell. I believe I sense with my inner ear more than my hands when the front of the car is losing grip. Also modern heavy cars have really large heavy wheels and tires. The wheels and tires have so much rotational inertia that they damp out any feelings from being transmitted to the steering.

Definitely having a really tight harness will help a person to focus on things like steering feel rather than working hard just to keep in position behind the wheel when on track. I've noticed a big difference on track when using a harness and being relaxed in the corners rather than having every muscle in my body tense trying not to slide around thereby losing control of the car.

Steering feel in a modern car might just be an urban legend more than an actual thing, due to the big, heavy tires and wheels that have so much grip plus electrically power assisted steering. I think with a much lighter car that has less power and tiny wheels you will feel the tires let go, but when you get to a 4,000 lb monstrosity with 300+ section width tires, it's less likely.

I look at the following criteria:

• On-center feel:
-how wide is the deadzone before the front end responds
-how well does it hold a straight line (which from my understanding largely comes down to caster angle)
-how busy is the front end or how much does it tramline

• Resistance/Load:
-when does resistance kick in; does it kick in early or does it start too late
-does it increase in load proportional to the amount of lock dialed in
-does it build up and lighten intuitively based on the front tires reaching or exceeding their friction circles
-is it over/under boosted, making the front end too heavy or too darty/floaty

• Texture/Feedback:
-does it transmit road bumps and textures; can you tell what general surface you’re driving on based on said feedback
-does the wheel provide sufficient bump/rebound/deflection feedback

•Accuracy:
-does it go exactly where you expect it to?
-is there a ton of slack in the input/response?
-do you have to saw at the wheel or make micro-corrections to hold a line

•Ratio:
-is it linear?
-is it fast (eg 11:1) or slow (eg 17:1)?

Wheel:
-diameter and thickness
-are the 9-and-3 ergonomic or is it shaped like one of those aftermarket monstrosities that people stick on their GTIs and Mustangs

The main things affected by HPAS to EPAS are the resistance and loading characteristics. EPAS systems tend to be extremely linear, to an artificial degree, with less proportional and intuitive loading based on what the front tires do. On the flip side, they provide massive levels of adjustment, don’t make fluid-pumping noises when crawling around parking lots at full lock, and are more fuel efficient too.

 

[BoostRabbitGT]

Hack and OppoLock, thank you for your replies to my questions. Even if my driving is limited to the streets, I think I have a better understanding now of handling/steering feel than I did previously.

 

[Hack]

I look at the following criteria:

• On-center feel:
-how wide is the deadzone before the front end responds
-how well does it hold a straight line (which from my understanding largely comes down to caster angle)
-how busy is the front end or how much does it tramline

Really good post and I'd like to discuss.

These first things you mention make me think about the GT350. I loved how that car really wanted to turn. The dead zone was very small, the car would respond and turn really quickly, and you could feel imperfections in the road.

The EPAS was not set up to be numb. I understand the EPAS can prevent most feedback from reaching the steering wheel. The GT350 is one of very few modern cars I've driven where I could actually get feedback from the road.

• Resistance/Load:
-when does resistance kick in; does it kick in early or does it start too late
-does it increase in load proportional to the amount of lock dialed in
-does it build up and lighten intuitively based on the front tires reaching or exceeding their friction circles
-is it over/under boosted, making the front end too heavy or too darty/floaty

A lot of modern cars feel artificial. The effort to turn the wheel never changes by much. But older cars with manual steering have very heavy steering when the car isn't moving but excessively light steering at highway speeds. I think I prefer the modern steering over an older manual steering car (or at least the ones I've driven).

• Texture/Feedback:
-does it transmit road bumps and textures; can you tell what general surface you’re driving on based on said feedback
-does the wheel provide sufficient bump/rebound/deflection feedback

I'm not sure I've noticed this kind of feedback. I can tell in my inner ear when I'm on gravel and the car is moving around without touching the steering wheel, but I don't think I've noticed much else - other than the wheel gets "lighter" on gravel.

Transmitting bumps and textures sounds like cowl shake and bump steer. Please correct me if you mean something else.

•Accuracy:
-does it go exactly where you expect it to?
-is there a ton of slack in the input/response?
-do you have to saw at the wheel or make micro-corrections to hold a line

Slack is a pretty obvious one that modern cars don't have, but most 60s and 70s cars do. Are there some notable old cars that don't have slack?

•Ratio:
-is it linear?
-is it fast (eg 11:1) or slow (eg 17:1)?

Are some cars not linear? Example?

Wheel:
-diameter and thickness
-are the 9-and-3 ergonomic or is it shaped like one of those aftermarket monstrosities that people stick on their GTIs and Mustangs

The main things affected by HPAS to EPAS are the resistance and loading characteristics. EPAS systems tend to be extremely linear, to an artificial degree, with less proportional and intuitive loading based on what the front tires do. On the flip side, they provide massive levels of adjustment, don’t make fluid-pumping noises when crawling around parking lots at full lock, and are more fuel efficient too.

I'm sure they cost less and save fuel, which is why they are on most cars. It's too bad that almost all companies prioritize cost and fuel savings over the driving experience.

 

[OppoLock]

I'm not sure I've noticed this kind of feedback. I can tell in my inner ear when I'm on gravel and the car is moving around without touching the steering wheel, but I don't think I've noticed much else - other than the wheel gets "lighter" on gravel.

Transmitting bumps and textures sounds like cowl shake and bump steer. Please correct me if you mean something else.

I could’ve worded it better, but it’s more to do with how the suspension is engineered and tuned and how that translates to confidence behind the wheel. Ideally, your suspension will absorb bumps and control vertical motions by maintaining as close to constant contact with the ground as possible when driving over irregular surfaces. You want to know what’s happening at the front without having to fight and wrangle the wheel back on track. Too soft, you don’t know what’s going on. Too stiff, and your car’s skiddish and the wheel will get deflected and pulled out of your hands, say whenever you hit a bump or kerb.

Cowl shake would typically be a sign of poor chassis stiffness. Bump steer is directly tied into one of the aspects I briefed just above.

Slack is a pretty obvious one that modern cars don't have, but most 60s and 70s cars do. Are there some notable old cars that don't have slack?

A better way of putting it is that select modern cars are more rigid and accurate than others. The only cars that have noticeable slack are riding on large sidewalls with soft suspensions and loads of unsprung mass. It’s almost unfair to use this as an example, but a Wrangler for instance, and to a lesser degree, something like an F-150. If you’ve rented or driven one for any period of time (or any like vehicle), you’ll get it.

But in the context I’m providing, if you’ve driven a few examples of modern performance cars, you’ll note that some have very little play in the steering and the front end more or less responds 1:1 with the tiniest of inputs. Almost any larger German performance car (and I’ll use Audi as an example because I’ve driven several and they really exemplify this), like an A4-A7, has zero feel, is heavily boosted, but is laser accurate with “tight” video-gamey steering.

But there are plenty of them that aren’t so hot. If you ever drive an F30 3-Series, for example, it has floaty, light, numb steering. It’s like the worst of all worlds.

Are some cars not linear? Example?

A ton of modern cars have variable gearing steering ratios, and often it’s an option. Usually this adjusts ratio based on road speed and is subtle unless you’re in extreme scenarios (crawling in a parking lot = super fast rack where you can fully maneuver without crossing hands/shuffling, or going very fast and having a slow ratio for subtle inputs/corrections).

But that’s not even really what I’m referring to. Some cars have darty off-center turn-in and it’s half to do with the rack as much is it is to do with the way the suspension’s setup. Last car I drove that bothered me in a noticeable way was a W204 C63. Darty nose, but it didn’t feel linear as you continued to dial in lock, so while the steering was accurate, felt good, and had very little slip, you were constantly making corrections to hold a line—say on something like a decreasing radius on-ramp—because the lock didn’t dial in the way you expect it to.

I’m sure there’s a bunch of professionals that would check my opinions, but this is just what I’ve come to observe over the years.

 

[Ericc B]

When a Ford engineer calls something a night and day difference compared to a previous version in my experience that usually means it is about 1% better than before.

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