Your thoughts on IRS

[moose13]

Throwing my hat in the ring here. I have regularly driven two mustangs in my life: A 2012 V6, and my current 2016 GT. I understand where OP is coming from that the live axle is a different sensation and in some cases, preferable. That being said, I find it weird that most of this conversation has been about spirited/enthusiastic driving...

In the first few months of the '16 ownership, I hit a bump on a wet morning doing 35 on a tight on-ramp, and the car stepped out on me. I caught it without having do anything heroic, but was probably only possible with my full attention and both hands on the wheel. But I do remember recalling how the '12 drove after the fact, and thinking; sheesh, with the old live axle, I'm probably either facing the wrong way on that ramp or in a ditch right now. Obviously I'm never going to intentionally test that hypothesis, but I think based on my experience, the IRS is much more predictable and easily correctible in *unexpected* code-brown scenarios.

Just my two cents.

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[Sivi70980]

I've always loved the Mustang, but I've never wanted to own one until the S550. They were always cool and fun, but not great to ride in. My buddy got a 16 GT, and I was immediately sold.

When I test drove the 2018 GT I was skeptical and keeping my lust for the exhaust note in check till I hit some twisties, then it was game over man. Placed my order same day.

 

[gadgtfreek]

Throwing my hat in the ring here. I have regularly driven two mustangs in my life: A 2012 V6, and my current 2016 GT. I understand where OP is coming from that the live axle is a different sensation and in some cases, preferable. That being said, I find it weird that most of this conversation has been about spirited/enthusiastic driving...

In the first few months of the '16 ownership, I hit a bump on a wet morning doing 35 on a tight on-ramp, and the car stepped out on me. I caught it without having do anything heroic, but was probably only possible with my full attention and both hands on the wheel. But I do remember recalling how the '12 drove after the fact, and thinking; sheesh, with the old live axle, I'm probably either facing the wrong way on that ramp or in a ditch right now. Obviously I'm never going to intentionally test that hypothesis, but I think based on my experience, the IRS is much more predictable and easily correctible in *unexpected* code-brown scenarios.

Just my two cents.

I never owned a solid axle Stang, but I can see with simple muscle memory it is easy to control this car when it wants to swing its tail one way. And my car almost always goes the same way so it is very predictable. Other than speed humps and railroad tracks, the car rides better than my 2018 Accord.

 

[ctandc72]

FWIW, I bought my first S550 (new '17 V6 to replace my daily driver that was totaled when someone turned in front of me then panic stopped) BECAUSE of how it handled compared to the S197. I friend who is a big Mustang person talked me into test driving a Mustang. I drove a '13 GT and simply wasn't impressed. Honestly, I felt it didn't handle nearly as well as a string of mildly-modified 3rd Gen F-Bodys I had owned / built / driven over the years.

He convinced me to drive a S550. He even found a local dealer that had a used EB 6 speed. I drove it and was actually impressed by how it handled. That spurred me buying a new '17 V6 / 6 speed and I liked the platform enough to buy my '19 GT new. The S550 is NOT a small or light car, but it doesn't handle like a large car.

A lot of this "argument" is totally ridiculous since what one person thinks is "aggressive" as far as driving / cornering is often totally different from someone else's perspective / experience.

From a drag strip standpoint, things haven't changed since the 80s - when I working 2-3 jobs to put all my money in my '67 Chevelle......power finds the weakest link. Once you start increasing power and then get more successful in putting that power to the ground, from a launch, you will find the weak link and that's true for the S550 as well.

U-Joints, drive shafts, axle shafts, half-shafts, etc etc

What many Mustang owners tend to forget (Same as Corvettes, Challengers, Camaros etc etc) is that many people buy a Mustang as just a car. They don't mod it beyond visuals - if that - and with that in mind, the manufacturer needs to make the car as quiet and comfortable as possible - it's a compromise. Always has been unless you're talking much more expensive cars.

 

[Gregs24]

Swing axles are, in fact, a type of IRS. Just not a very good type, with serious limitations.

I think 'serious limitations' is being generous ! I would use the term 'death trap'

 

[Gregs24]

I've always loved the Mustang, but I've never wanted to own one until the S550. They were always cool and fun, but not great to ride in. My buddy got a 16 GT, and I was immediately sold.

I agree with this 100%. Pre S550 cars were a liability on UK roads

 

[NoVaGT]

I've had an 05 GT, 2012 Brembo GT, 2016 P1 GT, and a 2019 PP1 Magneride GT.

The 05 only had 300HP, and a rather soft suspension. It was a real GT car, more about relaxed cruising, but easy to toss around in corners for some fun.

The 2012 Brembo GT was actively trying to kill me. That SLA rear suspension, moving side-to-side, front-to-back, and up-and down was exhilarating, creating torrents of "is this the corner I die in??" adrenaline. The combination of S197/SLRA with Coyote power was......just silly.

The 2016 showed me that Ford fucked up it's IRS design, by mating it to a sub-frame that also held the diff, and which was in-turn softly mounted to the car.

Anyways.....2015+ are definitely better handling cars, but there's room for improvement for the IRS.

 

[Cobra Jet]

My prior 18 Mustangs were all solid axle... my prior 2016 S550 was my first IRS equipped Mustang and my current 2018 being my second IRS equipped Mustang.

A solid axle diff to an IRS is a noticeable difference, period. Noticeable in all aspects of driving, no doubt.

My first non-Mustang IRS diff was my prior 1995 BMW M3 and even then there was a noticeable handling difference between a solid axle vehicle and one with an IRS.

Going from my 2016 to the 2018 S550, even though both S550's were IRS diffs, I still could tell a difference in better handling with the 2018 and the subtle improvements made with the model year changes. That is also both (2) S550s being equipped with the Performance Pack non-MR platforms.

The S550 IRS is a hell of an improvement over the first IRS attempt with the 1999 and subsequent 2003/04 SVT Cobras. The 2003/04 Cobra IRS setup had a lot of complaints and issues with the mated engine/power bands when it first debuted. The S550 IRS setup is superior to that older rear suspension in so many ways.

Sure folks still complain about the S550 IRS, but I think it's because of:
1) not owning different types Mustangs to really feel/know the improvements made to the S550 in stock form

2) having much larger expectations of a stock IRS platform under any domestic vehicle when it's used beyond "daily driving"

3) trying to compare suspension characteristics coming from "luxury or performance based" Euro/Asian Automotive Manufacturer XYZ (such as BMW, Porsche, Audi, Lexus, etc) to a Mustang as far as "luxo-handling" and the superior Euro/Asian design functionality

4) pushing a stock IRS platform beyond its intended capabilities

5) not able to decipher/understand the differences between S550 platforms and their INTENDED road use (drag racing, auto-x, road racing or just plain old daily driving on shitty roads). Each S550's suspension and optional upgrades was designed for different purposes and different Buyer expectations. Think about it and how each S550 was marketed. Too many people mouth trash S550 suspension platform X because they bought the wrong platform for THEIR intended use.

IMO, spending the $$$ for the MR upgraded suspension would be for folks who intend to use the car more for "touring" or road racing (or maybe even in States where the road surfaces are pock marked to shit). I don't see spending the extra $$$ for an MR suspension as beneficial when the Buyer is just going to use the car for straight line performance - even if the MR adjusts to user selected Mode settings.

Aside from that being said, most who want straight line performance end up ripping out the suspension or totally rebuild the IRS to perform better in only a straight line.

It's kind of like what's the point in getting drag springs installed then complaining the car handles like shit for evasive maneuvers, hitting curves on the highway or wanting to use it for road racing ...

Best advice I can recommend is know what your intent is with any vehicle prior to purchase, such as performance aspects expected and what percentage will it be used for just straight lining or just going to hit the curves.

 

[Norm Peterson]

I think 'serious limitations' is being generous ! I would use the term 'death trap'

They weren't all that bad if you knew how you needed to drive them (or at least, how not to drive them). One of my uncles had a swing-axle Corvair that I got to drive a few times as a teen. Not as nice as the '65 that I test-drove later, but not nearly as uncontrollable as Ralph Nader would have had you believe.


IRS systems that used fixed-length half-shafts as upper control arms certainly had their faults as well, especially as play developed in certain bearings. A Jaguar XKE could rather suddenly step over into oversteer on drop-throttle. Quite the attention-getter, that. Even the C5 Corvette could display a bit of nervousness on corner entry that felt like excessive rear toe changes to me.


Norm

 

[Norm Peterson]

The 2012 Brembo GT was actively trying to kill me. That SLA rear suspension, moving side-to-side, front-to-back, and up-and down was exhilarating, creating torrents of "is this the corner I die in??" adrenaline.

No S197 should have felt that bad. Not unless the shocks and struts were nearly dead.

That said, being able to get the nose to tuck in toward the apex on properly timed lift throttle could be very satisfying on the track (not something you'd be apt to notice in street driving).


Norm

 

[NoVaGT]

No S197 should have felt that bad. Not unless the shocks and struts were nearly dead.

That said, being able to get the nose to tuck in toward the apex on properly timed lift throttle could be very satisfying on the track (not something you'd be apt to notice in street driving).


Norm

Oh, the car was new. And then it got a set of some after-market awesome rear shocks. The shocks did help, but not nearly enough.

And yes, it felt like exactly what it was. A live axel rear suspension. Side-to-side, front-to-rear, all over the place.

 

[RaceRed5.0]

The IRS is a corrupt organization that needs to be disbanded...oh

The suspension is pretty awesome comparing it when I drive my dads F-Body Trans Am its almost night and day.

 

[vanquishvzla]

taxation is theft

other than that, if you don't feel the difference between both suspensions, you are only driving in straight line

 

[2morrow]

I can tell the difference every time I drive it. Especially when i push it to the limits.

Without the addition of IRS it wouldn't have enjoyed the success it has been experiencing especially in the global market.

 

[vanquishvzla]

I can tell the difference every time I drive it. Especially when i push it to the limits.

Without the addition of IRS it wouldn't have enjoyed the success it has been experiencing especially in the global market.

best mustang color... hands down...

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