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Your thoughts on IRS

Sivi70980

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hlh1

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Per my signature I've had several solid rear axles that were ok, but the first time I drove a S550 I was amazed. The IRS made the Mustang a GT car, instead of a drag car. I can get on the gas in a hard turn with the IRS and keep traction (I know, traction control helps here) and not go out of control sideways like would happen with my 95 Cobra with a Vortech. I always had to be very careful with the throttle on the solid rear cars. Sure, it's fun stepping out with the solid axle but I can hook up and go with my 19GT.
 

8GTOKLR

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OP:

Stock Sloppy Solid vs IRS...The Solid is better

2000 Trans Am Owned
2003 Cobra Owned
2002 M5 Owned
 
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Dr. Norts

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8GTOKLR

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At what exactly?
The solid has less moving slush than the IRS. Mounting points, pivot points etc...

Count it out when you watch any video of the S550 by an aftermarket company showing the IRS deflection

Subframe mounting (4)
Upper and lower crtl arms both sides(8)
diff mounts (4)
Verical links (2)

Thats 18 areas of slop. oops dont forget toe links thats 20
 

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Norm Peterson

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Per my signature I've had several solid rear axles that were ok, but the first time I drove a S550 I was amazed. The IRS made the Mustang a GT car, instead of a drag car. I can get on the gas in a hard turn with the IRS and keep traction (I know, traction control helps here) and not go out of control sideways like would happen with my 95 Cobra with a Vortech. I always had to be very careful with the throttle on the solid rear cars. Sure, it's fun stepping out with the solid axle but I can hook up and go with my 19GT.
The S197 Mustang's stick-axle suspension underwent major handling improvement over the triangulated 4-link suspensions used on the Fox/SN95/New Edge Mustangs that preceded it. Those earlier Mustangs were known for snap-oversteer.

The S197 probably represented as much improvement over the Fox (Fairmont)-based 4-link as people are saying the S550's IRS has over the S197. Maybe even more improvement.


Norm
 

edco

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Interesting thread. I rural road surf and safari. Handling/suspension is more important than power to me. Bought the '17 V6 just to experience the IRS. No comparison in stock trim, the S550 is better. However, the '07 GT is handling modified over a four year quest. It is very good and IMO better than the ā€˜17 IRS pony in stock trim.

2007 GT
After-market mods: Caster camber plates, KYB GR2 shocks and struts, 1.2" lower springs, Steeda upper 3rd link, rear control arm relocation brackets, adjustable rear control arms, Detroit true track helical diff, Center Force dual friction clutch, Fays2 Watts link, Steeda G-Track front brace, Eibach sway bars, Ford racing strut tower brace, GT 500 front control arms, Baer Front brakes, Coast 4" dia. one piece aluminum drive shaft, Ford Racing 3.73 rear gears, Steeda X-Brace. HR 1" Track Spacers, P275/40R18 all four corners.

It took time to get the roll center, alignment, camber angle, pinion angle, and Watts link tuned. It was worth it. With Tremec 3650 trans on extreme climb/dive/turn E. MO hills the GT corners and runs with the best German cars and a Maserati.

2017 V6
On the S550, I spent no where near as much to tune the handling. The S550 is just a better chassis over S197. S550 Mods: Steeda: IRS Sub-Frame Braces, Extreme K-Member G-Trac Brace, Adjustable rear toe-links, Billet vertical Links, Caster camber plates, Billet rear shock mount. Then, H&R 24 mm wheel spacers. Eichbach sway bars. Bilstein shocks and struts. Under $3K mods total. I run the stock wheels and tire size. If you can afford the mods, buy them. Steeda engineering works! After mods the car feels like a different car. The tires sound different. Everything is more precise and tight, with great feedback and response. Best handling car I own.
 

Sivi70980

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OP:

Stock Sloppy Solid vs IRS...The Solid is better

2000 Trans Am Owned
2003 Cobra Owned
2002 M5 Owned
Pretty sure lap times at tracks around the world disagree with this.
 

obgod3

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I dont know how someone cant tell the difference but I am sure it an happen also. My 19 vs my buddyā€™s 13 Boss 302ā€¦.my 19 all day long. The boss is amazing and super fun to drive but Ill take the IRS all day long. I had a 83 GT and a 89 LX 5.0 and frankly I would never compare those to the new mustangs at all.
 

TeeLew

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It's much easier to build more anti-squat into either 3-link or triangulated 4-link stick axle suspensions than into most any IRS (S550's integral link included). That goes to initial launch bite and short times.


Norm
I think it's worth adding that the same anti-squat 'hit' which drag racers are able to use to their advantage with drag slicks tends to hurt braking and corner-exit power down on roadrace cars. (Regardless of what Herb Adams wrote ~30 years ago in his book)

Many moons ago, Trans Am (the race series) allowed both live and independent rear axle cars. It worked until the IRS guys figured things out & dominated. At that point, they outlawed the IRS.
 

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TeeLew

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Ok small fry. How did you drive that 800whp mustang? You must have drove it like Ms Daisy if you never kicked or walked the backend out. My opinion is the IRS rolls too much for me in that situation and your douche bag opinion doesn't mean $hit to me. Everyone has an opinion like a$$holes and yours is exceptionally large. Peace out boy scout.
Internet gold...
 

bluebeastsrt

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Well at least the angry little fella didnā€™t drop his pants and wip out a ruler like the OP did.:giggle:
 
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dman

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Bob, You do realize you ASKED for opinions on the subject, right? Just because you don't like mine...

Also, it's great to hear you've attended an SCCA driving school, i'm sure WTC or aussie super cars are beating down your door to sign you

And it's clearly not just me thinking your comment is ridiculous, just read the thread you posted, asking for opinions on the subject...

I do apologize for being so sarcastic however. No offence meant.

If it's a driving experience related discussion, when was the last time you were on a track? It was less than a week ago for me...

Actually you're somewhat local to me, there's a track day right by you in Poco, at Mission raceway July 19, $200 on the fastest lap between you and I? Friendly competition of course.

I'll even pay my $200 beforehand to you, if you win, you keep it. You lose you give me my $200 back + 200 of your own.
Yaā€™ll know what MaMa said? Shut up and drive! Dman
 

PaddyPrix

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OP:

Stock Sloppy Solid vs IRS...The Solid is better

2000 Trans Am Owned
2003 Cobra Owned
2002 M5 Owned
Perhaps I'm a few minutes behind, but the difference between the current IRS and the 03-04 Cobra IRS is night-and-day different, I mean, 15+ years development changes things an awful lot. The 10R80 is 15+ years better than the AOD-E, just as the GT500's TVS R2650 is better than the 03-04's (h)Eaton M112.
 

Garfy

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It only effects ride, handling, cornering and stability. But if you drive mostly smooth straight roads you probably won't notice much difference.
He should notice the better ride no matter what because there's a very noticeable difference between a solid axle and the Independent. It's like when they had 4x4s with solid front axles vs. independent; the solids were very harsh up front. As for handling on cornering and such, unless you drive it harder, you won't notice a difference (if you drive it so your "insurance driving app" doesn't dock you for hard accel, braking, turns, etc. then you won't notice a difference).
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