The real reason the Mustang has a solid rear axle

[Throckmorton]

I just came across this article searching for info on the geometry of the Mustang's solid axle:
http://blogs.motortrend.com/2010-ford-mustang-near-enough-is-not-good-enough-2358.html


Basically, the Mustang was supposed to share platforms with the Falcon sedan, including a light and cheap IRS (compared to the old LS). But for some reason the Mustang engineers insisted on a subframe for the suspension, which took up too much space and would have prevented the Falcon from seating 3 in the back.

So the platforms diverged, and the Mustang engineers designed an IRS just for the Mustang.
That was the suspension the Mustang would have had, if the product development executive didn't convince President William Ford Jr. that they could save $100 per car with a solid rear axle.

Ironically the solid axle ended up costing $98 more than the IRS would have. :thumbsdown:

 

[Arkaign]

And yet it still kills the Camaro and Challenger head to head without IRS

 

[mb]

And yet it still kills the Camaro and Challenger head to head without IRS

To me the downside of the solid real axle is the harsher ride and how the car hops around on roads that aren't perfectly smooth. I thought I really wanted a 2011 Mustang but I'm a one car guy, and after test driving it I don't think I'd like it as my DD especially since my city doesn't have any money to fix the roads around here.
I know it's a sports/pony car and not a luxury car but that doesn't mean it has to completely lack refinement.

 

[Arkaign]

To me the downside of the solid real axle is the harsher ride and how the car hops around on roads that aren't perfectly smooth. I thought I really wanted a 2011 Mustang but I'm a one car guy, and after test driving it I don't think I'd like it as my DD especially since my city doesn't have any money to fix the roads around here.
I know it's a sports/pony car and not a luxury car but that doesn't mean it has to completely lack refinement.

I hear ya. A lot of cars even with IRS are very similar in ride quality, it's a tradeoff for the suspension being quite hard and tight. One of the most fun but harshest DD's I've seen was an E36 M3 CSL that one of my old boss's had in the 90s, each and every tiny part of the road surface was felt as you drove along, very raw and tactile. Ironically that car would probably have its hands full trying to keep up with just a 2011 Mustang V6 Premium lol. Amazing how tech moves along.

 

[Pulsar]

Ironically the solid axle ended up costing $98 more than the IRS would have. :thumbsdown:

So the engineers thought the cost savings would be $100, but that ended up over-running because of unforeseen problems.

Yet you, engineer extraordinaire and knower of all things, are perfectly ready to believe that the cost of the IRS would not have changed, and would not have faced any challenges that could have affected it's price as well.

Never mind that the solid axle still beats the hell out of anything close to it at that cost.

Keep it up. You regularly remind me why it's important to teach rational thinking skills.

 

[exdeath]

The real reason is to piss off car snobs who really want but won't get one because they are afraid of having one less "technology acronym" than someone else.

The hardened IRS in my Cobra is just as bad on bumpy roads, that has more to do with solid bushings, heavy stiff springs, and rock hard shocks.

Point being any car that is set up to handle like a dream on smooth track pavement is going to ride like shit on cobblestone. If it doesn't, there is a compromise being made in the suspension somewhere. Even magnetically adjustable shocks can only adjust so much with a high spring rate.

 

[exar333]

I hear ya. A lot of cars even with IRS are very similar in ride quality, it's a tradeoff for the suspension being quite hard and tight. One of the most fun but harshest DD's I've seen was an E36 M3 CSL that one of my old boss's had in the 90s, each and every tiny part of the road surface was felt as you drove along, very raw and tactile. Ironically that car would probably have its hands full trying to keep up with just a 2011 Mustang V6 Premium lol. Amazing how tech moves along.

The ride quality has more to do with shocks, strucks, tires, etc. than IRS or SRA IMHO. The SRA 'harsh' ride has been exaggerated. I wouldn't decide against a car for this reason alone, it's not just nearly as influential to performance as many other things with a car. There are so many suspension modifications you can make to a car to change rideability, IRS or not.

 

[Throckmorton]

So the engineers thought the cost savings would be $100, but that ended up over-running because of unforeseen problems.

Yet you, engineer extraordinaire and knower of all things, are perfectly ready to believe that the cost of the IRS would not have changed, and would not have faced any challenges that could have affected it's price as well.

Never mind that the solid axle still beats the hell out of anything close to it at that cost.

Keep it up. You regularly remind me why it's important to teach rational thinking skills.

Considering the differences we are talking about, even if the IRS overran by the same amount, the cost is peanuts given the benefits. How much do you think it cost Ford to make a 300hp V6, vs a 275hp V6? And do most drivers care about the difference? Most would notice the better handling on bumpy roads, and the trunk space.

You know the Explorer and Expedition both have IRS right? And those are vehicles that are very negatively affected by the technology. They are worthless offroaders unlike the previous generations, and the IRS are much bulkier and heavier to deal with the truck duty stresses that a solid axle easily handles. But they got IRS for lower load floors and slightly better ride (I doubt cornering grip was a factor)

 

[Throckmorton]

The real reason is to piss off car snobs who really want but won't get one because they are afraid of having one less "technology acronym" than someone else.

The hardened IRS in my Cobra is just as bad on bumpy roads, that has more to do with solid bushings, heavy stiff springs, and rock hard shocks.

Point being any car that is set up to handle like a dream on smooth track pavement is going to ride like shit on cobblestone. If it doesn't, there is a compromise being made in the suspension somewhere. Even magnetically adjustable shocks can only adjust so much with a high spring rate.

But an independent suspension doesn't have to be that stiff. Just set it up so that the camber gain is equal to body roll like a solid axle. Yes, I know, too much camber change on braking-- who cares when the suspension travel isn't that much since it's a sports car?

I've read that the Miata ratio of camber to roll is something like 0.5- still not 1.0 but more than most cars-- My Miata with its stock springs had a decent ride, leaned more than you might think in corners, but stuck to the ground even going over bumps. Rock hard suspension is just a bandaid.

My Jeep XJ has a lot of grip that I attribute to the solid axles keeping the tires perpendicular to the ground... but even tiny bumps makes the rear loose. In the perfect bump free world that the Mustang handles perfectly in, it would also handle perfectly as long as it didn't flip.

 

[Vic Vega]

To me the downside of the solid real axle is the harsher ride and how the car hops around on roads that aren't perfectly smooth. I thought I really wanted a 2011 Mustang but I'm a one car guy, and after test driving it I don't think I'd like it as my DD especially since my city doesn't have any money to fix the roads around here.
I know it's a sports/pony car and not a luxury car but that doesn't mean it has to completely lack refinement.

2005+ Mustangs do not do this. I've driven quite a few of them.

 

[Vic Vega]

The ride quality has more to do with shocks, strucks, tires, etc. than IRS or SRA IMHO. The SRA 'harsh' ride has been exaggerated. I wouldn't decide against a car for this reason alone, it's not just nearly as influential to performance as many other things with a car. There are so many suspension modifications you can make to a car to change rideability, IRS or not.

It sure has. What the bench racers on this forum and many others seem to forget is that the best riding cars for years and years had a solid rear axle. In fact to this very day one of the best riding cars you can buy, the Lincoln Town Car has a solid rear axle.

 

[Throckmorton]

It sure has. What the bench racers on this forum and many others seem to forget is that the best riding cars for years and years had a solid rear axle. In fact to this very day one of the best riding cars you can buy, the Lincoln Town Car has a solid rear axle.

Yes, and the Grand Cherokee I had rode like a Cadillac with its coil sprung solid axles.

But the Mustang isn't a luxury car-- it's a performance car.

 

[Throckmorton]

Ford is bizarro-world-- low clearance bulky IRS on a pickup, but solid axle on a Mustang!

 

[theeedude]

I might get a Mustang if Ford puts an IRS in. Not getting solid axle car, that's just ghetto.

 

[exdeath]

But an independent suspension doesn't have to be that stiff. Just set it up so that the camber gain is equal to body roll like a solid axle. Yes, I know, too much camber change on braking-- who cares when the suspension travel isn't that much since it's a sports car?

You better have a stiff suspension when you have over 400 hp at the crank and an equal amount of torque tossing your 3,500 lb car around like a stuffed toy.

 

[exdeath]

Ford is bizarro-world-- low clearance bulky IRS on a pickup, but solid axle on a Mustang!

The Mustang is built for performance on smooth roads and tracks, not for rock climbing where the wheels need to be able to articulate on opposite ends of their travel independently.

You can't have both. If you do, I ll repeat what I said above: you are compromising both somewhere.

 

[theeedude]

There are plenty of high powered IRS RWD cars without stiff suspensions.

 

[skyking]

It would feel just as crappy as the torque steer and negative crap that a front wheel drive high HP car suffers. Either go stiff or go home

 

[Throckmorton]

The Mustang is built for performance on smooth roads and tracks, not for rock climbing where the wheels need to be able to articulate on opposite ends of their travel independently.

You can't have both. If you do, I ll repeat what I said above: you are compromising both somewhere.

Solid axles are BETTER offroad, except at high speed on hard dirt roads. They articulate more because of the effect of one wheel on the other. The Explorer, Expedition, and Sport Trac have the IRS for a lower load floor (not sure if that applies to the Sport Trac) and for a better ride on the way to the mall which I doubt most buyers even notice. And think of how much money they spend engineering and building those big beefy truck IRS systems.

 

[theeedude]

The Mustang is built for performance on smooth roads and tracks, not for rock climbing where the wheels need to be able to articulate on opposite ends of their travel independently.

The problem for me is that the fun roads around here are in the mountains, and they are not always smooth, especially with the budget crunch states and localities are experiencing. You never know when you hit a rough patch. IRS is just a lot more resilient on bumps, all things being equal, and that inspires a lot more confidence in the corners. One rear wheel hitting a bump does not upset the other, so you are far less likely to have loss of traction in both rear wheels.

 

[ElFenix]

old news is old. the whole purpose of this thread is to start a fight.

 

[mb]

2005+ Mustangs do not do this. I've driven quite a few of them.

The 2011 I test drove did... I'm sure it is much better than the old ones (I was only was a passenger in those, never drove one) but it still hopped around.

 

[Throckmorton]

old news is old. the whole purpose of this thread is to start a fight.

How is this old news? I've seen people most many times about the huge cost savings of the solid axle in the Mustang, which is the opposite of reality.

We are having a spirited discussion about IRS vs solid axle, despite Pulsar's hateful post.

 

[Throckmorton]

The 2011 I test drove did... I'm sure it is much better than the old ones (I was only was a passenger in those, never drove one) but it still hopped around.

That's inherent to the solid axle design. There's no way to engineer it out. When one tire hits a bump, it goes up and angles the other tire outward, causing it to lose traction, and also physically pushing the vehicle to that side.

 

[JeffreyLebowski]

That's inherent to the solid axle design. There's no way to engineer it out. When one tire hits a bump, it goes up and angles the other tire outward, causing it to lose traction, and also physically pushing the vehicle to that side.

If you hit something so hard that it would cause the whole thing to move, it doesn't matter if you are in a IRS or have a log out back you're going to feel it.

The Mustang has and continues to keep a solid rear axle, because for getting power to the ground, it still rules the roost.
This is why the 2010 GT with 315HP is able to have trap times only .1 seconds off of the much higher horse power V8 Camaros and Challengers.
The 2011 5.0 will rape those cars.

If you want to go as fast/quick as possible. Get a solid rear axle. IF you want IRS and want a pony to puttz around in buy a Slomaro or Challenger.

You can belly ache and hem and haw over Fords "horrible" choice to keep a solid rear axle out back, but when it comes down to it. They are smarter than GM or Dodge on the subject. Hence they are the only ones to have kept their pony car in production with no stoppages. The Camaro and Challanger can say that.