I know Farago’s answer, but hear me out. As I mentioned when I reviewed the Bullitt, I’ve driven many Mustangs. And do you want to know the truth? The fact they all have live axles… really doesn’t make any difference. Like, let’s get real here. None. As far as I can tell, the only time you can tell from the driver’s seat the new Mustang is without IRS is when you hit a bump going around a corner. “Dude!” I hear you yelling, “You’re admitting that bumps upset the live axle!” No, not really. I’m simply saying that live axles feel different from IRS. The car doesn’t explode. But what about dangerous? Naw. I mean do you see Mustang FR500Cs killing their drivers any faster than the BMW Z4s, Lotus Exiges, Aston martin V8s or Porsche Caymans it competes with in GT4? Right, you don’t. “But, but, but!” I hear you stammering. “Those ‘Stangs are highly tuned. Regular Mustangs aren’t.” Says who? Here’s what I’m saying after driving an awful lot of Mustangs. Knocking on live axles is just another anti-American car Jeremy Clarksonism. What’s next, knocking the Z06 because it sports traverse leaf springs? Oh wait– he did that, didn’t he? What say you?
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Don’t listen to Jonny. Any car that bounces sideways in a corner is not your friend. The Boxster/Cayman doesn’t do it. ALL Mustangs do. Unless you live in Pfeffenhausen, you have mid-corner bumps.
I see nothing wrong with live axles. I’m with Jonny here. People get all fancy and stuff making multi-link IRS and everything and then what do they do? They tie it all down with sway bars. Granted the unsprung weight is a little bit more in the live axle. But I don’t care. You just get used to how the car handles and all will be well.
Dropping off my friend’s 1979 Toyota Corolla (1166 cc, 4-speed manual) back to his house one day, I took a road less traveled and found myself hurtling down a bank with a sharp left approaching. The brakes are useless at their job, so I downshifted from 3rd to 2nd and turned the wheel hard and quick. The chassis flexed and moaned as the front wheels bit. The rear end, however, was more interested in chasing its own tail. Worse: A 911 C4 was coming the other way, and we wouldn’t want our (okay, my friend’s) Japanese steel punching Zuffenhausen candyfloss, now. Would we? I pushed my right-foot toes deeper into the muddied carpet, flung the wheel into opposite lock, caught the slide in a weird slow-speed oversteer moment. The inside (left) wheel spun away while the outside (right) wheel accelerated me out of the bend and onto a level straight, though it had inherited most of the car’s weight. The live axle on the rear-drive Corolla helped to prevent me from painting the Porsche’s rear flank a different color (by prolonging the slide, otherwise the rear would’ve snapped into line and also into some expensive German metal), but it got me into the oddest slow-speed experiences I’ve had in a car. Independent suspension would’ve helped the unsettling of the car in the first place. A differential would’ve split the torque going to the wheels appropriately and the car would’ve stayed composed. I’m sorry, Mr. Lieberman. Live axles are not cool.
Wouldn’t the bouncing in the corner have more to do with suspension stiffness?
My Saturn has a big trunk because of a beam axle. No strut towers taking up space. Plus it’s simple so there isn’t as many rubber bits to replace and adjustments when the car gets old.
Live axles are great for carrying heavy loads on vehicles not expected to be driven all that fast.
Not so much on cars expected to be driven fast.
davey49, the bouncing has to do with the right and left wheels being connected by the axle housing. What one wheel experiences, the other will too due to a positive mechanical connection.
I’m going to repost what I say in the GT California review:
–snip–
* A solid axle car can handle quite well. What it can’t do is ride well at the same time. You lose a modicum of body control, that you notice only when hitting a bump under power.
* The Mustang is very cheap for the power it puts out. I’d imagine Ford is making quite a bit more money on this car than GM or Chrysler do or will make on their respective pony cars.
* For a four-seat car with this kind of performance, it’s quite light. Again, the Camaro and Challenger will likely weigh a lot more.
For what most owners ask it to do (ad-hoc drag-racing, light track use), it’s a good choice. If you want the Ultimate Cornering Machine, you’ll need to give on power, price and/or reliability.
Where the Mustang falls down, comparatively, is in it’s powertrain. Ford’s engines just aren’t as strong as it’s competitors. If GM survives long enough to punt the Camaro out the door, this is going to be painfully obvious. Ford’s only hope is to keep the price and the mass down, and that live axle helps both.
–snip–
The Mustang is not Châteauneuf-du-Pape, it’s not even Ernest & Julio Gallo. It’s Baby Duck: cheap, crude and effective at it’s intended task. If you can appreciate it as such, it’s the right tool for the job.
You wouldn’t want to drag-race a Porsche, or even an Evo or STi because, frankly, you’ll kill them. Why expect a live-axle Mustang to perform outside it’s core competency?
Ill never go back to a live axle. They were cool back when we were drag racing Mustangs, Camaros, Novas, Chevelles. Torque arm setups were the best. No axle hop, no leaf springs to twist up, no 4-link to bind.
But now that I use the steering wheel for more than doing donuts, IRS is the girl for me. Forget-about-it stability, less damping needs, plus a bit of toe-in to keep the rear wanting to keep center.
I’m not completely sold on today’s ‘thirtytwelve link’ rear suspensions however. A properly engineered semi-trailing arm is light, simple, strong and effective. Works for me.
Live Axles have their place…mass produced fleet vehicles, trucks, etc. But here in 2008, there is no logical reason why the Mustang has a SRA.
Think about how backwards Ford really is…they fit IRS to their SUVs…but not the “sportiest” car they produce. And remember all of they hype around the 2002 Explorer getting IRS? Ford made it seem they re-invented the wheel.
I believe that if a vehicle has 4 wheels…then they should be treated…independently.
And, frankly, Ford should actually listen to their customers and give them what they want. Everyone would like to see IRS in the Mustang.
But…since a few people think that SRA is ‘just fine’, maybe the Mustang should have a solid front axle. It HAS to be better than just SRA…
S.Chaudhry, Live axles DO all have differentials. And your description of the outside rear wheel accelerating your Corolla while the inside wheel was up in the air is colorful, but wouldn’t have happened, unless you had a limited slip dif, which is highly unlikely in a ’79 Corolla.
I’ll never forget the revelation of the MB300E’s IRS ripping around bumpy back roads at speed, after the TurboCoupe’s (Mustang-like) live axle.
IRS > live (cart) axle. The Europeans figured that out ninety years ago.
Who cares about those dumb axles when you have such a nice rump in the picture? Are you guys homos?
The live axle in my Corolla GT-S handles quite nicely, thank you.
Mr. Niedermeyer, I respect your authority and believe in your word. I do understand that live axles all have differentials. If the Corolla’s outside wheel found better traction due to other reasons (the road being rougher closer to the middle inviting friction: I’m in a RHD world, or some pothole I flew over), I’m glad it happened! Aren’t you? A differential’s purpose is to supply more torque to, in this case, the inside wheel, is it not? It’s also possible that the car was in a four-wheel (and pretty much uncontrollable) slide that I assumed was corrected by my foolish right foot. The whole incident lasted just over 2 seconds and as the car accelerated out, I was only glad I didn’t hit the Porsche. My friends have done some crazy stuff with that car on the same corner since I told them about the close call and the Corolla’s been a good sport about it all, never cracking in half like a candybar, as I always fear it might. Nevertheless, the question here is about live axles and whether they are up to no good. Just like you had an epiphany with your Mercedes-Benz after the T-Bird, so did I after driving another friend’s 1996 BMW 3-series. That was the first RWD experience for me, and I drove it round many bends for many miles until the day he sold it recently. I’m not with Mr. Lieberman. Independent suspension is the way to go.
I think what Jonny is saying is that if you had 1000 people drive a live axle car and also drive an IRS car maybe 3 or 4 would actually notice a difference. Assuming that you could drug them into not knowing what car they’re driving so they weren’t biased in the first place.
Does anybody actually buy a Mustang for it’s “driving quality”? I thought it was all about history and having a pretty car. Maybe a rumbly V8 that’s a good drag racer. It seems like just about any car (Cobalt?) drives better than a Mustang.
Unless you are racing, you are unlikely to encounter a large enough bump to send a live axle car out of control. It might skip a little, but that’s called “car control.”
If you are pushing hard enough on the street that you lose control, well, I feel no sympathy for you.
Adub:
Unless you are racing, you are unlikely to encounter a large enough bump to send a live axle car out of control. It might skip a little, but that’s called “car control.”
If you are pushing hard enough on the street that you lose control, well, I feel no sympathy for you.
No offense, but you clearly have not driven a live axle car over Minnesota’s roads. In the winter, the frost will put “speed bumps” everywhere.
That being said, it is a small price to pay for all of fun RWD brings when it snows.
Drag racing, yes. Cornering, no. Not saying it’s the worst thing in the world, as I owned a modified 1989 Mustang GT. And yes, stock it was horrible. Everything about the cars chassis/suspension sucked. But after $1,000 investment (Mustang aftermarket parts are VERY affordable), it handled well (not great). I installed subframe connectors, better shock/springs, and bigger sway bars. So what’s my point? Tell Ford to ‘just do it right’ from the start, IRS to begin with…
As for traverse leaf springs? Well, not only does the Z06 have them, but the ZR1 as well. And since you’re on this website, I can assume I don’t need to type the cornering stats of the ZR1.
I own a Mustang. Once I got rid of the regular tires, I found it to be as good a handler as any car in its price range, maybe even better.
But the constant tail hop under hard cornering gets on my nerves. It can be charming at times to drive such an unforgiving car, but I’m pretty sure my next RWD car is going to have IRS.
S. Chaudhry – An open differential (not posi, not locker, etc) gives exactly the same amount of torque to each wheel (doesn’t matter if it’s inside or outside). That’s why you get stuck in the winter, the wheel with the least traction dictates the max torque applied to each wheel.
I’ve owned three of Ford’s MN-12 platform cars from the 1990’s (two T-Birds and a Mark VIII), all of which were equipped with IRS. Going from those cars to a Mustang (or to a Crown Vic, which I’ve also owned several of) made it very clear that IRS provides a big ride and handling advantage over a SRA, especially when only one of the rear wheels hits a pothole at speed in the center of a corner.
One of Ford’s alleged reasons (other than cost) for sticking to the SRA in the current Mustang was that a lot of folks who drag race Mustangs were tearing up the IRS rear axles in their 2003-2004 “Terminator” Mustang Cobras. But most of those folks were launching by dropping the clutch at something like 7,000 RPM – not a healthy scenario for *any* stock drivetrain component, even if it is of a slightly weaker basic design (IRS) than what replaced it (SRA).
Besides, if a Mustang owner gets serious enough about drag racing, there’s a good chance he or she will seek out a Ford 9″ rear axle housing from a late-Seventies Lincoln Versailles or go with a custom racing piece.
For the rest of us (probably 90%+ of Mustang buyers), I think the benefits of an IRS setup would definitely make the care more enjoyable to live with on a daily basis.
+1 for Don.
Though I love the thrash-proof durability of my Fox Bodies, my daily driver is a Mark VIII for a reason: its got IRS for modern car driving feel…and its paid for. (But that’s a whole ‘nother story.)
Not that I haven’t seen how well Griggs Mustangs do in the corners, but the finesse isn’t there. Maybe one day there’ll be a Mercury Cougar with the extra cost and finesse of the Mustang’s true potential.
It’s not so much the fact that the rear wheels are connected that is an issue with a solid axle, it’s the unsprung wieght. Many a fine-handling Italian and Britich car back in the day had “deDion Tube” setups. This is sort of a combination of a solid axle and an IRS. The Wheels are carried on a beam axle that curves around behind the differential, which is mounted to the car. This allows both light unsprung wieght by keeping the very heavy diff attached to the car, and excellent wheel location with no camber change. Extremely expensive, of course. Not all IRS is wonderful, the swing-axle rear suspension of my Spitfire does not handle nearly as well as the solid axle in an MG Midget. Does ride better though!
Cost is an entirely legitimate reason to use something; it means more car at the same price point.
The Mustang isn’t a sports car. The point of the Mustang has always been to look good and to be a cheap V8-and-RWD platform. You want to pour a few thousand into it to make it competitive sports car, fine. There’s a lot of things you can pour a few thousand into and turn into a competitive sports car.
Or, to put it another way: why are you driving a car? If you’re looking for precise cornering, get a Miata. If you’re looking for a big ol’ V8 and some powersliding hoonery, get a Mustang. If you’re looking for both at the same time, get a considerably more expensive car.
Live axels don’t get a bad rap. Most people criticize their handling performance, and they do have a disadvantage over an IRS in handling. Unsprung weight is the enemy of handling and ride. Put some lightweight wheels on your car to get an idea of how important unsprung weight is. Not to say a live axle car can’t be fun to drive or handle well, it is just not an ideal setup for handling.
We have three live axle vehicles in our little fleet, and I enjoy all of them. A ’93 Volvo 240 wagon, an ’89 F150 and a ’72 Volvo 1800ES. Sure the ’67 Jaguar with IRS is a more refined car with a superior ride to any of those, but so what?
A live rear axle certainly isn’t a deal killer for me. In fact, rear drum brakes aren’t my preference, but they also are not a problem for any normal use of a road vehicle. My biggest gripe about drum brakes is that I hate changing the shoes on the things. All those clips and spring, yuck. Maintenance wise, a live rear axle is usually easier to keep on the road for the long haul. Fewer bushings, seals and u-joints.
Holy crap, they’re using traverse leaf springs in the Corvette? I know that times are tough, but putting leaf springs from the chevy traverse on the Corvette is going to far.
[rim shot – the correct word is transverse]
Solid rear axles increase unsprung weight, but allow for lower overall weight. They’re incredibly durable compared to most multilink and SLA setups, and they help reduce the costs related to RWD. I would rather have a live axle RWD car than a FWD car.
Live rear axles can get upset in corners, but generally launch much smoother than IRS suspensions in high powered cars.
A well developed “inferior” technology can sometimes be better than the “best” technology. SLA front suspensions are generally considered to be the best setup by far. F1 cars use them. Ferraris use them. Yet BMW and Porsche make very well handling cars using strut suspensions that were originally invented for British economy cars.
I had a 1989 Mitsubishi Galant with a live axle rear end, and it was a fantastic handling sedan, similar in feel to today’s Mazda6 or TSX. You’d never know it wasn’t an independent suspension cornering through bumps at a fast pace.
It sure beat our Mercury Sable and Toyota Camry of that era, which had 4 wheel independent struts.
JL– Pining for the simple days of the ae86 Corolla GTS again?
Solid axles aren’t ideal for handling, but you can make them work if you try hard enough. The Honda Fit seems to get along spectacularly for having a torsion beam rear.
Sure, there’s the bump-steer problem… but guess what? Many manufacturers use independent suspensions to provide a better mix of ride comfort and handling… because independent and, to a greater extent, double-wishbone, suspensions provide more camber and toe adjustment as the suspension squats. But while trying to dial in a softer ride, they need to rely more on stiffer anti-roll bars to provide cornering stability… which leads to… whoops… bump-steer. My car has independent suspension at all four corners, and quite a bit of bumpsteer if you hit something mid-corner. But the fact that it can do a 300 foot slalom at over 70 mph stock is more than enough compensation for this.
Still, live-axles are far from ideal from a handling perspective, and if Ford can afford to stick IRS on the Explorer, why not the Mustang?
I have had a 1989 5.0 LX since new. It replaced a 928S so I certainly was able to compare crude vs. sophisticated suspensions.
To improve “tracking” I upgraded the chassis with sub-frame connectors, improved brakes, better calibrated springs/shocks, larger sway bars and variable camber kit. A mix of Griggs and Ford racing parts. This made a significant difference in the “feel” of the car when either cornering or straight line driving. Did nothing for the somewhat disconcerting “hop” you get when hitting uneven pavement in a corner. I have not had the car “lose it” and have learned to live with the slight feel that the rear end is going to break free.
I still have the car and drive it regularly. What I have come to appreciate is the feeling of driving “fast” the Mustang gives at legal speeds compared to a more sophisticated chassis which require much higher speeds to give the same feeling. Human reaction time does not change (making the broad assumption that you know what the correct reaction is) whether you are driving a 1980 corolla or a 2008 Boxster. That might explain the trouble drivers seem to get into with those more sophisticated cars.
“Solid axles aren’t ideal for handling, but you can make them work if you try hard enough. The Honda Fit seems to get along spectacularly for having a torsion beam rear.”
Although twist-beam axles are obviously interconnected, to draw a parallel between their operation and that of a solid axle is really pushing the idea. In practice the way a torsion beam works is much closer to an independent setup than to its beam brethren.
Anyone who’s actually spent time setting up a chassis for handling knows that live axle works just as well as IRS in 90% of situations.
IRS in a factory car is a no-brainer, UNLESS it’s going to be used a lot for drag racing (Mustang, Camaro), because the MAIN reason for IRS is ride comfort in harsh conditions. IRS helps isolate vibration and bumps from uneven surfaces, which are encountered quite often on streets.
What Adub said is largely backwards. On the race track, at least most race tracks, the surface is usually quite smooth–making the MAIN reason for IRS null and void. It carries smaller advantages, like a greater adjustability on toe and camber (contrary to popular belief, you can change BOTH of these on a live axle–with a torch and a hammer or tube bender)… The live axle is also more reliable, more simplistic, and lighter.
But the close-minded, “I read howstuffworks.com” theory about the transfer of energy from one wheel to another isn’t a good enough excuse for “IRS is better.” Proper spring and swaybar selection on a live axle will help with the same problems, and typically the longer the locating arms of the rear end (ie. truck arm suspension on a NASCAR stock car), the more room there is for each end of the axle to flex and move without significantly affecting the other side.
Will an IRS car be more pleasant and less of a bear to get around a corner? Absolutely. But in terms of absolute grip and lap times, the differences will be minor. There’s no reason NOT to use IRS provided it can take the horsepower, but there’s nothing really wrong with a live axle either. Just witness the domination of the Mustang and F-Body in 1990s sports and touring car racing, Motorola Cup being the best example, beating up on BMWs and Porsches.
The main problem with live rear axles is unsprung weight. That significantly impacts ride quality.
Torsion beam rear suspensions have significantly less unsprung weight.
I can live with the live rear axle in my 4Runner. It gives me increased ground clearance, more strength, and it is, after all, a truck.
But the Mustang should have a more modern rear suspension.
Respect – What a live rear axle will teach you the first time you fly through that bumpy curve.
Nice pic by the way. Two thoroughbred live rear axles for the price of one. Hopefully Junior Mint is of age. If not, I take back that last click.
The reason I don’t own a Mustang is that it has a live axle. I drove a friend’s ’06 V6, and before I’d even left the parking lot, I encountered bumps that made the car shimmy like an 19th-century wagon.
I don’t care how well it handles, that’s just unreasonable.
I must say that the lady in the photo has minimal “unsprung weight”.
My previous car (’97 Camaro) would definitely get “out of sorts” on bumpy turns, but was ultimately controllable due to its low center of gravity – usually just a bit of countersteer was required to keep you out of trouble.
That said, the high unsprung weight gave the car a somewhat uncompliant ride over washboards.
Hi, I’m new here and am not taking any sides on the live axle vs. irs debate. Both have their merits as previously discussed.
I just want to point out to Mr. Niedermeyer that some of the greatest European cars of the last 90 years, such as the 250 GTO and the BMW 507(pushrod engine), used solid axles. Every article that I have read on these cars either downplay the fact, ingore it, or even go as far as to suggest that they had independent rears.
I’d like to hear those who bash American muscle cars comment on this. Thanks.
jgeorge:
Heh, excellent point. And the fact is, come into the 70s, and they all started converting to IRS, in many cases for “technology for the sake of technology.” But, in terms of manufacturing normal street cars, the advantages of IRS in terms of ride quality far outweigh its disadvantages. I for one was speaking in terms of pure grip and handling.
Two other cars with legendary handling and live axles that come to mind are the Alfa Romeo GTA and the Lotus Cortina. Not too shabby.
jgeorge:
Hehe, well said. Oftentimes modern articles do forget to mention such things. The fact is though, that in terms of manufacturing street cars, the majority of those sporty car manufacturers switched to IRS because its advantages (ride quality) outweighed its disadvantages. My post in particular was referring more to straightforward grip in a racing environment.
Two other live axle cars with legendary handling that come to mind are the Lotus Cortina and the Alfa Romeo GTA. Not too shabby.
I was always taught that unsprung weight was counter-productive to suspension’s main job: smoothing off road irregularities. You don’t get much more unsprung than a solid rear drive axle, along with the springs, linkages, wheels and brakes. True, the rear wheels are always parallel, but that’s about it. It is a cheap solution, but hardly an elegant one.
BTW Jonny, you are aware that Mustang offered IRS in some of the old Fox platform-based Cobras, right?
tigeraid: Two other live axle cars with legendary handling that come to mind are the Lotus Cortina and the Alfa Romeo GTA. Not too shabby.
BUT the Alfa Romeo GTA gave way to the Alfa Romeo Alfetta with a de Dion rear suspension. (And the Alfetta/GTV6 won more road racing championships in its time than the GTA/GTV did in its.)
Re: 250 GTO – Ferrari cobbled together road cars to pay for the racing effort. Enzo’s last thought was to provide the best product for his customers- it was his way or the highway. And some of those legendary Ferrari classics are just that – legends. Some were truly bad or terribly designed. Most won’t hold a candle to run of the mill modern cars despite 7 figure price tags.
Maybe the live axle worked fine in a GTO, my point is that Ferrari was NOT on the cutting edge of technology during that period, mainly due to the Enzo Mentality.
KnightRT “The reason I don’t own a Mustang is that it has a live axle. I drove a friend’s ‘06 V6, and before I’d even left the parking lot, I encountered bumps that made the car shimmy like an 19th-century wagon. I don’t care how well it handles, that’s just unreasonable.”
Knight RT: Your friends ’06 V6 does not have a rear stabilizer bar as standard equipment unless it had the pony package…thus the shimmy. Agree this is unreasonable—thats why I installed a GT rear stabilizer bar soon after I purchased my V6. As far as wheel hop due to live rear axle—-in my daily driving–which is mostly city / straight highway—not much of an issue.
I would not buy a mustang to do corners. I’d treat it as a GT car mostly. If I wanted to do corners, there’s alot of cars that would do that alot better. But few of them drive slowly down city streets as prettily as mustangs. so of course i want one. A bullitt, please.
PS – The Corvette Z06 does not have leaf spring rear suspension – it’s independent double wishbone. I would assume (hope) the ZR1 is the same.
I believe the Corvette has a single transverse composite material leaf spring both front and rear. This does not preclude independent suspension. (And is not to be confused with longitudinal leaf spirns for live axle suspensions.)
JEC: True, Ferrari cobbled together road cars to finance his race cars. However, these road cars were identical to their racing counterparts save for leather and such. The 250 GTOs that won the World Manufacturer’s Championship in 1962, 1963, and 1964 might as well have been road cars with higher lift cams. Simply put, both road and race Ferraris are legends because they won races.
I find the ride quality and comfort on solid axle cars/trucks (except for the mustang/camaro) to be excellent. Maybe its the suspension tuning but they have that proverbial ‘magic carpet’ ride. Also, on potholed Northeastern roads they feel like they are beating up the road instead of being beat up by the road. As a driver though, that rear axle shimmy is disconcerting. Having said this, I much prefer an IRS.
The question was ‘Do Live Axles get a Bum Rap’. The answer is yes. Everyone here seems to either directly agree or inadvertently answer the question by giving live axles a ‘bum rap’. Touché!
I think the point to be gleaned from all this brouhaha is that the enthusiast community is a very small segment of the buying public. Given that Ford is able to sell 50k plus Mustangs without IRS, and without substantial noise from the masses is self-evident. The business case is, obviously, closed.
SPIN-SPIN-SPIN: DOES A W111 MB 220 SEb DE’DION-POSI BEAT A 1971 BMW 2002 SEMI-TRAILING ARM-POSI: I CAN LOCK THE BRAKES WITHOUT TOUCHING THE STEERING WHEEL AT OVER 100MPH BUT THAT’S NOT REALLY POSI ON A JAGUAR 420 4.2L XK-ENGINE WITH 4 WHEEL DISK BRAKES ON STRESSED IRS!!!
RALLY DIRT, MUD AND ICE AREN’T REALLY ONE-LEGGER TERRITORY. I HAVE EXCELLENT CONTROL ON A STRESSED MEMBER IRS: MY TR-6 HAD A NASTY SEMI-TRAILING ARM TOE-IN PROBLEM AND THE BMW 2002 DIDN’T HAVE THE 6-CYLINDER TORQUE REQUIRED TO EXPLOIT THE MISSING TR-6 POSI. I DIDN’T OWN THE MB 220 SEb, I OWNED A HIGHER IRS.
THE DE’DION DATABASE IS PROBABLY ON MB 300SLR EARLY 1950s GRAND PRIX