[yz250]

hey i've got an 01 cobra and i was hoping someone could explain the difference between a live axle and an IRS to me. Thanks.

[sinisterblack98]

Your car has the IRS or independant rear suspension, the rear axle is "jointed" at the centersection allowing the wheels to react "independantly" of each other thereby offering better handling by each wheel not upsetting the other.

A straight axle is just that, no joints, straight tubes, both wheels are on the same plane and react to each others movement (somewhat). Works great for straightline acceleration, not as nearly as well for cornering or smoothness. Just look at the rear of a pickup to see one.

[99SVTAddict]

That pretty much sums it up.
Solid axle...tried and true...works great for the 1/4 mile.
IRS....each wheel is able to "do it's own thing" or be independent of the other....good for twisties, bad for 1/4 mile.

I loved my IRS on the road...now that I'm making power and going to the track more, I just gave up. I am having the "anit-hop" rear put in next week

[Steel City]

Originally Posted by sinisterblack98

Works great for straightline acceleration, not as nearly as well for cornering or smoothness.

I agree, the solid axle is the way to go for straightline acceleration, ie drag racing, far more durable too. However too many people are under the assumption an irs is a far better handling than the solid. IMO you can make a better handling car with a solid rather than an irs. Not saying the irs cant be upgraded to handle comparably, there are plenty of upgraded irs's running there balls off on the road course! Weight alone is a big difference as you can save at least a 100 lbs switching from an irs to a solid.

[Steel City]

Originally Posted by Steel City

I agree, the solid axle is the way to go for straightline acceleration, ie drag racing, far more durable too. However too many people are under the assumption an irs is a far better handling than the solid. IMO you can make a better handling car with a solid rather than an irs. Not saying the irs cant be upgraded to handle comparably, there are plenty of upgraded irs's running there balls off on the road course! Weight alone is a big difference as you can save at least a 100 lbs switching from an irs to a solid.

Oh one more thing. The irs definitely takes the cake for daily driving. Much nicer ride and very smooth. Especially on off ramps were there are expansion joints etc....The ass end wont kick out and takes everything within stride.

[sinisterblack98]

Originally Posted by Steel City

I agree, the solid axle is the way to go for straightline acceleration, ie drag racing, far more durable too. However too many people are under the assumption an irs is a far better handling than the solid. IMO you can make a better handling car with a solid rather than an irs. Not saying the irs cant be upgraded to handle comparably, there are plenty of upgraded irs's running there balls off on the road course! Weight alone is a big difference as you can save at least a 100 lbs switching from an irs to a solid.

My $.02...A better handling car with a solid? Ever see a formula one car with a solid rear axle? Why don't the Corvette designers switch back to a solid axle for better handling?

A solid (think...truck) will never equal a comparably modified (suspension) IRS for overall handling.

[103]

When it comes to Ford's IRS... I vote for solid axle. And my car handles great. Also, the setup for a solid axle in a Mustang is far different than in a truck. I mean, come on, that's like saying, "IRS, look at the current Explorer!" And you just can't compare out IRS with the Vette IRS. I have a much better time driving my car now that the IRS is gone...

[sinisterblack98]

Originally Posted by 103

When it comes to Ford's IRS... I vote for solid axle. And my car handles great. Also, the setup for a solid axle in a Mustang is far different than in a truck. I mean, come on, that's like saying, "IRS, look at the current Explorer!" And you just can't compare out IRS with the Vette IRS. I have a much better time driving my car now that the IRS is gone...

Yeah but are you talking about launch or cornering and street manners? My solid feels like poop in a 70 mph offramp if I even hit a small bump, the ass end always jumps out and straightline traction on uneven pavement is terrible. I feel more confident with my gf's Explorer on the same offramp or full throttle on most Michigan roads. Sure the body rolls and the tires squeal but I can feel each tire reacting instead of the oversteer inducing twitch my Cobra rear has.

[Steel City]

Originally Posted by sinisterblack98

My $.02...A better handling car with a solid? Ever see a formula one car with a solid rear axle? Why don't the Corvette designers switch back to a solid axle for better handling?

A solid (think...truck) will never equal a comparably modified (suspension) IRS for overall handling.

Formula 1???? The irs in a vette is much nicer than our irs. Gm built that car for that particular irs, ford just took an irs and bolted into ours. You think truck when you think of solid because you don't know any better. Do some research about solid axle stangs, you will find that there is an abundance of aftermarket products to make a solid axle go straight line or on the road course.

[qksl2]

You shouldn't compare a modded solid axle susp to a stock IRS. Mod for mod, the IRS will easily outhandle the solid axle.

Ian

[Steel City]

Originally Posted by qksl2

You shouldn't compare a modded solid axle susp to a stock IRS.

Im not, how do you figure that? Im also not saying you cant make a great handling irs either. To say that....."Mod for mod, the IRS will easily outhandle the solid axle" is a retarded.

[Thunder5.0]

I have to agree, the irs handles better than the solid axle in everyday driving. Even if you upgrade the stock axle suspension it will never have the feeling of the irs. This goes for everyday driving both in the street and highway.
At the 1/4 mile track, the irs sucks because of the excessive wheelhop. If you are a straightline racer go for the solid axle and 410's.

[103]

You need 4.30s min. Otherwise you shift to fourt right at the end...

[bditty50]

IRS rear rearend will out handle a solid axle any day. I have a solid axle on my coupe with all Maximum Motorsport 3 link and torque arm and it handles excellent it pulls a over a G. I'm still going to swap it for a IRS with all the right parts even though its more costly to upgrade I'd prefer the handling of the IRS. With the solid axle I'm worried about hitting a small bump on a hard turn and spinning out of control. Also with the setup I have the suspension has no travel I found myself caught on a rounded curb in a cul de sac. The car is not very low but, with the 3 link and torque arm the car can get high centered and have two wheels touching diagonal and the car is just balanced. That just shows you how much the suspension moves when on strong turns.

[Kilgore Trout]

Stock to stock the IRS blows the solid away (except for the wheel hop problem).

[Uncle Meat]

Funny how so many people state the IRS will out handle a straight axle even when both are heavily modified. If you look under ANY of the current or past Mustangs that professionally road race they ALL use a form of modified straight axle...

U.M.

[cold96snake]

Originally Posted by Uncle Meat

Funny how so many people state the IRS will out handle a straight axle even when both are heavily modified. If you look under ANY of the current or past Mustangs that professionally road race they ALL use a form of modified straight axle...

U.M.

Good point, UM.
Now, for a DD stang w/ a live axle, I must admit I don't take too many tight turns at 80+.

[95 yellow 5 0]

don't swap the IRS unless you're goin to the track.
i never go to the track.. it's too far away.
get some supporting mods to the rear and you get the handling of IRS and you cut down the wheel hop.
i'm sure if you try to sell the car in the future to someone they're gonna see a solid axle in a 99+ cobra and be like "hmmm they beat the **** out of this thing."

[Kilgore Trout]

Cobra solid axle swap makes the baby jeebus cry

[BennyBlown2v]

Originally Posted by Uncle Meat

Funny how so many people state the IRS will out handle a straight axle even when both are heavily modified. If you look under ANY of the current or past Mustangs that professionally road race they ALL use a form of modified straight axle...

U.M.

I would argue that is mainly for A) weight savings, B) reliability/access to parts, C) ease of tearing apart, and D) strength. All of the other cars in the classes with the mustangs in the past had IRS suspension, and as you probably know a few years ago the mustangs were getting absolutely destroyed by the Vipers and Vettes.

Fact is the Cobra IRS was a retrofit to the mustang body. Some have great success with a modified CIRS platform, others do not. For roadrace, the Kenny Brown IRS subframe was a great peice...though it's also incredibly hard to find now.... Also KB made tubular upper and lower control arms, which saved weight (also removed sprung weight).

Personally I liked the IRS equally to the solid axle, and I've had both, twice lol...and both reasonably modified (IRS w/ bushings and coilovers, solid with bushings, coilovers, and panhard bar).

I have plenty of friends who's terminators do great with the IRS at the track, the IRS-->solid swap craze was IMO really a hasty "easy fix" solution, for most I believe. For me, going back to a solid was more of a financial thing - nobody wants to buy a modified GT, and ESPECIALLY a modified GT with a suspension from an entirely different car.