Opinions Wanted for Live Rear vs IRS

Hello everyone, I am a new member here and future Mustang owner. I am torn on the subject of this thread as I have heard many different things about it. I am currently on the prowl for an 03-04 Mach 1 or 03-04 Cobra. Not interested in GT's in this generation, nor am I interested in S195 GTs. I'd be purchasing one of the new 5.0s if I could afford it.

My dilemma is that I've heard that you can't really tell a difference between a Mach 1 and a Cobra, in terms of handling, during normal day driving. I have heard the contrary as well. I know there is a definite difference when you're pushing it on the track, but also have seen the reviews about the new 5.0 pushing a .9-something on the skid pad as well. So I am a bit confused as I have never really owned a car with a live rear before.

I have always owned imports, and really wanted the handling (or the closest I can get to) in a muscle car. Just to put it into perspective for everyone, my normal day driving is a 35+ mile hike up to work through some country roads, then hitting the interstate (I95 to 9A in North FL) going around 80+ mph, taking exits and on-ramps pretty fast. So it's a decent haul each way (50-55mins). Because of the traffic, I had to swap my '06 Frontier with my wife's '06 tC.. So needless to say, I am prepping the tC for a new home while searching for the Mustang.

My truck handles pretty well as I am able to take 45mph corners at around 60mph, so I think the live rear in the Mach shouldn't matter much. But that is why I am on here, hoping to get some educated opinions on the matter from you guys. I plan on keeping the car forever, and future plans (Mach1 or Cobra) are to convert to IRS if it is a Mach 1, drop the new Coyote 5.0 in, and a good 6-spd manual tranny.

I really want the Cobra as that is the obvious choice, but I am at my wit's end with this tC, and my patience is all but gone. So I am contemplating settling for the Mach 1 as it is way cheaper, but then again the Cobra has IRS already, the 6-spd I want. However, Cobras around here are still in the 19-20k range, but most good ones with decent miles are 20k+ and I dont want payments that long, so I am saving up to at least throw down half on the car to pay it off quicker. This is where the patience thing has me in a bind.

I think I might go for the Cobra, and hope that the 5.0 Coyote swap would lighten the front-end should the terminator engine ever decide to take a poo. Which should balance the car out, and hopefully lighten it. The Mach 1 also is a decent amount lighter, therefore easier to corner with. I am really sorry to have you guys read a book on my little issue, but trying to provide as much info on my thoughts and situation as I can. Thanks to all who have good input! You guys seem like a great community and I hope to be posting my new-to-me Mach or maybe even Cobra.

Thanks Darkside, did you notice a blatant power loss when accelerating with the added weight of the IRS? I know what you're talking about refusing to give up grip because a buddy of mine back in HS (he was in the Marines) had an '03 Cobra which he did an Eibach drop on, and he said that thing handled as if it was on rails. I just want to make sure the power is there when I need it, because on those back roads I hit on the way to work, there are A LOT of slow people. In slow, I mean driving 5-10mph under the posted, and there is so much traffic coming the opposite way that it's hard to pass. With such a limited window, I want to make sure I can effortlessly get around them as they tend to boil my blood when driving so slow! Almost got into a head-on the other day too, in the wimpy tC because it's acceleration will rival that of an Amish buggy. It seriously has to be an open road when trying to pass people in the tC, and some of those are just asses because they will speed up while you're passing! So I want to definitely be able to leave them behind should they decide to be a dumb dumb and put lives at risk.

jegg said:

Since you want to swap in a coyote...Just buy a new edge GT and build it up the way you want. Why buy a cobra and tear into it? The numbers for an all stock '03-04 cobra is dropping these days. Everyone wants one and everyone wants to mod it.

Also, why spend the extra money on a cobra when you are gonna swap out the engine anyway?

Go for a GT build the front and rear suspension swap in the coyote and call it a day You'll save tons of money and still reach your goal.

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Thanks for the input Jegg! I still want to enjoy the cars for what they are, not planning on doing the Coyote swap for quite sometime. I do really like how sexy that ass-end of a Mustang w/IRS looks too! I drool every time I see one. I just want to mod them up a bit and enjoy them. Since I am planning on keeping it for a long time, the engine will eventually go, so that's where the Coyote heart comes in.

N8Dogg98 said:

If you want to save a little money so you can keep the tC, what about a 99-01 Cobra. They have IRS AND a 32-valve V-8 that is virtually identical to the engine in the Mach 1. It has both things you want and desire AND it's not that difficult to find unmolested low-mileage examples

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Thanks N8Dogg. I thought the 03-04 Cobras were the first ones (besides the '00 Cobra R) with IRS? And I really hate the tC, no plans on keeping that slouch. For a four cylinder, it sucks gas like a V8... Also like some of the newer features in the new edge bodies, like TCS, and also not trying to get something too much older than the tC.

Thanks again N8, I will start looking into those Cobras and see what comes of it. I almost forgot about those. Usually when I think of a Cobra, the 03-04 versions pop in my head.

Well no wonder you didn't notice anything. I have done some research and I think I remember the IRS adds 150-200lbs, but with the Mach's torque I don't think it'd be a huge difference. Do you or anyone else know if the 2001 Cobras came with TCS and any other features that are in the Mach?

darkside03gt said:

The irs does not add 200lbs. The weight has been exaggerated buy all the irs haters. Its more like 70-90 depending on what has been done to it like adding a diff brace or upgraded half shafts. You will find that a lot of people who claim it weighs a billion pounds have never even seen one out of a car let alone installed one. I had one guy try to tell me it was so heavy him and his friend couldn't pick it up. Complete bs!

What iam getting at here is you will find a lot of people who hate on the irs but have never touched one. Its a great add on to the car you just have to be willing to deal with its issues.

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See, and before I even thought of researching it, I thought to myself it'd be lighter if its not around the same weight as the SRA.. Then to be sure before I invested in a Mach, I read about the "weight gain" the IRS adds. That guy must've been pretty weak if him AND a friend couldn't lift that!

To me, as long as the person knows exactly what they're doing, then an IRS swap should be pretty clean no? What issues are you referring to? Half shaft snaps? I guess my plan now is to look for the best car in the following priority. 03-04 Cobra, 01 Cobra, or 03-04 Mach.

007 said:

Live axle is crap. Awful awful crap. The rear of the car is so unstable on any surface that isn't totally smooth. And yes.... I've upgraded the suspension already. Its still terrible.
I won't buy another Mustang until they do away with this cheap crap rear suspension. When I drive my Benz it really rubs salt into the wounds.

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That bad huh? I read that the 2013 Mustangs (GTs and up I think) will now feature IRS. Finally, Ford gets with the times!