Opinions Wanted for Live Rear vs IRS

[COL3MANUS]

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.

 

[darkside03gt]

Honestly I would buy the mach1 and then swap in an irs. You are going to get a bunch of irs haters in here but you will also find that most of those guys are 1/4 mile guys who don't want the added weight. For you however it will make your camute to work a lot nicer. The irs really smooths out the car and helps balance it sine all these cars are nose heavy.

I would not do the swap without upgrading the bushings first though. Mm and full tilt both make kits bit full tilt gets my vote hands down. Yes it will add $$$ to the project but you will thank me later. Your handling will be much improved. Even if you buy a cobra this should be your first mod.

For me the irs was a must have after driving a cobra with mm bushings installed. The car just feels more planted and when pushed hard it refuses to give up grip. Yes you can make a solid handle just as well but for a street car I say go with the irs. I did and don't regret one bit of it.

 

[jegg]

I was in the same boat! Except I have a GT that I wanted to swap an IRS into. Instead I went with building up the solid axle with the panhard bar/torque arm set up and it handles like its on rails. One thing about building up a SRA is that road noise is a lot more noticeable. I've never ridden in an IRS mustang but I can't imagine the IRS being as noisy as a built SRA.

I think either way IRS or SRA...you'll be fine and happy. THe only reason I went built SRA was because I kept hearing opinions about how IRS swaps are hit or miss. Could be just incorrectly done swaps. Some people have problems with the swap and some don't. Of course if you did get the cobra the swap wouldn't be an issue for obvious reasons. As Dark03 said...if you go IRS...upgrade the bushings.

Here's my take on your situation...

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.

FYI-Maximum Motorsports sells k-members that work with the coyote motor.

MM K-member for Mustang, 1996-2004 [MMKM-2] : Maximum Motorsports, the Latemodel Mustang Performance Suspension Leader!

As far as suspension parts go...

If you want parts that will withstand the rigors of daily driving and road racing Maximum Motorsports would be my choice.

Griggs also makes good stuff but I've been told that Griggs focuses on race only applications.

Good Luck Man!

 

[N8Dogg98]

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

 

[COL3MANUS]

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.

 

[COL3MANUS]

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.

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.

 

[COL3MANUS]

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

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.

 

[N8Dogg98]

Dude for around $12K you can find a damn nice 99-01 Cobra. W/ an upgraded bushing kit from MM that thing will handle awesome. Then if it isn't fast enough you should have enough money left over for either a KB or a vortech kit

Besides, the 99-01 Cobra's have aluminum engine blocks and weigh less than the 03-04 Cobra's. Nothing against the 03-04 Cobra's at all, but it seems like you want IRS, a 32 valve v-8, and don't want to spend 19K, therefore a 99-01 Cobra is the obvious choice. If passing power is a concern, I guarantee you even a stock 99-01 Cobra would be more than adequate.

 

[COL3MANUS]

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.

 

[darkside03gt]

I didn't notice a drop in acceleration because 1. The 03irs irs comes with 3.55s and 2. I installed a kb 2.1 at the same time. The added weight actually balance the car out a lot.

The thing I noticed right away was how smooth the car was. Then I noticed the handling once I got it aligned. I had an mm pan hard bar on my solid andit wasn't as nice as the irs is.

 

[COL3MANUS]

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?

 

[N8Dogg98]

^ yes the 99-01 Cobra's came with TCS. The 99-01 Cobra is basically identical to the Mach 1 aside from different rear suspension set ups, different gauges, seats, and IIRC slightly different cylinder heads.

 

[darkside03gt]

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.

 

[N8Dogg98]

^ true, and by the time you add a PHB, LCA's, upgraded sway bar, and a TA to the SRA, it probably weighs damn near the same as the IRS anyways...

 

[SteedaGT9150]

IRS FTW!!

 

[007]

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.

 

[Stumbaugh]

IRS= fail

In all reality tho, it depends on what you want the car for. If you are wanting to drag race the car, you are stupid for wanting an IRS. But if you are wanting a car to take corners with, then an IRS is the way to go.

 

[darkside03gt]

IRS= fail

In all reality tho, it depends on what you want the car for. If you are wanting to drag race the car, you are stupid for wanting an IRS. But if you are wanting a car to take corners with, then an IRS is the way to go.

Sorry but i dont 100% agree with your statement. Just take a look at all the 03 cobra guys that still run the IRS. It can be made to hook and hook well. Most termi guys ditch it because of broken half shafts or busted center sections more so then weight.

 

[COL3MANUS]

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.

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.

 

[COL3MANUS]

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.

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