IRS to SRA questions

fromadig91 said:

So I broke my drive shaft and broke my diff cover, now I am faced with the dilema to either go SRA or (re)build the IRS...

Few things I need to know right off is the following

1. IF I switch to a SRA would one out of a 2000-2004 GT be better then one out of an 03/04 Mach?

2. I need a Posi unit, or "traction lok" as ford refers to it, both tires spinning simotaniously and receiving equal power, correct me if I am wrong but didn't the 2000-2004 GT's come with limited slip? which is NOT the same thing? My understanding is limited slip is a "one tire fire" that slips the other wheel in and out of power to get traction....similar to the posi, yet different.

3. Do I keep my same lowering springs and other suspension parts? what needs to be changed?

4. What other major components need to be changed? say I get my hands on a 03/04 Mach rear end, what needs to be done to actually make this work?

5. Is there an indepth guide, or any guide for that matter on doing this swap on here or any other forums?

6. Is it really better to swap to SRA or to just repair the IRS, slam, brace, and add some bushings?

7. What are the major pros and cons of this operation?

Click to expand...

I'll grab the low hanging fruit...

#1 - both the GT and Mach share the same rear end, but the Mach has a couple of advantages - 3.55 gears standard and vented discs.

#2 - I'm not sure of the different terminology and how Ford uses it, but I thought all the V8 Mustangs had the limited slip diff..?

#3 - No, your springs would have to be changed as well. Also, your exhaust tubing won't work with a solid axle.

#4 - I'd grab everything including shocks and springs. It's my understanding that it will bolt right up.

#5 - I haven't seen a guide, but then again, I haven't looked either. There is likely something out here on the WWW.

#6 - I dunno - that's a personal choice. The advantage of the solid axle is durability for drag racing. The advantage of the IRS is cornering. Which is most important to you and how deep are your pockets? Either one can be made to work well in different conditions, but these things cost money. It sounds like your issue is funding, so I think you need to figure out the cheapest route and take that.

#7 - pretty much summed 'em up in #6.

Ok so did you brake the ujoint contecting the driveshaft to the rear-end? And what exactly happend to the diff cover? did the gears fail or did the cover just get beat up from the driveshaft? The reason i ask is if the u-joint failed because your car has been hammered on and had fun with then there is really no need to replace all that just because of this unless your planing on drag racing. I mean i would love to put IRS in my 98 get just because i dont drag race it except for the occasional stop light ricers...i would rather have a nicer ride quality and handle better. What im getting at is address what caused the failure and determine what your needs are as well as budget. btw maximum motor-sports has extreme setups for IRS rears...

What year is your cobra?

I google Cobra irs swap and heres a write up on how to do it

03 Cobra IRS Swap

^ what he said

I would prefer an IRS, but the budget didn't allow it at the time, and I'm not about to trade my car for a Cobra right now.

Seems to me an entire rear suspension swap is overkill to fix what broke on your car, but that's just me. You might invest in a reinforced diff cover for the future, but I wouldn't trash the IRS because of this.

Have you taken the diff cover off yet to see if there anything odd? The pinion gear may spin freely if something inside has broken loose. You may have broken some teeth on the ring gear that got wedged between the ring carrier and diff cover resulting in the diff cover breaking....So if it was me i would take the cover off and take another picture...

Hey, just a quick note from my virtaul shopping on EBay Motors - here's a complete Mach 1 rear end for $650... http://cgi.ebay.com/ebaymotors/MUST...r_Truck_Parts_Accessories?hash=item19b7058bb3

The stock rear diff mounting point is a known weakness on the IRS, there is a $150 brace that would have prevented that. If keeping the IRS I would get that brace and the front mount brace. You can use the diff cover from a Tbird/Cougar/Mark VIII with the 8.8 as they are all the same and where the Cobra cover was sourced from. The Cobra aluminum diff housing is a Mark VIII actually. If its just the diff cover alone that is broken that would cost you very little at a local junk yard as they are full of Tbirds and Cougars.

Cobra owners crack their diff covers all the time if they do not have a Billet Flow IRS brace or a similar device. The diff cover is a functional part of the rear suspension and its not up to the task in stock form. Wheel hop is what cracks them sooner or later it will happen.

The bottom line is that you cannot even do burnouts with a Terminator in stock form and that is bull****. It takes a good 1000+ dollars to correct the design flaws and that is if you do your own labor.

Who knows if it was the burnout you did or the million ones that came before it people do burnouts with these cars no matter what they say when they are selling it.

I am not clear on exactly how much and what is damaged I did not examine the posts clearly enough. However I can tell you this happens to Cobras all the time and you should repair it. If you do an SRA swap your Cobra will be un-sellible. At best you will sell at a much lower price than you otherwise could have.

One of the first things any smart buyer will ask is what's modded. Trust me an SRA swap will only be well received by a very small percentage of potential buyers. You will severely limit the ability to resell especially for a good price.

Do not do SRA swap. There is a reason that GT guys will line up to trade with you.

Kilgore brings up an excellent point - furthermore, putting a SRA in will tell any potential buyer, "I DRAG RACED THE CRAP OUTTA THIS CAR!" and will immediately lower it's value.