Built SRA or Upgrade IRS

[03Snake04]

I am at a crossroad of upgrading the IRS or going SRA for the future occasional trips to the track. I know of someone who has a "built" SRA for sale. Listed below are the parts to it. He said all i would need is a new cat-back which I am aware of, but that it would be a complete swap otherwise. I know nothing about the parts included or quality brands for the swap so those who have a SRA or swapped to one, can you guide me into making a better decision.

My reason for looking into this SRA over the IRS upgrading is because the IRS just feels so sloppy to me, it howls and squeaks everywhere and the "slack" drives me up the wall. I would hate to start upgrading it and never get rid of that slack from the T56/IRS combo.

So, Are these quality parts?
Does this appear to be a complete swap?

Qa1 adjustable shocks
Coil-Over Kit
Relocation kit for coil-over
Steeda adjustable uppers
Hpm lowers
Miller anti-rollbar
Speed sensors
Cobra brake brackets
Ford racing rear end girdle
Welded axle tubes
Strange axles with studs
Auburn locker
4.10 gears

The gear would def be replaced with a 3.55 or 3.73 for my taste

He says all parts are brand new and he wants $2,000. Any help to get me more familiar would be appreciated

 

[mineral154]

i have a built tt and the irs has been upgrade with all steeda parts, it has never hopped or clunked. my last 06 gt with the solid 3 link rear hopped all over just an fyi

 

[VADEi2]

I'm at 569rwhp and just upgraded my IRS with FTBoogie kit and all I can say is WOOOOOW!! no wheel hop and now I'm debating going turbo

 

[03Snake04]

well wheel hop doesnt seem as issue .. its the slack and the clunk! i dunno it just feels so sloppy ..

what does a complete upgrade irs part list consist of?

a complete bushing kit and what else? i got a lot to read on as i really dont want to lose my irs, but something needs to be upgraded for sure!

one more thing, the previous owner said he put in a delrin bushing kit? is that the right kit to replace the stock bushing with? is that the same kit at bruces and/or boogies?

 

[LIGHTNING LARRY]

Moved!

:wf::wf:

 

[SVT03Chris]

Cody, That list looks to be a pretty solid setup for a SRA.

I love mine and wouldn't have it any other way. It was one of the (many) reasons I fell in love with my car before buying it. I can't complain that it dropped 105lbs off the car too :rolling:

As far as gears, I have 3.73s and I feel they are just perfect for a Twinscrew setup like you have yourself.

 

[03Snake04]

i think i am going to go with this setup .. i dont think i will regret missing the irs ... cause honestly i hate it .. noisy clunking little booger!:bored:

 

[SlowSVT]

i think i am going to go with this setup .. i dont think i will regret missing the irs ... cause honestly i hate it .. noisy clunking little booger!:bored:

Not trying to crital but based on your post it is apparent you don't really have much understanding of what is at play here or even what you hope to gain. The IRS enjoys numerous advantages over a solid axle which is a low cost alternative for the factory. An IRS suspension is more compliant with the road surface improving grip because it reduces un-sprung mass at each rear wheel by 65 lbs (mine is close to 100 lbs) over a stick axle. The IRS is also fully adjustable for camber and toe-in where an SRA suspension geometry is pretty mush a fixed entity. My guess is that for every mile you put on at a drag strip you will put 1000's of miles on the street where the stick axle is at a clear disadvantage. On a road racer no one in there right mind would do this swap :dw:

There are very few instances IMO that would justify swapping to an SRA into a Cobra which was designed to handle curves. Unless your planning on tailoring a 9 sec car to the drag strip but other then that it is doubtful it will make you win races or make for a better car. There is quite a bit more aspects to this story but it would make for a very long post. I would be learning more about this topic before you decide whether you want to make this move. Once it's gone it's not likely it will find its way back into your car and it will diminish its appeal should you sell it down the road. Anyone seeing a stick axle's on a Cobra first impression is the car has been drag raced extensively and should be avoided like the plague :nono:

 

[Quasar Z]

This debate has always brought out the best and worst in people. I had an IRS in my convertible with MM bushings, BF brace, FLSFC's and H&R Sport springs. It still hopped and I have read about others that have everything done and still have wheel hop. I wanted a permanent, guaranteed solution so I went to a solid rear and solved my problems. I did not want to sink any more money and time into reducing hop, I wanted it eliminated.

As far as these cars being designed to handle curves, I would respectfully disagree. With an iron block, Eaton blower and substantial weight these cars are not really suited to handling. The IRS is very neat and exclusive to the Cobra so I would have kept it if it didn't hop - some people are fortunate and don't have hop, especially with the coupe's.

Do what you want with your car. Ride quality is not impacted much and if you like taking off ramps fast you can still do that. If you are a serious road racer or autocrosser, you probably have the wrong car to begin with in my opinion. If you are just doing this because of the clunk, that can be fixed easily and you can retain the IRS.

 

[03Snake04]

If you are just doing this because of the clunk, that can be fixed easily and you can retain the IRS.

If this can be fixed easily please elaberate on how? I have seen ppl do full bushing upgrades and still have the clunk? This is what I am afraid of

I am not thinking of switching for drag racing, autocrossing, smoothness of ride or any other issue. My reason was because of the backlash/slack in the IRS ... if it can be permanantly taken out with no more clunk... please tell me how!?

 

[Quasar Z]

If you are getting the typical clunk, it is due to the rear differential support bushing. The stock front subframe bolts are also a known cause for clunking. Look on the following site to learn more about this:

FTBR Frequently Asked Questions

Can you believe it, a guy with a SRA that is actually impartial:dancenana:

 

[SlowSVT]

This debate has always brought out the best and worst in people. I had an IRS in my convertible with MM bushings, BF brace, FLSFC's and H&R Sport springs. It still hopped and I have read about others that have everything done and still have wheel hop. I wanted a permanent, guaranteed solution so I went to a solid rear and solved my problems. I did not want to sink any more money and time into reducing hop, I wanted it eliminated.

As far as these cars being designed to handle curves, I would respectfully disagree. With an iron block, Eaton blower and substantial weight these cars are not really suited to handling. The IRS is very neat and exclusive to the Cobra so I would have kept it if it didn't hop - some people are fortunate and don't have hop, especially with the coupe's.

Do what you want with your car. Ride quality is not impacted much and if you like taking off ramps fast you can still do that. If you are a serious road racer or autocrosser, you probably have the wrong car to begin with in my opinion. If you are just doing this because of the clunk, that can be fixed easily and you can retain the IRS.

"These cars are not designed to handle"

Tell that to a Cobra R guy, or the employees at Maximum Motorsports LOL. Better yet maybe AC427 will send you a link to one of his road race video's. There are quite a few vette, BMW's and Porsche owners who have a healthy respect for a well sorted SN95 Cobra.

Read the chassis development section in the book about the development of the Terminator "Iron Fist, Lead Foot". I think your perspective will change in a hurry. If this car was not a good platform for cornering it would not be in my garage.

This debate does not bring out the worst in people. Only their ignorance about these cars as noted above :nonono:

 

[SlowSVT]

If this can be fixed easily please elaberate on how? I have seen ppl do full bushing upgrades and still have the clunk? This is what I am afraid of

I am not thinking of switching for drag racing, autocrossing, smoothness of ride or any other issue. My reason was because of the backlash/slack in the IRS ... if it can be permanantly taken out with no more clunk... please tell me how!?

I had the clunk in my car but it only did it when transitioning from foreword to reverse. It sounds a bit hoaky in a $34,000 car but it won't lead to anything breaking. I am a bit perplexed why someone would replace an IRS with a solid axle just to eliminate the clunk. If I had a solid axle car I would be more then happy to get a case of the cluck in order to gain the advantages of an IRS.

Not sure if you have done so already but did you replace the 13 mm front sub-frame bolt with 14 mm or better yet 9/16"? The mount was designed for 14 mm but the factory requested if they can use 13 mm to facilitate assembly. The IRS sub-frame will rock up and down in the torque boxs from the loose fitting bolts when the car is shifted into revered and back. It's a very easy job and would be the first place I would go. You might also want to replace the rubber differential mounts with aluminum mounts as well. For some those mods have completely eliminated the clunk.

 

[Quasar Z]

"These cars are not designed to handle"

Tell that to a Cobra R guy, or the employees at Maximum Motorsports LOL. Better yet maybe AC427 will send you a link to one of his road rave video's. There are quite a few vette, BMW's and Porsche owners who have a healthy respect for a well sorted SN95 Cobra.

Read the chassis development section in the book about the development of the Terminator "Iron Fist, Lead Foot". I think your perspective will change in a hurry. If this car was not a good platform for cornering it would not be in my garage.

This debate does not bring out the worst in people. Only their ignorance about these cars as noted above :nonono:

Ok, you got me. I am ignorant about these cars and their storied history of being road race champions:rollseyes I did read "Iron Fist Lead Foot" and will tell you that there are not a whole bunch of successful Terminators out on the road course circuit or autocross track by experience, not speculation. As an owner of an '03 Cobra, I think it is a great car for what it is. It is not even in the same league as the Corvette's that I have owned and raced.

Bringing up the 300 or so 2000 Cobra R's produced as well as Maximum Motorsports? Is MM currently campaigning an '03-04 Cobra, or better yet do you think a good portion of their business comes from these cars? Your two examples are not very good as they represent an extremely small percentage of the Mustangs that are raced. The bottom line is that a heavy, iron-blocked and supercharged car is not the greatest road racer. Will people road race them? Absolutely! Does that mean they are the best car (or even Mustang) for that purpose? Apparently you think so but again, I will respectfully disagree without insinuating that you are ignorant:beer:

 

[mineral154]

[nomedia="http://www.youtube.com/watch?v=64Y1xpTYXUU"]YouTube- Griggs Racing GR40TT 2007 Virginia City Hill Climb[/nomedia]op:check out the chase down of the zo6 while your there solid 3 link vs. irs. and i guess my point to all of this is if your the man like Guy is it dont matter what your driving.

 

[Powershift03]

Bringing up the 300 or so 2000 Cobra R's produced as well as Maximum Motorsports? Is MM currently campaigning an '03-04 Cobra, or better yet do you think a good portion of their business comes from these cars?

I work part time for MM, and own a 2000 Cobra R. So, I can tell you a lot of the parts sold by MM are indeed for IRS Cobras. In fact, the current MM Fox road race car is running a built IRS. The "clunk" in the IRS is all the slop allowed by the factory bushings. They can be upgraded.

Both solid axle, and IRS, cars can be made to handle the drag strip or road race... with the proper parts. If your planning to run 9s in the quarter (or faster) a solid axle swap would be a good idea. But, there are a ton of 10 second Cobras on IRS. And yes, ac427cobra is a perfect example of what a sorted out IRS can do. Just ask any of the Vette owners he races against. :lol1:

An IRS is currently in the Fox...

 

[Quasar Z]

I work part time for MM, and own a 2000 Cobra R. So, I can tell you a lot of the parts sold by MM are indeed for IRS Cobras.

If a good portion of the business from MM is coming from IRS cars, they must not be from this site judging by the number of people that run the FTBR bushings and H&R springs. I would hope that MM would be knee-deep in developing and selling parts for the 2005-up Mustangs instead of focusing on cars that have not been produced for nearly 7 years. It doesn't really matter, as you work for them and know the market better than I do.

With that said, I fully agree with you that a SRA or IRS car can be modified to run well at nearly any type of motorsports. I road raced my Corvette's and drag raced them and can tell you that they only came home on a flatbed after time at the dragstrip.

If my convertible didn't hop so bad I would have definitely kept the IRS. In a hardtop car this is not nearly as big of an issue due to the rigidity of the chassis. I love my SRA because it fits my needs and unlike others on this site, I am not trying to thrust my opinions upon anyone else. I am just sharing my experiences and encouraging people to do with their cars what they like instead of worrying about what others think.

 

[SlowSVT]

If a good portion of the business from MM is coming from IRS cars, they must not be from this site judging by the number of people that run the FTBR bushings and H&R springs. I would hope that MM would be knee-deep in developing and selling parts for the 2005-up Mustangs instead of focusing on cars that have not been produced for nearly 7 years. It doesn't really matter, as you work for them and know the market better than I do.

With that said, I fully agree with you that a SRA or IRS car can be modified to run well at nearly any type of motorsports. I road raced my Corvette's and drag raced them and can tell you that they only came home on a flatbed after time at the dragstrip.

If my convertible didn't hop so bad I would have definitely kept the IRS. In a hardtop car this is not nearly as big of an issue due to the rigidity of the chassis. I love my SRA because it fits my needs and unlike others on this site, I am not trying to thrust my opinions upon anyone else. I am just sharing my experiences and encouraging people to do with their cars what they like instead of worrying about what others think.

For a guy with both road racing and drag racing experience who trailers his cars “to” and “fro” you don’t strike me as a very technical detail guy. Road racers tend to be a very suspension savvy and have no problem sharing that knowledge and you are telling a guy to replace his IRS with a live axle :dw: Not only that but your drag racing a wet noodle convertible.

What’s wrong with this picture?

 

[Powershift03]

If my convertible didn't hop so bad I would have definitely kept the IRS.

Just out of curiosity, did you attempt to cure the wheel hop issue? Or, did you decided to swap out to an SRA instead?

Here is a quote of a simple explanation of wheel hop right off the MM web site, and it doesn't matter coupe or convertible....


A major complaint of IRS owners is wheel hop. The undamped compression of the rubber bushings in the rear suspension is the primary cause of wheel hop. That undamped movement is amplified by repeated loss of traction. Wheel hop occurs because the rear tires continually oscillate between losing and then regaining traction. The extremely soft stock bushings contribute greatly to this oscillation because the rubber compresses easily and then springs back, over and over again. To reduce wheel hop the stock rubber bushings must be eliminated.

 

[cobrakidz]

I know of owners that changed the IRS bushings and it helped a lot.