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Ok guys, I already have a built straight axle and full adjustable rear suspension. Was wondering if it would be better to swap that into a Termi or leave the braced IRS in it? What kinda weight reduction would the swap be?
 

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IRS weight > SRA weight
 

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someone here in vegas did it to a whippled cobra has 700hp on 100 octane and loved the solid axle swap. i like my swap too it feels more solid. i got in his car, mine you can feel the bumps way more than on his. Its just the way you choose your after market parts, control arms, bushings, shocks, ect.....

oh and when i first did the swap the car feels way lighter
 

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its about 150lbs difference,the sra being lighter ofcourse.
 

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its about 150lbs difference,the sra being lighter ofcourse.
Bear with me as I'm still learning, but is 150 pounds really enough of a difference in weight or is it more that the SRA is better built to handle the power without breaking?

Why is it that the SRA puts power to the ground more efficiently than a SRA, in regards to hard launches/straight line acceleration?
 

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IRS are mostly made for curving maneuvers like road racing, etc. It is harder for them to squat down for launches. Most Cobra owners will swap their IRS for Solid if they take their car to the track a lot. Really depends on what your usage is going to be.
 

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id say if you have sra then id keep it, if you have irs and go to the track A LOT then switch to sra and make it bulletproof, if you go to the track just sometimes then just beef up the irs some and just have fun, or if you have sra and go to the track just sometimes then just beef that up some.
 

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There's a few things going on here.

The first is that drag racers have been working with the 4-link SRA since 1979. That's a LOT of experience.

The second is that the Cobra IRS was designed first and foremost to bolt-in in place of the SRA, handling, and launching were secondary concerns.

I say unless you're REALLY serious in whatever form of racing you're doing, build what you have, whether that be the SRA or the IRS. If you're really serious about 1/4 mile, eventually you'll want the SRA for the added strength. If you're really serious about handling, eventually you'll go to the SRA for the better geometry (unless you're on really bad surfaces, then you may want the IRS for it's better roadholding ability on the rough).
 

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its about 150lbs difference,the sra being lighter ofcourse.
No not quite, the difference is only actually about 80lbs. This is the way i see it...

IRS>SRA for looks and road racing

SRA>IRS for drag racing/launching and weight

Now its up to you to decide which are more important to you, unfortunately you cant have the best of both worlds without it costing an arm and a leg
 

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No not quite, the difference is only actually about 80lbs. This is the way i see it...

IRS>SRA for looks and road racing

SRA>IRS for drag racing/launching and weight

Now its up to you to decide which are more important to you, unfortunately you cant have the best of both worlds without it costing an arm and a leg
Sorry but its 148 pounds not 80. Where did you pull that number. How do I know because this kid I used race all the time full bolt on 03 Cobra with 150 shot would race me without the shot after I got my cams. My car was running rich and intercooler has been leaking since I switched block unfortunelty which is bad also. We always were neck and neck with mine not running up to par. I had 520hp and 520 toruqe wieghing in at 3800 with me in it. He has hard top with 490 hp weighing at 3800 with him in car.
So once he did sra he pulled a car and half on me 80 pounds would have not been a car and half. Just google it.
 

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Discussion Starter #13
i am wanting it to be mean on the street. ill make a few passes on the track but im not concerned about a time slip. from what i have heard/seen an irs cobra will rape a sra cobra out of the hole on the street. and that 150lbs is not gonna make up the difference of a car or 2 out of the hole. how many of you have experience with launching on the street in your cobra with sra vs your old irs?
 

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Sorry but its 148 pounds not 80. Where did you pull that number. How do I know because this kid I used race all the time full bolt on 03 Cobra with 150 shot would race me without the shot after I got my cams. My car was running rich and intercooler has been leaking since I switched block unfortunelty which is bad also. We always were neck and neck with mine not running up to par. I had 520hp and 520 toruqe wieghing in at 3800 with me in it. He has hard top with 490 hp weighing at 3800 with him in car.
So once he did sra he pulled a car and half on me 80 pounds would have not been a car and half. Just google it.
verts weight more then coupes... like 200ish pounds more i think its a little less

i asked in c my 4d's thread about his sra swap and the answer i got was 75

100 pounds usually equals out to about a 10th of a sec in the 1/4
 

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verts weight more then coupes... like 200ish pounds more i think its a little less

i asked in c my 4d's thread about his sra swap and the answer i got was 75

100 pounds usually equals out to about a 10th of a sec in the 1/4
I know the coupes to the verts are 200bls but I was talking about the SRA is a 147 weight reduction when installed to a Cobra.
 

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from what i have heard/seen an irs cobra will rape a sra cobra out of the hole on the street. ?
Pff .. not sure you who you've been talking to. My friends `04 cobra has a full Delrin bushing kit, adjustable sway bar ends and a few other bits, there is no way that car will launch the same on the street as a equally well set up SRA.. sorry man.. not happening
 

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I have built a few 600hp cobras at the shop and the ones with the irs had axle wind real bad, you cant feel it that bad until you start making big power, then it becomes move evident... the solid axle helps to get the power to the pavement as well. Its way better IMO.. Try finding someone with one and get them to take you for a cruise so you can feel it for yourself..
 

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I know the coupes to the verts are 200bls but I was talking about the SRA is a 147 weight reduction when installed to a Cobra.
he has a coupe cobra = 3600 stock

you have a vert = 3800 stock

by what you wrote there isnt 300+ pounds of difference in your guys cars

that right there makes the diff in your guys race.... plus with racing there are way to many variables so its not a good analysis.

from what ive heard and what people are sayin in this thread there is more to it then just weight. sra puts power to the ground better.
 

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Sorry but its 148 pounds not 80. Where did you pull that number. How do I know because this kid I used race all the time full bolt on 03 Cobra with 150 shot would race me without the shot after I got my cams. My car was running rich and intercooler has been leaking since I switched block unfortunelty which is bad also. We always were neck and neck with mine not running up to par. I had 520hp and 520 toruqe wieghing in at 3800 with me in it. He has hard top with 490 hp weighing at 3800 with him in car.
So once he did sra he pulled a car and half on me 80 pounds would have not been a car and half. Just google it.
Ok because of some race you had you now know the difference in weight is 148lbs? You sir are one hell of an engineer :stickpoke

I'm sorry but I didn't just pull that number out from anywhere but from articles that have credit. Here is one for reference 1999 Ford Mustang Review - The Car Connection

It clearly states that the difference in weight is 80lbs
 

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Ok because of some race you had you now know the difference in weight is 148lbs? You sir are one hell of an engineer :stickpoke

I'm sorry but I didn't just pull that number out from anywhere but from articles that have credit. Here is one for reference 1999 Ford Mustang Review - The Car Connection

It clearly states that the difference in weight is 80lbs
No Actually I pulled the number from weighing the vehicle of two friends of mine who have removed the IRS on their 2003 Cobras and installed a solid rear axle.
Here is the definition of Unsprung weight you might be confused.

(mechanical engineering) Unsprung weight= The weight of the various parts of a vehicle that are not carried on the springs, such as wheels, axles, and brakes. These were also all different on 03 04 Cobras except the wheels which were different but have nothing to do with SRA since you would install the same wheels.

The 1999 IRS assembly weighs about 80 pounds more than the solid-axle setup on the Mustang GT, but it allows a 125-lb reduction in unsprung suspension weight. And wait heres an added bonus you should have bothered to look up the differences between 1999 IRS to 2003 and 2004 Cobras since thats the year of Cobras we are talking about.

2003 Ford SVT Mustang Cobra review
one of the biggest differences between a regular Mustang and an SVT version lies in the suspension. In place of the venerable solid axle found in the rear of regular Mustangs lies an independent rear suspension (IRS) system. Even though the 2001 model was the first SVT Mustang with IRS, much has changed for 2003. Upgrades include revised bushings and stiffer spring rates for the coupe. A new tubular cross-brace has been added which stabilizes the differential under hard acceleration. At all four corners, gas-charged Bilstein dampers work to keep the suspension under control while providing a ride that's like Goldilocks' porridge—not to firm and not to soft. It's just right. The rack-and-pinion steering system gets a new, low-lash intermediate shaft and higher rate steering gear bushing for 2003. These changes noticeably improve steering feel by helping to reduce play in the system. Additional upgrades include tubular anti-roll bars that are thicker than stock, 26mm rear and 29mm front.

Everything above = 148lbs google things before you make your self look like you dont know what your talking about.:eek:
 
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