Differences Between '01 and '03 Cobra IRS

BlackGT89 · Dec 13, 2009

I know this is a little off topic here, but I tried the SVT forum to no avail. I want to transplant an IRS into my Fox body but I have a few technical questions. I've seen several '03 IRS's on Ebay, but I thought they were a little over priced, so I put it off. Now I've found an '01 IRS that seems to be at a good price (with about 75,000 miles). My question is this, is the '03 IRS far superior to the '01 to deserve the almost $1,000 more price ? I know they both are 31 spline and the '03 half-shafts are supposed to be improved in some way (?) and they come with 3:55's. Can someone tell me what exactly is different (or better) beside those things ? I will probably get rid of all the rubber bushings, add the differental cover brace and swap the 3:27's for 3:73's if I get the '01 IRS. I will probably need to decide today so any info would be great !

srtthis · Dec 13, 2009

03 has carbon clutches...

and honestly i think thats it... i really cant remember anything else.

BlackGT89 · Dec 13, 2009

Thanks man ! Anybody else ?

srtthis · Dec 13, 2009

If you haven't yet check svtperformance.com
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EPIK · Dec 13, 2009

Carbon clutches in the 03/04, & I'm pretty sure the 03/04 have slightly stronger half shafts, but I'm really not sure how much stronger. I think the 03/04 also has some extra bracing as well. The 01 is still pretty strong, just make sure you stay away from 99 Cobra IRS, as its only 28 spline....

If you replace all the bushings & get a nice IRS brace, it will be strong enough & won't have bad wheelhop, which is the culprit for most IRS breakage....

Take a look at this site. They have the BEST IRS bushing setups on the market

Full Tilt Boogie Racing Homepage

& here is a good thread from SVTP that you should take a look at...

Cobra Mustang IRS Delrin/UHMW/Alum bushing kit w/adj. sway bar links & bumpsteer kit - SVTPerformance

lancec2c30 · Dec 13, 2009

Yeah, if you plan on a diff brace and swapping out rubber bushings. The 01 setup should be fine.

Mustang5L5 · Dec 13, 2009

$1000 dollar price difference? How much are people asking for the 03/04 IRS??

I almost purchses a few in the $600-800 range for an 03/04 IRS.

BlackGT89 · Dec 13, 2009

Mustang5L5 said:
$1000 dollar price difference? How much are people asking for the 03/04 IRS??

I almost purchses a few in the $600-800 range for an 03/04 IRS.

Most 03-04's I've seen on Ebay are going for about $1,300 - $1,400 (one may have included a catback exhaust also). The '01 I'm watching now just jumped from about $300 to $515 this morning, so no telling what it will max out at.

srtthis · Dec 13, 2009

BlackGT89 said:
Most 03-04's I've seen on Ebay are going for about $1,300 - $1,400 (one may have included a catback exhaust also). The '01 I'm watching now just jumped from about $300 to $515 this morning, so no telling what it will max out at.

if it wheel hops... about anything you throw at it is gunna break it. if you get rid of the wheel hop it will go along way

SVT32VDOHC · Dec 14, 2009

03-04 Cobra has beefier axle shafts. I've heard the difference in wheel hop in 99-01 Cobra's vs 03-04 Cobras is night and day. My 04 is honestly not that bad. When it's cool outside, it might hop pretty good, but when it's a hot summer day/night NO hop!!

And PS....99% of wheel hop is in the tire. IRS and a street tire= You need a Nitto at least. M/T...even better.

srtthis · Dec 14, 2009

SVT32VDOHC said:
03-04 Cobra has beefier axle shafts. I've heard the difference in wheel hop in 99-01 Cobra's vs 03-04 Cobras is night and day. My 04 is honestly not that bad. When it's cool outside, it might hop pretty good, but when it's a hot summer day/night NO hop!!

And PS....99% of wheel hop is in the tire. IRS and a street tire= You need a Nitto at least. M/T...even better.

i'll agree that a set of drag radials like nittos help alot but i dunno if id say 99%. set of good IRS bushings go a long way (and this is coming from a guy who has HATES installing them) lowering springs help a little bit, strange adjustable shocks help a little bit.. i've even had customers back in the day say that after a subframe install they noticed less wheel hop.

SVT32VDOHC · Dec 14, 2009

srtthis said:
i'll agree that a set of drag radials like nittos help alot but i dunno if id say 99%. set of good IRS bushings go a long way (and this is coming from a guy who has HATES installing them) lowering springs help a little bit, strange adjustable shocks help a little bit.. i've even had customers back in the day say that after a subframe install they noticed less wheel hop.

With my car it was 99%. When I first got it, you couldn't even touch the gas with a street tire. Just taking off like a granny would give me wheel hop. The Nitto solved the problem. All summer, I'm good. October and November...slight wheel hop. At the track, not a bit of wheel hop...just spin.

From what I've read on the internet from other owners of Terminators, my car has less of a problem than theres do.

srtthis · Dec 14, 2009

SVT32VDOHC said:
With my car it was 99%. When I first got it, you couldn't even touch the gas with a street tire. Just taking off like a granny would give me wheel hop. The Nitto solved the problem. All summer, I'm good. October and November...slight wheel hop. At the track, not a bit of wheel hop...just spin.

From what I've read on the internet from other owners of Terminators, my car has less of a problem than theres do.

i'll agree with that...that some need more then others. seen some that wouldnt wheel hop a bit... then some that would do it if you looked at it funny.

SVT32VDOHC · Dec 14, 2009

srtthis said:
i'll agree with that...that some need more then others. seen some that wouldnt wheel hop a bit... then some that would do it if you looked at it funny.

Years back I race a 99 or 01 Cobra with my 96 Cobra. We took off, and he stepped on it sooner than me, and I heard this HORRIBLE knocking/hopping. At the time, I didn't know what the hell was going on. We raced again and the same thing happened. I smoked the guy because he couldn't even touch the gas.

BlackGT89 · Dec 14, 2009

Wow, I'm suprised the guy in the '01 didn't go sliding on his butt on the pavement with the rear end falling out with that much wheel hop ! I rode in an '03 once and he took from from a stop and there was a little rythmic chirping from the tires, but it launched for real !

Seems like I read somewhere that the '03 and up have an additional brace called a launch brace or launch arm, or something like that, but I've not been able to document it for sure. If I bought an '01 IRS I would definately beef it up as much as I could, but if I buy an '03 I will probably not poor anymore money into it. The '01 I was looking at on Ebay went for $886, I bowed out at a little over $700.

SVT32VDOHC · Dec 16, 2009

BlackGT89 said:
Wow, I'm suprised the guy in the '01 didn't go sliding on his butt on the pavement with the rear end falling out with that much wheel hop ! I rode in an '03 once and he took from from a stop and there was a little rythmic chirping from the tires, but it launched for real !

Seems like I read somewhere that the '03 and up have an additional brace called a launch brace or launch arm, or something like that, but I've not been able to document it for sure. If I bought an '01 IRS I would definately beef it up as much as I could, but if I buy an '03 I will probably not poor anymore money into it. The '01 I was looking at on Ebay went for $886, I bowed out at a little over $700.

I think the brace you're talking about is the factory 03-04 IRS brace that is used as an improvement to the 99-01 IRS brace. A couple sites I saw this on, had in parenthesis...(original equipment on 03-04's).

BlackGT89 · Dec 16, 2009

SVT32VDOHC said:
I think the brace you're talking about is the factory 03-04 IRS brace that is used as an improvement to the 99-01 IRS brace. A couple sites I saw this on, had in parenthesis...(original equipment on 03-04's).

Yes, I finally found it on svtperformance.com (as mentioned earlier but the website was down when I tried it). Outstanding website ! Here's a quote:

The front torque brace on the ‘99 SVT Cobra, the ‘00 Cobra R and the ’01 Cobra did not incorporate attachment to the front differential mounts. This is another area to help stabilize the differential. The ’03 and ’04 Terminator incorporated attachment of this front pinion brace to the front differential mounts. Some people refer to this as a “hard launch brace”.

I guess now my question would be can this brace be obtained and retrofitted to an '01 IRS to hopefully make it as strong as the Terminator IRS. Guess I will continue my research ! Thanks for all the input.

ac427cobra · Jan 22, 2010

BlackGT89 said:
Yes, I finally found it on svtperformance.com (as mentioned earlier but the website was down when I tried it). Outstanding website ! Here's a quote:

The front torque brace on the ‘99 SVT Cobra, the ‘00 Cobra R and the ’01 Cobra did not incorporate attachment to the front differential mounts. This is another area to help stabilize the differential. The ’03 and ’04 Terminator incorporated attachment of this front pinion brace to the front differential mounts. Some people refer to this as a “hard launch brace”.

I guess now my question would be can this brace be obtained and retrofitted to an '01 IRS to hopefully make it as strong as the Terminator IRS. Guess I will continue my research ! Thanks for all the input.

Yes, a Terminator or an aftermarket front differential brace WILL fit on ANY IRS assembly.

It's very important to remove ALL OEM rubber AND/OR poly located in the front AND rear differential mounts.

BlackGT89 · Jan 22, 2010

ac427cobra said:
Yes, a Terminator or an aftermarket front differential brace WILL fit on ANY IRS assembly.

It's very important to remove ALL OEM rubber AND/OR poly located in the front AND rear differential mounts.

Ahhh, that's what I was wondering. Thanks for the info !
I might go ahead and go straight axle 5 lugs and switch over to the IRS later since my search for a decent IRS (that won't break the bank) is going a little slow.

ac427cobra · Jan 23, 2010

BlackGT89 said:
Ahhh, that's what I was wondering. Thanks for the info !
I might go ahead and go straight axle 5 lugs and switch over to the IRS later since my search for a decent IRS (that won't break the bank) is going a little slow.

After you convert your car to an SRA, I don't want to be the guy that said "I told you so" when you start complaining about poor ride and handling!

Differences Between '01 and '03 Cobra IRS

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