Am I Crazy?

[Sny714]

I dont have as much power as any of the 03+ cobras obviously but I hook without a problem at the track. I was cutting back to back 1.7 60's on 275/40/17 DR's while only launching around 3500rpm. Im sure if I had 450+rwhp that would be a different story though.

 

[ac427cobra]

I dont have as much power as any of the 03+ cobras obviously but I hook without a problem at the track. I was cutting back to back 1.7 60's on 275/40/17 DR's while only launching around 3500rpm. Im sure if I had 450+rwhp that would be a different story though.

450 RWHP on a built IRS with OEM 31 spline Terminator halfshafts is no problemo! :idea:

 

[BlownAway03]

Since the swap back to the IRS I can't imagine what state of mind I was in when I originally traded it for the SRA. Rough spots in the roads that used to pound me with the SRA are barely even feel now. For 10 second street cars and up I think the IRS is the way to go. I hook better on it, it rides a hundred times better, and I think that it just separates our cars from the "lowly" mustangs. After all, what performance car still uses a solid axle besides the Shelby?:nonono:

 

[EvilTwins]

Well you certainly answered your own question right there, and I couldn't agree with you more...

 

[Finaltheorem47]

The IRS has limits, just as a stick has limits. By going with an automatic, you'll most likely be able to run somewhere in the 700 RWHP range and be ok. With a manual trans, 600-650 RWHP+, launching at 5k is what kills the IRS.

750 RWHP, launching at 5k will kill an 8.8 SRA. You're looking at 9" territory then.

FWIW

So from a roll the IRS would be more than fine? Hypothetically, I'll make a scenario. You are on a auto x track and your driving a 1100RWHP car and as you come out of a turn at 15mph (hypothetically of course) onto the straight and peg it. Would it be probably to break your IRS? Can you expect half shafts to break 99% of the time from launches?

My IRS is also a 2001 meaning its got 29 spline axles and diff, so if I upgraded my IRS instead of tossing it, it would be smart to swap all that stuff for 31 spline also, so that will add to the total.

Sorry if I'm getting into thread stealing territory.

 

[Jroc]

So from a roll the IRS would be more than fine? Hypothetically, I'll make a scenario. You are on a auto x track and your driving a 1100RWHP car and as you come out of a turn at 15mph (hypothetically of course) onto the straight and peg it. Would it be probably to break your IRS? Can you expect half shafts to break 99% of the time from launches?

My IRS is also a 2001 meaning its got 29 spline axles and diff, so if I upgraded my IRS instead of tossing it, it would be smart to swap all that stuff for 31 spline also, so that will add to the total.

Sorry if I'm getting into thread stealing territory.

I'm pretty sure that the 01's had 31 spline halfshafts where the 99's had 28 spline halfshafts. 03 Cobra haftshafts are stronger than the 01's though. I think 03 Cobra halfshafts run about $190 or so a piece.

 

[ac427cobra]

So from a roll the IRS would be more than fine? Hypothetically, I'll make a scenario. You are on a auto x track and your driving a 1100RWHP car and as you come out of a turn at 15mph (hypothetically of course) onto the straight and peg it. Would it be probably to break your IRS? Can you expect half shafts to break 99% of the time from launches?

My IRS is also a 2001 meaning its got 29 spline axles and diff, so if I upgraded my IRS instead of tossing it, it would be smart to swap all that stuff for 31 spline also, so that will add to the total.

Sorry if I'm getting into thread stealing territory.

What I am saying is the 'shock' of a 4-5k rpm standing start launch, with a high HP car is what kills halfshafts no matter how much the IRS has been stabilized. When you get over 600 RWHP you are starting to push the physical limits of the intended design. Some have been sucessful with over 600, some have not. Once you're 700 or over, you're in SRA territory and most likely a 9" at that! An 1,100 RWHP car will snap 8.8 SRA axles all day long.

Your auto-x scenario is true to a certain extent, but I doubt an 1,100 RWHP car could do much of anything without a nodular iron 9" SRA under it. You'd certainly twist that SN-95 chassis a few inches quite easily standing on the gas pedal! :idea: A properly prepped IRS could easily survive duty behind a turbo, automatic 700 RWHP car, even at the strip.

As Jroc stated, your 2001 has 31 spline halfshafts. But the '03 and up 31 spline halfshaft is a beefier unit than what you have.

FWIW

:thumbsup::coolman::beer:

 

[85FourEyedGT]

Its a love/hate relationship with the IRS, it handles great, has a great ride, and at the track ive seen stock irs's cut 1.5's on slicks, yet theres always that thing in the back of your head that tells you that at any moment ur just gonna feel that big clunk and ur axles will be done lol