Ford guys - IRS vs. stick axle

[MikeP99Z]

I have some folks looking to pick up a Mustang to road race in either CMC or AI. They are fixated on the 99/01 Cobra due to the motor, and more so the IRS.

Cost/benefit analysis for running the IRS - or has everyone here converted theirs to stick axle? Issues with the IRS?

Problems with this era Mustang?

Competitive chassis or not?

Input appreciated, thanks.

[cjlmlml]

here we go....

[kbrewmr2]

www.corner-carvers.com

bring nomex.

[Chuck]

For CMC, I believe the answer is clear, no IRS allowed. Quote below from the CMC eligible vehicles.

1996-04 Ford Mustang 4.6 DOHC N/A V8*(2000 Cobra R and 2003-2004 Cobra models excluded; 4.6
DOHC may run CMC2 only)
* IRS cars must replace the IRS with standard Mustang live axle

Chuck
CMC#14[/quote]

[MikeP99Z]

Thanks Chuck, if they continue to pursue this car I'll let them know to convert for CMC or its AI.

[MikeP99Z]

here we go....

Ut oh, I didn't do a proper search.

LOL - I'm just looking for the simple answer to say either don't bother with this car, or just find a regular GT shell and drop XX motor in it.

[MikeP99Z]

Also, what's a good DFW mustang forum with used cars?

[marshall_mosty]

Mike,
I think the consensus would be:

1. Smooth track would favor the stick axle
2. Rough track would favor the IRS
3. Standing starts would suck with an IRS
4. Alignments are critical for the IRS to work properly
5. AI power levels might prove too much for the half-shafts
6. Diff cooler is a MUST for IRS to live

[cobra132]

Ditto what Marshall said except the half shafts are stout. I have an 03 cobra rag top with delrin bushings etc. About the same p/w as my AI car but obviously heavier. The AI car with MM setup has a ton more grip. Not an apple to apple comparision, but if I were building from scratch I would favor the solid axle. Also the IRS is a pain to work on unless you drop the whole unit, which is not hard to do. FWIW FMR

[RichardP]

I have some folks looking to pick up a Mustang to road race in either CMC or AI. They are fixated on the 99/01 Cobra due to the motor, and more so the IRS.

As is typical with people thinking that they might like to try something, they are focused on the wrong thing. They need to decide what class they want to run in first and then build to that. Beyond both being V8 pony cars, CMC and AI are diametrically opposed in concept.

Beyond that, a "good" IRS is theoretically an advantage in road racing. The Mustang IRS is not "good" and can't be made "good" under the AI rules. There are certainly plenty of band aids that make it serviceable for AI but most people trying it in AI eventually give up and go solid.

I would recommend CMC. If they go AI, I would recommend going with something other than the Cobra motor and the IRS.


Richard P.