live axle vs. IRS

[N8prues96gt]

What are the pros and cons to both setups?

and what would be involved in swapping in a 03 cobra irs into a 96gt?

[Gene Fine]

Swapping them is literally as simple as unbolting the live axle, and bolting in the IRS. Just stick it under the car, lift, and bolt in.

As far as choosing the live axle vs. the IRS, that really comes down what you plan use your car for. By installing the IRS, you eliminate any chance of having fun with it at the dragstrip. Also, without significant reengineering, it sucks on the roadcourse. I've probably spent $2000 getting my IRS to work properly, and even then, I'm seriously considering binning it and going to 3-link.

What are your plans for the car?

[nates02gt]

Yeah I agree with Gene. I looked at swapping an IRS for my Live axle last year and decided not to. There are big problems with wheel hop among other things. Every shop I talked to said that you could build up a live axle to be better than any IRS. Keep the live axle and put your money into it.

[N8prues96gt]

Well my long term goals are 5.4 4v with a turbo kit. but i want the car to still be a daily driver. i'm not planning on going sctricly drag or road. so it's still fairly open.

I'm just curious as to what the ride is like is the ride much nicer than a solid axle or about the same. and why would ford put the irs into a car such as the 03 cobra if there are really no upsides to the suspension?
thanks for the help guys
-Nathan

[Gene Fine]

The ride is significantly better than on a live axle car, which is part of the reason why Ford went to the IRS in 99. The main reason was that market research showed that customers were cross-shopping the Cobra against the Corvette, and the lack of an IRS was a major marketing problem.

Because of cost considerations, though, the IRS is a flawed design. It is designed to use the same suspension pickup points as the live axle, which prevents it from having optimal geometry.

[N8prues96gt]

ok. now how much could i pick up a new or used irs if i decided to go to one. and how much would a modified irs run me if i took it to a shop? thanks again gene.

-Nathan

[Gene Fine]

Well, I've got a modified IRS I may be willing to sell. ;)

Check your PMs.

[N8prues96gt]

one last question If i change it out for 99 -03 IRS would there be any differences in the IRS itself?

And Would i need everything after the drive shaft or would i need the driveshaft also If i swapped them out?

THanks
-Nathan

[Gene Fine]

A few differences. The 03 has slightly revised geometry and stronger axles. It also has more solid bracing on the subframe.

Yes, you will need to change the driveshaft as well, along with the exhaust.