IRS vs live axle?

[Dr Fildo]

I know that the cobra one year (I think '98) came with an independant rear suspension. I'm guessing that it was not well received, b/c it was not offered again -

1. Was it any good?
2. Could you bolt it onto a '95, if you wanted to?

 

[GDTrumbo]

As I recall all '99-'04 Cobras are IRS. Although there are slight differences between the '99-'01 units and the '03-'04 units.(No Cobras built for the '02 model year) Either do not hold up real well on the drag strip with high horsepower.

GT

 

[Dr Fildo]

I'm not looking to race, just wondering why they never put it on the regular GT, and how it changes everyday diving characteristics? With the standard live axle, any time I drive over a bump that goes straight across the road, I get a noise from the rear that sounds like the car is gonna break in two, and wondered if that is also a problem with the IRS.

 

[glittle75]

they were offered in the years stated above, and they are good for everyday driving, and for autocross type events.

so far as at the track, they are very hard to launch well, ive only seen a handfull of people anywhere that can launch a 400+hp car with IRS without hopping down the track. theres alot of wheelhop when you launch a IRS setup, and you cant launch them hard, you have to ease into it alot. and it takes a while to get used to.

but pretty much any body style that came with IRS 94-04 it will bolt right up to a live axle car.

 

[Dalamar]

From what I've read, they're are the best feeling suspension for street driving, and takes dips and turns really smoothly.

Hard launching / drag racing tends to break the half shafts and smash bushings when you're over 450 HP.
MM makes an updated bushing kit, and you can get stronger shafts if you're into that.

The other thing is you get wheelhop durring high HP & hard launches becuase each side pivots independantly.
this can be addressed with the sway bar and spring rate.

I'm sure Replica or R3dn3ck could tell you more about them.
I've got an IRS right now for my 67 project car, just swapped the bushings a few weeks ago.

 

[Magic]

they were offered in the years stated above, and they are good for everyday driving, and for autocross type events.

so far as at the track, they are very hard to launch well, ive only seen a handfull of people anywhere that can launch a 400+hp car with IRS without hopping down the track. theres alot of wheelhop when you launch a IRS setup, and you cant launch them hard, you have to ease into it alot. and it takes a while to get used to.

but pretty much any body style that came with IRS 94-04 it will bolt right up to a live axle car.

Yes, its a direct bolt in pretty much. Just need to drill a cpl holes on the frame for two mounting bolts.
99-01 IRS had a 28 spline shaft. 03-04 had the 31 spline shafts.

For wheel hop with the IRS, there are kits from companies like Steeda and Maximum Motorsports etc that make urethane bushing kits for the IRS and other components to strengthen them up.

 

[GDTrumbo]

I'm not looking to race, just wondering why they never put it on the regular GT, and how it changes everyday diving characteristics? With the standard live axle, any time I drive over a bump that goes straight across the road, I get a noise from the rear that sounds like the car is gonna break in two, and wondered if that is also a problem with the IRS.

The major reason was the cost. This unit also adds quite a bit of weight. The addition of the IRS will nearly balance the car out 50/50 fore & aft.

If you have weird noises back there, start checking upper & lower control arm bushings or for bent parts. If the pinion snubber (or outboard snubbers) is dried out and/or has fallen off can cause some nasty noises.

GT

 

[Dalamar]

The addition of the IRS will nearly balance the car out 50/50 fore & aft.

Hadn't thought of that, interesting.

 

[Dr Fildo]

No, the noise is not unusual - It has been happening since I drove the car off the lot in the summer of '95 - just a little unsettleing.

Tons of great info here. Thanks guys. I'm thinking about upgrading

What do you think the cost of the switch would be?

 

[ThePope]

If you go on svtsnake.com or svtperformance.com every now and then you will find a cobra guy looking to trade rear ends. But other then that, I seen complete rears go for $900 bucks. You best bet is to post up that your looking to trade for a IRS setup. Someone will respond. All the cobra guys like solid rears.

 

[realitygt]

only differences between 99,01,03,and 04 are the halfshafts, 99 was 28 spline and 01 up were 31 spline, They're known for cracking w/o a girdle, and over on svtp I've seen ppl cut 1.4 60's with stock irs with bushing upgrades

 

[19mustang95]

If you go on svtsnake.com or svtperformance.com every now and then you will find a cobra guy looking to trade rear ends. But other then that, I seen complete rears go for $900 bucks. You best bet is to post up that your looking to trade for a IRS setup. Someone will respond. All the cobra guys like solid rears.

not many people will want to trade for a 94-98 Solid axle since it is shorter than the 99-04 Solid axle and IRS. I have an IRS in my car, and i wouldnt want to go to a solid axle unless i raced a few times a month...