04 IRS

[fox racer]

Hey guys, I'm new to the whole IRS scene, but I might be getting my hands on an IRS rear out of an 04 Cobra to put in my Notchback. I just have a few quick questions:
1) Is there any way to tell the difference between, say, an 03/04 IRS and a 99/01 IRS?
2) Are there any mods I should do prior to the install of the IRS?
3) What are some weaknesses of the 04 model, that I should be looking ro upgrade first.

 

[Uncle Meat]

1) Is there any way to tell the difference between, say, an 03/04 IRS and a 99/01 IRS?

03/04 has beefier 31-spline axles I believe and a larger torque brace than the 99/01.

2) Are there any mods I should do prior to the install of the IRS?

Depends on your intended use. Level 5 half-shafts, poly bushings, IRS brace, pinion snubber, etc.

3) What are some weaknesses of the 04 model, that I should be looking ro upgrade first.

Besides the half-shafts themselves the rear diff covers get blown out under hard launches. Again an IRS brace can help prevent this.

U.M.

 

[fox racer]

Thanks UM. The car, for now, will be a street car, hovering around 300hp/320ft/lbs torque. I was thinking about MM Poly bushings (frame bushings), MM upper mount support (that peice of metal that is welded to the upper mount), and the Diff case brace. I read your post on how the case flexes so much that it cn break the seal, so I figure easier now then later.

I have very little hands on experience with the IRS setup, are the differences in years easil visible, or should I bring someone more knowledgeable to help me when I purchase it?

 

[WhiningCobra]

if you aren't going to road race or daily drive the car. i suggest you'd stay far away from a IRS. they're a pain, it clunks and it'll snap even on a slight launch. and it just adds weight. if i can do it again. i'd get a solid rear.

 

[VR4]

01s also have 31 spline but im pretty sure the 03/04 shafts themselves are bigger than 01s

bushings in 03/04s are slighty stiffer but i doubt youll notice the difference.


biggest weakness is the diff cover. BF IRS brace works wonders. considering youre putting it in a fairly light car i personally wouldnt worry too much about the halfshafts. i would do all the bushings in poly/delrin before installing it though.