IRS vs Straight Axle
 

I was looking into a the c4 irs swap or a straight axle set up... I am new to road racing and I was wondering which one would perform better?

for a 98-02 f-bdoy

another thing to consider is the relative complexity/cost of retrofitting the IRS .vs going with a a more common upgrade. A lot of 4th gen folks go with a 12 bolt or Ford 9 inch, which are both solidly proven upgrades. Kits are plentiful, and you don't have to do a lot of chopping and welding to make them work. If you're seriously wanting IRS, you might be best served by just getting a C5 and playing with that.

That said, you might want to look at this very informative thread: https://ls1tech.com/forums/suspensio...s-4th-gen.html

What bang will you get for the buck, going with IRS, compared to solid axle? Dunno. People will get religious in that argument, I'm sure. The car in my sig did 3 minute laps at Road America with a leaf spring suspended 8.5 inch 3.23 10 bolt. Brakes were its primary limiting factor--NOT the suspension/axle setup. It now has a 3.73 rear axle, Wilwood front brakes and LS1 rear brakes.

Yeah I've been doing my hw..on the c4 swap..I was j/w which one was better...I just want a new project that's different and when I'm done I can look back and say yep I did that and it does really good on the road course

another possibility is digging an IRS setup out of a Lincoln Mark 8. You'll need a new diff. unit (stock one is open, I believe) and a kit to convert from air ride to coils and shocks (commonly available). The donor car should be much cheaper than a Corvette or Mustang Cobra. It has a Ford 8.8 center section.

I don't know how it measures up to the Corvette IRS, but it might be worth a look.

Granted, an old truck has a lot more space to work with, but this page should hopefully prove helpful: http://www.team321.com/truckirs/TEAM...RSInstall.html

thanks bud