When do I need to upgrade from 28 to 31 Spline axles?

04YELLOWGT said:

I would worry about beefing up the IRS. That will break befrore your axles will.

Click to expand...

BennyBlown2v said:

Uhm...he's talking about "beefing up the IRS"! Halfshafts (axles) are one of the FIRST things to brake on a Cobra IRS; the actual subframe is incredibly strong, so are the control arms and even the diff cover isn't that bad unless in a higher HP application (stock 03/04 cobras are known to break them) or when you have excessive wheelhop. The halfshafts in the 99 cobras aren't that great, I would swap them out for some 03/04 cobra parts (31 spline). Also you should look at 03/04 (cobra-r style) brace, and a billetflow IRS brace to keep the cover from breaking. DSS also makes halfshafts which can support 1000+hp

Hard launches and wheel hop are what kill these parts - so eliminating wheel hop is a great start! I would checkout www.maximummotorsports.com as they have the best IRS parts bar none; get subframe bushings, diff bushings (I use urethane, but aluminum is best), and control arm bushings. Also, IMO, the BEST mod for the IRS and reducing wheel hop is a set of coilovers as they allow a higher wheel rate with lower spring rate so you can run a softer spring with better results in handling.

Click to expand...