IRS vs. live axle weight diff.

spyne said:

U.M., I don't think you are comparing apples to apples in this photo. The 8.8 in the pic shown doesn't have brakes, shocks or upper and lower control arms, all of which are on the IRS piece. That's not to say that the solid axle isn't lighter, it is, I just don't think this picture gives an accurate representation of the differences.

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Uncle Meat said:

I still think the IRS in the 03/04 Terminators weighs more than the IRS versions in previous years. The torque brace and half shafts were beefed up for the Terminators so I'm sure the weight difference is a little greater than what many think.

U.M.

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The IRS reduces rear lift under braking, making driving the Cobra hard a much more forgiving task. It improves the vehicle's attitude and control, with a full 0.75 ins. (1.9 cm) more suspension travel available. And it reduces the unsprung weight of the Cobra by 125 lbs. (57 kg). As expected, the IRS carries with it a fairly stiff weight penalty. To help compensate for the system's extra 70-lb. (32-kg) heft, SVT engineers extracted close to 50 lbs. (23 kg) from the car. The result: a weight distribution that moves from a 57%/43% front-to-rear split in the 1998 model to 55%/45% with the 1999, a significant enough amount to equal the effect of moving 80 lbs. (36kg) off the front wheels. Ford didn't limit its tweaks to the rear wheels, however. Besides the addition of the IRS, Ford also addressed other aspects of the chassis to improve the car's handling characteristics, like widening the rear track by 1.2 ins. (3 cm) to match the space between the front wheels and lowering it overall by 0.25 ins. (0.6 cm).

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