But is it worth your time and expense to put an IRS in your Mopar? Only you can answer that, but if the answer is yes, Heidts can help you with that project. Although $7,995 is a big chunk of change for the upgrade, as we explained earlier, a modern independent rear suspension does have its benefits. So to get the skinny from the guys who actually build the kits, we asked Mike Hawley, Heidts sales manager, to explain why buying this kit is worth the money: "This Universal HHP IRS is an excellent solution for classic Mopar builders. Obviously, the current LX-platform cars utilize an IRS, so it's an ideal means for builders and customers to modernize their older cars with comparable ride and handling characteristics. Since this new universal IRS is rated for high horsepower applications, they [will also hold up to just about anything you can throw at it]. Quite simply, this is the most cost-effective means to get a modern IRS, with its outstanding ride and handling, under an earlier Mopar chassis. We can't wait to see what kind of Mopar muscle will be built with this IRS under it!"

Actually, when we started writing this, they were in the early stages of having a universal IRS kit available for all muscle cars, and we got the chance to travel to KC's Classic Cars in Bradenton, Florida, as they completed an install into a '70 Challenger. Hopefully the guys at KC's and Heidts can get together and make a true Mopar IRS kit. Please remember that this is not a bolt-in kit, and is not for the novice installer. You will be required to weld and fabricate mounts and brackets to support the trailing arms and such, so be ready. The new universal IRS features a fully-welded and boxed, cut-to-fit upper crossmember, heavy-duty upper and lower control arms, fully welded uprights, heavy-duty CV-joints and axleshafts, as well as Heidts' own cast centersection that can be loaded with a wide range of gear ratios and differentials. The Heidts IRS also makes use of standard 101?2-inch inboard mounted disc brakes with four-piston Wilwood calipers. Based upon the intended vehicle application, the kit is available in both 56- and 58-inch framerail width versions. Finally, we asked Mike why he would tell Mopar guys that changing to a Heidts IRS is worth doing. He replied: "For the classic Mopar muscle cars, there is simply nothing else out there like the Heidts IRS. The Heidts High Horsepower Universal IRS allows owners to update their classic Mopar muscle with a proven, industry-leading IRS solution without having to fabricate their own, saving themselves a lot of time, money, and hassle."

Price Tag

Universal Independent Rear endIRU-101 - smooth brake rotors; IRU-101-D - drilled and slotted brake rotors$7,995

Terms you need to Know

Unsprung weight: the weight of the suspension, wheels, and other components directly connected to the springs.

Sprung weight: the mass of the body and other components supported by the suspension.

Camber angle: the angle between the vertical axis of the wheel and the vertical axis of the vehicle when viewed from the front or rear. If the top of the wheel is tipped out more than the bottom, that's called positive camber. Likewise, if the bottom of the wheel is farther out than the top, it's said to have negative camber.

Heidts Hot Rods
111 Kerry Lane
KC's Classic Cars