Chevy Corvette IRS - Be Independent

For decades, hot rodders have been updating the front and rear suspensions on their vintage hot rods to more modern technology. Lately trucks are seeing the benefit of this same technology. The early conversions were simple swaps to stronger rearends like the 9-inch Ford, with its better leaf springs and shackle arrangements.

However, many classic trucks' rearends were mounted with short leaf springs and short shackles with bronze bushings. The short leaf springs didn't offer a smooth ride, as do longer springs, and the little shackles didn't move as freely during compression and rebound. The bronze bushings didn't help because they transmitted excessive road noise and harshness to the chassis-compared to the now commonly standard rubber bushings. (Plus, it was necessary to lube them periodically, or they could seize or wear out the bushing, becoming less effective.)

Recently custom truck owners began looking for smoother and stronger technology. One crossover wave was to the Jag and early Corvette rearends; they found their way neatly under the better hot rods and custom trucks. The Jags catch your attention with their twinkling half-shafts, but alignment of a Jag IRS can be problematic. In addition, hot rodders generally prefer more affordable American parts. Therefore Vette rearends are generally preferred. Corvette rearends are plentiful and can handle large amounts of horsepower. The '63-82 Vette rearend is stout and features trailing arms to control the fore and aft movement of the rear wheel. The Corvette IRS also uses a transverse multileaf spring to control the ride-which just doesn't look as cool as the Jag's coilover shocks. As a result, many builders changed their Corvette rearend springs to coilover springs.

In 1984, Chevrolet redesigned the Corvette rear suspension. The newer version featured a four-link mount in place of the trailing arms, and was primarily aluminum instead of less- attractive cast iron and steel. The new configuration was lighter with less unsprung weight-which rides better and, of course, looks much better. The steel multileaf spring gave way to a fiberglass monoleaf, and the brakes were much larger, looking like something from a racecar. Naturally, custom truck enthusiasts began creating mounting brackets for these rear ends.

As more enthusiasts looked to install these rearends, enterprising companies started to offer ready-made kits to make the installation easier for the do-it-yourself builder. One of the companies at the forefront is Flat Out Engineering in Orange, California. Owner Don McNeil has decades of experience in the hot rod chassis business and knows a trick or two about independent suspensions. Altered Engineering, also of Orange, California, had a request to install a Vette rearend in a '55 Chevy truck frame. CCT thought it would be interesting to follow along and see how the install and assembly was accomplished.