OBS GMC Sierra Upgrades: Wilwood Big Brake Kit & Aldan American Coilovers

By John Gilbert – Photography by the Author

With the OBS designation comes a rebirth of interest in the 1988-1998 C/K1500 series and that means in addition to parts than have been available for years there is also a current surge in new products. Naturally since Aldan American is a high-end shock absorber manufacturer they chose to source the latest developments in OBS brake and suspension components to complement their product by using Wilwood dropped spindles and accompanying Wilwood 6 piston big brake kit.

01 Aldan American being lifted on a Bendpak 2 post lift — Aldan American’s Gary Nelson used the Bendpak 2 post lift to raise the 1994 Chevy C/K1500 extra cab short bed up to show stock ride height.

The passage of time has a funny way of changing things. Take for example back in late 1987 when Chevrolet and GMC, after 15 years of producing essentially the same body style for its line of C10 pickups, introduced the C1500 and K1500, which C10 fans then referred to as the “new body style.”

In the 21st century the name has changed but the game is still the same: guys remain infatuated with the clean lines of the C1500 and K1500 series but the slang name is now OBS (meaning old body style). The C/K series wasn’t the first truck to be offered as a customized special right off the showroom floor … as history reveals, that was the 1956 F-100 right off Ford dealership floors.

02 Chevy C1500 K1500 limited wheel space — The stock 15-inch-diameter 1988-1998 Chevy C/K1500 wheel and tire does not provide room for larger-than-stock-diameter disc brakes.

Read More: 1969 C10 Front Suspension Overhaul

That said, the C1500 and K1500 series, or OBS as people now seem to prefer, was the Typhoid Mary of the sport truck movement, but it wasn’t enthusiasts who coined the “sport truck” name. The sport truck designation originated with Chevrolet naming the earlier Chevy C10 CST model—CST signifying “custom sport truck.”

The debut was a big deal. General Motors invested millions of dollars redesigning and engineering the new C1500 and K1500 series and then backed it up with major publicity campaigns that included supporting Gary Sowerby in 1987’s Fastest Transit of the Americas—Tierra del Fuego, Argentina to Prudhoe Bay, Alaska, with co-driver Tim Cahill in a 1988 GMC Sierra.

03 old oem brake system — Updating and improving the front brakes and suspension on Aldan’s OBS meant discarding the original pressed steel control arms and disc brakes.

In addition to the Argentina to Alaska reliability run, General Motors’ campaign to gain public awareness of the new C/K series included sending 12 pre-production 1988 C1500 and K1500 to Stanton, California, and tasked Boyd Coddington’s craftsmen with giving the trucks the Hot Rods by Boyd treatment.

Without having any idea just how popular the sport truck movement would become, this was a real leap of faith by GM that paid off tenfold. There weren’t aftermarket parts in mid 1987 made specially for the C/K1500; the series created a new category that exploded. Hot Rods by Boyd’s guys lowered the 1988 GMC Sierra 4 inches in the front, not with dropped coils/spindles (because they didn’t exist yet), rather, Boyd’s craftsmen fabricated new lower control arms and whacked the coil springs. In the rear, Boyd’s prototype 1988 GMC Sierra used a flip kit fabricated by Hot Rods by Boyd to drop the rear end 6 inches.

04 Aldan American coilover and shock absorber bolt in kit from Aldan American — Aldan American coilover shock absorber bolts directly in place of the stock coil spring with detached shock absorber. Note ball joint separator in use.

The OBS featured in this article was acquired recently by Aldan American to serve as a shop truck and test mule. Factory finished in Quasar Blue, the 1994 extended cab short bed with a 4.3 Vortec V6 was lowered with a basic front/rear drop the minute it was in Aldan’s hands. For the front suspension, unlike Boyd’s, unsurprisingly Aldan installed a pair of their own Aldan American coilover shock absorbers and the nose dipped.

In the rear, Aldan American’s R&D guy Gary Nelson installed a pair of drop shackles with a pair of shorter-than-stock length Aldan American shock absorbers mounted in the stock position. Typically, a drop executed in this manner affects ride quality immediately, but thanks to the damping benefits of high quality shock absorbers the results weren’t as drastic.