Low and Lethal: A 2500HD with a Unique Suspension Setup

We first noticed Mike Durand’s ’10 GMC because of its unmistakably low stance. Despite the huge drop, he also told us he used the Duramax-powered ride as a work truck and a hauler. That didn’t seem possible, until we looked underneath the 900 horsepower ride, and saw a different story.

As the owner of Dmaxstore.com, Durand deals in all sorts of Duramax parts every day, from transmissions, to turbos, to cosmetic upgrades. Suspension was one area he felt the market was a little lacking, so he set about doing some experimenting, using his own truck as a test bed.

PERFORMANCE FIRST

The idea was to build an ultra-low truck that still had all the usefulness of a regular-height ride, including suspension tuning. Durand knew he wanted a big drop in the rear, so that was the fi rst project he tackled. The frame was c-notched for clearance, and the rear was dropped a whopping 5 inches. Alpine Designs Off Road helped out with building suspension for the truck that still had plenty of travel, and would work with the lowered stance. The overload springs were removed, and in place of normal rear shocks a cantilever suspension was built incorporating QA-1 double adjustable shocks, and Air Lift rear airbags. The front suspension and steering were also upgraded, with a complete Kryptonite Stage 3 steering kit, Kryptonite lower control arms and McGaughy’s Spindles that dropped the GMC 3 inches in the front.

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4_DMAX1703 — The HSP Diesel-built compound turbo kit is state of the art, and incorporates such features as a wrapped and shielded exhaust hot-side to help the turbos spool and keep underhood temperatures to a minimum

5_DMAX1703 — Durand chose to retain the factory variable-geometry turbocharger for its quick response on the track or the street. The 71mm turbo is from High Tech Turbo, and is suited quite well for the application.

DMAX POWER

With such a creative suspension design, Durand knew he needed the truck to lay down some power to test the practicality of the setup. He quickly progressed into the 13s, then 12s all on a single turbo with no nitrous. He had bigger plans though, and over the winter set about building a serious powerplant for his GMC. The new engine was fitted with an LBZ crankshaft, ATI balancer, and SoCal Diesel main girdle. Swinging from the crank are Crower connecting rods and Fingers pistons, with ARP studs and bolts keeping everything together. SoCal Diesel provided the heads, and a cylinder swap camshaft that is designed to reduce stress on the crankshaft.

6_DMAX1703 — Outside air is compressed through a large 83mm S400-frame turbo from BorgWarner. Exhaust exits through a 5-inch downpipe and MBRP mid-pipe, before exiting under the truck.

7_DMAX1703 — All the air in the World won’t do any good if the fuel isn’t there to support it. A PPE Dual Fueler kit mounts a second CP3 up top, which works in conjunction with the factory unit to send fuel to Dynomite Diesel Performance race injectors.

8_DMAX1703 — The Allison 1000 six-speed transmission has been built to the hilt in order to handle hard launches at the dragstrip. At 6,700 pounds, the GMC is no lightweight, so the transmission received billet shafts, an upgraded converter and flexplate, as well as a PPE transmission pan.

Durand planned on upgrading the turbos with his new build, so he had HSP fabricate up a set of compounds for the truck using a 71mm turbo from Hi-Tech Turbo, and an 83mm S400 from BorgWarner. The fuel system was also upgraded, with an AirDog 165 lift pump, PPE Dual Fueler, and custom injectors from Dynomite Diesel Performance. A set of HSP exhaust manifolds and up-pipes take care of air on the exhaust side, while a Banks intercooler chills the intake charge on the other end.

With the new engine build came another 300 extra horsepower, so Durand wanted to make sure his Allison 1000 transmission was up to the task. The Stage 6 transmission was built at Dmaxstore.com, and features billet shafts, a Precision torque converter, SoCal Diesel flexplate, and alto clutches.

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10_DMAX1703 — Durand’s GMC has two different sets of wheels and tires for a variety of occasions. The first setup is 22×9.5- inch Fuel Mavericks, which have 305/40R22 Toyo tires mounted on them. If he needs more traction, he switches to Nitto NT555 drag radials, which are mounted on 20×10-inch Sota Reprs.

9_DMAX1703 — Durand put a lot of thought into stopping his truck as well as accelerating it. Wilwood TX6R brakes were installed, which feature huge six-piston calipers for maximum stopping power.

11_DMAX1703 — From the outside, the only cue that something is going on underneath the truck are the prototype Kryptonite traction bars. That’s just the start though, as there’s a lot more going on underneath the truck.

12_DMAX1703 — The rear suspension is one of the wildest setups we’ve ever seen on a diesel. The factory leaf springs were retained, but a custom cantilever rear suspension was built by Alpine Designs that gives the truck nearly infinite adjustability.

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13_DMAX1703 — For the extra load of a trailer, air springs from Air Lift were added, and can be aired up or down depending on the weight with a Air Lift wireless 72000 controller.

14_DMAX1703 — Mike added 3.42 gears front and rear, to spread out the gear spacing on the truck. The rear axle also has a Mag-Hytec pan to keep the fluid cool, and a Truetrac from Detroit Locker for traction.

15_DMAX1703 — Though it’s not as wild as the rear suspension, the front end has received its share of upgrades, including a Kryptonite Stage 3 steering kit, and lower control arms from McGaughy’s Suspension

17_DMAX1703 — A Street Scene rollpan keeps the lines of the truck clean. For towing, Durand relies on a gooseneck hitch, rather than a bumper-pull design.

16_DMAX1703 — The front of the GMC has been modified with a bumper cover from Street Scene, that works well with the GMC’s stance.

With Mike Durand thrashing to get the truck finished for 2016’s Truck Mania, there was little time left for testing before the big show. With the DSP switch on the ATP-tuned engine up on level 5, the GMC was able to put down a whopping 917 rear-wheel horsepower on Northwest Dyno Circuit’s dyno. The truck also made a few laps on the track (on level 2) where it ran 11.60’s at 122 mph. Durand is confident that when the Allison learns a bit more and he turns the truck up, 10s are in the lowered work truck’s future. DW

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Pinaki Bhattacharya

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