Project Duramax Diesel Gets a Lift

Chevy 2500HD Build-up Part I

Aug. 01, 2005 By Mike Lyon

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When I purchased my first diesel truck, my goal was aimed at towing the toy hauler to the dunes without a struggle. The Duramax engine with the Allision transmission took on this task with no hesitation. In stock form it towed great, but I felt it was lacking in the suspension and off-road capabilities. This truck is a daily driver, as well as a tow rig. I needed it to ride better on the bouncy California freeways, tow a heavy load and, be capable while off-road. This truck is not the typical pavement queen, it will see off-road action! The OEM heavy duty suspension was stiff and the narrow tires were not to my standards. I decided to add a lift kit and wider tires to make it fit my needs. After lots of research, I decided to use the California Super Trucks (CST) lift along with Fox Racing Shox.

Since CST started in 1996, they have designed and developed a lift kit for just about any truck. Plenty of research and development goes into their kits. All of this R&D is evident in the quality parts and the off-road trucks they build. Take a look at their web site and drool over some of their race/show trucks. Amazing stuff! One thing that stood out to me about their lift was the one piece sub-frame and the replacement upper control arms. With these components and dropping the factory suspension down a true 6”, the CST lift kit offers strength and durability. Keeping the stock angles on the tie-rods and front axles ensures no extra wear and tear on these components which means no extra costs in the future. Other great features include supported upper control arm drop mounts, heavy duty steering drop down brackets with heim jointed support links , and, for my application with 4 wheel drive, the differential is dropped down a full 6”.

To keep this truck riding smooth, we chose CST’s dual shock hoop in the front with Fox Racing Shox with the added reservoirs. In the rear end we opted for a taller leaf spring rather than lift blocks. We felt this would help with less axle wrap, as well as enabling better off-road capabilities. The leaf springs are actually for a ½ ton truck. This worked out well for us as it made a huge difference in how it rode on the freeway.

I also needed this truck to be able to tow a heavy load and these springs alone couldn’t handle the job. I decided to install a set of Firestone air bags with a compressor. This kit comes with detailed instructions and I was able to do the complete install in a couple of hours. The compressor is very handy and allows me to adjust the amount of air on the fly. I replaced the stock rear shocks with a set of Fox Racing Shox to compliment the front.

The Fox Racing Shox have proven to work great both on-road, as well as off-road. Fox has been a long time leader in the shock industry. Back in 1974, Bob Fox first used a prototype air shock on a Maico dirtbike. Since then they have become huge in the off-road industry for everything from mountain bikes to high dollar desert race cars. Fox races what they sell and can be seen at just about every off-road race testing and improving their design.

For this truck we used four 8” shocks with reservoirs in the front and two 12” units in the rear. These are the 2.0 non-coil over models. The 2.0 models feature a smooth bore seamless alloy body, a high-flow/large bore damping piston with high quality valve shims, is nitrogen gas pressurized, has Teflon lined steel spherical bearings, billet aluminum end caps and can be easily rebuilt by the customer. Fox assembles everything inhouse and ships to it’s distributors. I also had Empire Motorsports send a set of their beefy, polished aluminum reservoir clamps for the front shocks. These are larger than most clamps and only 1 is needed for each reservoir.

Other items to make this project come to life include the KMC XD325 wheels. These are 17” in diameter and 9.5” wide. They feature a large reinforcement ring on the outside of the wheel with a smaller one on the inside. For tires I used a set of 35x12.5x17 Pro Comp A/T’s. Since this truck would be used primarily on the road and in the sand, I chose the all terrain tire. These tires are not overly noisy on the road and work extremely well in the sand. This wheel and tire combination looks great, as well as providing a strong footprint on the ground.

I had the lift kit installed at Off-Road Warehouse in Escondido, CA. Jesse ‘the man’ Martinez did most of the work. Jessie has installed just about every type of lift kit on the market. He made numerous comments on how well the CST kit was made and how well everything fit together. One thing he really liked was how all the hardware for the kit was in marked bags. Lots of time was saved by not having to hunt for the right bolt.

Installation

Without going into a step by step process of the lift I will touch on some highlights. Obviously the 1^st thing is to remove all the stock components like wheels, the front and rear suspension components and the steering and differential brackets. Jesse also had to cut out the stock bump stops.

Once everything is removed, it’s time to install the good stuff! Jesse started by installing the 1 piece sub-frame . Once that is in place, the steering components get bolted in along with the upper control arm drop down brackets and the control arms. The lower control arms are bolted to the one piece sub-frame. Once everything was tightened up, Jesse installed the OEM spindles, brakes and the dual shock hoops.

In the rear end the process is pretty straight forward. The OEM leaf springs are replaced with the taller spring packs. The FOX Shox are installed and everything is bolted back together. It turns out the spacers on the end of the shocks were too narrow. The Off-Road Warehouse crew was able to make some new spacers that fit perfectly. The last step is to install the wheels and tires, align the front end and it’s finished!

I want to extend a huge thanks to Jessie and the Off-Road Warehouse crew for the fantastic job they did!

Testing

Since the addition of the lift kit I have put the truck through some serious testing. On the freeway it does still bounce somewhat but is much better than stock. Off-road the ride is amazing! The Fox Racing Shox offer a very plush ride and the taller leaf springs allow the rear axle to articulate on uneven terrain. The wider tires seem to float over the sand, where as the narrow stock tires would seem to dig in.

After a few moths of driving with the lift kit installed I decided to try a sway bar. The truck felt pretty stable, but I felt I could improve that with the addition of a Frederico Racing rear sway bar . Some say a sway bar on an off-road truck is not necessary, but our truck is mostly used for towing. This sway bar is made of solid 1 ¼” 4140 chromoly and it bolts in with no modifications needed. Once installed, I immediately noticed a difference just pulling out of the parking lot. It turns out I never really realized how much body roll this truck had. Making tight turns or even changing lanes on the freeway, I noticed that the truck felt much more stable. So much so, that I now noticed that the front end felt ‘tippy’ even though it comes with a sway bar from the factory. I decided to install Frederico racings front sway bar as well. The OEM sway bar is a 1 ½” hollow bar where was the Frederico bar is solid chromoly. You can expect a 10-15% increase in roll stiffness by upgrading to a solid bar of the same diameter and geometry.

Finished with Part I

Over all I am very pleased with everything that was added to this truck. It looks great and performs even better. Towing close to 12,000 pounds the truck is very stable even with the taller ride height. But I’m not finished with this truck! By adding the larger tires I reduced the gas mileage as well as the gear ratio which means less power.