2015 GMC Sierra 2500HD CST Suspension 8-inch Lift Install
Adding Altitude and Off-Road Prowess to a Brand-New GMC
Here at Truckin, we always get excited when a new truck model comes out, since we know it’s just a matter of time until someone customizes it. We may not be wealthy and brave enough to buy a $60,000 truck and immediately modify it, but we know someone out there will be. Case in point, we recently came across this owner of a factory-fresh 2015 GMC Sierra Denali HD, and he told us he was ready to bite the bullet and lift his new truck. Needless to say, we jumped at the chance to get our hands on it.
To procure a lift kit for this new GMC Sierra, we called up CST Suspension. CST offers a full line of upgrades that fit 2015 HD trucks, including just about every bell and whistle you can imagine. We started off by ordering the company’s 8- to 10-inch lift kit (P/N: CSK-C3-16-1, $3,360) and added on four Dirt-Series 2.0 reservoir front shocks (P/N: CSR-6523 and CSR-6524, $273 each), two Dirt-Series 2.0 reservoir rear shocks (P/N: CSR-6526, $273 each), a dual front shock bracket kit (P/N: CSS-C5-6, $626), and Dirt-Series uniball upper control arms (P/N: CSS-C2-10, $721). We topped it all off with a set of 24x12-inch RBP Blade wheels and 37x13.50R24 Toyo Open Country M/T tires, which complement the new, aggressive stance. All the work was done by the experienced techs at Industrial Motoring, in Anaheim, California. Follow along to see how our modifications to this brand-new Denali made it a real head-turner.
1. When it arrived at Industrial Motoring, the GMC Sierra 2500HD looked like it had just rolled off the dealer’s lot -- it even still had dealer plates and window stickers in place. However, that was all about to change.
2. Here’s an overview of the massive quantity of off-road–ready upgrades CST supplied for this application. On the left, you have the standard CST 8- to 10-inch lift kit, to which we added six 2.0 reservoir shocks (top right), a dual front shock kit (bottom right), and uniball upper arms (far right).
3. Installation began with the truck up on a lift and wheels removed. First, the tie-rod ends were disconnected from the spindles, and the sway bar endlinks were unbolted from the lower control arms.
4. Next, a Maxx Cam torsion key tool was used to release tension from the torsion bars.
5. The brake rotors, calipers, and dust caps were removed from the hubs, and an impact gun was used to remove the hub nuts.
6. After removing the Sierra’s factory skidplates, the driver-side halfshaft was unbolted from the front differential and removed from the truck.
7. The spindles were disconnected from the upper and lower ball joints, then set aside. The front shocks were also removed at this point.
8. Then, the lower control arms and torsion bars were removed from each side of the truck.
9. Next up was the steering centerlink. It was unbolted and removed along with the factory tie rods.
10. The four bolts holding the rear crossmember underneath the front differential were taken out, and the crossmember was tossed in the scrap heap.
11. The driver-side rear crossmember mount needed to be cut for our kit to go on, so it was marked using CST’s supplied paper template. Then, a sawzall was used to cut away the excess metal.
12. The driveshaft U-joint was uncoupled from the front differential, and it was lowered out of the truck. This will allow us to install CST’s differential drop bracket.
13. The drop bracket was attached to the truck, and the differential was bolted onto the bracket in its new, lower position.
14. To accommodate our lift, the front bumpstop brackets needed to be cut off. An air cut-off saw made easy work of this task.
15. Since we were installing dual front shocks, we cut notches in the fender liners and bolted on these fabricated dual shock brackets from CST.
16. A little extra muscle was employed to lift the tough new front subframe into place before bolting it down with an impact gun.
17. The factory lower control arms fit perfectly into the subframe, now 8 inches lower than their factory location.
18. The CST kit includes this dropped steering centerlink, which was bolted to the truck’s pitman and idler arms.
19. Additional adjustable links tie the centerlink to the subframe, providing sturdy pivot points and keeping the steering setup as rigid as possible.
20. Secondary front shock brackets were set in place on the lower control arms, and holes were drilled before bolting it down with the included hardware.
21. The wheel hubs and brake backing plates we set aside earlier had to be bolted to the new CST spindles before they could be put on the truck.
22. The CST uniball upper control arms were added to the truck, then mated to the new CST spindles. These control arms will provide us with even more suspension travel and better durability.
23. The factory endlinks were removed from the old centerlink and screwed tightly onto the new centerlink with a set of Channellock pliers. New, longer bumpstop brackets were also added.
24. Now we could install the dual CST Dirt-Series 2.0 reservoir shocks in their new upper and lower mounts. These shocks are made in the USA, fully rebuildable, and valved specifically for this application.
25. Engraved and anodized billet brackets secure the shock reservoirs to the mounts we installed earlier. Not only do these dual reservoirs look great, but they make sure our truck’s shocks stay cool and retain a smooth ride.
26. The brake rotors, calipers, and dust caps were reinstalled on the hubs, and our frontend was nearly complete.
27. These extended sway bar endlinks were connected to the lower control arms, and the tie-rod ends were bolted to the spindles.
28. Finally, we needed to drop the torsion bars, so their mounting crossmember was removed, and these drop brackets were added.
29. After bolting the torsion bar crossmember to the drop brackets, the stock torsion keys were reinstalled and cranked, completing our front suspension.
30. The rear lift was painless to install. The Industrial Motoring techs simply supported the rear axle, removed the shocks and U-bolts, and added this 8-inch fabricated block beneath the leaf spring. Dirt-Series 2.0 reservoir shocks replace the factory units.
31. Observing our handiwork, we know this Denali HD was ready for some serious off-roading. Now we’re ready to hit the trails with improved ground clearance, a smoother ride, and extended suspension travel for better articulation. And, let’s be honest -- it looks cool, too.
32. The finishing touch for our 2015 GMC Sierra 2500HD was a set of 24x12-inch RBP Blade wheels and 37x13.50R24 Toyo Open Country M/T tires. They perfectly match the truck’s new altitude and fill in the squared-off wheel arches nicely. Looks like it’s high time to go get our new truck dirty.
Here’s how the 2015 GMC Sierra 2500HD looked after our modifications were complete. It took some guts to cut up a brand-new $60,000 truck, but it was well worth it in the end.
2015 GMC Sierra 2500HD SpecificationsVIEW ALL
|Fair Market Price||$31,532|
|Editors' Overall Rating|
|Mileage||N/A City / N/A Highway|
|Horse Power||360 hp @ 5,400 rpm|
|Torque||380 ft lb of torque @ 4,200 rpm|