2007 GMC Sierra Buildup - Belltech 641SP Lowering Kit

For this month's Fantastic Four we've got a crew cab GMT900, the most popular cab configuration of the most popular fullsize truck on the market right now. If you've got a new Chevy or GMC, pay attention, because we did the hard work of finding parts that work together to make a great-looking, functional cruiser. On the performance front, we improved mileage, power, and sound thanks to K&N Filters and Heartthrob Exhaust. The tandem gave us a 22-RWHP boost in power and improved the Sierra's throttle response. We decided to trust the handling of a tuned Belltech suspension that will allow for a customizable ride height. Using an adjustable mounting point at the shackle and spacers in the sport-tuned coilover shock in the front, we can dial-in the suspension in exactly how we like it. Combined with the 2-inch drop spindle we'll have a range of 1-4 inches of drop. and unlike many lowering kits where the ride suffers, this kit was specifically engineered to provide improved handling and comfort. We haven't forgotten that we want this truck to look its best, so Elite wheels, General Tires, and T-Rex grilles were all called upon to make sure this truck ups the ante on all fronts with color-matched style. Check out how our neighborhood 4 Wheel Parts install tech, Jason Green, transformed the ride and handling of this Sierra before we upped the looks and performance at our very own Tech Center.

We rolled the Sierra into 4Wheel Parts completely stock.
Belltech's kit came with spindles and adjustable height coilovers for the front and hangers, shackles, shocks, and flip kit for the rear. Everything we needed for improved handling, a smooth ride, and looks that'll turn heads. This kit isn't your typical drop kit, it was designed with a no compromise attitude, and we couldn't wait to get it bolted on.
Belltech's kit came with spindles and adjustable height coilovers for the front and hanger
Jason began the front end disassembly by popping the hood to access the three bolts on each coilover from the engine bay. Then he lifted the truck, removed the wheels, and removed the coilover.
Jason began the front end disassembly by popping the hood to access the three bolts on eac

The two caliper bolts were removed, the wheel speed sensor was unclipped, and the caliper was hung from the frame to eliminate tension from the brake lines. Next, Jason unbolted the hub from the spindle. Here you can see the steering has also been removed and the sway bar end link is loosened, ready for removal.
The two caliper bolts were removed, the wheel speed sensor was unclipped, and the caliper
With the factory coilover mounted in a spring compressor, Jason removed the nut securing the shock to the mounting plate. Here's the side-by-side comparison. Note that the Belltech adjustable shock is nearly the same size.
With the factory coilover mounted in a spring compressor, Jason removed the nut securing t
For our application, the lowering will be all in the spindle, but if we had wanted to go lower or higher we could have tailored the number of these spacer rings to dial in the ride height.
For our application, the lowering will be all in the spindle, but if we had wanted to go l

Back to the spring compressor, the new shock met the factory bracket and spindle as well as the factory internal bumpstop. Jason also transferred over the threaded tabs from the factory shock.
Back to the spring compressor, the new shock met the factory bracket and spindle as well a
The factory hub was bolted to the Belltech spindle. This can be done with the spindle mounted, but the uppermost bolt needs to be inserted before the upper ball joint now that the hub is located closer to the top of the spindle.
The factory hub was bolted to the Belltech spindle. This can be done with the spindle moun
Jason bolted in the spindle, replaced the brake rotor, and finally the caliper on his way to buttoning up the front suspension.
Jason bolted in the spindle, replaced the brake rotor, and finally the caliper on his way

For the rear, Jason first dropped the factory trailer hitch to make room to loosen the leaf spring.
For the rear, Jason first dropped the factory trailer hitch to make room to loosen the lea
After removing the U-bolts, a C-clamp was used to hold the spring pack while the leaf spring center bolt was removed and reinstalled upside-down. This is necessary to index with the flip kit hardware.
After removing the U-bolts, a C-clamp was used to hold the spring pack while the leaf spri
The spring was then removed to access the bumpstop bracket and spring hanger.

A cutoff wheel cut the weld and an air chisel pried the bumpstop bracket off before a flap disc sanded the weld smooth. A few coats of spray-on undercoating protected the bare metal.
A cutoff wheel cut the weld and an air chisel pried the bumpstop bracket off before a flap
The factory bumpstop was secured to the recently sprayed frame.
The rear shackle hanger got the same air chisel treatment to remove the three factory rivets before the Belltech hanger was bolted on. Since we were going for only a 4-inch drop, the flipped hanger and longer shackle will actually lift the rear of the truck, otherwise we'd have had 6 inches of drop.
The rear shackle hanger got the same air chisel treatment to remove the three factory rive

A bracket on the axle housing was carefully cut out to avoid damaging the rear brake line before the flip kit hardware was sandwiched between the axle and spring.
A bracket on the axle housing was carefully cut out to avoid damaging the rear brake line
With the Belltech brackets in place, the factory U-bolts were reinstalled before Jason mounted the impressive Belltech Street Performance shocks. At this point we were anxious to get the truck on the road, but there were a few more steps to go.
With the Belltech brackets in place, the factory U-bolts were reinstalled before Jason mou
Jason installed a small spacer at the transmission mount to correct driveline angles. We were ready for the wheels and tires... Sorry, you'll have to wait.
Jason installed a small spacer at the transmission mount to correct driveline angles. We w