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One Ton GMC S15 Jimmy - A crawler for the whole family

Posted in Features on March 4, 2016
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Once you have kids, life changes. For some, this means selling their wheeling rig to spend weekends at Little League games and dance recitals. For Lance Morgan, it just meant upgrading his rig. “I had a Toyota pickup,” Lance explains. “I got this S15 Jimmy from my mother-in-law, Ronda, with the plan to swap the 4.3L engine into the Toyota. Then we found out that my wife, Ashley, was pregnant, so I decided to sell the Toyota and build the Jimmy.” Lance works as a mechanic at Independent Specialists in Reno, so he knows how to turn a wrench and operate a welder. These skills came in handy considering how little aftermarket support there is for the S15 platform.

The 4.3L Vortec V-8 engine stayed, along with the 4L60E transmission and the NP233 transfer case—well, mostly. Lance used the front half of the NP233 with the rear half of a Jeep NP231 in order to gain a floor-mounted shift lever. A set of full-width 1-ton axles was chosen to provide plenty of strength without breaking the bank. Even with 40-inch tires, Lance hasn’t had any issues with the factory axleshafts or hubs. The aftermarket provides plenty of upgrades when Lance finds the limits of the stockers. A custom link suspension using affordable Cherokee coil springs was fabricated for the front. The only part of the build Lance farmed out was the bumpers, which were built by his friend Brian Washburn at Cap X Fab.

The whole process only took two months, which left a lot of time before baby Kennady was born for baby showers, nurseries, and working long hours to put some money away for an extra mouth to feed. Kennady is now 10 months old and enjoys hitting the trails just as much as her parents do. It is a good thing that Lance can build a capable rig so quickly because the way things are looking, he is going to have to build another one for his daughter in a few years’ time.

Power comes from a 4.3L engine mated to a 4L60E four speed automatic. The factory transfer case is an NP233, which is similar to an NP231 but uses electronic shift. The GM transfer case has a different mounting pattern than Jeep, though, so Lance used the front half of the NP233 with the rear half of an NP231 to gain a lever shifter and added an Advance Adapters slip yoke eliminator at the same time.

Steering consists of an Astro van box that has the pitman arm facing forward, which eases packaging of the track bar. Lance tapped the steering box to mate it to a 1 1/2-inch bore, 8-inch-stroke hydraulic ram from Tractor Supply that mounts to the Barnes 4WD diff cover and Ruff Stuff tie rod that was constructed from 1.5-inch, 0.250-wall DOM tubing and fit with 1-ton GM tie rod ends. The steering knuckles were tapered to place the tie rod on top of the knuckles for improved ground clearance and a lower drag-link angle.

The front suspension is a three-link kit from Barnes 4WD, with two lower links and a single upper to reduce binding during articulation. A track bar is used to limit side-to-side movement and follows the same path as the drag link to minimize bumps steer. The links are constructed from 2-inch, 0.250-wall DOM tubing and fit with 1 1/4-inch rod ends.

The front axle is a high pinion kingpin Dana 60 out of a Ford F-350. Unlike solid-axle GMs that use a passenger front drop, IFS Chevys and GMCs use a driver-drop transfer case. The axle has been upgraded with 5.38 G2 gears and a LockRight locker. The factory axleshafts have held up admirably to the huge tires.

Coilovers package nicely, but they are expensive. To keep the budget reasonable, Lance used Rubicon Express Cherokee 3 1/2-inch lift springs on mounts from Ballistic Fabrication. He reports that the springs are a little soft, even with the nitrogen charged 14-inch-travel Bilstein 5100 shocks and retrofit sway bar from a Ford Explorer. Lance plans to swap in a set of Early Bronco coil springs in the near future.

The rear axle is a simple, yet strong, Corporate 14 Bolt. These full float axles use a 10 1/2-inch ring gear and 1 1/2-inch axleshafts, so there isn’t much need to upgrade. Lance did add 5.38 G2 gears and a Detroit Locker. The disc brakes from East Coast Gear Supply shed weight and Lance shaved the bottom of the 14 Bolt for increased ground clearance. A heavy-duty cover from Barnes 4WD keeps the gear oil inside the shaved axle.

The rear suspension is about as simple as it gets. Lance retained the factory leaf springs but beefed them up with one additional leaf. The leaves work in conjunction with 2-inch extended shackles and 12-inch travel Pro Comp ES9000 shocks. Clearance for the 40-inch Pro Comps comes from placing the leaf springs on top of the 14 Bolt axle.

Down to the worn leather bucket seats, the interior of the Jimmy is close to stock. Lance did add a Scan Gauge to monitor the engine and tranny and a JVC head unit for tunes on the trail. His next project is a full interior rollcage that goes through the dash.

It doesn’t get much better than this. Lance and his wife, Ashley, report that their daughter, Kennady, loves wheeling. “It rocks her to sleep,” Ashley explained. “She only starts crying when we stop.”

Bryan Washburn at Cap X Fab built the custom front bumper from 29 separate plates that were welded together. The bumper was built out of 1/4-inch and 3/16-inch plate and then fully welded together. Note how far the Smittybilt X20 10,000 winch is tucked back between the frame rails to maximize approach angle. The winch is wrapped in Smittybilt synthetic winch line and uses an aluminum hawse fairlead.

Cap X Fab also built the plate rear bumper, which wraps around the sides of the Jimmy to protect the corners. Lance typically doesn’t run the tubular tire carrier with the fullsize spare when he goes on day trips, instead saving it for longer trips to trails like the Rubicon and Fordyce Creek Trail. We like how the tire carrier sits on the rear D-ring mounts when it is closed to take pressure off the spindle.

Running big tires isn’t an issue when you have 1-ton axles. Lance’s Jimmy rolls on 40-inch Pro Comp Xtreme MT2s on Pro Comp steel wheels. These tires provide great traction on the trail without the need to trailer the S15 to every trail.

Tech Specs
’98 GMC S15 Blazer
Drivetrain
Engine: 4.3L V6
Transmission: 4L60E four speed automatic
Transfer Case: NP231
Front Axle: Dana 60 w/ G2 5.38 gears and LockRight locker
Rear Axle: Corporate 14 Bolt with G2 5.38 gears and Detroit Locker
Suspension
Springs & Such: Rubicon Express 3 1/2-inch Cherokee coil springs, Bilstein 5100 shocks, Barnes 4WD three link (front), factory leaf springs sprung over and Pro Comp ES9000 shocks (rear)
Tires & Wheels: 40x13.50R17 Pro Comp Xtreme MT2s on 17x9 Pro Comp 98 Series steel wheels
Steering: Astro van steering box, surplus hydraulic ram
Lighting: Zenex 8k HID headlights, 12-inch Outlaw LED lightbar
Other Stuff: Cap X Fab bumpers, JVC stereo, Scan Gauge, K&N cold-air intake, Smittybilt X20 10,000-pound winch

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