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Rock crawler
Jack Cline sits in his newest rock-crawler built from a 1985 Jeep CJ7 with a 401 cubic-inch Jeep engine. The machine was built from scratch at the Auto Skills Center at Vance AFB, Okla. (U.S. Air Force photo/ Zach Sproul)
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Building an extreme rock-crawler from scratch

Posted 8/17/2011   Updated 8/17/2011 Email story   Print story


by Zach Sproul
71st Flying Training Wing Public Affairs

8/17/2011 - VANCE AIR FORCE BASE, Okla. -- At first glance, Jack Cline's rock-crawling machine is a wild looking thing. The bright yellow panels and purple frame jump out at you. Add over-sized tires and you have one mean machine ready to climb over anything in its path.

Cline's rock-crawler, built almost entirely at the Vance AFB Auto Skills Center, is based on a 1985 Jeep CJ7 with a 401 cubic-inch Jeep engine. The frame is relative light, weighing in at only 580 pounds. The machine has 1-ton axles, two transfer cases and a Turbo-400 transmission.

This isn't Cline's first off-road vehicle. He has been tinkering with machines most of his life. "I've always worked on something along the lines of motorcycles, cars and Jeeps while growing up," said Cline, a hydraulic shop lead with CSC Applied Technologies here.

His current rock-crawler started out as two 2-inch by 3-inch rectangle tubes and nine pieces of inch and three-quarters round tubing. "I brought in 11 pieces of material and that is what we started with," Cline said. "It is a project built from scratch."

Most of the work on Cline's rock-crawler -- framing, sheet metal, welding and engine work -- was done at the Auto Skills Center. The colored-powder coating of the frame was done off base.

Work on the rock-crawler started two weeks before Christmas of 2010. Fast forward nine months and the project is near completion. A lot of man-hours went into this project, said Cline. "I took many days off and vacation time as well to work on it," he said.

"The guys here at the Auto Skills Center, Greg Ludlow and Nathan Shearon, put a lot of their own hard work into helping me out on this project," Cline said.

"These guys know their jeeps inside and out," Cline said. "I cannot thank them enough."
Cline's rock-crawler features Holley fuel injection that allows the vehicle to run even if it tips over on its side or sits straight up on the tail. There is a master kill-switch that completely shuts off everything onboard if the crawler turns over. It has a longer wheelbase which allows room for four passengers.

This crawler, as well as Cline's first rock-climbing Jeep, a 1981 model with camouflage paint, is street legal with working lights and tags. The 1981 Jeep is usually parked outside one of the maintenance hangers on Elam Road.

Cline chose bright yellow for the newest rock-crawler so people can see it on the road way. "Some people tend to have problems seeing my camouflage Jeep and I have almost been hit several times," he said.

When hitting the rocky trails, Cline likes to go to Disney, Okla., near Grand Lake. He plans to have his new rock-crawler up and running in time to get to Moab, Utah, this fall. "But most likely that will have to wait until sometime next year," he said.

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