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1993 Jeep Wrangler YJ - Time Machine

Posted in Features on October 1, 2004 Comment (0)
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1993 Jeep Wrangler YJ - Time Machine
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Some of you may remember the LT1 Wrangler project we did back in 1993. For those of you who don't, we enlisted the help of Chevrolet and installed an LT1 V-8 and a 4L60 automatic in a YJ Wrangler, running the buildup in a series of features. John Currie was in the middle of building an almost identical vehicle of his own, and he helped out tremendously on this project.

Both Jeeps ran well, especially since Mark McPhail from the GM Motorsports Technical Group came to California and ensured that everything was up to par. So imagine our surprise when neither Jeep would pass smog, even though they both put out less than 1/10 of the allowed emissions. To make a long story short, the California Air Resources Board (CARB) had a number of rules that precluded the use of LT1 motors in our Jeeps. Left with few alternatives, both John and I eventually sold our Jeeps to out-of-state buyers.

Last year, we were perusing Truck Trader online and were surprised to see John's blue LT1 YJ for sale. After some negotiating, we purchased it and brought it to Utah, where it could be legally owned and operated. It had been more than a decade, but the YJ hadn't changed a bit. Other than the tires, which the owner had swapped out at some point, everything was exactly the way it'd been in 1993. Apparently, the owner had bought it from John, parked it in his driveway, and then let it sit. He finally just got tired of it constantly being in the way.

This YJ is a window to the past, showing us exactly how we used to build Jeeps for hard-core trail use. Along with the LT1 and the 4L60 (the "E" didn't arrive until the following year), John had installed a Dana 300 with a twin-stick shifter. Tom Wood (then of Six States) built the driveshafts, which connect to the 57-inch-wide Ford 9-inch front and rear ends. Outers from an '86 CJ were used up front, Currie disc brakes were used in back, and both axles sported Detroit Lockers and 4.56 gears. While a flat crossmember would have worked just as well back then as it does today, this YJ doesn't have one. To mount the 300, John actually built a nice little skidplate below the factory crossmember. It hung down too far back then and still does today.

So, after all these years, how did the old YJ run? To sum it up in one word, badly. It chugged and missed and overheated. Since it hadn't chugged, missed, or overheated before it went into hibernation, we figured it could be fixed. The LT1 was the first Chevrolet V-8 where engineers experimented with distributor placement and design. As it turned out, the Optispark distributor wasn't really one of their better ideas. Sitting under the water pump, it could get wet and corrode inside, causing all kinds of havoc. After removing the Optispark, which was a pain, and disassembling it, it turned out that this one was completely corroded inside. We replaced it with a brand-new one from Street & Performance, and - voila! - the chugging was gone and the LT1 ran well again.

It still overheated, though. John had used a stock radiator from a '92 Camaro, which was aluminum with plastic tanks. It worked well back then, but something had happened to it to destroy its efficiency over the years. One morning, we noticed a drop of coolant under the Jeep. It turned out to be leaking from the joint between the aluminum and plastic on both sides of the radiator. Rather than try to fix it, we contacted Modine, who offers a bolt-in replacement radiator. It arrived quickly, and we installed it in about 10 minutes. The Jeep now runs at thermostat temperature, no matter what the load.

The suspension used leaf springs under the axles. The leaf packs had sagged a little over the years, so we decided to make a change. We wanted to keep the spring-under design, so we chose to use a set of Rubicon Express 4-1/2-inch extreme leaf springs. They made a huge difference. The Jeep sat up a couple more inches and rode great on- and off-road. While this technology can't match the coil suspensions we see today, it still works well on the trail, and there's still a place for leaf springs on backcountry 4x4s.

The fabric and windows had faded a bit, so we ordered some new carpet and a Bestop Replace-A-Top from 4 Wheel Drive Hardware. The top is made of sailcloth fabric and is incredibly quiet on the highway. What an improvement!

On the trail, we were surprised to find that this old-tech Jeep could still go just about anywhere it could fit. Yes, it hung up on the low crossmember, and the turning radius wasn't what we're used to because of the narrow frontend, but the YJ was still powerful, easy to control, and felt very stable on obstacles. The few changes we made had just made a good Jeep better. We're sure that with its new lease on life, John's old YJ will be seen in the backcountry for many more years.

SPECIFICATIONS
Year/make/model: '93 {{{Jeep Wrangler}}}
Engine: {{{Corvette}}} LT1 V-8
Induction: OE fuel injection
Transmission: GM 4L60
Transfer case: Dana {{{300}}}
Frontend: Currie 9-inch with
Detroit Locker
Rearend: Currie 9-inch with
Detroit Locker
Suspension: Rubicon Express 4-1/2-
inch extreme springs
Ring-and-pinion: 4.88
Tires/wheels: 35-inch Goodyear {{{M}}}/TRs/
15x10-inch Mickey
Thompson Classic IIs

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