Jeep Wrangler TJ: G2 Gears, Detroit Truetrac, M.I.T. Drivetrain Work [Video]
Hoping to get our Jeep Wrangler ready for the trails, we moved on to the next step in our TJ build. Our journey began when we purchased a used 2000 TJ Wrangler we found on Craigslist. We wanted to build a trail-ready TJ in stages without completely breaking the bank. For now it would be a great adventure vehicle for weekend fun, leaving open the possibility for something more hard-core in the future.
In our first story for the build, we headed to Off-Road Warehouse’s Temecula shop to help us replace the TJ’s suspension components with a 4-inch Skyjacker lift (TJ401K-SVK-H) as well as replace the upper control arms. We also replaced the tires with new BFGoodrich 33-inch Mud Terrain KM2s which we installed on the new ATX Wheels Slot 15x7 wheel.
When we purchased the Wrangler it only had about 50,000 miles on the motor (great since it was a 2000), but it did have a salvage on the title from a front-end collision years ago. After the Skyjacker kit was installed, it was clear the front axle was a bit out of whack. While we wanted to move up from the 3.73 stock gearing to compliment the larger 33-inch tires, we also had an important decision to make – replace the axles, upgrade to a larger axle, or repair the existing axle.
The stock TJ comes with a Dana 30 front axle and a Dana 35 in the rear. Although moving up to a Dana 44 or larger would increase the vehicle’s off-road durability, the change comes at a cost we aren’t yet ready to incur. Replacing the axles finding used housings of the same size was an option that might not cost a fortune, as we found some on Craiglist and also at local wrecking yards. The only problem is the uncertainty of the axle since it’s hard to tell exactly what has happened to it during its lifespan, or even how many miles are truly on it.
After some research we came across a shop in San Diego County called M.I.T., an acronym for Mechanically Inclined Technicians. The shop, which goes by the moniker of “Driveline Specialists,” is owned by longtime off-roader Jeffrey Sugg. The company could not only perform the work on installing new G2 gears and Eaton’s Detroit Truetrac Differentials, but they could also repair our bent front axle. If repairable, the axle joint would need to be welded and resealed – something the shop could handle in house or send that day to a nearby welder.
M.I.T. offered a realistic option for all of our needs. They could assess the front axle and repair it (or even offer a replacement if need be), and as opposed to just finding another axle we would know for certain that the repaired stock axle would be sound.
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We headed down to M.I.T.’s shop in El Cajon, California. The company has been in business since Sugg first started it back in 1989. A few years later he married wife Karen, and the two mange the business today (he the shop, she the finances) out of its nearly 10,000-sqaure-foot facility that features 10 working bays. The shop has six technician busy spinning wrenches, while Kenny Thomas and Cathy Martin help man the counter and phone lines in the showroom.
“We do a lot of work on custom vehicles, hot rods, off-road… it pretty much runs the range. Anything with axles and transmissions in it we’ll work on,” Sugg said, noting they even work on a number of commercial vehicles but the core is mostly enthusiasts. “You will always tend to see more off-road material in here than anything else.”
Sugg actually created the first slip-yoke eliminator kit for the NP231 and NP207, but he lacked the financial backing to battle for the patent on the design. His Jeep and drivetrain knowledge runs deep, which explains why even his shop technicians still run some of the work by him to see if he can catch anything they might’ve missed. Although the shop, which has been in the same location but has expanded a number of times over the years, focuses on driveline work, it does also tackle a number of other jobs.
Other Jeep Wrangler TJ Stoies:
Skyjacker Suspension, BFGoodrich Tires and ATX Wheels
Bestop Supertop NX Softtop
“Our core business is drivetrain, is gear systems, but we also do suspensions, we do a lot of custom work, and we also do engine conversion work, so pretty much anything to do with the drivetrain area we will handle,” Sugg said. “We do custom axles, we repair stock axles, we straighten them, we modify them, we’ll do transmission transfer case conversions, driveshaft upgrades.”
M.I.T. is clearly the right shop for our needs. The stock gears in our 2000 Jeep Wrangler feature a ratio of 3.73, which just wasn’t cutting it when we moved from 31-inch tires up to 33-inch BFGoodrich KM2s. After speaking with Jeepers with similar setups and Mark Mathews at G2 Axle and Gear, we decided upon a 4.56 ring and pinion for our TJ. G2’s gear set would help get our Wrangler up to speed, literally. Since our diff covers were a little dinged up, we also opted to replace them with G2’s differential covers, which are constructed from lightweight aluminum to help dissipate heat while its added reinforcement ribs provide rigidity and strength. We also didn’t want to skimp on the oil we used, so we opted to try Royal Purple’s synthetic gear oil to bath our new gears.
When it came to our differentials, we turned to Eaton’s line of Detroit Truetrac differentials. Hailed as the first helical gear differential ever introduced to the automotive aftermarket, this limited-slip differential fit our needs well. Rock crawlers would opt for an air locker or something more hard-core, but the Detroit Truetrac would provide significantly improved traction over our stock differential without requiring a more costly locker setup and regular maintenance.
The gear-driven limited-slip Truetrac (shown above) is designed to remain open until traction is needed on the trail, essentially providing torque to the wheel with the best footing. For our all-around trail use, the Detroit Truetrac compliments our setup and intended use.
Helping us with the install was Mario Lopez and Moises Prado, two very skilled technicians who have performed their fare share of axle and gear work. While Lopez went to work on the rear axle, Prado worked on disconnecting the front and removing the stock gears. The big surprise of the day came when Lopez shoved an alignment rod through the rear axle to only hear it thud and not come out the other side. “That’s not the sound you want to hear,” he told me. Not only was the front axle bent, but the rear one as well. Lopez said this happens more often than you’d think, but it certainly caught us off guard. At least we were at the right shop to fix it.
Fortunately the rear axle’s bend wasn’t too bad, and the larger Dana 35 was not a difficult repair – just unexpected. The Dana 30, on the other hand, was repairable but is a much trickier fix, since the smaller housing has less material to work with. Prado was able to work his magic on the custom axle-bending setup that Sugg built for this very purpose. Without giving away his trade secrets, it’s a very effective way to repair bent axles, and the alignment rod will ultimately tell the story of whether the axle is back to being straight.
M.I.T. proved to be a great resource for us. Not only do they offer a number of services, they also offer a wealth of knowledge and resources. If an axle is not repairable, there’s a good chance the shop has another housing lying around. If we decided to upgrade to a larger housing in the future for more serious rock-crawling, they also can perform custom work and axle conversions.
After our break-in period, we’re looking forward to hitting the trail. We have more work to do on our TJ, but now it’s finally ready to get dirty. Stay tuned.