Toyota Tech: Drivetrain Lift
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By: Tim Stucky. February, 2002.
|Drew Persson showing off his drivetrain lift|
During the spring of 1999, I installed a 2" body lift on the truck to give some much needed tire clearance and keep the tires away from the fenders. Along with the body lift, I raised the front bumper and built a new rear bumper to take advantage of the extra 2" of clearance. The body lift also raised the body off the frame enough to allow a set of 2X2X3/16" nerf bars to be welded to the frame so they wouldn't hang lower than the frame. In short, for my uses, adding the body lift was the key to many other mods. Happy with the lift and new mods, I wheeled the truck through the summer and in November '99, I went on a run with Drew Persson who owned a mild looking '86 4runner. Drew's rig was somewhat typical, a JP Eater dual transfer case unit, lockers front and rear, 35" tires, and ironically, nearly stock suspension. What wasn't typical, was that he was able to walk up the very steep rock pictured at left, when I failed to do so despite having nearly the same amount of lift. I later learned that Drew had a 3" body lift and a 3" drivetrain lift, which allowed him to raise the entire drivetrain from the engine to the gas tank up 3". The result was a nearly smooth underbelly and an incredible breakover angle.
|4Crawler Offroad's 2" spacers||How they look installed|
Plans for a similar drivetrain lift on my truck began to take shape, however, other mods such as suspension and steering came first. Almost two years later with the idea still in mind, I was on a wheeling trip and learned that 4Crawler offroad was making motor mount spacers similar to Drew's. A few days later, I had a set on the way and eagerly waited for the school term to finish so I could get started on the project. The drivetrain lift is a fairly complex project and isn't for those unfamiliar with the Toyota drivetrain. It involves modifying the motor mounts, transfer case crossmember, the horsecollar crossmember, the gas tank, its related mounts and the fuel lines.
To begin, the stock motor mounts were each loosened and the drag link was removed so the motor could be carefully jacked up from the oil pan. Once the motor was lifted high enough, the spacers were slid into place and torqued to specs. With the engine now sitting 2" higher than before and in stock position relative to the body, the radiator, which was spaced down 2" for the body lift was moved back up to stock position and the engine portion of the drivetrain lift was done.
|Cut and welded 2" higher|
Next was the horsecollar crossmember. It gets it's name due to it's resemblance to the horsecollars that were tethered to horse teams that pulled wagons. This crossmember is located above the transfer case output flange and runs between the frame to provide overall chassis strength and resist flexing as well as twisting of the frame under torque. It must be raised 2" in order for the rear transfer case flange and driveshaft to clear. The front of the gas tank also hangs from the crossmember so the rear gas tank mount must be modified so the tank sits level and the sender works correctly. To move the crossmember up, the factory welds were cut off on each side with an oxy-acetylene torch, cleaned up, and the crossmember was simply welded back on 2" higher. The rear gas tank mounts hang from a round crossmember that runs above the rear axle. They were also cut off with a torch and rewelded 2" higher. After raising the gas tank, the fuel lines that run along the inside of the frame rail needed to be unbolted to alleviate the stretching and stress caused by moving the tank up 2". The result is a gas tank that is 2" higher, a little more out of reach from rocks, and nearly flush with the frame!
|The stock transfer case crossmember||The low profile unit||How it mounts to the frame||Another view|
With the horsecollar crossmember out of the way, it was time to deal with the transfer case crossmember. The stock unit is thick, bulky, and robs precious ground clearance. The choices were to leave it alone and run a spacer between the transfer case and crossmember, remount the stock one 2" higher, buy an after market one which can get expensive, or build your own. I chose the latter in order to incorporate strength, functionality and clearance for my crossmember. Starting with a 4" wide piece of 1/2" thick flat steel, it was cut to the appropriate length to fit between the frame rails, and bent to be mounted above the bottom of the frame rails for maximum clearance. Mounts for the crossmember were welded on the frame for the crossmember to hang from, and the stock rubber mount was used to connect the transfer case to the actual crossmember. Again, the result is a crossmember that is stronger than stock, more aesthetically pleasing, and a gain of nearly 5" between the ground and the crossmember.
|Notch for cv rear driveshaft|
After effectively raising the drivetrain another 2" from the axle, I encountered driveline vibrations and needed to run a cv style rear driveshaft as well as a set of 3 degree axle shims to get rid of driveshaft vibrations. In my experience, to run the cv style rear driveshaft, the bottom of the horsecollar crossmember had to be notched to allow the cv joint to clear when the drivetrain is under torque. The front driveshaft also needed to be lengthened to avoid being pulled apart under maximum flex. After tying up the odds and ends, I took the truck up to the hills to try out the newfound clearance and see what it would do.
The first place I went was to the same rock I saw Drew Persson climb in late '99 and failed to climb myself due to the dragging transfer case. Easing up to the steep rock, I expected to hear the familiar sound of the transfer case dragging as I went up, but much to my surprise, the truck crawled right up without a hitch! As a result of the drivetrain lift, the underbelly of the truck is much smoother than stock and I haven't dragged the transfer case crossmember since. The problem will never be completely eliminated because there will always be bigger rocks to crawl, nonetheless, the drivetrain lift is a great way to take advantage of an already existing body lift and raise all the important stuff without out adding any more suspension lift and sacrificing flex.
|Testing the newfound clearance
|Up without scraping!|