The last time we showed you our '97 Wrangler project, it had just received new Dana 44 axles with 4.56 gears from Drivetrain Warehouse. When you consider we're only planning on running 32s under this Jeep, 4.56s seem like a lot of gear. However, we've been planning on ditching the three-speed TF999 transmission in favor of something better since Day 1.
While we're still die-hard manual transmission fans, we do acknowledge the fact that a large number of Jeep owners prefer an automatic. So, without too much joking, it was with a certain obligation to our readers that we ditched our plans of a manual five-speed swap and started figuring the very best way to stick a TH700R4 behind our 4.0LWhile it may seem simple on paper, swapping over to the big Chevy transmission is actually quite an undertaking. We enlisted help from some of the best companies in the industry to make this happen. There are certain considerations to be taken into account, such as crank-sensor relocation, overall driveline length, getting the shifter to work with the factory console, and so on.
For starters, we contacted Advance Adapters and told them what we were up to. You can check out the "Parts, Pieces, and Prices" sidebar on page 69 to find everything the company was able to send us to facilitate the swap. Needless to say, the company's grasp on what it takes to make just about any Jeep swap a reality is mind numbing. Advance Adapters has two TH700R4-to-NP231 adapters that will work. The first is 2.5 inches long and fits the 4WD version of the tranny. It comes with a new 27-spline input gear for the NP231. The second is only 1.50 inches long and works with either the 2WD or 4WD tranny. It includes a new 23- or 21-spline mainshaft that must be installed in the transmission. We followed Advance's recommendations and had the 1.5-inch kit's mainshaft sent off to TCI to be installed in our new transmission.
Jay Miller began by removing...
Jay Miller began by removing the stock harmonic balancer and installing the Advance Adapter balancer kit that repositions the crank-position sensor from the Jeep bellhousing to the front of the block. The Advance kit includes very detailed instructions for positioning and adjusting the sensor to read properly.
With Steal-J on the lift,...
With Steal-J on the lift, the stock tranny was removed and the Advance Adapter AMC-to-Chevy adapter plate and flexplate were installed. It was right around this time we figured the tranny wouldn't clear the floor without a 1-inch body lift.
TAG pulled a 1-inch Currie...
TAG pulled a 1-inch Currie Enterprises body lift off the shelf and installed it on our Jeep to provide clearance between the engine/tranny adapter and the transmission itself. The Currie kit employs metal spacers that utilize the factory rubber isolators and includes the necessary longer Grade 8 hardware.
When considering a company to build our TH700R4, few could match TCI's reputation for quality or flexibility with customer service. TCI routinely custom-builds transmissions, so assembling our Maximiser 4x4 transmission with Advance's mainshaft caused absolutely no drama. TCI's TH700R4 arrived to us fully built with a chrome oil pan, converter, 3 gallons of TCI's Max Shift transmission fluid, TCI's vacuum-operated lockup converter switch installed, and the dyno sheet verifying the transmission had been test run not twice but three times to ensure proper operation before it was shipped out.
Installing a TH700R4 adds a lot of length unless you get creative. Using Advance Adapter's 1.5-inch adapter helped, but we were able to keep our rear driveshaft length within 1 inch of stock by using TeraFlex's Extreme Short Shaft kit (PN 231ESS). Once everything was installed, we called up Tom Wood for a pair of his newly designed, silky smooth 1310 CV driveshafts. The shafts feature Tom's own CVs, not Spicer's. The CVs are forged from steel, not cast iron, and have a modified shape to reduce stress risers and improve grease distribution for longer life and cooler operation.
TAG signed on to be the official shop of our Steal-J buildup, and halfway through the transmission swap, we sort of felt bad for them. We ran into a few glitches and unforeseen problems that would have sent some lesser shops into a tizzy, but the crew at TAG, namely shop foreman Jay Miller, handled every eventuality without throwing one wrench and turned the mess of Jeep parts scattered across the work bay into a reliable runner. Read on for the full skinny on the install.
Our TCI TH700R4 came with...
Our TCI TH700R4 came with the dyno sheet attached, as well as instructions for installing the supplied lockup torque converter and wiring up the torque-converter switch. By the time you read this, all TCI TH700R4 transmissions will come with TCI's proprietary valvebody that prevents shift stacking, no matter how the TV cable is adjusted. This is one of the most frequent causes of new transmission failure, so keeping the installer from burning up the tranny due to an improperly installed TV cable is a big selling point in our book.
Miller filled the torque converter...
Miller filled the torque converter with TCI's Max Shift fluid, then installed it over the input shaft. The converter has a pretty low stall that is good for rockcrawling. Normally, a high stall is good for getting off the line, but our Jeep's 4.56 gears, along with the 3.06:1 First of the TH700R4, allow for brisk acceleration from a stop.
By the time we finished the...
By the time we finished the installation, we learned Lokar had come out with a newly introduced TH700R4 floor-mounted, cable shifter. We didn't know, so we plodded through the installation of the company's standard tranny-mounted shifter. Miller modified the brackets slightly to work with our tranny's 4WD adapter. Ultimately, we were able to modify the factory auto shifter bracket and console to fit the Lokar shifter, but the company's cable-operated shifter should be considered a must for anybody doing the swap in the future.
Notice the cut exhaust where...
Notice the cut exhaust where the catalytic converter wants to be. More on that later. Here, Miller has installed the T-case adapter and tranny mount, along with Advance's T-case shift linkage bracket. It, too, required modification because of interference with the Lokar linkage-actuated shifter. Again, the cable shifter would have saved us time and effort. Advance's tranny mount uses poly bushings that are exceptionally harsh at idle. We later replaced them with some rubber bushings that came with one of the company's Dana 300 tranny mounts (PN 716021).
Without this mini bullet Super...
Without this mini bullet Super High Flow Converter from Random Technologies, this author would have even less hair. The factory cat is massive and interfered with the transmission oil pan. Attempts to cut the cat and lay it on its side proved too hokey. The stainless Random cat is a direct replacement for the factory Jeep cat, placing the O2 sensor in the right spot and includes the correct 2 1/2-inch inlet and 2 1/4-inch outlet to mate to the factory head pipe and muffler.
With the exhaust situated,...
With the exhaust situated, we installed the TeraFlex Extreme Short Shaft kit in our NP231 with zero problems then heaved the T-case into place. We found the electronic Hall-effect speedo sensor wiring didn't match our older '97 TJ's plug, so Miller wired in a newer connector to our chassis harness. The TeraFlex instructions include a section on wiring your speedo properly.
Tom Wood's Custom Drive Shafts...
Tom Wood's Custom Drive Shafts created two beautiful 1310 CV driveshafts. Our stock front very nearly worked, but fell short by about 1.5 inches. The rear shaft features Wood's newly designed forged steel CV. As of this writing, we've logged over 10,000 miles on the shaft with a 2-inch suspension lift and haven't been able to get it much more than warm to the touch. It's a long-life unit, to be sure.
With the drivetrain finished...
With the drivetrain finished and filled with fluid, Miller adjusted the TV cable with the "rule of thumb" technique. Basically, with the engine off and the throttle held wide open, you tighten the TV cable until there's no slack. A quick testdrive will ensure the TV is in the ballpark. If the transmission stack shifts, meaning rapidly shifts through the gears to Third or Fourth, the cable needs to be tightened. Stack shifting means not enough line pressure, and the tranny will burn up. With our TV cable adjusted, we fine-tuned the vacuum-actuated lockup switch mounted on the side of the tranny. Now, at 75 mph, our Jeep cruises at 2,500 rpm with 4.56 gears and 32-inch tires.