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1994 Jeep Wrangler YJ - Big Mini: Part 7

Posted in Project Vehicles on May 21, 2014
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In the November 2013 issue we brought you what was supposed to be the last installment for Big Mini. Carrying on its tradition of nothing fitting where it was supposed to, the torque converter didn’t bolt-up. We were just going to hog out the flexplate to make it work and call it done. However, cooler heads prevailed and talked us out of our rotary tool.

As it turns out, not only shouldn’t we have been able to bolt our LS-1 4L60E to our LT-1 engine, but the pump seal should have been munched by doing so. The driveshafts were the right length, the transmission mount and belly skid were all sorted out, and we had the Jeep generally ready to fire and drive. But we learned that if we tried to fire and/or drive the Jeep, we probably would have immediately toasted our transmission.

Since we consider automatics to be something close to black magic, we listened to the advice we were given and undid (once again) a lot of the stuff we’d installed, fabbed, and routed so that we could pull the transmission out and see exactly what we’d destroyed (“Automatic Rabbit Hole,” May ’14). We learned a ton about the 4L60E and a whole bunch of reasons why hogging the flexplate holes out was a bad idea. And we were glad, in theory, that we pulled it back apart again.

That said, we added the adapter kit from Pace Performance, which allowed us to bolt our LS-1 4L60E to our LT-1 engine. It was the lowest-cost option to solve our pickle. However, that pushed the transmission back in the frame, causing the tranny mount we’d built before not to work and our belly pan to hit the T-case. While we were in there redoing work we’d already done, we decided to make some improvements before taking it out on the trail. Of course, that opened a whole other can of worms.

We should have known better. Over the years that we’ve worked on this Jeep, nothing has gone where it was supposed to, and almost every part we put in had to be modified for one reason or another. Some projects are like that. This one might be Murphy’s bedfellow. We’ve at times called this Jeep Christine, thought about having a nice little bonfire, and wanted to walk away from it more times than we’d care to admit. The minor improvements we decided to make in drivetrain positioning touched many more aspects of the build than we thought they would and caused us to redo many of the things we thought were done.

But we stuck with it for another beat-ourselves-in-the-head-with-a-hammer session and got it out on the trail -- finally. Granted, it still needs some finishing and polishing, but for now, it’s time to work out the kinks of a Jeep brought back from the dead, drive it, and enjoy some of our hard work.

As we mentioned in the 4L60E story in the last issue, this adapter kit made by GM that we got from Pace Performance (PN 19154766) let us use the “wrong” 4L60E with our engine. At $206.95, it was a great solution to our problem, and we ended up with a 4L60E that was better than the ones that came behind the LT-1 originally. It sets the transmission back 5⁄8 inch, and we knew our existing transmission mount wouldn’t accommodate that. However, we thought we’d be fine with drivelines and most everything else.

This is now the third installation of this transmission into this Jeep. We are building this Jeep on an inclined driveway and while it’s not gravel, we still can’t use any kind of wheeled jack to lift the transmission up. So, using a tree saver on our ’cage and a come-along, we were able to lift the transmission with relative ease. We wrapped the transmission with another strap, and after finding the balancing point, were able to use this come-along to lift it.

In the previous image, you might have noticed that the skidplate on the left has four mounting holes. If you’ve spent any time under your Jeep, you know that is one more than stock. The left skid is TnT’s standard belly pan skid. The one on the right has five holes and was a custom-built part for us. If you can take responsibility for your measuring, TnT is more than happy to build custom parts like this for you as well. As for the added holes, TnT supplies these weld-in bungs and enough new bolts to bolt the skidplate in.

When we first installed the tranny/T-case combo, we didn’t clock the Atlas II up because we didn’t want to mess with the floor. We’d already Rhino Lined the inside of the Jeep and didn’t want to screw that up. This time, we were hell-bent on a flat belly. We modified an air hammer bit by rounding it out and call this combo our “Atlas installation tool.” It makes massaging the floor out of the way a lot easier than swinging a 3- or 5-pound maul over your head while lying on your back. We thought we’d have to cut the floor to clear, but didn’t have to. We were even able to bolt the seats back in on their stock brackets.

The original belly skid we built covered from the front of the transmission oil pan to the back of the rear output on our Atlas II. It weighed 95 pounds. While this is transmission install number three, this is easily in the double digits for belly skid install/removals. We wanted something lighter. While we were reinstalling stuff, we decided we’d clock the Atlas II flat. These two 6061 aluminum skidplates are from TnT Customs. They offer 3 of additional ground clearance, and each skid is 63 pounds lighter than the steel skid we replaced.

Since we had Advance Adapter’s super short adapter between our tranny and T-case, the black part is the trans mount. It is meant for a regular GM mount, but with our new flat belly pan that was just too tall. So we turned to Advance Adapters for this tranny mount (PN 716008) to reduce the overall height of the mount. However, because we were using the super short adapter, we had to modify our existing mount to clear the bushings. So, we lopped off the corners and welded new plates in to restore the strength we’d lost.

By this point, we’d had that black transmission mount bracket and the Atlas II out enough times that we were tired of the 1⁄16 of a turn on the wrench to remove the nuts from the studs sticking out the back of the transmission. So, we modified one of our 17mm wrenches so that the closed end of the wrench would slip between the nut and the face of the Atlas II. With our new Atlas-installing wrench, we are almost able to turn the nut 1⁄4 of a turn at a shot.

Here is what we ended up with. The bushings out at the frame might be excessive, but we wanted to be able to drop the entire crossmember out for easy access and removal should we end up with a transmission install number four in the future. Our belly skid and tranny mounts are completely separate so we can drop the skid easily without having to play around with supporting the drivetrain. Also, we had ordered the skid from TnT without any tranny mount provisions for that reason. However, the bottom of this tube is under 1⁄4 inch from the top of the skid, so even if we did hit the skid hard enough to make it deflect, it’s got steel behind it to back it.

Our four-speed Atlas II weighs 150 pounds, and we were uncomfortable hanging that much weight off the back of our aluminum tranny. You know us, we love cast iron gearboxes and tend to not trust aluminum ones as much. We spent a lot of time researching good ways to support the Atlas, just in case. Advance Adapters advocates a triangular sort of setup (more on that later), so we discussed the idea with several KOH racers and teams that beat their stuff hard all the time. Before we got to build or modify our mount, Mel Wade at Off Road Evolution built this one. It did exactly what we wanted and appeared to have enough clearance to clear our flat belly skid.

Our four-speed Atlas II weighs 150 pounds, and we were uncomfortable hanging that much weight off the back of our aluminum tranny. You know us, we love cast iron gearboxes and tend to not trust aluminum ones as much. We spent a lot of time researching good ways to support the Atlas, just in case. Advance Adapters advocates a triangular sort of setup (more on that later), so we discussed the idea with several KOH racers and teams that beat their stuff hard all the time. Before we got to build or modify our mount, Mel Wade at Off Road Evolution built this one. It did exactly what we wanted and appeared to have enough clearance to clear our flat belly skid.

But, of course, we wanted to run a brake assembly on the output of our Atlas, so we needed to change that mount just a bit. We figured the best way to do that was to go down there with the parts we had and compare them to what the company had already built, then modify it for a brake assembly. As it turns out, the best way to incorporate a brake into the previous mount was to use the brake stuff we had and modify it as seen here. Also, instead of using a GM trans mount, the company came up with the idea of using front JK upper shock mounts for the T-case tail mount.

Although we have our suspicions, we aren’t sure exactly why the driveshafts that were bolted up before no longer worked. The rear was too long and the front too short. Sure, we moved the tranny and T-case back, but not that far, and sure, we clocked the T-case up… but again we didn’t think that it would be enough to affect the drivelines. But it did, and so we boxed them up and sent them back to Tom Woods Custom Driveshafts, where for about $70 each the company was able to make them the right length for us again.

Engine Mount Engine Mount Transmission Mount To keep from breaking aluminum components in a regular Jeep, you want the drivetrain to be able to sort of rock naturally. Think about how it kicks over when you rev your engine. In a tube chassis, you can get away with hard-mounting stuff. In a regular Jeep where the frame will flex, it is important that the drivetrain can move independent of it. Not flopping around like a fish mind you, just some independent movement. It is also important if running extra mounts like we did that they are all roughly of the same stiffness. The poly mounts that Advance included with the 716008 kit were designed to have the same durometer as the company’s engine mounts for that reason.

All of this work gets done in our driveway, which is on a mountain range that separates the desert from suburbia. Because of the different climates on either side of our mountain it is often too windy to weld in our driveway, so we occasionally make notes like this so that when the wind dies down we can get out there a lay some bead. In this case, we discovered that the factory missed the body mount with the weld bead, so we made ourselves a note and came back to weld the mount to the frame later.

Because our engine is set further forward in the frame to accommodate the longer 4L60E and four-speed Atlas II combination, we were never quite able to anchor the transmission dipstick to anything. It just sort of floated in the air between the engine and the firewall. We also had some trouble getting the tranny into first gear due to the way we had to route our cable. But it wasn’t until the factory throttle cable ended up in a loop that touched the exhaust manifold that we had enough. You really do get what you pay for, and these Lokar parts fixed all our issues in one fell swoop. As an added bonus, they all installed in a matter of hours—just like they were supposed to.

We used the adjustable billet aluminum tranny shift arm to get first gear back, and it worked great. We also got a kick out of the company’s sense of humor. Note the “transmission not included” notation on the instructions in the background.

Lokar’s throttle cables are cut-to-fit, but you order a rough length to begin with. We were pretty close in our estimate. The lower mark is where the cable hits the bracket, and the upper mark is where we actually cut. We wrapped it with tape and cut it with a hacksaw, then we were able to get the aluminum ferrule back on by twisting it. From there, it is easy to get the actual cable cut to length.

The last thing was some power to start the Jeep, as in the months we had the transmission out this last time, we forgot to hook the old battery up to a charger and it died. We went with a Northstar battery from West Coast Batteries. It is a bit less expensive than some other flat-plate AGM batteries, but offers the same kind of kick. Since we are running just one battery, we wanted the peace of mind that comes with a quality battery.


Advance Adapters
Paso Robles, CA 93446
West Coast Batteries
Corona, CA 92879
TnT Customs
Cheyenee, WY 82007
Off Road Evolution
Fullerton, CA 92833
Pace Performance
Lokar Performance Products
Knoxville, TN 37932
Tom Woods Custom Driveshafts

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