You first met our '68 M-715 in the Nov. '06 story "28 days to Failure." This author nearly killed himself turning a derelict and incomplete military Jeep into a runner in a mere 28 days. In the end, the truck ran, but the engine was a total goner, so the planned excursion to Ouray, Colorado, didn't happen. After that heartbreaking incident, the M-715 earned itself the moniker the evil truck.
Next, you saw us replace the tired, smoking '73 Camaro 350 that doomed the trip with a hot little 290hp 350 crate engine from GM Performance Parts in the July '07 issue, "the evil truck revisited, Part I." the following month, we added a detroit Locker and a nice new Beachwood Canvas Works replacement top. And that's how we've been enjoying the evil truck for the last year or so.
However, now that we've got a nice top to keep the rain off our heads and a strong, reliable engine, we've been feeling the itch for longer, extended road trips. It's nothing the stock t-98 can't handle, but the factory NP200 isn't exactly known for its ability to operate at sustained freeway speeds without burning up. And with the stock 5.87 gears, it's not like we'll be roasting our t-case for any semblance of rapidity. the lack of an overdrive and the military-spec gearing garner a whopping 3,300 rpm at 60 mph.
Out With The Old, In With The Bold After taking stock of our inventory on hand and doing some head-scratching, we determined we could add overdrive, clean up our storage shed, and even get a few inches of rear driveshaft length in one fell swoop.
We had equipped an SM465 transmission with a Novak PN 463r dana 300 adapter years ago. It's since been on the shelf. the Novak adapter is only 3.2 inches long and utilizes a new main shaft that had Something old, something new ... well, you get the idea. here's our new drivetrain. From front to back it's the ranger torque Splitter with 27 percent overdrive, an old SM465 we readied to be installed in a previous project and have since been holding on to for years, and an Atlas II highlander. You may think it's a long combo, but thanks to our M-715's divorced t-case we'll actually be gaining length in the rear driveshaft. For FSJ-truck, Wagoneer, and Cherokee guys, a setup likethis may be the hot ticket. to be installed in the tranny.
For overdrive, we've always wanted to try an Advance Adapters ranger torque Splitter. Although it's available in 1.7:1 underdrive, we've always eyeballed the 0.73:1-overdrive model. In addition to being compact, rugged, and simple, the ranger can be built with any combination of GM, Ford, or toyota Land Cruiser bellhousing bolt patterns, so it can double as an adapter. We asked Advance to build ours with a 4.686-inch bellhousing index hole on the engine side to match our existing Chevy bellhousing and a 5.125-inch transmission bearing index to match our SM465. But you can also use a ranger to mate a Ford engine to a Chevy tranny and so on. the ranger can swallow 420 lb-ft easily and will turn our 5.87 axle gears into 4.29s for much better freeway rpms.
To back up our new drivetrain we insisted on an Atlas II from Advance Adapters. With its 3.0:1 low range, the Atlas II highlander model we spec'd out gives us a great final crawl ratio without totally killing our fun in the dunes or mud. We had the t-case built with 32-spline front and rear output shafts because our M-715 is a heavy truck that may someday see a lot more power than we have now. The Atlas II offers incredible strength in an unusually lightweight and compact package.
This month we'll show you some of our prep work to get the drivetrain ready to come together. Next month we'll cover the actual installation into our fullsize Jeep.
This author obtained the Novak...
This author obtained the Novak SM465 to dana 300 adapter (PN 463r) years ago when he worked at Jp's sister publication, 4-Wheel & Off-road. Since then the adapter and tranny have been kicking around, almost finding homes in three other project vehicles. the reason we mention this is because Novak has slightly modified the adapter since we got this one, but its 3.2-inch overall length is the same as the one shown here.
It's not exactly hard to teardown...
It's not exactly hard to teardown an SM465, and the Novak instructions are detailed and walk you through step by step. Just remember to maintain a clean work area and keep the gears oriented in the same direction as they come off.
Honestly, we don't even remember...
Honestly, we don't even remember why we built this crude gear puller, but when it's midnight and you're trying to get stuff done before work the next day necessity is the mother of invention.
In order to mate the ranger...
In order to mate the ranger overdrive to the transmission, the snout of the input bearing retainer must be shortened. the directions that Advance Adapters supplies with the ranger are very detailed about this operation.
Our SM465 is a late-'80s four-wheel-drive...
Our SM465 is a late-'80s four-wheel-drive model that was originally fitted with a long factory adapter and 32-spline output shaft. to run the Novak adapter, the main shaft must be swapped out for the one supplied in the kit. the new Novak shaft is a quality induction-hardened piece for long life and brute strength.
By far the worst part of the...
By far the worst part of the procedure is installation of the new bearing bushings onto the new Novak shaft. We wound up putting the shaft in the freezer overnight and then placing the bushings in the oven for a while at 375 degrees before installing them. this contracts the main shaft and expands the bushings so they come together slightly easier.
You can use any method you...
You can use any method you like, but we found a reciprocating saw was the best way to make a clean, straight cut in the bearing retainer. Make sure you don't damage the input shaft seal when you clamp the retainer in your vise unless you've got a spare.
The resulting cut usually...
The resulting cut usually leaves no more than 3/4 inch of material from the face of the transmission. however, as was the case with our SM465, you may need to leave more material to retain the input shaft seal. Just be careful, because a replacement retainer is around $100 if you mess up.
The ranger overdrive is very...
The ranger overdrive is very compact. At only 80 pounds, it can easily handle more than 400 lb-ft and has a GvW rating of 25,000 pounds. In addition to overdrive for freeway driving, we'll also be able to split gears for climbing steep grades. Or, since the ranger mounts in front of the t-case, we can use it to drop our Atlas II down from 3.0:1 low range to 2.19:1 for dune driving. technically, the ranger overdrive effectively gives us 16 forward gears and 4 reverse gears.
If you notice the small Allen-head...
If you notice the small Allen-head bolts you'll see how the machined-aluminum adapters are affixed to the ranger's case. This allows for the mixing and matching of any bellhousing and input application Advance offers. Currently, Advance has the ranger for 4.686- and 5.125-inch Chevy patterns, 5.125- and 4.848-inch Ford patterns, and 5.125-inch toyota Land Cruiser patterns. Pick your poison and create your ultimate engine and drivetrain combination.
Since the ranger mounts in...
Since the ranger mounts in front of the transmission, the transmission and transfer case must be moved back 71.2 inches. While it may seem like a lot, nowadays there are plenty of ultrashort adapters and transfercase output shafts available that can really cut down on drivetrain length. We think the ranger is a great candidate for any fullsize Jeep pickup or SUv and would even be a fantastic way to put an SM420, SM465, or t-18 into a Wrangler or CJ, provided the lift heights are kept realistic.
Before we took it off the...
Before we took it off the bench, we double-checked the fit to make sure we had removed enough material from the transmission input bearing retainer. It's a precision fit, but you still don't want to have to use the bolts to suck the ranger to the transmission. It should slide right up with no interference. If not, chances are you didn't remove enough off the bearing retainer and it's bottoming in the bore of the overdrive, which can damage the unit.
You can get dizzy just thinking...
You can get dizzy just thinking about all the different ratios and options you have when choosing an Atlas II, but we never considered anything other than the 3.0:1 highlander
One really cool option we...
One really cool option we appreciate with the Atlas II t-case is the availability of Advance's cable shifters. Besides preventing irritating rattles that can present themselves with solid-mounted linkage, the cable shifters should allow us to position the shifters anywhere we need to. that's important to us, because we don't really want to hack any more floor out of our vintage military truck than we have to.
In addition to building the...
In addition to building the Atlas II to our specs, with 32-spline output shafts, 1310 yokes, and a 1x23-spline input shaft, Advance Adapters even installed the correct speedometer gear for our 5.87 gears and 38-inch Super Swampers. Tune in next month as we sling the drivetrain between the framerails.