PART 4: We’d rec­om­mend this driv­e­train com­bi­na­tion for just about any 4x4.

LIKE MOST FOLKS WE LIKE TO think our ve­hi­cles are more than just a lit­tle unique. That’s even eas­ier to do when you start with an un­com­mon starting point like our 1989 Range Rover Classic. There may be Range Rovers in Europe, South or Cen­tral Amer­ica, Asia, Africa, or Aus­tralia that are bare bones, have a tur­bod­iesel, and a five-speed man­ual (de­ranged), but most of the re­main­ing ex­am­ples in the U.S. are nor­mally go­ing to be slathered in leather, re­plete in elec­tron­ics, and pow­ered by that Buick-de­rived alu­minum V-8 oil leaker spin­ning some sort of au­to­matic trans­mis­sion. And while we have cov­ered the de­tails and in­stal­la­tion of the Dana Ultimate Dana 60 axles (“Derange Rover,” Part 2, Sept. 2018; bit. ly/2zya0eK) and hinted at the Cum­mins R2.8 en­gine (we’ll talk more about the finer points of the en­gine in­stall in sub­se­quent sto­ries), the man­ual trans­mis­sion and trans­fer cases (yes, there are more than one in the Derange Rover) are some of the most im­por­tant parts that make our De­ranged Rover more than a lit­tle unique—es­pe­cially in the US. And hands­down, our fa­vorite T-case sys­tem is the Mag­num Box dou­bler setup from Of­froad De­sign that will re­ally push the Derange Rover’s on- and off-road ca­pa­bil­ity.

One way or an­other, all this sounds like a great com­bi­na­tion to us; namely a mid­sized SUV with plenty of torque and a mul­ti­tude of gear­ing op­tions for the road and trail. So with a lit­tle re­search and the right parts from the right af­ter­mar­ket com­pa­nies (some of whom just hap­pen to be sup­port­ers of the 2018 Ultimate Ad­ven­ture) we can have what may be the world’s most ca­pa­ble Range Rover. The best part is you, too, can du­pli­cate this build. We’d rec­om­mend this driv­e­train com­bi­na­tion for just about any 4x4, from daily driver to full-on, one-off trail buggy.

If you’ve read this far in the is­sue you know we’ve com­pleted the 2018 Ultimate Ad­ven­ture and can at­test to how well this com­bi­na­tion of parts works in the Derange Rover. The rig has plenty of torque for the road, even fully loaded and at high­way speeds. The NV3550 five-speed shifts well and seems more than fit­ting be­hind the clat­ter of the Cum­mins R2.8 Turbo Diesel (we’re test­ing a new tune from Cum­mins that al­lows 310 lb-ft of torque and 161 hp). The Of­froad De­sign Mag­num Box plan­e­tary low-range and Ford NP205 pro­vide plenty of gear­ing for the most tech­ni­cal crawl­ing at 5.33:1 with both boxes en­gaged, while the 2.72:1 Mag­num and 1.96:1 NP205 ranges al­low for the wheel speed nec­es­sary for slick eastern mud/rock trails. Also, the front- and rear-dig ca­pa­bil­i­ties make ne­go­ti­at­ing tight trails a breeze.

So, how did we as­sem­ble these parts? Check it out!

1 We know, we know. Au­to­matic trans­mis­sions are the wave of the fu­ture (since the

1950s). But we like push­ing a clutch pedal and stir­ring the gear oil our­selves. Still, keep­ing that Cum­mins R2.8 in its power band is im­por­tant to max­i­miz­ing the fuel econ­omy pos­si­ble from this en­gine. A six-speed man­ual would be nice, but there isn’t re­ally a good medium-duty op­tion, so we stuck to a trans­mis­sion we know well. The NV3550 came in Jeep SUVs from roughly

2000 to 2004. The trans­mis­sion has a 4:1 First gear, a 3.57:1 Re­verse, and a 0.78:1 over­drive. Our NV3550 seems to have come from a 2002 TJ (says “02” on the bell), and since it says “good” on the out­side in junk­yard paint and is full of oil we sim­ply slapped it in. The trans­mis­sion came from our good buddy and UA crony Keith Bai­ley, from the Off-Road Con­nec­tion in Ful­ton­dale, Alabama. We picked it up in Moab dur­ing Easter Jeep Sa­fari 2018.

2 With that trans­mis­sion in mind it was easy to call up long­time UA spon­sor Of­froad De­sign (Car­bon­dale, Colorado) for one of its Mag­num Box plan­e­tary un­der­drive units cou­pled to a Ford (driver drop) NP205 trans­fer case. This gives us a ton of gear­ing op­tions as well as in­de­pen­dent front and rear drive ca­pa­bil­i­ties. The guys at ORD built the unit to bolt onto the

NV3550 and with bul­let­proof 32-spline front and rear out­put shafts. A pair of 1350 dou­ble­car­dan drive­shafts from JE Reel Drivelines and a pair of cor­re­spond­ing 32-spline flanges will send the R2.8’s torque to the front and rear Ultimate Dana 60s.

3 To cou­ple the Cum­mins R2.8 crate en­gine to the NV3550, we con­tacted our friends at Axis In­dus­tries. Axis makes adapter parts that are sec­ond to none and blur the line be­tween adapter parts and art­work. We used the com­pany’s bell­hous­ing adapter ring and studs last year on the of­fi­cial 2017 Ultimate Ad­ven­ture ve­hi­cle, the UACJ-6D, but since then Axis has changed a few things.

4 One change that Axis made to the R2.8L– to–Jeep 4.0L adapter kit is that the kit now in­cludes a fab­ri­cated re­place­ment R2.8 flex­plate in­stead of the cus­tomer hav­ing to send in the orig­i­nal Cum­mins fly­wheel to be ma­chined down. Then a crank hub adapter bolts to the R2.8’s crank­shaft. This kit works with the Jeep NV3550, AX15, and NS6G370 six-speed trans­mis­sions. We pre­fer the five-speed NV3550 or AX15s since in our ex­pe­ri­ence the six-speeds aren’t as durable.

5 We bolted a Jeep 4.0L fly­wheel from Cen­ter­force (PN 400469) to the crank hub adapter from Axis. A Cen­ter­force Per­for­mance Clutch Disc (PN 384193), a Cen­ter­force II Pres­sure Plate (PN 361890), and throw-out bear­ing for a 2002 TJ Wran­gler (PN N1764) round out the clutch pack­age. Don’t for­get a clutch align­ment tool!

6 We used some Daystar poly body bush­ings for a CJ-5 and a 2002 TJ Wran­gler trans­mis­sion mount, to­gether with some bits of steel from Of­froad De­sign and our scrap metal pile, to iso­late the trans­mis­sion and trans­fer case from the Rover’s frame. We later added more 2x3x0.188-inch rec­tan­gu­lar tub­ing and some an­gle iron to form a trans­fer case cross­mem­ber.

7 With a firm plan in place to set the driv­e­train as far to the pas­sen­ger side of the fram­erail as pos­si­ble (about 1 inch off­set from cen­ter­line), we slid the as­sem­bled trans­mis­sion and trans­fer cases un­der the Rover. Us­ing a cou­ple of floor jacks and heavy-duty ratchet straps to act as safety belts, we lifted the unit be­tween the fram­erails.

8 We then as­sem­bled the en­gine to the trans­mis­sion and placed the whole ki­tand-ca­boo­dle where we wanted it. This al­lowed us to fine-tune the place­ment of the T-case cross­mem­ber, bolted and heav­ily tack­welded in place as shown here.

9 A few holes had to be cut in the floor of the Rover for clear­ance of the mas­sive NP205 T-case. Also, we are switch­ing from the fac­tory pas­sen­ger-drop T-case to a driver-drop unit to match the Ultimate Dana 60s. This unit, and the Mag­num it lives be­hind, will ab­so­lutely hold up to every­thing we can throw at it and then some.

10 With every­thing fit­ting in place we dropped the tack-welded trans­mis­sion/ trans­fer case cross­mem­ber and fin­ish-welded the part. We added sev­eral small tri­an­gu­lar and plate gus­sets to the cross­mem­ber. The whole driv­e­train sits flush be­tween the fram­erails, al­low­ing the Derange Rover to have a flat belly. We may add skid­plates to the bot­tom later on, but for now this will do what we need it to.

11 To shift the NV3550, we se­lected a B&M Pre­ci­sion Sport Shifter (PN 45048). This stain­less steel and bil­let shifter is en­gi­neered for 1999-2004 Jeep Wran­glers with NV3550 man­ual trans­mis­sions, and it shifts with crisp au­thor­ity. To tog­gle the Mag­num Crawler Box and NP205, we in­stalled Of­froad De­sign’s trans­mis­sion adapter twin-stick NP205 shifter and one of ORD’s floor-mounted Mag­num shifters. These shifters work like but­ter and, cou­pled with the pre­cise ma­chin­ing in ORD’s Mag­num and re­built NP205, pro­vide the crispest T-case shift­ing we’ve ex­pe­ri­enced on the trail no mat­ter the sit­u­a­tion.

12 Con­nect­ing the NP205 twin-stick shifter goes a lit­tle some­thing like this. The throw and place­ment of the sticks is vari­able thanks to the ad­justable na­ture of this shifter. The floor­mounted shifter for the Of­froad De­sign Mag­num Box was easy to mount to the Rover’s high and flat trans­mis­sion tun­nel. Shift link­age was easy to cus­tom­ize for this ap­pli­ca­tion and should be sim­ple in lots of other 4x4s. You can also see the an­odized blue alu­minum of the B&M shifter in front of the Mag­num Box’s link­age.













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