WJ Drive systems, or, What is QuadraDrive?

Jeep has a confusing naming system for their available drive systems.

2wd WJs are not covered here - this is a really a 4wd blog. 

QuadraDrive

       AWD/N/4Lo NP247 TCase

       Varilocks factory "limited slips" in both axles

          I've quoted "limited slip" because these units, like a Gov Loc, will lock up.

          They're very good when properly driven. I have yet to find a decent Youtube video tho.
SelecTrac

       2wd, 4Part Time, 4Full Time, N, 4Lo - NP242 tcase. 

       Select units came with Varilocks on both diffs, but most were open in both diffs
QuadraTrac

       AWD/N/4Lo NP247 TCase

       Both diffs are open

Axleshafts are not interchangeable between Varilock and open differentials.
If you plan on going to an ARB or Detroit locker (or lunchbox locker), Varilock owners will need to swap out both axleshafts to open differential units in each axle undergoing this upgrade. IF you're thinking lunchbox locker, you'd need to change the carrier, making it prohibitively expensive - you might as well do a real locker.

I have an Aussie lunchbox locker in the back of my QuadraTrac truck and I get outdriven by QuadraDrive trucks.

Plan accordingly.  :)

JOATJeep's modifications

Current specs

• 16 mpg mixed (calculated, does not include CAI)
• San Diego has crappy CA gas, and hills. Lots and lots of hills.
• As good as 18 on the highway at decent speeds (speed limit +)
• 32" OEM tire (added 1mpg)
• stock gears
• Rear Aussie lunchbox locker

Engine (order of install starts at bottom)

• "Cold air" Intake kit
• Cannot recommend this modification
• Read my Amazon review 
• Best reduction I've seen is between 2-4 degrees (Scanguage II)
• Generally running 20-30 degrees HOTTER than stock everywhere but on the highway.
• MPG seems to have increased but then the increase goes away, need to confirm with fill, but could be as much as 1-2mpg. I rely on gallons added/miles driven as for all mpg values I post.
• Talked to Airaid, of course they're owned by K&N. It's all making sense now. Here's K&N's version's HP
• Throttle body
• Doesn't seem to have done much
• Crisper throttle response. Added after everything else, I can't say it made much of a difference. Easier to bark the tires from a stop I guess.
• Bosch V3 4 hole injectors (for the 4.7) 
• Stronger low and end midrange. The first mod I would recommend
• EVIC no longer accurate
• 2002 HO cams, intake, and fuel injectors
• NOTE - Bosch 4-hole injectors are much better than the HO injectors
• Decent upgrade, FlashPaq required to get best results
• 3" cat back exhaust
• my truck is a 2-cat truck to begin with, so no 3rd cat to delete or deal with (CA, delete would be bad)
• Y pipe goes into 3" beautifully thanks to Ed Hanson exhaust (San Diego)
• Ran Kolak 3" exhaust - it's decent, sounds good. 
• Didn't fit with custom long arm
• Replaced with 3" with Model TBD Magnaflow. Louder than Kolak, but fits with long arm, dumps in front of the axle. It's great. Went flanged to allow tcase removal (not necessary, but can help)
• SuperChips Flashpaq
• Change ECU tire size to fix speedo
• 87 MPG tune
• Improves shifts
• Revs more smoothly to redline
• Running 91 performance tune
• MPG is better than 87 MPG tune
• In Miles/$, it's about the same/slightly better when Premium is <= $0.20 gallon more than 87
• Power is definitely better
• Shifts are crisper, much less retard, now pulls to redline

Drivetrain (order of install starts at bottom)

• NP242HD SelecTrac tcase (2wd, 4Hi, 4FullTime, N, 4Lo) swapped in, replaced NP247 (AWD,  N, 4Lo). See 
• Increased MPG by about 1mpg
• 4Hi is much more predictable than AWD when bombing around curves offroad
• 4FullTime will probably never be used - it's basically an open diff between front and rear axles. Useless.
• Direct bolt-in IF I would have had the rear driveshaft. 32 spline shaft (vs 27), and different length, so it's critical to get the shaft
• Because of that, used IRO SYE and a Tatton's driveshaft (bought through IRO)
• Aussie locker
• Spartans had issues with shearing teeth. Lots of noise on the interweb about that.
• Aussie had nearly no issues found 
• Was installed with NP247 in the truck, worked great. 
• Transmission rebuild at around 120K. Tremendously disappointed with the tranny life on these. Check valve wore out and transmission lost pressure, fragged the whole thing
• Used TransGo rebuild shift kit parts to repair check valve galling into aluminum housing.  With the SuperChips, the resistor is not used
• Did not install the shift springs as wasn't looking for a hotrod shifts

Body (order of install starts at bottom)

• Rough Country Swaybar disconnects
• The only Rough Country anything making it onto my truck. :)
• ScanGauge II
• Fantastic little tool. Reads and resets codes, MPG, instant MPG, intake temps, etc, etc.
• Fixed left front pin on the front seat frame (welding involved)
• Custom long arm, 0.25" walled tubing. 
• 3 link in front
• maintains rear 3-link/A-arm style
• Design means no more rear upper A-arm bushings wearing out quickly
• Handles fantastically on pavement
• Currently shock-limited travel
• JK Rubicon wheels

Converting your V8 WJ to a Selectrac transfercase (NP242J or NP242HD)

If you're reading this, you probably have an NP247 - AWD, N, 4Lo - and are looking for additional 4wd options.

The hardest thing for me find online was learning how to recognize the different cases, and how to install a 6 cylinder case in a V8 - and whether I wanted to.

• TLDR version - scroll to the bottom for how to install a 6 cylinder tcase in a V8. 

There are a variety of transfercases available for your V8 WJ. The holy grail is the NP242HD. These came behind V8s, have 2wd, and are reported to provide up to 1mpg more on the road.

The NP242HD has 2wd, AWD, 4Hi, N, and 4Lo.

The AWD on the 242HD is just like an open differential, unlike the NP247 that is likely in your Jeep now. The 247 uses clutches to manage torque between the axles. With the 242HD in AWD, you could conceivably have only one tire spinning. The '93 ZJ Grand Cherokee came out with a transfercase that only had that mode, resulting in Jeep's Trail Rated campaign - those early ZJs didn't wheel worth a darn and people sued over it.

Fortunately, the 242HD locks in 4Hi and 4Lo, so you get the conventional 50/50 power distribution between axles that you're used to.

There are some strength differences as well, with the WJ/J version rating about 560ft/lbs less than the HD version. The chart below is really helpful. And remember - NP (New Process) became NV (New Venture); so an NP242HD is the same as an NV242HD. As if this wasn't hard enough to keep straight already...

The NP242 comes in 2 flavors - the NP242HD - found in V8s, and the NP242J or NP242WJ - found in 6 cylinder WJs. The 6 cylinder NP242J will not bolt directly up to your V8 engine. Read on.

Here's an example tag for a 6 cylinder tcase, the NP242WJ.

The input snout on a 6 cylinder transfercase is short (shaft surrounded by the studs), the V8 unit is about 2x as long.

The tailshaft for the NP242J/WJ has a rubber boot. The transfercase in the pic below lost the boot a long time ago. The V8 transfercase has a metal tailcone instead of the rubber boot. Driveshafts are NOT directly interchangeable.

A bonus of the 6 cylinder case is that you can run without a rear driveshaft if something bad happens to it. Like a very poor man's SYE. :)

What follows are several recipes for installing an NP242

NP242WJ / J
Here's a great video of installing an NP242J (from a 6 cylinder) into a V8 WJ. It also covers what to do with that optional connector on the transfercase (Hint, your WJ is already wired for it!). This is also the other 6 cylinder NP242J tag you'll find out there.

The video above is great to see the differences between the shifter you have now and the Selectrac shifter.

This is purported to also work with an NP231J transfercase, which has the same gear selections as the NP242WJ/J. The chain is narrower and therefore the tcase is rated for less overall torque, but it seems to live OK behind the V8.

NP242HD
If you're using an NP242HD, it's a bolt-in. You need the transfercase and the rear driveshaft from the donor vehicle. Boom, done.

This is your strongest option; the 242HD case is slightly stronger than the 242WJ/J cases.

Choosing a rock slider for your WJ

I've been looking long and hard at rock sliders for the WJ.

I long ago learned this is the #1 mod you make if you actually wheel your truck, or the rocker panels pay.

This is a good read: Choosing rock rails

For commercially produced rock rails, JCR came out at the top for me. They're well rated by owners, and they provide door protection - with the depth of the door, that's important. They're priced in the middle, which makes them great value for being the #1 pick.

I also really liked the Spadano offering. It replaces the rockers with their slider, creating more ground clearance. This is a great solution if the rockers are rusted or otherwise damaged. The new door joint isn't as pretty as stock if that's important (see the pics). Since mine are immaculate, cutting them up doesn't make sense.  These are also one of the more expensive solutions.

Here are the other ones I reviewed. Check out the links.

Rating	company	price	Notes
10	JCR	399
9	Spadano	450	Rocker replacement! BUT - front fender is unprotected. Not as pretty as stock.
	DB MEtalWerx	350
	Rocky Road	329	Not very good side protection (seems like, site provides conflicting text/pic)
	Hard Rock 4x4	380	Doesn't really protect underbody, hangs out
	Kevin's offroad	400	Not that sexy. "I have the KOR sliders on mine and if I'd known ahead of time that they mount "inside" the pinch seam, I would have went with another brand. I'm now going to have to modify mine to extend outside the pinch seam. Mine were also supposed to be the "new" design, but they don't stick out nearly as far as they describe them on the website. I measured them and they seem to be the old design. "
	TAG	425	Lame
	IRO	500	Are you insane?

Rough Country shock mount breaks factory shock mount...

I have two Grand Cherokees, the second one came with a 4" long travel Rough Country (RC) lift and a blown motor - this one is burgundy.

The rear of my truck was factory springs with 2" spacers, so it sagged compared to the front which had new 4" springs.

I borrowed the rear 4" springs, shocks, and shock mounts from the burgandy one while I saved $$ for the engine replacement in the burgundy one.

The RC shocks are low end hydraulic units, cool looking enough, but also fatter by a bit than the stockers. Combine that with wide tires at OEM wheel offsets, and rubbing is guaranteed. 

You get this bracket (black, RCX), and move the shock to the inner side of the shock mount. There's a spacer to go in the shock bracket, and a longer bolt. The shock is upside down in this shot (not my truck).

I get what RC was trying to do, but they didn't make it.

I lost 2 shock bolts that vibrated out with the RC shock mounts, and that should have said something. Both were on the left rear, but the right rear would become loose. All over just a few thousand miles. 

Loose bolts allow hammering, and hammering breaks things. You can see the break is rusty, so it's been broken for a while. What's interesting is that the mount breaks are TEAR breaks, suggesting that the suspension is topping out against the shock. This truck doesn't get jumped.

Seeing as the shock broke loose a mile from my house after a banging over a couple of speedbumps, that's concerning. It's an RC shock and and RC spring; it shouldn't be topping out over speedbumps.

Note to self: stretch this out and take a look at whether it's topping out or not. Because this shock/spring combo is going back on the burgandy truck and that would be bad. Fixing one was more than I wanted to do.

Fortunately this is an easy fix. For some reason, the pic quality is low, and the fuzziness makes the welds look worse than they are. Don't mistake it, they're not great, but they are serviceable. This truck is going to get coil overs in the future, and this fix will certainly last that long. Time to practice up again. I used to be pretty good at this.

This one looks bad on the outside for sure. LOL Looked good when I was under the truck grinding it flat for the shock. Must have been tired.

One more excuse offered - my shop at my current house. Needed to run power through the window as there is no outlet on the outside and extension cords reduce welder efficiency.

Better than new because the metal thickness has been doubled. Let's see how it holds up!

Truck #5 - it will be a Jack of All Trades, Master of ALL!

After having my 4Runner locked up in divorce jail for over 2 years, I finally had the means to replace it.

Scanning Craigslist, I found a 2004 WJ Grand Cherokee Special Edition. It was charcoal, black/grey interior, CLOTH (no leather!!) and all the power goodies, but the seatbacks used a hand lever and the climate control was the less problematic version.

With no intent to buy it, I set out to look at it. It came with a cracked windshield, and - tho lifted - the tires rubbed when turned. While they said 285/75R16 on the sidewall, they were considerably shorter than those on the 4Runner - which measured a true 33". But it ran good, drove well, and - most importantly - only had 105K on the clock. The stereo was obviously upgraded (not just the deck) though the rear amp/speaker box were missing. They just take up space, so that was fine by me. The V8 made this much better to drive than my 2000 Cherokee (4.0 six) was.

The price started out higher than I wanted, but I found myself talking to a motivated seller and the price soon reached "If I don't buy this, I'm going to kick myself for years" levels. We struck a deal, money and title exchanged hands, and I was now the new, proud owner of my 5th offroad truck.

What had I done? LOL


Over the next few weeks, I found myself driving that truck everywhere. I've racked up 20K without trying. It's a great truck.

It came with about a 3" lift in the front and 2" spacers in the back.

Here's the vision and what I plan to be building - it needs to be a vehicle that will
- maintain creature comforts (AC, PW, PDL, etc.)
- perform very well on paved roads, including twisty roads.
- perform very well at high speed on race-level surfaces offroad
- perform very well when doing low speed offroad trips (rock crawling, etc.)
- seat 5
- pack all their gear in the back
- get reasonable MPG (15 or better in town, ideally 19+ highway)
- be reasonably fast

I'm sure I'll add to this list as I go, but that's what I've learned I like from my past trucks.
Happily, I still have the winch that graced 4 of them.

The blog starts well after the work did, so I have some catchup to do!