2007
Jeep Wrangler JK Rubicon
An In-Depth Review of the JK,
On-road and Offroad
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Offroad Performance
This JK had
it's first taste of the offroad on the
rocks of Rausch Creek a few
weeks before this trip so Mike had a good idea of it's offroad
capabilities over the leaf sprung Jeep CJ-5, his other Jeep.
Mike detailed a lot of his thoughts on his experience at Rausch
Creek on
Jeepfan.com.
"A few minutes into the trail the
initial love for this Jeep developed. I have little trail
experience with a coil sprung Jeep and I have to say that
they make all the difference. The uneven terrain of a
typical trail was completely absorbed by the coil springs.
The suspension of the new Jeep is very flexible, much like
the JK's predecessor, the TJ. We soon got into a rocky
section, I pushed the rear locker button, put the Jeep in
1st gear, and with both feet flat on the floor I let the
Jeep drive itself over the rocks. The 4:1 low range makes
for an excellent crawl ratio...The Jeep had no problem
maintaining idle and momentum with no throttle input. Only
once the whole day I stalled the Jeep."
Much of our weekend in the Pennsylvania
Mountains involved old, weathered and washed out logging trails
with some specific destinations that offered their own unique
challenges. Mud, hill climbs, water crossings and
rattlesnakes were among the encounters we had over the weekend.
As expected the JK performed flawlessly and made a lot of the
challenging hill climbs and deeply rutted trails look easy.
We were 4 wheeling with a few other vehicles including a Jeep TJ
Rubicon and a new 2007 Toyota FJ Cruiser, which was a lot of
fun. Lots of great trails, a rattlesnake and a
porcupine encounter made for an interesting trail report, which
can be viewed here,
Wheeling
in Rattlesnake Country.
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Some of the
highlights of the Jeep JK are Command-Trac® and Rock-Trac™
transfer cases, electric axle lockers, and
electronic-disconnecting front sway bar,
Electronic Stability Program (ESP),
electronic roll mitigation, all of which assist performance
offroad.
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Stock JK Wrangler Clearances
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Clearances |
P225/75R16 |
P245/75R16 |
P255/75R17 |
P255/70R18 |
LT255/75R17 |
Approach
Angle
Degree |
40.8 |
42.0 |
43.8 |
44.6 |
44.3 |
Breakover Angle
Degree |
21.8 |
23.1 |
24.9 |
25.5 |
25.4 |
Departure Angle
Degree |
37.4 |
38.7 |
40.3 |
40.6 |
40.4 |
| Front
Axle to Ground (inches) |
9.1 |
9.6 |
10.3 |
10.6 |
10.5 |
| Rear
Axle to Ground (inches) |
8.8 |
9.4 |
10.1 |
10.3 |
10.2 |
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Rear tow hook location centered |
Front tow hooks |
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Transmission: NSG
370 — Manual, Six-Speed Overdrive |
| Availability |
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Standard—All
models |
| Description |
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Synchronized
in all forward gears and reverse, multirail shift system with
top-mounted shift lever |
| Clutch |
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Hydraulic
actuation |
| Gear Ratios
1st |
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4.46 |
| Gear Ratios
2nd |
|
2.61 |
| Gear Ratios
3rd |
|
1.72 |
| Gear Ratios
4th |
|
1.25 |
| Gear Ratios
5th |
|
1.00 |
| Gear Ratios
6th |
|
0.84 |
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Gear Ratios Reverse |
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4.06 |
| Axle Ratio |
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3.21 Std.,
4.10 Opt. (Std. on Rubicon) |
| Overall Top
Gear |
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2.69 Std.,
3.44 Opt. (Std. on Rubicon) |
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Transfer
Case: NV241OR
Rock-Trac |
| Type |
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Part-time,
heavy-duty |
| Operating
Modes |
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2WD High; 4WD
High; Neutral; 4WD Low |
| Low Range
Ratio |
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4.0:1 |
|
Center Differential Type |
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None |
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Room for a Hemi! |
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Engine Performance
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Although the new 3.8-liter overhead valve V-6 engine,
featured on all 2007 Jeep Wrangler models, has 205 horsepower
and 240 lb.-ft. of torque, which produces more horsepower and
torque than its predecessor, it still lacks the punch that is
needed to thrill the driver. When comparing the 3.8-liter
to the 4.0-liter inline six-cylinder engine, the 4.0-liter
Power-Tech in-line six engine achieved it's peek torque and
horsepower at a much lower RPM, so to really feel the 3.8-liters
full potential on the road, you have to drive it hard and even
then it's slightly anemic. This seems to be a common
complaint among JK owners. However from an offroad
perspective, high RPM is not always desired for several reasons. For
starters, high RPMs over immovable objects like rocks can break
things. Secondly, high RPMs generally means loss of wheel
traction and loss of real control. With the right options a JK will yield an impressive
73:1 crawl ratio, which will basically allow the Jeep to idle over
the rocks and through the ruts with ease at a slow, controlled
crawl. Most of our 4 wheeling can
be described as slow and controlled, or at least we try to be
slow and controlled. The Jeep JK is well equipped with a
great combination of gear ratios to maintain a high level of
control and finesse over the obstacles as factory electric lockers keep you
moving and the push button front electronic sway bar disconnect
helps keep the wheels on the ground.
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Jeep JK Rubicon Craw Ratio |
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| 4.46:1 |
Transmission 1st gear (NSG 370) |
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Final Crawl Ratio |
| 4:1 |
Transfercase low range (NV241OR) |
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73:1 |
| 4.10 |
Axle gear ratios |
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Engine: 3.8-Liter,
OHV, 12-Valve SMPI V6 |
| Availability |
|
Standard |
| Type &
Description |
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Six-cylinder,
60° V-type, liquid-cooled |
| Displacement |
|
230.5 cu. in.
(3,778 cu. cm) |
| Bore x Stroke |
|
3.78x3.43
(96x87) |
| Valve System |
|
OHV, 12
valves, roller followers, hydraulic lifters |
| Fuel
Injection |
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Sequential,
multiport, electronic |
| Construction |
|
Cast-iron
block, aluminum alloy heads |
| Compression
Ratio |
|
9.6:1 |
| Power (SAE
net) |
|
205 hp (153
kW) @ 5,200 rpm (53.9 hp/L) |
| Torque (SAE
net) |
|
240 lbs-ft @
4,000 rpm |
| Fuel Recommendation |
|
Unleaded
regular, 87 octane (R+M)/2 |
| Oil Capacity |
|
6 qt. (5.7L)
plus filter |
| Coolant
Capacity |
|
13.36 qt.
(12.64L) Std. |
| Emission
Controls |
|
Three-way
catalytic converter, heated oxygen sensors, electronic EGR and
internal engine features
Meets Tier 2 Bin 5 (federal) and LEV 2 (CA)
emission requirements |
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Offroad Performance Options
Lockers
 The
Rubicon version of the JK is factory equipped with front and
rear electronic lockers. The X model and Sahara can be ordered
with a rear locker. Locker operation in simple and at the push
of a button. The lockers only work in 4WD low and under 18 mph
(see the article:
Locker Hacks). The locker
engage/disengage button is a two direction button. Pressing the
lower button once turns on the rear, pressing the lower again
turns on the front (keeping the rear on - the front will only
work if the rear is on) Pressing the lower button a third time
will turn the front off while keeping the rear on. Pressing the
upper button will turn all off.
Sway Bar
The Rubicon version
of the JK is factory equipped with a front electronic sway bar
disconnect. The X model and Sahara can be ordered with a sway
bar disconnect option. Sway bar operation in simple and at the
push of a button. The sway bar works in 4WD low and under 18
mph (see the article:
Locker Hacks).
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Suspension |
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| Front |
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Live axle,
leading arms, track bar, coil springs, stabilizer bar,
low-pressure (on 16-inch wheel packages) gas-charged shock
absorbers—std.; Monotube high-pressure (on 17- and 18-inch wheel
packages) gas-charged shock absorbers—std. Rubicon;
Electronic Sway Bar Disconnect System (ASDS) opt.
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| Rear |
|
Live axle,
trailing arms, track bar, coil springs, stabilizer bar,
low-pressure (on 16-inch wheel packages) gas-charged shock
absorbers—std.; Monotube high-pressure (on 17- and 18-inch wheel
packages) gas-charged shock absorbers—std. Rubicon
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Vehicle Clearances
|
Clearances |
P225/75R16 |
P245/75R16 |
P255/75R17 |
P255/70R18 |
LT255/75R17 |
Approach Angle
Degree |
40.8 |
42.0 |
43.8 |
44.6 |
44.3 |
Breakover Angle
Degree |
21.8 |
23.1 |
24.9 |
25.5 |
25.4 |
Departure Angle
Degree |
37.4 |
38.7 |
40.3 |
40.6 |
40.4 |
| Front
Axle to Ground (inches) |
9.1 |
9.6 |
10.3 |
10.6 |
10.5 |
| Rear
Axle to Ground (inches) |
8.8 |
9.4 |
10.1 |
10.3 |
10.2 |
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| Side by Side with the Jeep TJ Rubicon |
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Body styles and prices
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Price range |
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Trim lines |
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4-door SUV 2WD |
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$20,230 - $24,605 |
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Unlimited X, Unlimited Sahara |
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2-door SUV 4WD |
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$18,485 - $26,595 |
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X,
Sahara, Rubicon |
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4-door SUV 4WD |
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$22,230 - $28,840 |
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Unlimited X, Unlimited Sahara, Unlimited Rubicon |
Specifications
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Drive wheels |
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Rear or part-time
4WD |
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Seating |
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2 front, 3 rear |
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Engines
available |
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3.8-liter V6 (205 hp) |
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Transmissions
available |
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6-speed manual
4-speed automatic |
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Fuel |
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Fuel type |
Regular |
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EPA city/highway,
mpg |
16/19 |
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Fuel refill
capacity, gal |
21.5 |
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Dimensions and
weight |
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Length, in. |
173 |
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Width, in. |
74 |
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Wheelbase, in. |
116 |
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Curb weight, lb. |
4,550 |
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Percent weight,
front/rear |
50/50 |
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Typical towing
ability, lb. |
3,500 |
Room for Improvement
Like anything nothing is perfect. The Jeep JK Wrangler is the most
sophisticated Wrangler so far and possesses many features that makes
modern vehicles safer and useful but there still is room for
improvement. We have put together our list of what we think the Jeep
should have...
50 more horsepower - come on Jeep! This thing is over 4000 lbs a small
V8 or higher torque/horsepower V6 would be nice.
A locking mechanism to hold the rear gate open. Try holding the gate
open on a side hill and get a cooler out of the Jeep. Aftermarket?
Something to hold the front and rear doors open. Again,
Aftermarket?
More interior storage trays/compartments. There is no real good place
for a pair of sunglasses.
110V converter power outlet in the cargo area.
12V power outlet in the cargo area.
Lower ratio reverse - The 6 speed gearing is well suited for the Jeep
but reverse seems a bit high.
Better defroster ducts - In the snow ice forms on the sides of the
windshield AND the wipers freeze to the windshield when not moving
because they are below the defrosters reach.
How about an optional on board air system?
Trail annoyances
and oddities
 The
Jeep tends to run on at 2000 rpm. For example, say you are
running along in low range 2nd gear at 2000 rpm. Let off the
accelerator and the Jeep just keeps on going like it's on cruise
control. A touch of the brake or clutch and the Jeep slows back
down, weird! The fuel gauge - we were going slowly down the
side of a long hill, after 10 minutes or so on the hill the low
fuel warning alarm and indicator came on. When we started our
day the Jeep had nearly 1/2 tank of gas! It couldn't be out?
We stopped and checked outside the Jeep for a leak but found
nothing. We reached a level part and after a few minutes the
gauge started climbing until it returned to it's original
position. It turns out the sender is susceptible to extended
down hill slopes and will report the fuel level being lower than
it really is.
The Leak
 The only complaint
about the new JK is a leak
that Jeep has yet to address properly. The leak occurs when the
Jeep is sitting still in the rain. When you're driving, it doesn't
leak. So it seems to be a standing water channeling problem.
A visit to a "leak specialist" at the Jeep dealer but their
acknowledgement of the problem was not enough and the leak continues and
rain still drips in on the driver side door handle. The
problem seems to be coming from a seal above the windshield.
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 The "leak
specialist" suggested that it was due to the retractable top actually
being used. Not sure what they expect that explanation to mean.
But Mike has been looking at the seal and he thinks he has an
understanding of what the problem is. It seems it could be
solved with a little silicone sealant under the seal. We'll return
to that leak at a later time. Meanwhile Jeep has to get a grip on
fixing this before they get a bad rap. We're not sure on the
numbers of how many Jeeps JKs have experienced this leak but we know
this particular JK is not the only one.
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What
is Jeep Trail Rated ?
The Jeep Trail Rated badge on the
2007 Jeep Wrangler verifies that the vehicle has been designed
to perform in a variety of challenging off-road conditions identified by
five key consumer-oriented performance categories: traction, ground
clearance, maneuverability, articulation and water fording.
Jeep Trail Rated is an industry-leading
methodology established by the Nevada Automotive Test Center (NATC) and
Jeep Engineering to objectively measure and consistently predict
off-road performance for all Jeep vehicles. Through a combination of
natural and controlled field tests, as well as computer-simulated
environments, Jeep Trail Rated provides a repeatable and consistent
measurement of off-road performance for Jeep vehicles. Only Jeep
vehicles are Trail Rated.
Jeep Wrangler JK Highlights
- Off-road Capability –
Increased ground clearance, larger wheels and tires,
enhanced Dana front and rear solid axles, available
next-generation Command-Trac® and Rock-Trac™ transfer cases,
new electric axle lockers, and electronic-disconnecting
front sway bar
- On-road Refinement – All-new
100 percent stiffer frame in bending, 2-inch longer
wheelbase, 3.5-inch wider track, lower spring rates,
advanced shock tuning, increased jounce and rebound travel
- Interior Space and Comfort –
4.6 inches more hip and 5.1 inches more shoulder room
combined with additional 2 inches in couple, 1 inch in
rear-seat leg room and 2 inches behind rear seat
- Open-air Options – Dozens of
different door, top and windshield combinations; new
three-piece modular hardtop and innovative Sunrider™ soft
top
- Power and Torque – New
3.8-liter V-6 engine with 205 horsepower and 240 lb.-ft. of
torque
- Safety – Electronic Stability
Program (ESP), electronic roll mitigation, dual-stage air
bags, seat-mounted side air bags and Occupant Classification
System (OCS)
- Convenience – Available power
windows and door locks, full-screen navigation system,
368-watt Alpine® stereo with MP3 capability, SIRIUS
Satellite Radio
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Onboard
Air
