Differences between KJ & KK

[Demian1979]

Hello to all of you.
I would like you to emphasize me you from your experience the negative and the positive points between KJ and KK so it could be easier for me to choose between those two models.

Thanks in advance

 

[lfhoward]

Much the same vehicle under the skin, mechanically. Same 3.7L V6 (in the US). 3.73 gears is normal for automatic transmission with the V6.

KJ, 2002-07
Spare Tire on tailgate
Shorter body than KK, less passenger & cargo space
02-06 uses mechanically controlled throttle body; 07 is drive by wire like the KK
Early models have no ABS/traction control (plus or minus depending on your point of view)
Manual shift lever for transfer case
05-06 CRD diesel option available (in the US); requires careful maintenance
4 cylinder 2.4L gas engine an option in early years; comes with 4.10 gears
Rear suspension upper control arm is a boomerang with central ball joint
Front differential is a Dana 30-A, aluminum casting that is susceptible to cracking; deepest gears 4.10.
More aftermarket support (e.g. ARB bumpers, snorkels)

KK, 08-12
Spare tire under rear of Jeep
Longer body for more cargo space & passenger room
Rear seats fold flat; front passenger seat folds flat
Stiffer unibody construction than KJ
Heavier vehicle than KJ, not quite as good fuel economy
Electronic switch for transfer case
Manual transmission only available in 08 model year
11-12 models use a new computer so cannot use tuners like Hypertech in those 2 years
Rear suspension is more conventional floating axle with a track bar to center it
Front differential is strengthened; same Dana 30 as JK; can run deeper gears than 4.10
Comes with BLD (brake lock differential) that uses the ABS to stop a spinning wheel and transfer power to the other side.

In general, if you want to run larger tires:
29” tires are stock
30.5” tires require a 2.5” lift and regear to 4.10 is recommended
32” tires require a 4” lift and regear to 4.10 or 4.56 plus JBA upper control arms

Spacer lifts seem inexpensive but avoid them because they will cause more expensive problems down the road. OME (Old Man Emu) makes a good full spring lift kit that gets you to 2.5” with good longevity and performance.

 

[Demian1979]

Thank you Ifhoward for the prompt response.
BLD have only the 11-12 models ?
For off-road use which one of these you think is better ? of course with the right settings. Which one has better angles ?

 

[lfhoward]

BLD is on the 08 and up.
Some of the KJ's had a limited slip as an option since there was no BLD in those days.
BLD makes a lot of noise as the ABS cycles the brakes, but it does work.
Stock the KJ had more clearance than the KK, although anything with stock springs is going to be sagging by now. The extra length of the KK behind the rear tires is probably not as good off-road in terms of angles, but with a good lift kit it's fine.
Both the KJ and KK are great off road compared other "soft-roader" SUV's of the time. They have low range 4wd, which is better than any AWD vehicle off-road and more comparable to what you'd find on a Jeep Wrangler.
Forgot to mention, KJ got a refresh in the 05 model year so the bumpers/grille are different, KK refresh was 2011. On the KK the exterior stayed the same but interior is nicer on the 11's and up.
Also if planning to go off-road, try to stick with a 16" or 17" wheel. The 18's & 20's don't provide much sidewall so can't effectively air down for sand or rough terrain.
If looking at KK's, avoid the open roof Sky Slider option. It has not been reliable and can cost several thousand $$$ to repair. The company that made the mechanicals on the Sky Slider is no longer making them, too.

 

[Lardog]

I researched both before buying a 04 KJ. Differences have been covered earlier very well. I found that the KK seemed to suffer a lot of electronic control module problems and the Sky Slider Roof version was a disaster to operate and repair. I like the spare on the back gate and not slung under, too. My KJ is really easy to work on, if required, you can get to most things easily, it drives nice, and the "manual" 4WD is exactly what I like. And I think the KJ looks a little more "Jeepish", too. Off road, my KJ is great, but I've never taken a KK offroad.

 

[tommudd]

02-05 KJs all the way
less electronics etc to mess up
plus just look better
No offense Mr Howard LOL

 

[lfhoward]

@tommudd LOL!

Did my best to appear neutral there! Looks like you saw through it.

 

[Billwill]

Very good write-up from Ifhoward!.

The rear seats on the KJ can almost be flattened down....the KK having the spare tire under the Jeep makes the KK safer in a rear-end collision as the fuel tank is better protected!

Definitely agree that the KJ has a more "Jeep" look!

 

[Demian1979]

As far as the exterior is concerned, I believe that both are beautiful cars and with the same changes made unique. Now about KK electronic problems I did not know anything and it is serious, you have found something that is common or just rare problems and you say it more proactive; The problem about the Sky Slider Roof is something i knew and i will avoid.

 

[LibertyTC]

My 04 KJ suites me just fine, no ABS, TPM, no electric traction nanny's to limit powering out of mud/snow etc.
I bought the 04 because it simply works, has the lower fogs and no window regulator issues as well.
Come winter the Jeep likes snow!

You must be registered for see images attach

 

[Demian1979]

I've seen a lot of videos and what I conclude is that KJ in some difficult hurdles needs a bit of speed to get through while KK may be BLD's reason to climb without having to have speed. From approach and escape angles, KJ is even better for a while. Of course you are right about no ABS,TPM etc.

 

[lfhoward]

The electronic issues are in regard to the TIPM, the electronic fuse box/computer under the hood (Totally Integrated Power Module). All Chrysler/Dodge/Jeep vehicles of the era had TIPM’s and are susceptible to the same issues. I would say problems are not common, but when the TIPM fails it can be bad. It’s an expensive part to fix. There are a few stories out there about it catching on fire even. But most vehicles of the era do not have these issues and I wouldn’t let that stop you from getting a KK if you decide the KK has the features you want.

 

[Demian1979]

The electronic issues are in regard to the TIPM, the electronic fuse box/computer under the hood (Totally Integrated Power Module). All Chrysler/Dodge/Jeep vehicles of the era had TIPM’s and are susceptible to the same issues. I would say problems are not common, but when the TIPM fails it can be bad. It’s an expensive part to fix. There are a few stories out there about it catching on fire even. But most vehicles of the era do not have these issues and I wouldn’t let that stop you from getting a KK if you decide the KK has the features you want.

Great tip, as I read the average TIPM repair cost is $1,200 and many reports occur under 40,000 miles.

 

[Demian1979]

Whichever of the two I buy I intend to put a locker on both the front and back, so maybe it would be better to avoid the electronics ?

 

[lfhoward]

At this point I would suggest test driving both a KJ and a KK to see which one feels best to you.

 

[Demian1979]

Unfortunately I don’t have anyone with KK, my friends have KJ and wranglers.

 

[tommudd]

Next thing to think about is if you want to lift it ( either one of them )
Both take basically the same parts to a point, but then the rear suspension is set up differently beteen the two
Tire size also and then comes the regear
both use the 8.25 but the front is totally different as far as regearing

of course if you plan on buying either one replacing the springs and shocks would be one of the first things I would want to do.
Stock suspension on both was junk from the factory

 

[Demian1979]

Definitely i will lift it

 

[tommudd]

Definitely i will lift it

Well then use only OME springs with either bilstein or ome shocks
we can provide numbers for everything
the above is proven over the years to be the best available now
Personally I have done over 60 Liberty lifts using OME springs and either bilstein or OME shocks, not including any of my 3
next KKs front are pretty much the same using the same springs, shocks, bumpstops etc as the KJ
Rear is where it changes, same shocks but different springs
Now the kicker comes into the KK using a rear trac bar, something the KJ does not
As you lift the rear of the KK, it pulls the body over to one side, the higher you go the more it pulls it over
so a longer trac bar is needed
JBA used to make thses but no longer does sadly
so have to find a fabricator or ??/
Also it is wise to use extended sway bar links since with a lift the stock ones tend to pull the rear down and not provide full performance
lfhoward can chime in on this since he has first hand knowledge of it ( well its something we both learned on his )
The KJs do not have a rear trac Bar plus no sway bar issues

 

[Demian1979]

I think that I’m closer to KJ. What should i pay attention before i buy the car ? I mean the cunning points because every car has it’s own .