Bill's Huge List Of Why The JK is Better Than The TJ. :-)

Quote from 92Renegade

The 4.0L would not pass emissions standards set for the year 2010.

i've heard that from a number of people now. where exactly are you getting that from? not doubting you...rather, i'd like to read up on it. i have a car at home with an inline 6 that is very efficient...and the latest version of it is on the dealer's showroom with yet another inline 6. makes me wonder if Jeep really did ditch it for the lack efficiency or maybe some other reason?

i think the i-6 4.0 was a better engine hands down, its just about bullet proof. Its a shame that they changed over to the v-6 3.8 i have a feeling they arent going to hold up as well in the long run.

Quote from quadna

I've heard that from a number of people now. where exactly are you getting that from? not doubting you...rather, I'd like to read up on it. i have a car at home with an in line 6 that is very efficient...and the latest version of it is on the dealer's showroom with yet another in line 6. makes me wonder if Jeep really did ditch it for the lack efficiency or maybe some other reason?

Unlike alot of European cars which have made alot of changes over the years(variable valve timing,direct injection,etc) Chrysler did not and had no plans to update to old 4.0L. I read this in JP magazine and also heard from a few Chrysler techs i know.

Quote from Keith_C

It really wouldn't make sense to update it.

The I-6 was only used in Wranglers since the XJ stopped production, whereas the 3.8 is used in many Chrysler platforms.

I think it's more about economics and good business than anything else.

Thats not true the XJ stoped pruduction in 2001 and the wrangler had the 4.0L in it long before then, Sence 1991

Edit
O ok I think I understand what your saying the only vehical the 4.0 was in after the XJ's dimise was the Wrangler, sorry got confused there.

Andy

Quote

Bill's comparison was between the TJ and JK, not all the old school Jeeps.

Point noted, but in my defense I was basing my statement on REAL Jeeps. IMO, just because Chrapler slaps a Jeep badge on it doesn't automatically make it a "Jeep". If it doesn't have a solid axle....it's not a Jeep, period. Flame war number two............

Well that is the additude of an elitist if I've ever heard one. I seem to recall cj owners claim it is not a real jeep if it doesnt have round headlights. I for one like the JK, but I like just about all Jeep models with a few exceptions. Just remember the JK has a minivan based v6 where as my KJ has a truck based v6. ;D

http://www.daveysjeeps.com/images/Parts/jkbody1.jpg

Close enough to being a uni-body to me. Who seriously designed this....

Should have given it square headlights, LOL

Quote from Keith_C

It really wouldn't make sense to update it.

The I-6 was only used in Wranglers since the XJ stopped production, whereas the 3.8 is used in many Chrysler platforms.

I think it's more about economics and good business than anything else.

Those are probably both the reasons right there. I know Chevy had designs or an all aluminum I6 with variable valve timing but that article was over 10 years ago. If they didn't come out with it yet there must have been a good reason why.

The other reason they may have went with a V6 is because it's physically shorter which would make it easier to resize the JK.

So here it is. With every new change that Jeep has made from CJ's to YJ to TJ to JK, the Jeep world had initially rebelled but ultimately accepted the fact that each was an improvement over it's predecessor in reliability, capability, etc.

The JK was no exception to these criticisms and had it's fair share of skeptics. I for one, think it is the most capable platform to date with all the modern comforts while maintaining the Jeep heritage.

Drivetrain

Engine: (I might as well start with the most difficult.) The 3.8L V-6 is not so much an improvement as simply a change. Chrysler has been using the power plant successfully is several models so longevity should not be an issue. The V-6 builds it's torque at a higher RPM which makes it less jumpy when crawling. Also, fuel economy seems better.

Transfer Case: All models of JK use the same T-case housing as the Rubicon. (Without the gear reduction.) This is an improvement over the 231. ALL models have fixed yokes, front and rear, so no need for an SYE when lifting.

Axles: Big improvement over any of the TJ's axles with HP Dana 30 or 44 front and HP Dana 44 rear. Yes they are full width which many will complain about but it's only a couple inches on each side and lets face it, 99% of Jeeps don't see tight trails so the stability outweighs the rare trail issue. One area where many will disagree is the removal of the limited slip from the Rubicon 44. I personally prefer an open diff with a locker over a LSD locker option.
Also, it is obvious that the JK high pinion axle is less prone to damage as well as maintaining better drive line angles (especially on lifted vehicles).

Suspension and Steering

Front Lower Control Arms: The TJ uses stamped arms that are prone to damage. The JK uses a fully boxed arm that is significantly stronger. Both frame and axle LCA brackets are stronger and tucked much more out of the way from impact.

Rear Lower Control Arms: Once again the JK replaced theTJ's stamped arms with tubular arms that are stronger and the mounts are tucked much closer to the wheel for clearance issues.

Rear Axle Shock Mounts: The shocks are outboarded more than the TJ and mounted higher on the axle. The outboarding gives the JK's shock more leverage and thus, makes it more effective. The TJ's shock mount is low and prone to damage from rocks as well a being inward on the axle.

Tie-Rod: The JK's tie rod is much larger than the TJ's and it uses a crossover steering set-up that has correct geometry. The stronger rod is much less prone to damage. Also, toe stays consistent throughout suspension travel unlike the "Y" steering on the TJ. If you were to put a crossover steering set-up on the TJ, your Ackerman angle would be off thus effecting handling and even tire wear.

Better Geometry: Although the JK is already better suited to handle larger tires, the longer control arms and the their design will make the JK's control arm angle much less extreme if it does get lifted. 2-3" of lift will fit 35's without steep control arm angles that can effect performance.

Body and Styling

Although I am not a big fan of the look of the JK with stock tires, it is rather functional and looks great with larger rubber.

Highline front fenders: There is a reason that AEV doesn't offer the Highline kit for the JK. It's because it is already factory implemented into the design. This allows larger tires while maintaining a low center of gravity.

Cheap Bumpers: The JK's bumpers are cheap plastic. Why is this good? One, they are still more effective than the TJ's stock bumpers and Chrysler made a conscious effort to cut corners on parts that they new Jeep owners would replace anyway. This is the first Jeep with the after market taken into consideration during the design. This also kept the price point down so they could place their efforts into more important items such as axles.

Skids/underbelly: The placement of several items, including moving the fuel tank has created a much smoother underside which is a huge benefit off road. Even the four door with it's horrible break over angle, slides over rocks surprisingly well. The few things such as EVAP canister placement and muffler are very easily skidded if need be. The removal of the fuel tank from the rear was HUGE in improving the departure angle over the TJ. Also, the stock TJ "shovel" was replaced with a much smoother T-case cross member to prevent hang ups.

Ergonomics, Safety, Electronics

The JK rules the TJ so much on this aspect that I'll just hit the major points.

Power windows and locks: I don't want to hear it. They are awesome and that's it....especially with the four door. The doors can still be removed by unplugging the harness. When the harness is unplugged, the Jeep "knows" the doors are off and treats the interior light differently. It's much better than removing the #5 fuse on a TJ. The doors are no heavier than the TJ's either.

Visibility: The TJ's visibility was notoriously bad but none worse than the 03-06 models in which they had to lower the seats because of the airbags (which were retrofitted due to regulations). The JK has been designed with the airbags in mind and visibility is incredible compared to the TJ. The slight curve to the glass seems to make a difference also.

Seats: No question here. JK has more adjustment and is just more comfortable, hands down.

Safety: Optional side curtain air bags as well as a better (though not great) safety rating make the JK a safer vehicle in a crash or roll over.

ESP - Electronic Stability Program: Many old schoolers gripe about ABS and ESP but when off road, the ESP can be turned off with the press of a button. On road, in adverse conditions, ESP is incredible if you lose control of the vehicle. The JK's handling on snow, ice, and wet roads will be exponentially better than the TJ.

Modular hard top: The three piece hard top is great when the weather is good but you don't want to remove the whole hard top. It's kind of like T tops. The early models had some leaks but mine has been tight.

MYGIG Navigation: It's a factory 20 GIG hard drive coupled with navigation, satellite radio, DVD player, CD, Aux input, etc. It's not perfect but I like it and it wasn't available on the TJ. (I even hooked up an after market back-up camera to mine that works like factory.)

OPTIONAL FOUR DOORS: This was the big complaint from "real Jeepers" when it first came out but to be honest, it is so incredibly nice having a four door vehicle that I can take the top off of and hit the beach, camp, whatever. With two kids and a third on the way, reaching behind the seats of an unlimited TJ was not an option. The JK Unlimited gives us the best of both worlds.

This list wasn't to bash the TJ. As I've said before, I love my TJ much more than my JK because it's my baby...BUT, that said, dollar for dollar and feature for feature, the JK is the best, most capable Jeep ever built and it's current success is a testament to that. AND IT IS ALL JEEP FROM THE BOTTOM UP!!!

I think I forgot a few things but I'll post them as I think of them.

FLAME AWAY!!!!

when you look at the back of your TJ,
your shocks are positioned like this: | |

and JK's are outboarded like this: / \

meaning the shock mount at the axle is further outboard than the upper mount on the crossmember.

Good writeup Bill! I knew you wouldn't disappoint...I mean c'mon the guy owns one of each, you would think if you are going to get an unbiased review...he would give it! I am not going to join the "who has the biggest hammer" debate, however coming from a CJ background and liking the style of it, when it came to wheeling your junk, it just became more practical owning a TJ. TJ's are everywhere, so when it comes to getting parts, aftermarket parts, bolt ons, product reviews, etc...it was an easy choice going with the TJ. Plus they are getting older so picking one up cheap is pretty realistic.

Quote from Keith_C

Link doesn't work.

is this better?

http://www.daveysjeeps.com/images/Parts/jkbody2.jpg