Sunday, March 23, 2008

My Grand Cherokee ZJ problems.

My Grand Cherokee ZJ spec:
Manufactured : 1998 (the latest model)
Engine : 4.0 litre I-6
Trim : Laredo
Modification :

- lift 2”
- 31” tire
- After market shock and coil springs (OME)
- After market sound system.

List of problems and solutions:

  1. Front ring and pinion failed at 9,000 km. Symptom: noise from front differential. Solution: change the ring and pinion with the higher spec. This problem was common for latest version of Grand Cherokee ZJ.
  2. Air conditioner evaporator leaking at 25,000 km. Symptom: lost of refrigerant, AC not cold as used to be, the compressor clutch on and of frequently. Solution: inspect the evaporator, clean it. Found a big hole in the evaporator, could not be repair, then change the evaporator. Note: the evaporator made by Zanden, the size is relatively small compare to ZJ interior volume. The evaporator was located under the dash board, to uninstall it you need to remove the dashboard first.
  3. The master power window and central lock (on driver side) failed. Symptom: completely failed, no button functioning. Solution: Check the 30A fuse on the power distribution center under the hood, take it off and then put it back again. Usually the power window will work again normally. For better solution: make an on-off switch between the power window and the fuse, and turn off the electric charge when it not functioning. It is a common problem in Grand Cherokee ZJ, a continues electric supply to the central power window and central lock unit can make the system failed.
  4. Air Conditioner compressor failed at 38,000 km. The symptom almost the same with number 2, however usually the AC works fine at the beginning and failed after 1 hour trip (when the compressor reach its normal work temperature). Solution: Inspect the AC compressor, check for leaking. In my case, I open the compressor, overhaul it, and found most of the piston have been scratch badly, and some parts of the clutch have been damaged. I change the compressor completely. Note: My original compressor brand is Nippon Denso (ND), it is weird because the evaporator is manufactured by Zanden.
  5. Transmission high pressure hose leaking at 47,000 km. This is the high pressure hose from the tranny to oil cooler, leaking on the oil cooler side. Symptom: oil leaking and then dripping from the hose, loosen transmission oil, when the condition become worst, the automatic gear can jump suddenly to neutral in normal driving condition. Solution: change the high pressure hose, add the transmission oil. Note: to check your ZJ transmission oil level, park your car in flat area with engine running, move the gear lever to N and check the level using a dip stick.
  6. Engine misses throughout driving speed range starting at 51,000 km, the jeep engine misses in high rpm (i.e. above 2000 rpm). This problem occurs especially when driving a long trip. Solution: clean up the fuel tank, clean the fuel pump. Replace the fuel filter. Note: for my ZJ the fuel filter located inside the fuel tank, for pre 1998 ZJ, fuel filter located outside the fuel tank (more simple and easy to replace).
  7. Death Wobble, occur several times after I lift my jeep 2” and changed the stock tires with 31” tires (see my previous post). Solution: proper wheel alignment.

The rest are minor problems, like death battery, dirty power window motor. Generally the I-6 engine is very reliable and low maintenance.

See my other post about my ZJ compare to the Japanese 4wd in Cars and Bikes site.

Friday, March 21, 2008

Lifting Your Jeep

Why lift your Jeep? More height means more clearance for dealing with obstacles while offroading. It allows you to run larger tires, which also helps with conquering offroad challenges. Still another reason is that many folks just feel that a lifted Jeep with larger tires looks better, and I certainly agree with them. The added height and larger tires just give a Jeep a better more pronounced profile.

No matter the reason for lifting your Jeep, there are a number of ways to go about it. Before you pick which one is right for you, you’ll need to make some decisions along the way. First, you'll need to decide on what you’re looking to accomplish with the lift. Is it simply for show, or is it for go? Serious rock crawling anyone? Second, determine just how high you want to go. Looking for a little height for some mild wheeling or are you really serious about this height thing? Third, you’ll need to select the type of lift to use. Finally, install the lift or have it installed.

The basic methods for lifting a Jeep are Suspension Lift Kits, Body Lifts Kits, Shackle Lifts, Spring-Over-Axle Conversions, and Coil Spring Spacers. Jeep shackle lifts and coil spring spacers typically result in a maximum increase of 2 inches. Coil spring spacers are just what they say: spacers that are inserted under the base of the coil spring, resulting in lifting the springs higher. Shackle lifts are comprised of leaf spring shackles that are longer and lift the frame higher from the leafs. Both of these kits are rather inexpensive methods, but if you’re looking for more than a couple of inches, you’ll need to look elsewhere.

Spring-Over-Axle conversion kits allow you to change the location of the leaf spring from beneath the axle to sit on top of it. They’ll usually result in a lift of 4 inches or more. This can be increased by the size of springs you use with the over axle kit. Use of these can cause cantering, and steering linkage and driveline issues which must be addressed. It can become a little complicated for the less mechanically inclined among us (I’m one of them!). It will definitely change the handling of the rig. While the spring-over-axle conversion kits are rather inexpensive when compared to suspensions lifts, there is a good bit of time and money spent on fixing the issues it creates, which needs to be taken into consideration when assessing the costs of your various options.

With Body Lift Kits you basically unbolt the body from the frame, and place manufactured blocks between the Jeep's body and the rolling chassis. This raises the body of your Jeep but doesn't directly increase the clearance of your undercarriage. The body lift does allow you to run larger tires, which will increase your Jeep's clearance.

Suspension lift kits will directly increase the clearance of a Jeep. They call for installing taller suspension components (higher lift springs and longer recoil shocks). These systems deliver lift, better articulation, and better offroad handling. Unfortunately, they are the most expensive of the lift options, but they deliver the best handling performance.

When it comes down to choosing a lift, you’ll need to determine why you’re lifting the vehicle, and how much you’re willing to pay for it. If you’re only looking to add a couple of inches and you want the lift just for looks, a body kit, coil-spring-spacers or lift shackles may be just what the doctor ordered. If you’re looking to build a Jeep that is more offroad capable then you should look at suspension lift systems.

Many serious offroaders combine the suspension lift with a body lift for additional height. Installation of any of these lifting methods will usually change the handling of a vehicle. They all raise the center of gravity and will, therefore, affect side-to-side handling and cornering. This can be addressed by adding wider tires along with the lift. Depending on the type and size of kit you install and the model of your Jeep, you may need to install a dropped Pitman arm, longer control arms, longer brake hoses, a transfer case drop, and/or a CV drive shaft and slip yoke eliminator kit (due to a change of the angle of the drive train on TJs and some Cherokees). It’s important to not cut corners when lifting your Jeep. Why spend the money on a lift just to compromise the handling performance and face potentially serious wear and tear issues with key components? Do it right the first time and it will serve you in the long run.

Whatever system you select, the one thing for sure is that the added height will help give your Jeep that rugged tough look most of us seem to prefer.

Monday, March 10, 2008

LWB or SWB ?

After 20 years using various 4WD vehicles in various terrain, a basic question arise; which one better, short wheel base or long wheel base 4WD?

Muddy road:
A light weight short wheel base vehicle like Suzuki SJ410 is the best for this kind of terrain. The Suzuki will “float” above the mud. Some times a medium weight long wheel base vehicles like Defender 110 or Daihatsu Taft Hiline LWB are also good for this road. The muddy road condition is always not homogen, the opportunity to get hard ground is better with a long wheel base 4x4. The full size 4x4 likes Toyota Land Cruiser and Nissan Patrol will become the first vehicle stuck in the mud.

Gravel road.
LWB vehicles will give a better ride in this condition as long as the rocky road is not to rough. Riding a SWB 4x4 in this terrain will make your back pain getting worst.

Sandy dessert.
Both LWB and SWB are ok for this terrain. If you driving fast, LWB is better, more stable compare to the SWB vehicles

Rocky road
In this condition, a SWB vehicles with high departure and overhang angle will give an advantage to pass a rough rocky road. Suzuki SJ410, Wrangler Jeep and Toyota FJ40 will meet this qualification.

Steep hilly road.
The stability of LWB vehicles will take an advantage in this condition, especially when downhill.

For myself currently I choose a 4x4 to compromised all terrain above, Jeep Cherokee XJ. The wheel base is not short like Wrangler or SJ410, but still shorter than Land Cruiser or Nissan Patrol. With 32” tire, I can manage almost all obstacles and still feel comfortable while driving.
So, what vehicles is good for you?

Sunday, March 9, 2008

Mitsubishi Pajero 3.2 litre

The Mitsubishi Pajero is a sport utility vehicle manufactured by Mitsubishi Motors. It is known as the Mitsubishi Montero in the Americas and Spain, and as Mitsubishi Shogun in the United Kingdom. In this post I would like to discuss the third generation Shogun/Pajero (1999 - 2006) with 3.2 liters diesel engine.

Pajero is one of few real off-road workhorses, in the market it has competitors like Toyota Land Cruiser, Nissan Patrol and Jeep Grand Cherokee. Pajero can’t compared to the premium brand likes Range Rover or BMW X5, Pajero is though, real workhorse with bullet proof engine.

Pajero brief fact:
- Engine: 3200 cc four-cylinder diesel
- Output: 158 hp at 3800 rpm
- Torque: 275lb ft at 2000 rpm
- Transmission: 5 speed auto
- Fuel consumption: 26 MPG
- Weight: 2155 kg
- Top speed: 106 mph

Engines and Performance
The Pajero 3.2-litre direct injection diesel produce 158 bhp and 275lb ft torque. Although the power is slightly less than its competitor, however the high torque made Pajero is more flexible. The engine bit noisy, especially from the outside. While power is on the low side, the engine delivers tons of torque at under 4000 rpm, good for off-road driving and climbing steep grades. Fitted with Mitshubishi’s new INVECS-II five speed auto transmission, the Pajero has optional fully automatic mode or sequential manual shift. The quality of the automatic change reduces the temptation to use the manual option, although it can come in handy for accelerating hard out of junctions. The manual changes would benefit from being less hesitant.

Ride and Handling
In the asphalt road Pajero is quick and comfortable, body roll appears during cornering. The steering is good, its accuracy and a relative quick rack helping you make correction off road. As the result of fitting a multi link rear axle, Pajero lack of ground clearance. The traction system was rarely problem. The four-wheel drive system is switchable, operating as rear-wheel drive under normal conditions. The Pajero off road capability slightly less than its competitor Toyota Land Cruiser. The Pajero's soft suspension is generally forgiving and smooth on the highway. Road feel is never very lively in 4x4s, but the Pajero's rack-and-pinion steering is a big improvement over the previous model's setup. Road and wind noise make an appearance at moderate highway speeds. Cornering response is predictably ponderous, with pronounced side-to-side roll. Let's just say cornering quickly with the Pajero is not a very good idea. The Pajero features big ventilated disc brakes front and rear, necessary to haul this truck down from highway speeds, and they work adequately well in conjunction with ABS.
On rippled gravel surfaces, the Pajero exhibited little bounce thanks to the Pajero's fully independent suspension. Mitsubishi's compliant springs and shocks soak up most of this motion, producing a very smooth ride during mild offroading. Mitsubishi also does away with the classic body-on-frame construction of most 4WDs and opts for a unit body construction. This generation of the Pajero is the first to be built on a unit body, ditching the older body-on-frame design while also leading to a stronger structure that does not rattle over bumps. On really steep descents and climbs, the Pajero's torquey V6, low-range transfer case and brakes work together superbly, allowing good control when going downhill and providing plenty of torque for climbing back up.

Interior and Driving environment
The cabin is not complicated, is comfortable, robust and roomy. The quality is moderate. Pajero has seven seats. The third row of seats fold out of the floor, a neat system that creates valuable spaces when the seats are not in use. The shogun’s boot is narrow and tall, although with the rear seat folded it’s more usable. Driving position is good, visibility is excellent. The design of centre console is modern, however the fake wood in the dash look ugly. The Pajero dials composition and design is out of date.

Tuesday, March 4, 2008

Lifting the Grand Cherokee to fit 31” tire.

To fit 31” tire in ZJ Jeep required body lift around 1.5” to 2”. There are plenty of suspension lift kits available in the market. Before lifting the jeep, please check the front drive shaft type, if your ZJ equipped with U-joint drive shaft, it is save to lift the body up to 2”, but if the ZJ equipped with CV-joint front drive shaft, please do not lift the body more than 1.5”. To gain 1.5” to 2” body lift, we can use:

Budget Boost / Polyurethane Suspension Lift.
This is the cheapest way to gain 1.5 to 2” lift, just add polyurethane spacer on the top of the coil spring. Usually the spacers sold together with bump stop extension. For this method will cost around 60 dollar up to 150 dollar.

Change the suspension system with taller coil spring.
There are many suspension products are available on the market, one of them is Old Man Emu brand (picture above) manufactured byARB. The Old Man Emu suspensions are not typically noted as a lift kit. They are usually regarded as suspensions systems. However, depending on vehicle weight and application, a lift of 1-1/2" to 2-1/2" can be gained. Many lift kits require a sacrifice of ride quality for off-road performance, but Old Man Emu is able to combine both to give outstanding ride quality with excellent spring articulation. Old Man Emu recommends using 31" tires for best performance. This suspension system will cost around 500 to 700 US dollar.

Combination of the above system.
This is what I did with my ZJ. After installed the OME spring and shock, the 31” tire still rubbing the fender. I suspect that the installation of the new OME spring and shock have not reach 1.5” lift as their claimed. So, I added ¾” polyurethane coil spacer (cost me 59 USD, bought from 4WD store) and the tire just fit, not rub the fender anymore. However, the tire still rubbing the front lower arm in the maximum turn position. To avoid this, we can add a wheel spacer or reduce the maximum wheel turn through an adjustable bold.

The pictures below showing the ZJ jeep with 29" stock tire and with 31" new tire.

So what we got after installing 31” tire?
- Higher ground clearance
- Better look
- Plenty options of tire type (HT, AT, MT, super swamper, etc.)

- Don’t forget to re-align the will after installing the lift-kit
- After one year using the OME system in normal road driving condition, I feel the shock absorber going weak, this is much shorter than I expected. In near future I have aplan to change the OME shock with Pro Comp which is much cheaper with almost the same quality.