The Jeep Geek

The Jeep Geek's Blog
Jan 2011

Selec-Terrain

The new 2011 Jeep Grand Cherokee has a new feature that is a must have capability. Selec Terrain is a user tunable 4 wheel drive system that modifies a number of components based on the conditions of the road. This system makes the new 2011 Jeep Grand Cherokee a far more capable system than the previous generation...on road or off.

The Jeep Geek will now explain how this marvelous system works. First, it can be left in the auto position and the system will perform much as the previous generation of Grand Cherokees did. No need to think about it. The system leaves the traction control system in nominal mode, 45% of the engine power is delivered to the front wheels and 55% is sent to the rear wheels and the Transmission behaves normally.

If the driver places the switch in the snow position, then the system puts a bit more power in the front wheels, starts the vehicle in 2nd gear and makes the traction control system more aggressive. This gives a superior response in snow conditions...much like we are having today throughout the US.

Now once the weather turns nice and the driver wants to get their ya-yas out, the switch can be placed in the sport position. What happens is 80% of the power is delivered to the rear wheels (this is where you want power for racing...improves acceleration and handling). The traction control system is also turned off so that the driver is able to drift through corners. The shift points on the transmission are also tuned to be a bit stiffer. Finally, if the Grand Cherokee is also equipped with Quadra-lift then the Jeep will be lowered by about half an inch to improve aerodynamics.

Sand and mud settings are similar to snow, except that the Jeep is started in 1st gear. As The Jeep Geek wrote in last week’s article the key in navigating sand is to not spin the wheels...the opposite is true in mud so some driver intervention with the system may be needed.

The final selection is Rock. To enter this mode the 4 wheel drive system must be placed in low range. This is done by placing the transmission in neutral and pressing the 4wd Low button right next to the Selec Terrain switch. Once the Jeep is in low range, the switch can be turned to Rock and this mode is engaged. As before the traction control system is more aggressive. If the Grand Cherokee is equipped with the Quadra-lift system the Jeep is raised up to 4 inches giving a pretty good ground clearance. In this mode the 2011 Jeep Grand Cherokee is a pretty capable off-roader.

The Selec Terrain system can be ordered on any level of the 2011 Jeep Grand Cherokee and is a “must have” feature. This feature will improve the already impressive safety profile of the Grand Cherokee and allow you to “get there”.

Now The Jeep Geek will brave the sub-zero temperatures we are experiencing and conquer the snow build up from yesterday to get to work. He will do so without the selec terrain as The Hummer Recovery Vehicle is not equipped with this feature...maybe next year.
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Sand Gets Everywhere

Sand is one of the more challenging conditions to off-road in. There are a few techniques that will help improve your ability to avoid getting stuck...and The Jeep Geek may even give you a tip or two if you should find yourself buried to the frame in a sand dune.

You can find Sand in many areas of the country, although the western states have most of it. On the east coast most of the sand four wheeling is done on beaches. There are some amazing sand dunes on the outer banks of North Carolina...also in the desert regions of Western Arizona, Nevada, Utah, eastern California and parts of Colorado. The urge to have fun in the sand is almost overwhelming.

The Jeep Geek would like to point out a couple of things at this point. Sand dunes, especially on beaches, are easily damaged by off-roading. The most delicate part of the beach are the small areas where there are some grasses (or other plants) on the sand dunes themselves. These plants actually hold the sand dune together and provide the only cover for wild life on the beach. Please don’t drive over these areas. In fact, don’t even walk over them. Most sand dunes are small enough that you can drive or walk around them. Overall, “Tread Lightly”. As long as The Jeep Geek is lecturing, be sure you have permission to drive on the sand dunes...some are on private land, others are located on nature preserves and are off-limits to motor vehicles.

Now the fun begins. Why do people drive through sand dunes? Well, because it is fun...and the views are spectacular in some areas. But all this has some down side...sand is difficult to drive in and is hard on the equipment. Sand gets everywhere...The Jeep Geek still doesn’t know why sand gets in his underwear when out in the dunes...What’s up with that?

The first thing that is needed when driving in sand dunes is the right tires. The secret to success in sand is flotation. You need wide tires with paddle type of tread. Most off-road tires will work fine for this, but the standard on road tires are not going to work here. The next issue is inflation of the tires...they should be aired down to about 12 to 15 lbs. This is to provide a wider footprint. With a wide foot print and paddles to dig in slightly to provide a bit of traction you are almost ready to move forward.

Don’t spin the wheels if possible...keep your speed up to about 15 miles per hour...this means don’t use low range in the transfer case. Let the traction control system (brakes) do their job. Lockers on your Rubicon won’t engage in 4 wheel high, so don’t use them. Of course, don’t stop unless you need to do so to prevent hitting something. If you stop, you will likely sink down to your axles and get stuck. This is especially true if you stop while going up hill. Starting on sand while going up hill will cause you to dig into the sand bank. It is better (if you have to stop) to turn downhill before you stop. If you are on the beach, turn toward the ocean...the sand there is a bit firmer.

Keep moving if possible, but sometimes you just have to stop, and you get stuck. In that situation you have the opportunity to dig yourself out. Here are a couple of tips that may help. First, you will have to dig out the areas in
front of all four tires. Move forward slowly and turn your steering wheel back and forth to find some bit of traction to climb up out of the mess. This will only work some of the time. If this doesn’t get you out, you will have to resort to some thing else.

One method to increase traction in sand is to pour water on the sand in front of your tires...assuming you have something more than the bit of drinking water you normally carry. Experienced Jeepers carry two 5 gallon Jerry cans...one with gas and one with water. If this approach isn’t going to work for you, either because you tried it and it failed, or you don’t have enough water, then you can put a blanket or some other cloth on the ground in front of the tires and drive over that. This will likely tear up what ever you put down, but it is better than an unplanned long hike back to civilization in the desert. (If you have to walk out...do so at night...remember you won’t carry enough drinking water to make it out in the day time.)

Another useful device to have if you are sanding is a sand anchor. This can be connected to your winch and you may be able to extract yourself with this. Pull-pal makes a good one and this looks like a combination of an anchor with a couple of shovel heads attached. Don’t bother trying to hammer a pipe or stick into the sand to pull you out...it won’t hold, but the sand anchor will dig in and probably hold the weight of your Jeep.

Once you are finished playing in the sand and you are back home, time to get rid of all the sand...this is vitally important and a lot of work. First use compressed air and blow the sand out of the interior of the Jeep. (Did The Jeep Geek mention it gets everywhere?) Then use a high pressure hose (or steam cleaner) to get rid of the sand from the exterior of the Jeep...focus on the engine compartment and the whole underside of the Jeep...sand will prematurely wear out bearings and seals...so get it all off. Then the last thing is to do an oil change. Change the air filter(s) and oil filter while you are at it...trust The Jeep Geek...they are all dirty. This is also the time to clean all of your other gear...including your underwear...they are all full of sand. You will find sand for weeks afterward, that’s normal.

Driving on the sand dunes is fun, but will take its toll on your Jeep and on your body. Have a blast, but go prepared. Take the things you will need to recover in sand. Also an important safety tip is to let either the National Park Service or Bureau of Land Management (who ever controls the land where you will be going) know that you are planning to be out there. Set a time when you will contact them to let them know you are safely out of the area. This way someone will know if you are in trouble. You really don’t want to hike out in the desert. If you absolutely have to leave your Jeep, leave a note indicating the direction you are hiking and the time you left your Jeep so rescuers can find you.

Be safe out there and “Tread Lightly”.
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Jeep is 70 Years Old

The Jeep Geek does not write fluff pieces...this one may be close, but he is proud of the rich history that embodies Jeeping and Jeeps in particular. So he will commence crowing now.

1941 is when all this started. The Military wanted a replacement for it’s odd collection of motorcycles, Model Ts (yup, Model Ts) and sundry 2 wheel vehicles. They sent out an RFP (Request for Proposal) to a number of manufacturers. The specifications where for a 4 wheel drive vehicle with a two speed transfer case, 75 inch wheelbase weighing no more than 1300 pounds and able to carry 600 pounds of men and equipment.

The contract was awarded to Willys (with Ford building some of the vehicles). The rest was history...ok, so this part was history as well. But that is the point of this whole thing...70 years of history. No other brand has this rich history, sure, some brands have been around longer, some have more carlines but none have been involved in defeating our enemies for decades...what other car ensured the defeat of Hitler, Tojo, Mussolini? What other car brand brought wounded heros back from the front lines of Korea and Vietnam...not to mention that it was sold to countless militaries around the world?

Jeep also created the whole off-road industry that boomed after WWII. The Jeep Geek freely admits that other manufacturers have jumped on the band wagon by producing fairly good off-road vehicles...but they still call them Jeep Trails. Yes, The Jeep Geek is mighty proud of the unique history of the Jeep...so much so that he has changed his middle name to Jeep.

So what are the guys and gals in Detroit doing to commemorate this occasion? Well at this last weeks International Auto show they rolled out the 70th Anniversary editions of several jeep models. Pictured above is a Jeep Sahara in the new Bronze Star color. The picture below shows the seats in the 70th Jeep Grand Cherokee...the design elements remind one of the military. This brings up a story about The Jeep Geek’s father (who won three Bronze Star medals during his 28 year career in the Army).



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As the story goes, during the Vietnam war The Jeep Geek’s father (a Colonel) was driving in a remote area in a Jeep. This area had a road between two rice paddies that the Colonel was driving on. He heard a snap sound that reminded him of the sound a hand grenade fuse makes when the lever is released. From the corner of his eye he sees an object heading for his Jeep. This left the Colonel with only one option, leap from the moving Jeep. So that is what he did. He ended up in the ditch between the road and one rice paddy, the Jeep ended up in the opposite ditch.

Turned out that the hand grenade was a dirt clod thrown by a small boy. The locals gathered around laughing at the spectacle. The Colonel limped back to his wrecked Jeep and radioed for help...pride was the worst injury, but also ended up with a couple of broken ribs. After a couple of hours his Jeep pulled out of the ditch and the Colonel back at the base he regaled his colleagues with this tale (for which he did not win a Bronze Star).

For several years afterwards, at the Officer’s club in Saigon, during the Christmas season, the officers would sing the 12 days of Christmas and substitute “10 Colonels a Leaping” for “10 Lords a Leaping”.

The Jeep Geek thinks this story belongs in the greater lexicon of great Jeep moments in history.

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Trail Rating

As The Jeep Geeks stands ready to help prospective new Jeepers at the Pollard Jeep store in Boulder, he is often asked about the trail rated badge on some Jeeps. “This is just Marketing hype isn’t it?” On the contrary, it is an important aspect of off-road performance for Jeep. Some Jeeps are good off-road, some are not.

Now of all the 4 by 4 vehicle manufacturers, only Jeep has developed a set of standards to measure the ability to go off-road. This is key, because it is a guide to their engineering department to make sure that Jeeps continue to perform in the sticks.

Trail Rated as a badging came out in the 90s. Does this mean that Jeeps built before this didn’t perform well off-road? Of course not, it just means that Jeep engineers gave some significant thought to what is required to go off-road, and codified these characteristics. They have always built great off-road vehicles...more from instinct than measured against a set of standards. Now they either are awarded Trail Rated badges or not depending on how they are equipped.

To achieve a Trail Rated badge a Jeep has to pass criteria in 5 areas.
  • Traction. The Jeep has to have 4 wheel drive and have a low range in the transfer case. Some Jeeps are 2 wheel drive (not here in 4x4 country, but some parts of the country value 2 wheel drive jeeps...The Jeep Geek doesn’t know why.
  • Articulation. This is the ability for one wheel on the axle to stay on a surface while the other wheel goes over an obstacle such as a small boulder. If one wheel is on the boulder and the other wheel is hanging out in space, it provides no traction. (the co-efficient of traction of air is near 0). At some point even a trail rated Jeep is limited in it’s articulation...go over a high enough obstacle and even the vaunted Rubicon will experience a wheel hanging in space.
  • Ground Clearance. Occasionally The Jeep Geek is asked what the ground clearance of a particular Jeep is. His eyes glaze over and he begins to stammer and stutter. It is more complicated than measuring the lowest point of the Jeep to the ground. While Ford may measure ground clearance that way, it is a meaningless number. Ground clearance is not expressed in inches...it is expressed in angles...you know...degrees. The Jeep Geek will explain. In addition to how many inches of clearance for the lowest part of the Jeep, the issues are “Angle of Approach” This is the angle between the ground and a straight line from the bottom of the front tire, past the bottom of the front bumper. This will determine if you can start an uphill ascent...if the angle of the uphill ascent (like up a boulder) is steeper than the “Angle of Approach” you are not going to make it up, regardless of how high the lowest part of the vehicle is in relationship to the ground. “Angle of Departure” is the opposite of this effect...once you are coming down the hill (or the other side of this boulder), you want to make sure you can exit without leaving your bumper, fuel tank, or muffler behind on the trail. So the “Angle of Departure is the angle between the ground and the bottom of the rear wheel to the lowest point on the rear underside. Finally, the third relevant angle is the “Break-over Angle”. This is the angle formed from lines drawn from the bottom of the front and rear wheels to the bottom of the frame of the Jeep at the mid-point between the two axles. If your “Break-Over” angle is not good, you could find yourself “High Centered” on a large boulder that you are trying to conquer. The 2 door Wrangler has a better Break-over Angle than the 4 door Wrangler. This is one of the areas where short wheel base vehicles shine.
  • Maneuverability. There are obstacles on the trail that are better driven around than over or through...trees and boulders come to mind. The ability to turn sharply is needed on the trail. This is why full size pickup trucks struggle on the trail. Great 4x4 systems on say a dodge truck, but the length requires a lot of space to turn...(break-over angle also is not good) . Jeeps have always turned sharply, and this attribute also pays dividends on the road. They drive more car-like in that they are easy to park, move down narrow city streets, etc. Being able to maneuver is key to making it back home when off-road.
  • River fording. If you are going off-road, you are likely to encounter water...even in the desert. Streams, rivers, lakes, bogs, washes, ponds, etc dot the landscape. Frankly the most beautiful scenes that are encountered off-road are near water...this is where the trees grow, where the animals are, and if you enjoy fresh caught fish for dinner, you will be near water. The Jeep Geek has written an earlier article on river fording, but without the right stuff, you can’t get your vehicle into the water. Trail rated Jeeps have the right stuff.

You might end up on a Jeep lot and see two of the same model of Jeep, one that is trail rated and one that is not. There may be several reasons for this. Some models of Jeep have a choice of transfer cases...one with a low range, one without. The one with a low range may be trail rated, while the one without will not be. Also, sometimes a Jeep will have oversized tires and wheels that limit articulation, these won’t be trail rated, even with a low range transfer case. Replace the wheels and tires and you are good to go...or lift the thing. Ground clearance is low on the Jeep Compass and most of these are not trail rated...but for 2011 Jeep has produced a Compass that is trail rated.

In summary trail rated is about meeting standards. If your Jeep has the trail rated badge, you should be able to take it off-road...might not be able to conquer “Hell’s Revenge” at Moab, but you should be able to tackle moderate trails in your neck of the woods.
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