Category: Process Improvement

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Jeep Tire Rotation

Jeep Tire Rotation
and some tips on handling lugs nuts.

Rotating the tires on a Jeep is essential to long tread life. And with the cost of off road tires, you want them to last as long as possible. You can usually see a different wear pattern develop on the outer edges of the tires due the differences in the forces acting on the front and rear tires. Ideally the rotation would occur before the pattern is visible, but I usually wait until I can see it.

There are several schools of thought on rotating tires. Rotating tires means moving the tires to a different position on the Jeep. For example, you may simply swap the front tires to the rear. This inline pattern is how I most often rotate the tires. Some people add a side to side swap at the same time so that the tires are not only on the opposite axle but also on the opposite side of the Jeep. A swap in the X pattern means the tires will now be spinning in the opposite direction on the road.

Most of my tire experience has been with sports car tires and many of them have directional tires. So, I have gotten in the habit of simply moving the front tires to the rear and keeping them on the same side when I do a tire rotation. Either way you choose, here are some ways to accomplish the task:

How you rotate the tires depends on the equipment you have to work with. Since I have a lift and air tools, I lift the Jeep remove the lugs with an air wrench and move them to the new positions. I sometimes make a trip across my balancer if I have been having any vibration issues.

If you are armed only with the Jeep jack and the stock lug wrench, you are in for a bit of extra work. First, loosen the lugs on the side you plan to swap first. Remove the spare from its mount and have it ready. Jack up one corner and remove the wheel. Replace it with the spare but only put on three lugs. Set it down and move to the other axle. Break the lugs loose and then jack up that corner. Install the first tire there and install all the lugs. Now return to the corner with the spare and replace it with the tire from the other axle. Install the lugs and lower the Jeep. Repeat the procedure on the other side. Be sure to properly tighten all the lugs nuts when you are done.

If you have a jack stand, you can use it instead of the spare tire to save some effort. If you have two jacks you can save even more time and energy.

When loosening the lugs, note that they can be very tight. I prefer to use an air impact wrench for loosening. If you use a ¾ inch socket on the factory lug nuts, be sure it fits properly and is a deep well socket. Using a shallow socket will damage the chrome cover on the lug nut and make it so that no socket will fit it properly. If the cover is damaged, replace the lug nut. If you are faced with trying to remove a lug that is missing the chrome cover, get a cover from another lug nut and slip it inside you socket. This will allow a ¾ socket to fit the damaged lug.

If you do not have compressed air, I have found the electric impact wrenches work very well also. Even some of the battery powered units have plenty of torque and battery life for a tire rotation. Avoid the cheap guns that attach to the car battery. They are useless for tire rotation.

If you do not have an impact wrench, a long handled ratchet or breaker bar with a ¾ inch deep well socket works well. Be prepared to stand on the wrench handle if they were last put on at a tire shop. I don’t like to use a 4 way wrench because most of them are not deep enough to engage the lug nut properly.

Also, while the wheel is off inspect the lug studs threads. If there are damaged either chase the threads with a die or replace the stud. If the lugs are damaged in any way replace them. I prefer to run 13/16 hex lugs on my Jeeps instead of the stock size. However, I have to always remember that the stock lug wrench will no longer fit when I travel.

When tightening the lugs nuts, I always use a torque wrench. I prefer to use the clicker type for lug nuts for two reasons. First, the beam type wrenches are too hard to read sideways. Second, I would rather have precision than accuracy in lugs nuts. In other words, I don’t care if they are 73 or 76 I just want them all the same. BTW, I set the wrench at 75 ft lbs for the lug nuts.

I use a torque wrench because not only have I had the misfortune to have a wheel come loose while driving, I have seen wheel hubs damaged by too much torque. Also, a respected mechanic friend of mine, Jim Alton says that improper torque can cause brake shudder on Jeeps.

Rotating the tires at each oil change will help keep up with the uneven wear. Also, while the front wheels are off, it is easier to lubricate ht various grease fittings in the front suspension.

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Building a Rock Garden for my Jeeps

Building a Rock Garden for my Jeeps


Ever since I built my house in 1993, I have wanted some form of rock feature in the front yard. I started work on a water fall once but got discouraged by the cost and thought of constant upkeep.

Since I began using my Jeep off road instead of rally racing, I have wanted my own rock garden to test and play on. However, I have not been willing to invest money in buying rocks. Whoever coined the phrase “Dirt Cheap’ has obviously never bought dirt or rocks.

Here in east Tennessee there are usually rocks lurking just under the surface anywhere you dig. My property is no exception. There have been two large rocks lying beside my driveway that were removed when it was built.

Yesterday with some help from my neighbor and his tractor with a front bucket, I moved them into place to begin the rock garden. Moving them was a bit more difficult than I expected. I had expected him to simply scoop them up in the bucket and carry them up the drive way and drop them into place.

First of all the rocks turned out to be larger than I realized once they were separated form the dirt that partially covered them. That was a nice surprise in a way but not for the plan we had in place for moving them.

Plan B consisted of lifting a corner of the rock enough to get a log chain under it and dragging the rocks into place. Josh used his loader to lift a corner of the rock while I slipped in a wooden chock. We then used a shovel to help work the chain under and around the rock. He then used the 4wd tractor to drag the rock along the gravel driveway. It worked well to grade out the high center some at the same time.

We stacked the two rocks in a partially overlapping manner. The stack comes just to the rock rail on my Jeep when straddling it making it the perfect height for testing and posing for photos.

Next I will add some smaller rocks around the two large ones to make the entry and exit more interesting. I will also be on the look out for some larger rocks to add to the collection.

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Warped Brake Rotors on Jeeps and How to Prevent Them

Warped Brake Rotors on Jeeps and How to Prevent Them

When I picked up my new brake rotors for my Jeep the guy at the parts counter advised me to carefully clean the brake rotors of oils including oil from my fingers to prevent warping. This was new to me and got me thinking about warped brake rotors and reminded me that I have not had to deal with a warped rotor in a long time.

The first thing I learned years ago was that the pulsing sensation we called a warped brake rotor is not actually warping. You can put a dial indicator on the face of the rotor and spin it around and it will read very little run out when it is making a pounding sound when the brakes are applied. You can measure it all the way around and you will find very little difference in thickness either.

The real cause of the shudder is a chemical change in the metal of the surface of the rotor. You can sometimes see it but most of the time you can’t. Turning the rotor cuts off that surface layer making the rotor run smooth again adding to the warping myth.

The rotor surface chemically interacts with the brake pads under the heat of braking. Most of this interaction occurs during the bedding in process of the brake pads. Many high performance and racing pads have a critical bedding in process to establish the correct chemical bonding between the two materials. Usually this involves making controlled braking maneuvers at predetermined speeds to generate the heat needed for the reaction to take place. It is important not to come to a complete stop during the process so that the interface layer is kept consistent around the rotor face.

This leads to why rotors “warp” and how to avoid it. The interface layer is constantly maintained as the rotor face and the brake pad material wears away. A new layer is constantly formed with each use of the brakes.

If you come to a complete stop with the brakes hot, the reaction will continue under the pads where the heat cannot dissipate. If it is held there too long, it will create a bond that is a bit stronger or weaker than the area next to it on the rotor. As the rotor develops these uneven spots where the coefficient of friction is grater that the surrounding rotor face, the brakes will give the characteristic chatter that we call a warped rotor. The pulsing in the pedal will feel like the rotor is pushing the pads away from the surface.

I tried a lot of things before I finally got away from “warped” rotors. I tried the expensive rotors. I tried the cross drilled and slotted rotors. I tried various pad materials.

The thing that I found that helps more than anything is a simple driving technique. Some people call it the Limousine stop. I call it a creeping stop. If I suspect that my brakes are hot when coming to a stop, I will aim to stop a bit short and then just before the Jeep stops and is ready to rock back, I let off the brakes and let it creep forward about a half turn of the wheel. If I have to stay stopped like at traffic light, I will creep forward again another quarter turn of the wheel to help even out the heat buildup in the rotor.

There are times where it may not be possible to make such a stop. For example in an emergency or if you have to spot unexpectedly. You may also have to hold the brake longer than you wish thereby creating a hot spot. If this occurs, I repeat the performance pad bed in process and create a new interface layer. Depending on how bad the hot spot is, it may take several repetitions of heat cycling the pads to get them smooth again.

Since I have made this style of stop a habit, I have not had any more trouble with warped brake rotors. I can’t remember the last time I replaced rotor on one of my Jeeps due to chatter.

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Remembering Y2K

Remembering Y2K

As we count down the days to the end of the Mayan calendar, I am thinking back to the last potential apocalypse. I still remember all the hoopla that surrounded the change from 1999 to 2000. It seems many people were convinced that all the computers in the world were going to crash and we would be returned to the dark ages because the computers would not know what year it was.

At first I thought the whole idea was just silly. I had no idea anyone had taken the issue seriously. This is until I got a directive from my company that I had to certify each and every item in the plant to be Y2K compliant. Even in my relatively small plant employing just under 200 people, there were a lot of individual items that had to be certified.

Considering the relative importance of the situation, I first assigned the task to my co-op engineer. As he began to collect the data, and report back his findings to me, I began to realize that there were in fact many people who took the issue very seriously. Some companies were paying big bucks to have their equipment certified.

In order to not take resources away from solving real problems, he and I developed a checklist to quickly verify that the equipment would not self destruct at the stroke of midnight on December 31, 1999.

Naturally our first step was to see if the device even had a clock and even knew or cared what day it was in the first place. We also developed a form letter to send to manufacturers to get a document that added credibility to our own assessment.

Once we realized that not only did our own upper management actually task the situation seriously, but other companies were also taking the issue seriously we began looking into selling our services outside the company. Unfortunately by the time we realized people would actually pay us to do the work, most of the big contracts had already be let to people faster on the uptake than us.

So we just resumed our own process of certifying all the equipment we had and depended on. Naturally most of the stuff we looked at did not have a clock and could quickly be eliminated from the high priority list.

For most things with a clock, it was a simple matter to set the clock to a date past 1/1/2000 and see what happened. Only after we had tested most things on our list did we get stern warning from corporate not to test in this manner unless specifically told to by the manufacturer. Luckily we had completed most of our testing by the time they told us to quit.

One system of particular interest was the phone system. It did have a very important function of keeping the date and time of each voice message. About a week after we had run our clock forward and back again with no ill effects noted we received a dire warning from the manufacturer not to perform such a test. The assured us that it would indeed self destruct.

Sensing this was a scheme to cause us to hire one of their technicians to test for us, I called our sales rep and told her we had already done the test and nothing bad had happened. She informed me we were very fortunate that it had not crashed but was sad that we did not need their tech to test it for us.

Once we had complied huge notebooks of documentation for the equipment in the plant, we began thinking of how to best present the data to management and the auditors. Yes, they actually had auditors to make sure we actually did the certifications and did them correctly.

We first ranked items by criticality. The highest priority items were placed in the first notebook. These were items that would have the most impact on the operation should they fail on 12/31/1999. Of course these were items that might shut down production or make the facility uninhabitable for some reason.

My co-op engineer examined the data and decided in order to quickly point out how thorough we had been we would sort the data in inverse alphabetical order. After all our most important piece of equipment was made by Zerand and there was no point making them flip through the huge notebook looking for the Z’s.

The most rewarding consequence of the inverse alpha sort pattern was that it put the Zurn company at the top of the list. Zurn made the automatic flushers for our toilets and of course we ranked these as critical since no one wants to inhabit a building if the flushers are not working. The added benefit was the not so subtle hint as to where we thought all the data we had worked months to gather really belonged.

The managers go the last laugh on us however as they required us to be on site at the stroke of midnight on 12/31/1999 just to make sure we had not missed anything. We got to ring in the new millennium with a group of engineers and maintenance workers rather than our families. But, they did give us written authorization to have an actual Champaign toast at midnight.

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A Process Trouble Shooting Example

A Process Trouble Shooting Example

When I was at Westvaco, one of the important quality constraints on our product was the cut to print registration. By this, I mean the way the print lines up with the die cut of the package. Naturally some customers had tighter tolerances than others and one customer was particularly picky about theirs.

On these boxes, we found that some jobs ran just fine but on others we had a severe oscillation in the cut to print registration. We even had a term for it: “register rocking.” As the production run progressed, the cut would move from one limit to the other. And as the press speed increased, the registration would even jump to one side and then gradually creep to the other limit before it would jump back.

Our presses were fitted with the very best electronic registration systems available in the world. At the time, these were made by the Swiss firm Bobst. We had numerous conversations with Bobst engineers and had the electronics tested over and over.

Bobst always blamed the mechanical interface which was made by our press manufacturer. Of course Bobst also made presses and they wanted us to use theirs. However the Zerand press we had was much better suited to our style of printing and cutting.

We looked into every detail of the registration system. We considered the way the photo cell detected the registration marks. We looked for slop in the mechanical linkages. We looked for errors in the control program.

The intermittent nature of the problem made it even harder to trouble shoot. Several press runs would go fine and then one would pop up were the registration would not hold under any conditions.

Eventually we found that by carefully controlling the web tension we could stabilize the rock enough to make good product. However, the setting that worked went against common good printing practice and it was difficult to get the operators to run the press under those settings because they just seemed wrong.

Once we found that the odd pressures seemed to help, we began to look at why that would make a difference. Also, we began to recognize the types of jobs that gave trouble. We found that these jobs often paired older engravings with new cutting dies. We began to form a theory that maybe the two did not fit.

Due to the nature of the printing process and the tightness of the tolerances there was not way to directly measure the two. Both the die makers and the engraving manufactures assured us the parts were made to specification. Also, the printer operators assured us that there was no way that they could be wrong.

Despite a lack of cooperation from the press operators, we designed s few experiments to see if the die was in fact the wrong size for the print. What we discovered was the print was actually shrinking slightly as it went through the press. By the time it reached the cutter, the die was too big and most of the tolerance was used up in the error. We were actually getting the press to hold a much tighter tolerance than it was designed to achieve but most of that tolerance was used up in the error of fit.

The weird pressures we had been running had actually been stretching the paper slightly to help it fit. Due to the cost of the engraving and dies involved, it took a while to get new parts made and mostly the corrections were only made to new jobs. We also had to fight the people who simply could not see the complicated concept of how the parts did not fit.

Eventually we were able to get the engravers and die makers to change their algorithms for making the parts so that they actually fit by the time the product exited the printing press. Our press speeds went up about 20% once the operators no longer had to fight to keep the alignment that simply did not exist.