Jeep JK undercarriage rattle
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Any Jeep Wrangler owner have experienced weird noises their vehicle makes occasionally. We all realize that Jeeps are not really known for comfort and refinement. They are made for offroading and that’s where they shine, however daily driving, although fun, might make you go insane if you listen to every little unexplained noise your Jeep makes. Some of those noises are due to Wrangler’s shape, resulting in terrible aerodynamics. If you take the top off and install it back without making sure all the seals are perfectly aligned, you will experience loud wind noise. If you upgrade your front bumper or the fenders, you’ll increase drag and the noise will become even louder. Larger, more aggressive tires can be very noisy on asphalt. During daily driving you will most likely hear some squeaking inside the cabin, from the doors or seats for example. There might sometimes be some whining sounds coming from behind the dashboard.
Many of us driving Jeep Wranglers learned to react to all these noises by saying “It’s a Jeep thing” and cranking up the music. As long as the Jeep still runs, it’s totally normal.
Any Jeep owner who installed upgrades to their vehicle, and wheels their rig once in a while, accepts the fact that sooner or later there will be some hard to identify noises or rattling coming from the Jeep’s undercarriage.
These noises could be occurring at different times. It could be while the Jeep is not moving and simply idling, while you go over speed bumps or potholes, or when you’re braking.
Determining the source of the noise depends on this timing.
We all tend to expect the worse, but sometimes quick inspection of the undercarriage will reveal the culprit.
I would suggest that if the noise occurs while braking, you should obviously check your braking system. Inspect all brake rotors, calipers, anchor brackets (check the anti rattle clips), brake pads and of course the bolts securing all those parts. Putting the Jeep on jack stands and taking the wheels off will make this process much easier.
If the noise occurs while going over “obstacles” in the road, than it will most likely point to an issue with suspension. I would definitely check all the bolts for your shocks, control arms, sway bar links, track bars and drag links. You can find suspension torque specs here.
Noise or rattling occurring during idling will most likely be caused by a loose part of the exhaust system. There are of course other possible causes, like loose bolts or nuts in your driveshaft (more likely however to make noise while your Jeep is moving), or motor mount or transmission mount rubber dampeners deteriorating, however the noise would most likely be accompanied by vibrations you could feel when sitting in the driver seat.
Provided there is no vibrations, I would always inspect the exhaust first.
This post is meant as a quick guide to inspecting your vehicle’s exhaust system in order to locate the source of a Jeep Wrangler JK undercarriage rattle. I put this post together after experiencing rattling coming from underneath my own Jeep. In my case the noise would only occur while idling, after a cold start and only after putting my Jeep in reverse. It drove me crazy for few days, but I was finally able to locate and fix the problem. For me it was a broken spot weld on the crossover pipe heat shield, as well as a rear clamp which appeared tight however it wasn’t and it allowed the exhaust pipe to vibrate.
When it comes to the exhaust system, the most common cause of a rattle is the heat shields becoming loose, due to rocks hitting them, weak welds or corrosion. Your driving style and your climate will have a big impact on the shape of your exhaust system.
Remember: Let the exhaust system cool down before touching anything.
You can perform the inspection without any tools, however a screwdriver, mallet or a hammer might be useful. You will need few wrenches or sockets and possibly a hose clamp or two, in order to fix the problem. If you determine that the bolts securing heat shield above your muffler are rusted and the shield is loose, you will need few large washers and small u-bolts.
Disclaimer: Like I always mention I am not a professional mechanic, I just try to do as much work on my Jeep as possible. It helps me learn more about my vehicle and save some money that can be spent on parts and upgrades.
I take no responsibility for any injury or breakage which might occur if you decide to follow these steps. You have to decide if you’re comfortable working on your Jeep. If you’re not, please have a professional complete this project for you.
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Lifting your Jeep Wrangler JK results not only in higher ground clearance, better approach, departure and break over angles and ability to put on larger tires, but it also causes changes to your driveline as well as steering geometry. Make sure you educate yourself on this topic before installing a lift on your Jeep, especially anything over 3″.
Really popular modification that most Jeep owners will do to their Wranglers is to replace the factory front plastic bumper that came with their stock Jeep JK, with a heavy duty offroad bumper. Aftermarket bumpers offer a ton of advantages over the factory bumper, providing better protection for the front of the Jeep, but most of all allowing you to install a winch and additional offroad lighting. Depending on the design, aftermarket offroad front bumper might also increase your Jeep’s approach angle and expose the front wheels, making it easier to put tires on large obstacles. It might also include steel skid plate, protecting the electronic sway bar disconnect motor, if your Jeep has one.
Jeep Wrangler JK unfortunately lacks proper lighting in the rear cargo area. Any Wrangler owner probably experienced a situation when they were loading or unloading their Jeep after dark and could not see anything in the cargo area behind the back seats.
Changing the fluid in your Jeep JK front and rear differentials is an important part of routine maintenance. Fresh gear oil insures your differentials are well lubricated and function properly. And, unlike previous Jeep Wranglers, it is not necessary to remove the differential cover in order to do this. It is however recommended that you do so anyway from time to time (possibly every other fluid change) as it will give you a chance to inspect your gears and catch any damage or unusual wear. 
The most common situation when extended brake lines are necessary is when you install a lift on your Jeep. The distance between the frame/body of the Jeep and axles increases after a suspension lift, therefore longer brake lines are required during articulation. You might also want to replace your stock rubber brake lines with stainless steel braided brake lines when you realize that the stock lines are deteriorating due to weather conditions (very high temperatures in the summer or lots of salt on the road due to ice and snow in the winter) and when you begin noticing a much softer, spongy brake pedal feel. That feeling is most likely due to moisture getting into the brake lines, which leads to reduced boiling point of the fluid and forming of air bubbles, as well as corrosion of the metal components of the system and consequently contamination of the fluid.
When it comes to Jeep upgrades, brakes are often very low on the list of priorities. After upgrading wheels and installing larger 35″ tires, your stock brakes will have a very difficult time stopping your vehicle, both on the road and especially while negotiating thru an obstacle while offroading. When you increase the size and weight of your tires, you should really think about upgrading your brakes as well. It will improve your confidence while driving and just might help you avoid a collision or an accident. New, upgraded brakes are not cheap, however knowing that your braking power has been increased and stopping distance has been reduced is definitely worth the investment.
During routine maintenance and after doing any kind of modification to your steering, suspension, or drive train, all bolts and nuts should be checked to ensure that they have been tightened to specification.
A/C blend door actuator in your Jeep JK is a very important part of the heating and cooling system and is responsible for controlling the temperature of the air blowing thru the vents and into the cabin. To blow heat into the cabin, the blower motor sends air through the heater core and on through the dash vents. But when heat is not desired, the blend door actuator directs that airflow away from the heater core. Unfortunately blend door actuators can fail at some point and cause the inability to change the air temperature inside your Jeep. The reason I needed to replace the blend door actuator in my Jeep was due to the horrible and loud ticking/grinding noise that it was making every time I put the key in the ignition. I also noticed that the actuator resets itself and makes the same noise after about two minutes from turning off the engine. With the Jeep being topless and doorless, and me using public parking lots, I was afraid someone walking by would freak out and call the cops, thinking my Jeep was about to explode…
One of the greatest benefits of owning a Jeep is the possibility to drive topless and doorless. Removing the top and doors does however leave the interior of your Jeep exposed and unprotected. One of the items that could be stolen from your vehicle is your garage door remote. Most people have it attached to their sun visor, which makes it very visible to a passer by. This post describes the steps to hide your garage door remote inside one of the plastic panels of your Jeep and use a small, discrete push button switch to activate it.