How to Tell if your U Joints are Bad
When U Joints are worn or damaged they make squeaking noises that gain frequency with speed as well as vibrations when driving and other more serious symptoms. Finding the cause of the wear and choosing the right replacement U Joint for your vehicle’s duties or activities can decrease the chance of premature wear and failure and increase the interval between replacements.
* You can check your U Joints by listening for squeaking or popping while driving at very slow speeds, visually inspecting the grease seals for damage and leaking grease, or manually shifting the drive shaft to check for play in the joint.
Table of Contents:
What are U Joints?
U Joints (or Universal Joints) are steel crosses with a bearing cap at each end that allow rigid rods in the drive line to connect and rotate at odd angles and provide flexibility that reduces strain on the drive shaft when the vehicle moves.
Since they are relatively inexpensive, replacing U Joints at the very first sign of trouble can save a lot of headache and cash down the road.
Where are U Joints?
Generally there are two U Joints located along the drive line, usually near the engine and the rear differential in rear wheel drive vehicles. There are other drive train styles that use more U Joint connections along the drive line, such as in some 4WD vehicles.
1. Squeaking Noise
Unlubricated metal-on-metal contact between the bearings and the trunnion creates friction and a squeaking noise. Most noticeable at lower speeds.
* Lubricate if possible
2. Clunking Noise
Play within the joint causes the drive shaft to bang around when engaged. Most pronounced when shifting between drive and reverse. Also clicking or popping.
* Seriously Consider Replacing
Enough U Joint wear will eventually throw the drive shaft out of balance causing a consistent tremor. The transmission, could be sustaining damage.
* Replacement Threshold
4. Leaking Transmission
This could be a symptom of another problem but drive shaft vibration caused by a loose u joint can damage the seal on your transmission.
* Replacement + Transmission Work
5. Vehicle Won’t Move
Pretty self-explanatory and easy to notice. U Joint failure prevents the drive shaft from functioning so the vehicle will be in gear but won’t go anywhere.
* Possible Drive Shaft Replacement
6. Disconnected Drive Shaft
The U Joint has completely failed and can no longer keep the drive shaft connected… so it’s on the ground. Call a tow truck and get out your checkbook.
* Very Likely Drive Shaft Replacement
It is possible for normal wear and tear to be the culprits of a bad U Joint but most of the time the problem is tied to a lack of lubrication of the bearings, extreme vehicle use, or vehicle modifications which affect drive shaft angle or speed. If you can determine the cause of a failing U Joint you can select a suitable replacement and take steps to avoid having the replacement wear out prematurely. Here are some details about the most common causes for bad U Joints as well as some replacement suggestions.
Wear and Tear
U Joints typically have a very long lifespan but, no matter how meticulously maintained, they can wear out with enough miles, hard driving, or adverse driving conditions. In the case of trucks and SUVs that are used for off-roading and hauling or towing the U Joints have a hard job and are more likely to need to be replaced than with a daily driver.
- If the original U Joint gave you a good amount of mileage then you’re probably safe replacing it with an OE option.
In many instances a bad U Joint can be traced back to a lack or loss of lubrication. Since they are essentially a series of bearings, having proper chassis grease for your U Joints is going to be an important factor in how well those bearings operate. Some U Joints are designed to receive grease maintenance, which is especially useful in heavy duty, off-road, or lifted vehicles that can be hard on U Joints.
- Finding a U Joint with a greasable design makes lubricating maintenance something you can do in your own garage.
Putting your vehicle through the ringer with extreme applications like racing, off-roading, or continual excessive payload towing can put more strain on the drive shaft and can accelerate U Joint wear.
- Heavy duty tasks on a daily basis means you should probably have heavy duty U joints designed for tougher than average activities.
Lifting w/o Aligning
Installing a lift kit can change the angle of the drive shaft which puts more pressure on the U Joints and can limit their lifespan. Check drive shaft alignment after lifting to make sure it’s operating inside the manufacturer specs.
- Make sure your drive shaft angle is within tolerances, adjust if needed, and a stronger U joint wouldn’t hurt.
Suped Up Engines
If you’ve dropped a bigger engine or made modifications for higher horse power you are increasing the strain on the drive shaft, including the U Joints which will experience accelerated wear.
- Stronger than OE horsepower should have stronger than OE U joints
First off, Universal Joints are not exactly universal as far as fitment is concerned. The name can be a little misleading, but what we mean is that there are a variety of styles and very specific dimensions that must be met to fit a U Joint correctly. Be sure to find a part that is guaranteed to fit your year, make, and model or if you need to find U Joints by size make sure and get the correct measurements.
Which Replacement is Right for Me?
For a daily driver that spends most of its time on the highway or interstate you’re likely going to be fine with an OE replacement part or it’s aftermarket equivalent. If your vehicle is towing, lifted, or you have higher than original horse power then a more durable U Joint with features that improve operation and longevity might be a better fit. If you have greasable U Joints be sure to service them every oil change for best results.
Moog is an aftermarket parts company that manufactures high quality replacement U Joints or more durable upgrades for many makes and models. You can check out their options below:
* Disclaimer: We sell Moog Parts
Moog Universal Joints
Moog offers aftermarket U Joints with improvements over OE parts and takes more demanding applications into account with their design. Their U Joints range from replacements for daily drivers to heavy duty joints for maximum effective lifespan and operation in the worst conditions.
If you need to find U Joints you can visit Moog-Suspension-Parts.com and easily search by make and model or search for a U Joint by dimension. Here is a quick list of some of the U Joint options that Moog offers.
Super Strength U Joints are forged with a stronger steel alloy and use a greasing system that is accessed through the end-cap which results in a more durable U Joint. Also available without grease channels in the cross for even more strength in applications that can shock the drive line like racing, especially drag and dirt track.
These U Joints are specially designed for lightweight aluminum drive shaft yokes. Contact between aluminum and steel can create a galvanic reaction which can corrode the aluminum yokes. The bearing cups on these U Joints are chemically treated to prevent the galvanic reaction and corrosion.
The ultimate in durability and smooth operation. Components are ground to exact tolerances so that even microscopic imperfections are eliminated to further prevent premature wear. Special internal valves prevent dry start-up and provide consistent and constant lubrication over the working surfaces.
As stated before, U Joints are much less expensive than transmission work or a new drive shaft so inspecting or changing them at the first sign of trouble is the best idea. There are factors that can accelerate wear and cause premature failure so selecting the right U Joint to mitigate those factors can mean better operation overall and less of a chance they will need to be replaced.
Moog offers several replacement options, manufactured at standards above the originals, so we suggest trying them out if you’re needing to replace the U Joints on your vehicle.
From all of us at Suspension.com; Ride Smooth and Drive Hard.