Is Your 4WD Grinding When Turning? The Hidden Danger You Must Address Now!
If you hear your 4WD Grinding when turning, it usually indicates drivetrain binding. This issue causes difficulty in turning, grinding noises, and wheel hop due to torque transfer in the drivetrain.
So, the grinding noise can be caused by any of the above-mentioned issues which means you will need to do some troubleshooting.
If you hear grinding while driving straight in 4WD, it might suggest partially engaged transfer case gears, leading to improper teeth meshing.
To address this, slow down or stop your vehicle and attempt re-engaging 4WD.
In the next part of this article, I will cover why the grinding noise only occurs when you are turning.
Three common reasons for the grinding sound could be caused by any of the following:
| Issue | Description |
|---|---|
| Drivetrain Binding effect | Causes difficulty in turning, grinding noises, and wheel hop due to high torque transfer |
| 4WD gears not engaged properly | Partially engaged gears in 4WD resulting in improper meshing and grinding sounds |
| Driveshaft angles misaligned | Misalignment causing drivetrain binding and potential issues in performance and handling |
So let’s look into when it’s appropriate to engage in 4-wheel drive mode and under which driving conditions you need to exercise more caution.
4WD Grinding When Turning – Drivetrain Binding Effect
A part-time 4WD needs to be driven in 2H when driving on highways and going about your daily driving in town.
When driving on dry pavements and tarmac highways, you should always be driving in 2H.
Remember, a permanent 4WD will always be in 4H so just make sure the center diff is not engaged by driving in 4H-L.
Driving in 2H with a part-time 4×4 safeguards your drivetrain from the binding effects, prevents premature tire wear, and returns the best MPG for your 4×4.
Even when the highway surface is wet and dry pavements are wet, I would still recommend driving in 2H if the surface is a high traction surface and designed to offer sufficient levels of grip even under these conditions.
Adjust your driving style and keep a safe following distance instead.
4WD should only be engaged when:
| Driving Condition | Description |
|---|---|
| Off-road (dirt roads) | Driving on unpaved terrain, potentially uneven surfaces |
| Thick snow | Driving in heavy snow conditions often reduces traction |
| Sand | Driving in thick sand and dunes often reduces traction |
| Deep mud | Driving through substantial mud can impede traction and movement |
Basically, all surfaces that allow for enough slippage and where maximum traction is required, are safe for you to engage.
4WD Grinds when Engaging 4×4 On-the-Fly
Many modern 4WDs have intelligent, refined 4-wheel drive systems that offer on-the-fly 2H to 4H shifting.
Manufacturers assure us, that we can safely engage and disengage 4WD below their specified speeds.
There is no need to slow down to exit the vehicle anymore. Everything is becoming, easier, quicker, more automated, and user-friendly.
When the splines fail to mesh you hear a grinding noise
On certain 4WD trucks, when shifting into 4WD while accelerating, you will hear a metallic grinding noise and/or bang as it engages.
This might sound bad but isn’t necessarily a problem as long as you adhere to the manufacturer-recommended speed when shifting into 4H.
Failure to do so could result in costly damage to your transfer case and potentially break teeth off internal gears.
Engaging 4H while driving essentially locks the front and rear driveshafts together while one is rotating at a few thousand RPMs.
When engaging 4H on the fly and the two driveshaft splines fail to mesh what causes the grinding noise inside the transfer case?
Lets find out…
Why Grinding Occurs Inside the Transfer Case
If the noise is coming from the rear of your 4×4 it is most likely your rear differential.
Alternatively, if it’s more toward the front or middle it’s most likely the transfer case.
The transfer case is usually located next to or below your transmission.
I recommend using the process of elimination to confirm if it is the transfer case generating the grinding noise. How is this done?
Engage 2H and drive on an incline or a straight road under load and at varying speeds. Listen closely for any grinding sounds.
I find this exercise to be helpful since 2H only propels the rear wheels and isolates the transfer case and front driveshaft.
If it’s possible, remove the front driveshaft to eliminate everything forward of the transfer case like u-joints, bearings, front diffs, etc.
Damaged Spline Teeth
Once you’ve successfully established that it is the transfer case, the grinding is likely caused by the teeth of the spline that need to engage with the transfer case failing to align 100% with the internal gears.
The front output shaft bearing could also require replacement in the t-case.
These components all emit a grinding metal-on-metal noise once you attempt to engage 4WD.
If you are not a qualified mechanic, contact a reputable 4×4 repair shop to carry out the necessary repairs.
It’s going to be costly, so prepare yourself.
Transfer Case Oil
Before embarking on a 4×4 trail or extended trip, I always check my oil levels.
I make sure the engine, transmission, and transfer case oil levels are sufficient and topped up.
If you need to do an oil change on your transfer case, it’s usually a good time to inspect the quality of the old oil.
What exactly are you checking for?
When draining the TC, check for any metal filings.
This will indicate excessive heat build-up caused by high levels of friction.
If the lubrication levels are low, friction will increase causing premature wear on bearings and gearing components.
This will also result in the transfer case not engaging properly when you are driving and attempting to switch to 4WD mode while driving, thus resulting in an audible grinding noise.
Broken Clutch Slider
The grinding noise coming from that area could also be caused by a broken chain, or the clutch slider, located inside the TC, could be stripped.
When the slider teeth are stripped, it will have trouble engaging 4WD on the fly, resulting in loud metal grinding noises.
Why the Grinding Sound Disappears in 2-Wheel Drives
Many 4-wheel drive owners continue to add that the grinding noise disappears when they select 2H mode.
This is because when in 2H mode the transfer case and everything forward of that in the drivetrain system is disengaged.
The vehicle now operates as a rear-wheel-drive car by sending 100% of the power to the rear axle which splits it 50/50 between the rear wheels.
The transfer case and all 4WD components are eliminated in 2H mode.
Real-World Forum Experiences/Feedback
Only use 4WD when your tires are on a loose or slippery surface.
If the road is dry or just a little wet , your tires will have enough grip to bind your drivetrain on turns.
https://www.reddit.com/r/askcarguys/comments/llgzy3/4wd_makes_a_noise_only_when_im_turning_is_this_a/
Are you putting it in 4wd on dry or even wet pavement?
if so, thats your prob.
The drive line is binding up which is making your wheels pop / jump / and make all kinds of noises…
Take it in some mud, sand …. you prob wont hear any probs anymore.
https://www.gm-trucks.com/forums/topic/82615-grinding-noise-when-turning-while-in-4wd/
Helpful Resources
- https://www.gm-trucks.com/forums/topic/82615-grinding-noise-when-turning-while-in-4wd
- https://www.reddit.com/r/askcarguys/comments/llgzy3/4wd_makes_a_noise_only_when_im_turning_is_this_a/
- https://www.gm-trucks.com/forums/topic/82615-grinding-noise-when-turning-while-in-4wd/
Final Thoughts
I’ve established a few possible causes of the grinding noise when 4H is engaged as well as when attempting to shift into 4H from 2H mode.
In summary, any of the below-mentioned components could result in grinding noises when driving and turning in 4-wheel drive:
- Drivetrain Binding effect in the transfer case
- Damaged Spline teeth
- Low transfer case oil
- Broken clutch slider
- Bad U-joints
