If your rear end locks up then your wheels will stop spinning and then you could either flip the vehicle or you may just start skidding if one of the tires is still able to spin.
If you're driving slowly such as through town and your rear end locks up then you will just likely stop and nothing else happens.
Sometimes though it may not be your rear end locking up and instead your breaks if you have rear drum brakes.
I once had a rear wheel lock up and I thought my differential went out but turns out it was the breaks not releasing.
In that case my vehicle suddenly stopped moving and I had to have it towed out of the road.
If your rear differential goes out while driving then your vehicle will usually just stop moving.
Or if your differential goes out on the rear of your vehicle one of your wheels may just slide if one of your wheels is still turning.
Most often you'll hear grinding noises or other noises that alert you to the rear differential going out and most often it's the gears that are stripped out which then leads to the rear differential not turning the wheels like they should or at all.
Depending on the vehicle and the issue the rear differential has, what happens when the rear differential goes out while driving varies in severity.
If you have broken gear teeth or badly chipped teeth then you will experience a soft of “skip” in power or vibration that increases with speed.
Can You Drive With A Bad Rear Differential?
Yes, you can drive with a bad rear differential as long as the issue does not cause one wheel to spin faster than the other.
If this is the case, then your car will not be able to move in a straight line and you will have to pull over and call for assistance.
The signs and symptoms of a bad rear differential include.
Vibrations. A bad differential can cause vibrations that increase in intensity as you speed up and reduce as you slow down.
Grinding Gears. Grinding gears is another significant sign that your differential is failing and that the gears are wearing themselves out.
Whining Noises.
A knocking or clicking sound may be due to the splines on the axle shafts being worn out, in which case the defective shaft has to be replaced.
Another reason for this may be chipped teeth on one or more of the gears in the differential.
Again, they'll need to be replaced.
The average replacement cost for a whole rear differential is between $1000.00 and $4000.00
Luckily, you can just repair it or replace it with a used differential, which will decrease the costs a lot.
Most differential repairs will cost between $200.00 and $400.00 to repair.