It's probably fairly accurate to state that one of the most neglected items from a maintenance point of view would be the differential. You know, out of sight, out of mind, particularly if you are a mechanic of the DIY variety, bereft of a hoist facility. Laying on the ground, underneath the car is certainly no pleasure, and it gets worse when the time comes for refilling - you do need a special pump and appropriate hose for that task.
I have to admit that I am no exception to the rule in neglecting to change the diff oil at the recommended intervals. I do think that 6.9 diffs can be a little troublesome, with a whine when accelerating on a steady throttle, but also 'clonking' when slowing down and the box is changing to lower gears. I do know of loose bolt failure in one car with disastrous results, with one of the crown wheel bolts punching a hole in the diff casing, and in another instance, with a 6.3 diff having two or three almost finger tight only bolts in the crown wheel. Gleaming Beauty was prone to the aforementioned "clonking" problem and I was told that the star gears were worn. Some two months ago, I asked the local mechanics down the road from where I live to trace a harsh metallic noise that the car had been plagued with for some two years. I suspected a problem with the hub and also the U jointed drive shaft. Replacing the shaft with a rebuilt unit I had on hand cured the sharp metallic noise,, but I had also asked them to change the differential oil. That was duly carried out, and when I enquired about the state of quality of the oil drained, they thought that it looked "okay".
Anyway, since that oil change, the clonking has practically disappeared, and what is the moral of the story ? Don't skimp on maintenance just because the component is out of sight and out of mind. Regards. Styria
I have to admit that I am no exception to the rule in neglecting to change the diff oil at the recommended intervals. I do think that 6.9 diffs can be a little troublesome, with a whine when accelerating on a steady throttle, but also 'clonking' when slowing down and the box is changing to lower gears. I do know of loose bolt failure in one car with disastrous results, with one of the crown wheel bolts punching a hole in the diff casing, and in another instance, with a 6.3 diff having two or three almost finger tight only bolts in the crown wheel. Gleaming Beauty was prone to the aforementioned "clonking" problem and I was told that the star gears were worn. Some two months ago, I asked the local mechanics down the road from where I live to trace a harsh metallic noise that the car had been plagued with for some two years. I suspected a problem with the hub and also the U jointed drive shaft. Replacing the shaft with a rebuilt unit I had on hand cured the sharp metallic noise,, but I had also asked them to change the differential oil. That was duly carried out, and when I enquired about the state of quality of the oil drained, they thought that it looked "okay".
Anyway, since that oil change, the clonking has practically disappeared, and what is the moral of the story ? Don't skimp on maintenance just because the component is out of sight and out of mind. Regards. Styria
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