the past few days ive have had an intermittent rumbling from my truck. it only happens when im going very slow and happens in reverse and drive. at first i thought it was my tires but it is definitely not. any idea where to start looking? maybe the diff? I have found it happens mostly as i am getting in and out of parking stalls

 

check out your u-joints on the shaft, they shouldnt have any play. make sure the backlash is also still good on the gears. just try to rotate the shaft and see how much it move, should only wiggle like a 1/16th or 1/8th of an inch, not much

 

Thanks. Ill check that tomorrow and post back

 

does it do it when going straight or only when turning.

if when turning, and its coming from the front, check front axle u-joints and wheel bearings.

if when turning, and its coming from the rear, and you have a limited slip diff, then its probably a worn out LSD.

 

thought i would update for anyone that has a similar problem in the future. my buddy who rebuilds tannys and such said to dump in a bottle of friction additive. i did so and no more rumble. he said it was the clutches in the diff not fully releasing and that was making my truck rumble. its been about 3 weeks now and the rumble has stayed away. the additive cost 15 bucks. always worth a try in my opinion

 

Any truck with a limited slip diff needs that additive. Our trucks take 4oz.

 

Does the additive break down over time? I remember changing the fluid and adding the additive but why would it just start doing it? The truck had been parked for over a year

 

It's possible the fluid got stale from not being used, and the friction modifier was no longer useful.

 

Make sure that your diff was full of fluid and is not leaking. Mine did the same thing and I found that the fluid was low and had a mild leak around the cover. Fixed the cover leak and refilled with fresh 80W90 gear oil and additive - no more problem..