The Nissan Path

Hey gang!

I have a pretty prominent vibration on deceleration which my guess is the rear differential is dying.
No issue noticeable on acceleration or when stopped. Most obvious over 40mph.
Any chance anyone has had a similar issue?
Any help is appreciated!

I also have all the means to do the swap myself to a new rear end should it need replacement.

Thanks in advance!

Rear end failures aren't nearly as common as bad U-joints or vibration issues caused by coolant contamination of the transmission fluid. If you haven't checked them out, I would do so before assuming the rear end is bad. I was also check to see if there is any noticeable play when you grab the diff pinion flange and move it up/down. It could also be the brakes (rotor thickness variation creating a vibration when brakes applied).

I have 110,000 miles on my V8 and am having a similar issue with mine. Noticeable vibration and humming during deceleration between 55-40mph. In the months leading up to this new issue, I’ve had all wheel bearings replaced, rear CV axles replaced, several failed suspension parts both front and rear replaced, as well as power steering rack replaced. All of these replacements have fixed their respective problems, but had lead me to having this interesting vibration when decelerating. I’ve taken it to my local shop, had it aligned, had the tires road force balanced (they were slightly out, but not much) and had all drivetrain and suspension parts checked at my Nissan dealer. They did an inspection, a test drive (repeated the issue) and had it on the lift for 2+ hours. They could not ID a problem. All replacement parts were Nissan factory parts or high quality replacements (no cheap crap parts). Towed my 7,000lb travel trailer this weekend, (which I’ve had NO issues towing in the past) and the vibration is noticeable while accelerating and decelerating and is at its worst at about 45mph and fades in and out at speeds higher and lower. Does not matter what gear I am in, vibration seems to be consistent with driveline rotation, not nesessarily engine rotation. I will also add that I noticed my harmonic balancer pulley is slightly wobbling on it’s axis. I loosened the belt and tugged in it to make sure it was not loose and it was solid, but will need to be replaced. I am at a loss as to what can be causing this vibration (almost up and down, vs side to side). It is not felt in the steering wheel, but rather at my feet under the floor well, and the whole truck sort of ‘bounces’ up and down, that’s the best way I can describe it. Stumped!

It sounds consistent with a driveshaft U-joint. Just because they don't have play in them, doesn't rule out one of them binding. Also, keep in mind that the front shaft turns when driving even if not in 4WD.