Whine from rear diff

Hi Guy's,

I'm after a bit of advice about a whine that I think is coming from the rear diff. I say think, because it's hard to pinpoint exactly where the noise is coming from. The noise starts around 45 mph and gets louder as the car gets faster. It only makes the noise when under load and disappears as soon as the throttle is feathered or the clutch is depressed. The noise isn't a constant howl, more of a 'wom - wom' noise that eventually disappears when the noise of the speeding car overcomes the offending noise.

I bought my 2007 Jimny 2 years ago from a Suzuki dealer and was told by the salesman that the noise was common and not to worry about it. 2 years later, the noise is no worse, but it's starting to get to me.

Any ideas on what it could be, and if it is the rear diff, what can I do to get it fixed?

May thanks.

Paul

Tried an oil change to see if that changes the sound? - easy to do but remember to check the filler plug undoes before you drain the oil

Riccy

Sounds pretty normal. Every Jimny I've owned has had a bit of transmission noise. If it's been the same for 2 years I doubt it's going to suddenly give problems.

For peace of mind you could drain the rear diff oil. If it still looks like oil and doesn't have big lumps of metal in it then you have nothing to worry about.

We all think that , just drive it until it brakes and then fix it. even if the diff is going bad it will still drive for a few thousand k's and it will get really noisy before that.

Thanks Guy's,

The diff oil is changed every year (with the correct grade) in fact it was done 2 weeks ago when the full service and MOT was done. I was told that the old oil was clean when it was drained. Indie thinks it's a bearing in the diff.

In fact, the only dirty oil was from the gearbox, which is also drained and renewed every annual service. (Gearbox rebuilt at about 27K by Suzuki dealer under warrantee. Car now has done 32K.)

I'm comparing my Jimny to the old bangers I hire when on holiday (Skiathos). They are used and abused, but no transmission noise, quiet compared to mine! I do have the rear seats removed which allows more noise from the diff to reach me, I'm just getting tired of the noise and wondered if it was the diff and if anyone else had the same noise.

I am having similar noises for the last half a year (last 5000 km or so). The noise is more noticeable when the engine and the transmission get warm / hot than from cold start.

My noises are very similar to when a universal joint in a propeller shaft goes bad, but without the actual vibration.
The noise is like light lumping, and the frequency of the lumping is proportional to the speed of the vehicle. It is most noticeable at around 40-60 km/h and wind howl "overtakes" it above 80 km/h.

The noise gets most prominent when I go down a gentle downhill on engine braking, and when I press the clutch pedal or press the brake pedal, easing off the load on the engine and consequently on the transmission.

The noise is the same when in 2WD and in 4WD, so it has nothing to do with the front axle or the front propeller shaft.

One technician believed it was a universal joint connecting the rear propeller shaft to rear differential, as the joint turned out to be super dry.. I replaced it but no improvement.

Another technician beliieves that transfer box mounts are worn.
A third technician believes that some bearings in the rear differential are the cause
A fourth technician believes that the balance of the gearbox-to-transferbox propshaft or transferbox-to-reardiff propshaft is out of order. Did you know that propeller shafts come balanced from the factory and that they can lose balance in certain cases?

I am still in the process of investigating it.