Some "singing" noise

[drivetheglobe]

Hi,

Have some noise almost exactly at 94km/h (5th gear, measured with Navi, ca- 105 on Tacho)).
It is not present below or over that.
Sounds like differential - how can I make sure or can it be something else? I have quire new Oil everywhere (Diff, gearbox).
Have some 170 000 km on the Tacho

br & thanks

[loot]

If it is the diff quickly press the clutch and that should make it change sound as it'll be unloaded.
If it only does it in 5th then perhaps it is that gear? Not an effect science but you need to change the gear, speed, load to try and find the common denominator.

[drivetheglobe]

Thanks, will listen more carefully, but so far only heard it in the 5th but think that load changed (gas/non gas) does change it, but cannot try long as without gas it quickly will not have the needed speed

[drivetheglobe]

Could it be wrong oil in the rear axle? Observes I have renewed it in 2016. think dis use a SAE80W90 GL5 but did not have Ford Spec.
Hope did not use the 75W90 GL4 from which I see also some left over bottle in my garage...

[drivetheglobe]

I had a closer look in a manual I bought on e-bay for my car: Its saying SAE90 API/GL 6 (!!) , Ford Spec SRW-2C-9102-A.
If I try to find something for GL6, I find only a statement in http://www.oilspecifications.org ( https://www.oilspecifications.org/api_gos.php) and it says:

GL-5 Active The designation API GL-5 denotes lubricants intended for gears, particularly hypoid (see note) gears, in axles operating under various combinations of high-speed/shock load and low-speed/high-torque conditions.
GL-6 Inactive The designation API GL-6 denotes lubricants intended for gears designed with a very high pinion offset. Such designs typically require protection from gear scoring in excess of that provided by API GL-5 gear oils.

So seems GL-6 is some "inactive" standard and seems to be for more extreme conditions an ABOVE GL 5.

So could easily be that todays GL5 Oils simply don't fit anymore. Will try to get the original one!

[davetheshrew]

get axle on stands, gear neutral, handbrake off. spin the wheel and you willll hear exactly where its coming from, Im betting its your centre bearing, you willl have 2 propshaft center bearings to check. Ive had brand new ones whine in a day or two. I doubt it's your diff.

[V184]

get axle on stands, gear neutral, handbrake off. spin the wheel and you willll hear exactly where its coming from, Im betting its your centre bearing, you willl have 2 propshaft center bearings to check. Ive had brand new ones whine in a day or two. I doubt it's your diff.

You can normally hear centre bearings at slow speed