Gear Box Temperatures

Wetty,
I'll throw my oar in here for fear of being shot down, the bearings you have installed will take the temp it's the lubricant that breaks down and causes the lubrication issues leading to the bearing failures we run bearings in our machines regularly at around the 90 degree c mark but I run a synthetic oil. The cut off point that I start to get concerned is around the 120 degree C mark. The biggest issue then is if the outer casing is cooled this causes the bearings to lose the inner clearance because the inner race is still at the higher temp. I towed my camper trailer down a soft sand beach from Cervantes to Lancelin, checked the temp with an infra red temp gun, overall the temp was about the 100 degree mark, but I run a Royal Purple synthetic oil in both the gearbox and transfer case.

G'day Wetty,
Just curious, what are you concerned about?
Do you think 90-100 degrees is too high?

Moz

80-100 deg c running temps are the norm, and the first thing to let go is normally the seals, which most today are designed to run a max operating temp of 120-130 deg C.

Auto's run up to 100-120C towing on hills, and are mostly alloy case, so I wouldnt be to concerned about your alloy boxes in your Jack.

Like everything, run the best oil you can afford, a nd change it as required.

I would suggest if you are melting mounts you have greater problems than worrying about the oil temp, sounds like you are not running any oil. I run a turbo 400 behind a 6.2D Chev and operating temps are generally around 80c (summer) sometimes push to 100 when towing heavy loads up Greenmount.
If you are concerned about oil temperatures or other fluids contact shell or other manufactures (probably over east) and they will be able to tell you the breakdown temperatures of their various products.