Thread: URGENT - how hot is too hot for an LT95?

Gav,
After visit to the Nulon factory a couple of years ago, I decided i'd try some in my engine. I have a 4L late model disco 2 block, built up with 3.5 high compression heads and a modified cam in my 84 build 110. This is coupled to the same gearbox and transfer setup that you have. Mine gets bloody hot, on a hot summer day, on a long drive, it's not uncommon for the temps in my foot wells to go over 50 degrees. I've never taken measurements, but the transfer is too hot to touch.
Any way, back to the Nulon. For the same viscosity oil, my 110 went much better and ran quite a bit cooler. At my next oil change, I'm going to try it in my gearbox as well.

Originally Posted by disco 3 door

Hi Gav,
How did the flat terrain go from Glenrowan to Gundagi go.
Regards Shane.

Yeah, some bastard stuck some hills in there when no one was looking...

Originally Posted by isuzurover

Sounds like you have an IR temp gun? What temp are the diffs getting up to???

Yep, very handy to carry. Diffs got no hotter than 55. I actually took it along to check the hub temps on the trailer as I've had them apart last week. They didn't get above 30, and all the vehicle hubs sat at about 35 apart from the right rear which sat on 45. Will have a look at that later, but it didn't worry me as it never got too hot to hold my hand on it. Engine oil temp sat on 76 which is right about what the gauge on the dash said. Coolant temp was low 80's when I checked it out when stopped, which again is what the gauge said, but that did climb to nearly 90 going up some of the hills, but dropped straight back as soon as I crested them and backed off the throttle again.

Only the gearbox temps has me worried, and hopefully I can control that now

Originally Posted by bacicat

Yeah, some bastard stuck some hills in there when no one was looking...

Must grown out of the ground recently.

FWIW, the LT95 in my county has been around 92degC - towing our 1.5T camper at around 100km/h with ambients in the mid-high 30's. Temperature sensor was bolted to the back of the transfer case.

I find changing gearbox oil an absolute PITA, so have been running Syntrax, and now Penrite Pro Gear 75W85 full synthetic oil mainly so I dont have to change as often, but figure as a proper transmission oil its also probably giving a bit more protection. Particularly when the temperatures get up a bit.

From memory the Syntrax was in there for about 25K and still looked OK when I changed it. Only changed to the Penrite to standardise across the family "fleet".

Yes its dearer than engine oil, and probably overkill for an LT95 but works for me and allowing for the increased change interval probably not THAT much dearer than multiple fills of engine oil.

Steve

Originally Posted by DoubleChevron

This might be a dumb question. But how does a manual gearbox generate heat at all. The gears should all be in constant mesh, and there is no torque converter pump/slipping to generate heat.

Unless of course it has a failing bearing running red hot .....

You know it maybe quite normal. After all I've never heard of anyone having the capability of reading transmission tempertures. It is however bolted to something that runs at about 95degrees. So I'm not surprised the gearbox oil/gearbox eventually ends up at the same temperature as the engine it's bolted too.

seeya,
Shane L.

If anyone can, Billycan can!!! After today's efforts, maybe Miss Hot Pants might be more fitting!

Re oil temps in a manual box, any meshing gear will generate heat, especially under load. The overdrive is very small by comparison and by nature of its design really heats the oil too. This finds its way back into the transfer case and adds to the heat there. Helical gears also generate more heat, as when driven the gears are trying to be pushed apart due to the tapered teeth. This loads the bearing on the pressure side... again adding heat. Add to that the two hot exhaust pipes that are running past either side of the box as Gav has his foot nailed to the floor and it all builds up!!

I'm sure there is someone here who would suggest you call it ****box.
Perhaps Raf or Rafie?

Anyways, good to hear you're going so well. Going slower than 130km/h is so much more relaxing on the driver and easier on the car.
Take it easy and stay safe. I expect to read the pilgrims progress tomorrow night.

Pilgrim? Is that a good name?

Our gearbox got pretty damned hot pulling our camper up some steep climbs in Tassie. So hot in places that I couldn't hold my hand on it. We were running a synthetic oil in the transfer case and Roverdrive (as recommended) but a standard gear oil in the transmission. We ran 75W/85 Synthetic (GL-4) in the Transfer box/Roverdrive and SAE80 (GL-4) in the gearbox. (Both by Nulon).
While it got pretty hot, we never had any trouble, apart from a tendency for the transmission to lose oil, which we attribute to it not breathing well enough and pushing oil out of the seals. Had to top it up every few thousand kilometers.
Cheers

Coop