***Normal operating temp 2.5 Rockwell***

[altoids]

Whats the normal operating temp for the 2.5 Rockwell axles differential/chunk (mainly the rear b/c I don't have front driveshaft hooked up all the time) & what temp is considered "not" to exceed. After about a 30 mile run at 60-65MPH my pinion nut on rear is pretty warm. I'm not asking about hub temps they are fine. Thanks for replies in advance.

 

[Big Z]

Normal driving: 100-125. Straining: 150. Considerations: ambient temperature and 6.72s running 65mph.

 

[altoids]

Ambient temps been around 87*-95*. I know 65MPH is alittle speedy for Rocks.

 

[KsM715]

Whats "pretty warm"? Can you hold your hand on it, or is it so hot you have to pull your hand away as soon as you touch it?

 

[flighht2k5]

Whats the normal operating temp for the 2.5 Rockwell axles differential/chunk (mainly the rear b/c I don't have front driveshaft hooked up all the time) & what temp is considered "not" to exceed. After about a 30 mile run at 60-65MPH my pinion nut on rear is pretty warm. I'm not asking about hub temps they are fine. Thanks for replies in advance.

But even with the driveshaft off it's still spinning isn't it?

 

[altoids]

Whats "pretty warm"? Can you hold your hand on it, or is it so hot you have to pull your hand away as soon as you touch it?

I can hold my hand on it for about 5-8sec. Got a digital IR temp sensor to get accurate temperature.

But even with the driveshaft off it's still spinning isn't it?

Yes, the front still spins. Don't have my Ouverson manual lock out hubs yet.

 

[Tow4]

I've never seen more than about 140 on the center chunks of my Deuce or 5 ton after a long interstate run.

 

[altoids]

I've never seen more than about 140 on the center chunks of my Deuce or 5 ton after a long interstate run.

What speed do you average on the interstate runs?

 

[PropDr]

I can hold my hand on it for about 5-8sec. Got a digital IR temp sensor to get accurate temperature.


Yes, the front still spins. Don't have my Ouverson manual lock out hubs yet.

I would consider 200*f the safe limit.
What type and viscosity oil are you running?

 

[altoids]

I would consider 200*f the safe limit.
What type and viscosity oil are you running?

What makes you say 200*?
I'm running Lucas Heavy Duty 85w-140 & a quart of heavy duty oil stabilizer.

Hows the upper part of the chunk lubricated? Does the bull (ring) gear just sling it up there?

 

[Tow4]

What speed do you average on the interstate runs?

About 50 MPH; depends on how far I have to go. 55 MPH (more or less) is top speed for the Deuce and 53 MPH for the M818. Usually I'm not in a big hurry.

 

[PropDr]

What makes you say 200*?
I'm running Lucas Heavy Duty 85w-140 & a quart of heavy duty oil stabilizer.

Hows the upper part of the chunk lubricated? Does the bull (ring) gear just sling it up there?

Well my logic behind that is that mineral based oils break down rapidly above 285*f and that the extreme pressure and wiping action at the contact point of the gears can easily raise the thin layer of oil separating them another 100*+ causing the oil to fail and galling of the gear teeth.


Yes it's splash lubed, their is no oil pump.

Are the axles your referring to under the Jeep in your avatar?

If I was going to run them at high speed for long periods of time I personally would look at switching to a full synthetic polyester 85-140w climbing gear lube. The bad part about the stuff is it's expensive, hard to find, and as far as i know only one company makes it. The good thing about it is that it will run @ 500*f for hours on end and upwards of 800-900*f for brief periods without failing.

As an alternative the other thing I would look into is trying to find some 85-140w gear oil that meats the old defunct API GL-6 rating because it has a higher content of EP and antiscuffing additives, 10% as opposed to 6.5% in GL-5. Their are still quit a few performance oil companies that sell GL-6 but sometimes they refer to it as gl-5+ or severe duty gear oil.

Either one will lower the operating temp of the gearset.

I'm not sure what catagory the lucas gear oil falls into, all the bottle says is exceeds all API GL specs, I have no idea if that includes the old defunct API GL specs or just the current ones. It's anybodys guess as to the amnount of EP and antiscuff additives in it.

 

[altoids]

Well my logic behind that is that mineral based oils break down rapidly above 285*f and that the extreme pressure and wiping action at the contact point of the gears can easily raise the thin layer of oil separating them another 100*+ causing the oil to fail and galling of the gear teeth.


Yes it's splash lubed, their is no oil pump.

Are the axles your referring to under the Jeep in your avatar?

If I was going to run them at high speed for long periods of time I personally would look at switching to a full synthetic polyester 85-140w climbing gear lube. The bad part about the stuff is it's expensive, hard to find, and as far as i know only one company makes it. The good thing about it is that it will run @ 500*f for hours on end and upwards of 800-900*f for brief periods without failing.

As an alternative the other thing I would look into is trying to find some 85-140w gear oil that meats the old defunct API GL-6 rating because it has a higher content of EP and antiscuffing additives, 10% as opposed to 6.5% in GL-5. Their are still quit a few performance oil companies that sell GL-6 but sometimes they refer to it as gl-5+ or severe duty gear oil.

Either one will lower the operating temp of the gearset.

I'm not sure what catagory the lucas gear oil falls into, all the bottle says is exceeds all API GL specs, I have no idea if that includes the old defunct API GL specs or just the current ones. It's anybodys guess as to the amnount of EP and antiscuff additives in it.

Check out this pdf & let me know which one ya think is best. I'm thinking Amsoil Severe Gear 75w-140 (even thou they only test 75w-90's mainly in these tests).
http://www.amsoil.com/lit/g2457.pdf

 

[PropDr]

That article had some good info in it.

I don't think you can go wrong with either the Amsoil or Redline. Amsoil is a Poly-Alpha-Olefin type oil which is slightly les durable than redlines polyester formula but their both great oils. Either one is good for at least 100000 miles between changes as long as it doesn't get severely overheated or contaminated in some way.

Also old seals and gaskets tend to leak more with synthetic oils so you might want to have a few spares on hand after you switch over.

 

[altoids]

That article had some good info in it.

I don't think you can go wrong with either the Amsoil or Redline. Amsoil is a Poly-Alpha-Olefin type oil which is slightly les durable than redlines polyester formula but their both great oils. Either one is good for at least 100000 miles between changes as long as it doesn't get severely overheated or contaminated in some way.

Also old seals and gaskets tend to leak more with synthetic oils so you might want to have a few spares on hand after you switch over.

10*4. Thanks.

 

[HDN]

I was checking temperatures on my differentials on my truck out of curiosity today. With about 41 MPH worth of RPM on the drivetrain (going about 45 in actuality due to the 395s) in 80 degree weather:

Rear Pumpkins: 115-120 degrees Fahrenheit
Rear Top of differential: 120-125 degrees Fahrenheit

Front Pumpkin: 95-100 degrees Fahrenheit
Front Top of differential: 100-110 degrees Fahrenheit

Note that I don't have lock-out hubs on the front end. I used an IR thermometer to measure temperature.