Going to change diff fluid this weekend.  I'm thinking about getting on of those fancy diff covers.  I don't mind the price but only if upgrade is worth it.  Anybody know what normal temps are with a OEM diff cover compared to the aftermarket alum covers with "cooling" fins?  My Dana 70 is usually towing a 8k to 9k trailer most of the time.

Even with the fancy type I would still pull cover when changing fluid, just to get a visual of the insides.  And I would still use "dino" oil.

 

In your opinion is the fancy type are worth it?

 

 

I wouldn't bother personally.  I am sure Dana engineering specs load rate and heat vs capacity.

5 hours ago, Me78569 said:

And plug off I wouldn't bother personally.  I am sure Dana engineering specs load rate and heat vs capacity.

 

Thanks for response.  I did make a mistake in my posting.  I use "royal purple" not dino oil for diff fluid. 

I agree, engineers probably worked out the problems.  Over the years (way to many) I've only had one rear diff that needed anything fixed other than normal service.  Third member is probably most bullet proof of entire vehicle IMO.

 

Later this summer, just to see what is going on,  I think I'll play around with trans temp probe and mickey mouse the probe into diff.  And plug the  hole in trans off.  Nothing long term.  Just get an understanding of what diff temps are when towing.  That is assuming there is enough room on inside of diff for probe.   

 

Thanks again

 

Edited February 23, 20178 yr by 015point9

I'm probably one of the few people who's actually installed a differential temp gauge on both a stock cover and an aftermarket cover.....  Yes, differentials are pretty strong BUT they're not bullet proof like society tends to assume.  It can get hot in there.

 

I added a transmission and differential temp gauge because quite a few years ago we "upgraded" to a heavy size 5th wheel and I wanted to make sure no drivetrain component was running overly hot during the warm potential triple digit summer heat we tow in while meandering through the northern CA mountainous terrain.

 

What I did initially was change the fluid as I've done before but this time I filled with Royal Purple 75-140 and installed a thermocouple in the fill hole using a 3/4" to 1/8" reducer.  Kinda of a pain but it worked...

 

The temperature were pretty surprising as the stock cover with RP stayed in check until I hit the long mountain pulls.  Empty the temps would climb to around 175* simply because of the hypoid action and the thicker fluid.  Pulling the temps remained in the 185* range and would climb to about 195*-200* on pulls.  If the ambient was hot enough it may reach 215* or so, but at that point I'm staring at gauges and very easy on the throttle.  You'd be surprised how "speed" affect differential temperatures.

 

Then about a year later I installed a Mag-Hytec and refilled with the same RP 75-140.  Strangely the overall empty temps would eventually reach 175* on the freeway.  Just taking a little longer because of the added stock and dissipation offset.  Again, hypoid action and thicker fluid will cause the fluid to run at "X" temperature no matter.  Thinner fluid will run a little cooler and temperature will be affected by gear ratios as well.

 

Towing temperatures with the MH seemed to fall in the same range as before BUT take a lot longer to get to that point AND a lot faster to cool off.  When doing long mountain pulls the temps would tend to run a tad cooler but when the load was reduced the fluid temp would come down in a hurry whereas with the stock cover the temp would remain for a long time.  I'm guessing this was because there was almost half the fluid stock and no dissipation besides what air blows around the member.

 

So without going on and on about the technical data I collected, I will just say that I'm more than pleased with the MH cover.  It was easy to install (although I had to re-tap the thermocouple port due to size differences) and it allowed for the thermocouple to poke out the top.  And it has a dip stick for easy checking, two magnets, and a drain hole so the cover can stay put during fluid changes.  All in all I say they're worth the money if you do any significant pulling.  As mentioned in the beginning, differentials are not bullet proof and are subject to how well the fluid does its job.  Just as with any lubricating fluid, temperatures over 180* will start to oxidize over time and any temperature over 225* is getting dangerously hot.  I've seen were people cook the paint off their differentials so I can only imagine what the fluid looks like in there.

 

Edited February 23, 20178 yr by KATOOM

(Op here)  Thanks KATOOM

After reading your post I think I will get one with larger capacity and cooling fins.

Thinking about using the trans gauge and installing a toggle switch.  Toggle switched one way would be trans and toggle switch flipped another way would be diff? 

Thinking about using trans gauge for both seems "OK" to me on the surface.  But that is typing in front of key board. 

 

Actually making it happen might be another story. 

 

Thanks

 

 

 

You can find "dual" temperature gauges.  Some even say "transmission/differential" too.  A toggle switch would work but can you imagine what you'd be doing repeatedly flipping switches while pulling hills.....