2nd Gen Non-Engine/Transmission Differential Temps

[cscott]

I am thinking about installing a tem sensor in my diff.



What are the normal running temps and what is the danger temp?



I will be towing a 48ft GN @ 19000 lbs.



I'd hate to scatter parts on a nice clean roadway.



Craig

 

[RBeard]

I've heard 200 degrees is not unheard of. :--)

 

[Diesel Gunner]

My rig is smaller than yours, the trailer grosses at 10,800. When I go out I estimate that my CGVW is right at about 18,000 to 18,500. On very hot days (95 to 105 degrees) pulling a hill, like say up to the Lake Tahoe area, I easily hit 205 to 215 degrees on the rear differential.



Running the same on a cool day (40 to 75 degrees) I normally see temps in the 175 to 200 range.



Running on a long trip, empty, I am usually not able to get much over 150 degrees unless it is a very warm day.



My truck has 3. 55's with limited slip. Hope that this is helpfull to you,

 

[LSMITH]

If you are bombed you NEED synthetics in the rear axle. It is also a very good idea to have a temp probe in the rear diff if you tow heavily. The engine may make 900 ft/lbs and the transmission may send it all out back without problems but the rear diff was not designed to hold that kind of power for miles and miles. When you see your diff temps go way up you are outside of the parameters that it is designed for. Back out of the power if you see much over 220* in the rear diff. A good synthetic lube will drop temps about 30*over a standard dino oil.

 

[amsoilman]

On my 94', I had a rotory switch set up that I could look at the Engine oil, Auto Transmission, and Rear Differential temps. Surprising thing... ... ..... most of the time the Engine and rear temps would run almost the exact temps... ... usually never more than 195 Deg. Trans temp never would get above 160 when TCC was "LOCKED UP". These temperatures were during the summer months while towing 16,000 GCVW.



I do use High Quality Synthetics in the entire drive train.





Wayne

ansoilman

 

[Kirwin]

Dana 80 temps

I have been monitoring my rear differential for some time now and this is what I have seen. My truck has the same set up as yours with the exception of the dually. Truck empty at 75 F ambient, pushing 70-75 MPH I get up to about 180-190 F. Pulling my travel trailer (14,500 GCW) I see around 200-210 at 65-70 MPH. Speed seems to be more of a factor that load as far as I can see. Ambient temperatures also see to play a significant role. Driving in the rain will drop this temp 40-50 F. I am using Dodge's synthetic 75W-140 rear end lube changed every 15K. I didn't have the temperature gauge in before I switched rear end lubes but your owners manual tells you in the trailer towing section to change the factory fill lube to this if you will be towing a trailer. From the other posts on the TDR I understand that rear end temperatures are a concern when trailer towing hence Dodge's recommendation to upgrade to the synthetic lube. I did a thread on this titled Dana 80 temperatures a while back. You should be able to find it with a search. Ken Irwin

 

[Underdog]

You say you're going to be towing a 19,000# GN .

Considering that a 1999,3500 with 3. 5 gears and automatic

transmission is rated to tow 10,000#,I hope your truck is

BOMBED. Otherwise,I wish you luck !!

 

[cscott]

I know I'm a bit heavy.



So far I have a COMP box and I just had my trans redone by Mass Diesel with DTT valve body and torque converter.



My next items are new injectors and a Pac Brake.



I plan to go to 19. 5 inch wheels and change the gears to 4. 10's



I'm also thinking about doing something with air bags.



Hopefully all that will allow me to pull the GN.



Any suggestions would be appreciated.



Any idea where I can look up the towing & load specs on my truck?



Thanks



Craig

 

[Kirwin]

Factory weight ratings

From the 99 sales brochure page 24 and 25; 3500, 2wd, automatic transmission, 3. 54 rear axle ratio: GVWR is 10,500 lbs, GCWR is 16,000 lbs, max trailer weight is 10,000 lbs (note 5) . Note 5 states that any trailer over 10,000 lbs requires the use of a 5th wheel hitch. If you had the 4. 10 rear axle ratio it would be rated with a GCWR of 18,000 lbs. (All other weight ratings remain the same).

Now the hard part my 97 2500 weighs 7400 lbs empty with me in it and full of fuel. I would bet that your 3500 weighs more than my 2500. If we estimate that your truck weighs 300 lbs more, then I would estimate that your truck weighs 7700 lbs (conservative estimate). Therefore: 16,000-7,700 = 8,300 lbs for your max trailer weight. If you had the 4. 10 then it would be 18,000-7,700 = 10,300 max trailer weight. Note that with a manual transmission and either rear axle ratio the GVWR is 20,000. 20,000 -7,700 = 12,300 max trailer weight. If you are interested in a lengthy discussion on this topic see "3/4 tons must be great" in the towing and hauling forum. Hope this helps. Ken Irwin

 

[cscott]

Thanks for the info it does help.



As I mentioned I plan to install 4:10 gears and 19. 5 inch wheels.



Why would a goose neck be rated lower than a 5th wheel?



I have been reading some threads in the towing form and it sound like tires have a lot to do with the rating.



Thanks



Craig

 

[Kirwin]

Goose neck vs fifth wheel

I don't think that Dodge is talking about goose neck vs 5th wheel. They are talking a straight trailer hooked to the receiver on the back of the truck vs a in the bed mounted 5th wheel (or goose neck) trailer. The stock frame mounted hitch is only rated to 10,000 lbs (and thats with a weight distributing hitch) max trailer weight. You can get heavier frame mounted receivers but they don't come from the big three OEMs that way hence most owners manuals say that towing anything over 10,000 lbs must use a fifth wheel hitch. Fifth wheel hitches are available to haul much heavier trailers, but the extra framing to get the fifth wheel set up into the bed of a truck makes fifth wheel trailers heavier that a straight trailer of the same length. Just my . 02. Ken Irwin