Tried to pull an empty 16 foot flat bed trailer to a town about 40 miles away the other day and burned the deferential out. At least that is what I think went wrong. It did alright on the Hwy but when I came to a stop sign and tried to start again, my truck would barley move. I had my foot on the floor and I could not go over 5 MPH. I quickly stopped and got out and saw my trailer was covered with oil. I looked under the truck and the diff was dripping oil and was so hot it burned me when I touched it. I called a friend to come get the trailer (with his Chevy Colorado) and I limped to a walmart (it was after 9pm), and filled my diff with 85w145 gear oil. It took 3/4 of a gallon to fill it up. I drove the 40 miles back to my house and it did okay until about five miles away when it started slipping again and making a high pitched scream.

So, am I right to think my diff is gone? If it is, then I have a couple questions.

1. I don't plan to pull a lot of heavy stuff with this truck like big travel trailers. If I have to replace the diff, what is the best gear ratio I can go back with for non pulling mileage?

2. Do I have to change to whole diff to get a new gear ratio, or can I just buy new guts and put them in my current diff?

Thanks for the help.

 

I need some advice here. Can anyone answer my questions. Bump.

 

I would try to find a donar axle. Aside from damaging the ring and pinion gears there is a good chance you also damage the spider gears on the carrier. if you have a pick and pull type salvage yard you could probably get a used carrier for a decent price and then install it in your axle with new gears. Don't forget to check your axle shafts closssely for damage.
At a minimun I would replace theaxle bearings and seal along with new pinion bearings and carrier bearings

Matt

 

Yes - unless you want to invest in all the tools necessary for setting up a new R+P gear, just get a good used rear axle. The ratio is going to depend on what you have now - 3.55 is a good all around gear, 4.10 is for dedicated performance (heavy towing or racing/mudding whatever) and 3.08 or 2.73 is for max mileage. If you're comfortable with a drum brake job, replacing an entire axle isn't much more difficult.

Your current axle is clearly damaged - lack of lube, and pressing on after the initial overheat,etc. Be sure to get an axle with the speed sensor if your truck has a speed sensor on top of the current rear diff. I think 1992 and up have this feature.

 

look for another rear axle.
1993-1997 from an f250 or f350
sterling 10.25 full float (SRW)
your looking for one with 3.55 gearing (preferably with LS while your at it.)
you'll need new U-bolts.
couple hundred bucks,and you'll be back in business before lunch.

too bad your in Texas,im pulling mine probably tomorrow for true DRW axle swap.i'll be taking out axle code 39 (srw 3.55 non ls.) with low miles.ah well,they're everywhere.

 

Thanks for the replies. I guess a new (or good used one) rear axle looks like the best way to go. I guess the question now is, if I buy a used rear axle, how will I know if it is good and not damaged? I guess I should try to find one with at least a 30 day warranty or something.

 

Thanks for the replies. I guess a new (or good used) rear axle looks like the best way to go. I guess the question now is, if I buy a used rear axle, how will I know if it is good and not damaged? I guess I should try to find one with at least a 30 day warranty or something.

 

See if they will let you pull the diff cover off and look at the gears, If you pull yours you will see what a set of torn up gears looks like. Check for the obvious leaks at the pinion, diff cover, and axle seals. If buying from a private look extra hard at it if it is already cleaned up. After you buy the axle I would plan on putting in new carrier bearings, axle bearings and seals and as was said before new u-bolts. i personally would not go through the trouble of putting in another axle with out some preventative maintenance.

Matt

 

I have no doubt that driving it after it overheated did no good for it, but the real question is, what was already wrong with it that would caused it to overheat pulling an empty flat bed trailer for 40 miles at a maximum speed of 60 MPH? I must admit that I do not understand how these limited slip axles work. All I know is that I bought this truck about 7 months ago and I have been having nothing but trouble with it. Horrible fuel economy (11 MPG hwy), absolutely no power what-so-ever. I have spent hundreds with mechanics trying to get it to run right and not one single mechanic ever mentioned the stupid differential as a possible cause of all my problems. I think this diff has been bad since day one, because the Lord knows that I have done nothing that could have broken it. Heck! I almost never drove it over 60 MPH (trying to get better fuel economy). So far this F-350 diesel has been the least powerful and least reliable truck I have ever owned. I had a 1990 Nissan pickup with 250k on it that I use to pull a heavy 20 foot flatbed trailer loaded with oilfield pipe with no problem. This F-350 burned up the diff pulling and empty 16 foot trailer. My friend pulled the same trailer off with a Chevy Colorado and said he could not even tell the trailer was behind him. Something had to be already wrong with my diff for this to happen.

 

If your differential has been failing and seizing up it most certainly can rob you of power and fuel economy.

Keep in mind that those non-turbo 7.3s weren't the most powerful engines either.

 

I do not think that pulling the trailer was the problem it was a coincidence. Did you ever check the differentials when you bought it for proper fluid level? Chances are it has a leakand the fluid level became low/nonexistant and cause the demise of the axle. I also just bought my 92 in April. I am still going through it as finances permit.The only major maintenance item I have left is to service the axles. i havn't really put my truck through any work yet until I know it id ready, It will be ready after I service the axles next weekend. Since owning mine I have put $500 into the front axle, a new class V hitch, air bags on the rear axle, add aleafs on the front axle, and about $150 for a tune up, O2 swnsor a few other sensors under the hood. I feel your pain, but the fix for your truck isn't too bad to do

matt

 

As compared to what? This issue of engine power confuses me. I had a 79 F-250 with a 460 in it. It seemed to have endless power. Everyone I have talked to says diesels are more powerful then gas engines. So when you say that the 7.3 diesel was not very powerful, what are you comparing it to when you say that? Are you saying that it is not as powerful as say a 351 Windsor? Or are you saying that it is more powerful then gasoline engines of that era, but not as powerful as modern turbo charged diesels?

 

I think the diesel had mor torque, but less Hp than the 460 of that era, I am not 100 percent sure. But they are not the torque and Hp monsters like the modern era. Also the gearing makes a huge difference in fuel economy. 4.10's get worse economy then 3.55's. The bad axle was probably a major source of bad fuel economy on your truck. Aslo check to make sure your front brakes are hanging up, jack up one front wheel and give it a spin see how freely it spins,

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Matt

 

I would agree with you about the fluid being low causing the problem if it were not for that fact that my trailer was covered with oil and the whole differential was dripping with it. So, it had oil in it when it over heated. The over heating is was what cause all the oil to be pushed out.

But thanks for the encouragement. My Dad bought a 05 Dodge Ram a few months ago and it has been great. Unbelievable power and 23 MPG on the HWY. He towed a 35 foot fifth wheel (with double slide outs) 600 miles and said he did not even know it was behind him. Really makes me feel like an idiot for buying this truck.

 

So hios is 8 years old, yours is 19 years old. You can't really compare the two. If you had a similar superduty and compared them then maybe you could feel bad. So i paid $2K for mine and have about 4K total in it. Do I miss my 96 Suoerduty, hell yes, but I don't miss the payments. Just find aonther axle and get swapped in and you will be good to go. Did it push the oil out of the vent tube or did it come out of the pinion seal or the differential cover.

Matt