Changing the rear differential fluid for my first project on my 2001 F-350 7.3 DRW.

Noticed what looks like rust on the inside of the diff cover and on the magnet. Should I simply clean it and move on? See attached picture.


Some other thoughts in case it helps.

(1) I believe I have a Dana 80 as the cover reads as follows: DANA [next line] 47717 1[next line]208 0[next line]Rev D[next line]05 14 99. See attached picture.


(2)The small tag reads as follows: 41-10 [next line] 4 10. See attached picture.


(3) The large tag reads as follows: 4?10 (upside down triangle) 1C34 JA [next line} (upside down triangle) 606609-6 LS. See attached picture.


(4) I've also attached a picture of the large and small gear inside the differential. If someone knows what the numbers on the gears mean, I would love to know. (In case it's not clear in the picture, the large gear reads as follows: 09 11 00 Dana D 50551 J2L93 41 10 702 )




Thank you all for your help!!

 

Hello and welcome to FTE.

While it is possible that is rust, I doubt it. Looks like gear oil (old) to me.

Not sure about the numbers, but yes it should be a Dana 80 in a dually.

The small tag identifies gear ratio, in this case 4.10's

That ? between the 4 and 10 is an L, as in limited slip differential.

Don't know about all the other numbers (I suspect part numbers) but again the 41/10 are tooth counts on the ring (large) gear and pinion (small) gears.

 

It was definitely rust. I took a wire wheel to it and there was pitting underneath. I'm not sure I'll be able to save the plug but I'll try.

I'll take a look but I think the rust was below the oil line so I'm not sure how it would have formed.

Thankfully, the gears looked well oiled and had no play.

I sanded and repainted the cover. I hopefully will be able to reinstall tomorrow.

With the rear mounted 40 gallon tank, I'm going to have trouble getting the gear oil in without a pump.

Thank you.

 

Yupp, also just looks like oil to me.

 

Last question (I hope).

The bolts came off relatively easily.

I noticed they (the bolts) had some grey (dried) stuff on them.

Is that dried grey stuff the silicon gasket material i can't tell what color the gasket material under the cover was), some type of thread sealant, or ???

Thank you.

 

Probably old sealant.

 

if theres no rust or pitting where the ring and pinnion mesh, you should be fine. the cover bolts commonly get silacone or sealant on them during assembly.

 

Welcome to FTE!!

That is grey silicone sealant. If there was a gasket under there somebody added it after the fact. That grey sealant was the only thing sealing it from the factory.

Refill the diff with synthetic 75W-140. Skip the friction modifier.

 

Thanks. Purchased Mobil 1 synthetic gear oil (75-140) for the rear and (75-90) for the front.

Just not sure how I'm going to refill it with that tank in the way.

Really don't want to purchase a pump if I can avoid it.

Other posts have suggested adding the friction modifier (1 oz at a time) if I hear a clunking sound. Not sure why I would hear clunking from the rear wheels since I don't think they turn. ???

 

The oil you purchased is a top of the line synthetic gear oil with factory added limited slip additive. Enjoy the benefits of purchasing a quality product by not worrying about the LS additive. You wont need to add any as it has been taken care of for you.

The clunking noise you will hear will happen when you turn if there is not enough LS additive. This is because the clutchs will have too much grip and your outside tire will literally be dragged as it will be traveling the same distance as the inside wheel, but as we know, the outside wheel actually has further to go and needs to spin faster, but with no LS additive it will essentially be locked to the inside wheel.

But again, dont worry about it. If you notice some clunking, go to a dealer and get some LS additive, but you shouldnt have any problems.

 

Ive always used them little tapered nipples from the quart gear oil bottles at the auto parts stores,you can put a length of hose as needed where obstructed I prefer clear vinyl hose.

 

I am on level ground, am filling up a Dana 80 on a DRW truck and have filled 5 quarts and am still not at the fill line. I don't have any visible leaks.

Help - is this normal?

 

It should be 8.5 pints (4.25 quarts) with a stock cover on there.

 

Mike,

I agree - 8.5 pints is what the manual says.

I still seem to be about 1.5" below the bottom of the fill plug. I guessing I should just keep adding fluid until it leaks out.

My bigger problem right now is with the fill plug on the transfer case. In my other post, I note that the plug no longer goes in the whole way - it only goes in about 60% with an Allen wrench.

David

 

I could be wrong, but your Dana 80 should take 75-90. The sterling rear takes 140. Check your manual. I'd do it, but I'm at work and the truck is home. I also add the amount called for.