Diffs/transmission/TCase service

[SBeretz]

I am about to change all the fluids in my diffs, transmission, and t-case, what are the tq specs on the diff covers? Also, what hold do you use to fill the transmission? Is it the one in the middle of the G56? Or the one plug up high? Anyhow, thanks for the help. Truck has 49K on it, and I bought all Mobil one fluids for the diffs and Castol ATF+4 synthetic for the t-case and transmission. . Also, I assume the diff gaskets are reusable so any tips or tricks are appreciated. Scotty

 

[LRutigliano]

Torque spec for the diff covers from the Dodge Service manual is 30 ft-lbs, but I WOULD NOT torque to that spec. I would not go above 20 ft-lbs, maybe 25 ft-lbs MAX. These are M8 bolts and I have seen grade 10. 9 M8 bolts snap at less than 30 ft-lbs. Also, the thin steel cover could deform under the bolt head. Just my opinion.



I put blue loctite on mine and torqued to 20 ft-lbs.



Service and Drivers manual states to use synthetic 75W-90 in the diffs, but I've heard of people using 75W-140 in the rear diff for heavy towing. I tow and use synthetic 75W-90 and it looks pretty dark when servicing rear diff after only a few thousand miles. I have not done the research on the effects of using 75W-140 in the rear diff...



Hope this helps,

Louis

 

[LRutigliano]

Oops, forgot to mention that the diff gaskets are very high quality (metal with rubber over molded) and are reusable.

 

[SBeretz]

I got the diffs changed and back up. I used 75/90 Mobil One Front and 75/140 Mobil One Rear. Rear took 4. 5 quarts and front took 3. 5.

I need the plug size for the G56 transmission drain plug and fill plug. It is a huge size so I will have to go buy it. So if any of you know. . Let me know. Scotty

 

[MoparDave]

I think this is the wrench you want for the G56 14MM ALLEN-HEAD TOOL-Dodge Cummins and Ford Power Stroke Diesel Truck Accessories - Geno's Garage

 

[SBeretz]

I got it done, went to my local Sears and got one. Pretty happy, got the trans, diffs, transfer case and the tires rotated this afternoon. Truck shifts exactly the same as before, so hopefully everything is good to go. Truck shifted awesome before so I didn't expect it to get any better. I did note that transmission and transfer case fluids were bright red, and there was so little metal on the magnet that I really had to look. Same goes for the diff fluid, it was still very honey colored and little to no metal on the magnet. Hard to believe people change the diffs once every 15K, seems like a huge overkill. I do pull alot with the truck, toy hauler at about 13K loaded and my Jeep and trailer at about 8K, so the truck gets worked.

Oh, quick question, is all ATF+4 synthetic? I bought the Castrol ATF+4 but there was the advanced auto stuff for about 1. 50 less a quart. Just wondering if there is any difference. Scotty

 

[Spooled-up]

I just did my rear diff and noticed that there was a fill line stamped on the cover about 3/8" below the bottom of the fill hole near the center of the cover. Anyone else notice this? Mine took 3 qts and 11 oz to fill to this line. I remember on my '03 that there was a bulletin from AA about not filling to the bottom of the fill plug as this would over-fill the diff and result in foaming or something. It's posted in an old thread somewhere.



I've got to go get a 14mm allen now to do the trans. Transfer case is a 10mm allen.

 

[steved]

I just did my rear diff and noticed that there was a fill line stamped on the cover about 3/8" below the bottom of the fill hole near the center of the cover. Anyone else notice this? Mine took 3 qts and 11 oz to fill to this line. I remember on my '03 that there was a bulletin from AA about not filling to the bottom of the fill plug as this would over-fill the diff and result in foaming or something. It's posted in an old thread somewhere.

I've got to go get a 14mm allen now to do the trans. Transfer case is a 10mm allen.

My covers are stamped with a fill line also... I just filled to the hole.

If you search my name and ORU cover, you'll find a thread the has a picture of the old cover and the new cover... IIRC there's almost an inch difference between the fill hold on the ORU and OE covers (with the ORU being higher). I have not had any issues with foaming.

The ORU cover took 9 quarts of oil to fill...

steved

 

[Spooled-up]

After hunting at Sears, Sears Hardware, Lowes, Home Depot, CarQuest, NAPA, and 2 hardware stores, I finally found a 14mm Allen socket at of all places - Harbor Freight Tools.



I vowed long ago not to buy stuff from there again, but they had it in stock and I needed to change the fluid today before our road trip.

 

[Spooled-up]

Did the trans and transfer case tonight in the driveway in the rain



Trans took 6 quarts and 12 ounces to fill. Service manual says to tighten the drain plug to 42 ft/lbs.



Transfer case took 2 quarts and 18 ounces to fill. The service manual says to torque the drain plug to 30-40 ft/lbs. This was way too tight! I never made it to 30 ft/lbs and I thought it was going to strip.

 

[SBeretz]

I did mine in the driveway also, just after a rain (always raining in Eastern NC) and I did buy my 14mm at sears. Had to buy a 14,17 and two standard sizes to get the 14 but I did get them and my fill capacities are right there with your Spooled Up. Scotty