Another gear lube thread

[WWalters]

I know there are many experiences with gear lube posted to the RoundTable and you guys & gals are probably tired of them but I wanted to share mine. Last Friday I changed the lube in my trucks differential to Amsoil Series 2000 75-90. Initially I did not add the Mopar friction modifier. I subsequently drove the truck 6 miles to my favorite parking lot and did the 8-10 tight, low speed figure eight routine. I did hear a shuddering noise from the differential when I backed out of the driveway and some noise on the way to the parking lot. After my figure 8 routine I did not hear any noise from the differential. The next day, Saturday, I drove the truck about 50 miles or so and did not notice any unusual noise. Sunday I took off to do some errands. I started down the driveway when I heard the shuddering from the differental. This time it was more pronounced. I pulled back into the garage, removed the drain plug and subsequently added a full two ounces of the Mopar friction modifier. I then headed back to the parking lot and went through the figure 8 routine and also drove the truck about 10 miles or so. The shuddering did not subside. It was interesting that it was also occuring while I was backing out of the garage down a slight hill. When I returned home I let the truck set for a few hours to let the differential cool down so that I wouldn't loose too much gear lube when I opened the plug. I then added 2 more ounces of the modifier, and made sure the fluid level was slightly below the bottom edge of the fill plug hole. I then drove the truck, did my 8-10 figure 8's and everything is quite. My biggest concern is what damage, if any, I may inflicted on the clutch packs by driving the truck 60 miles or so when it is now apparent that the clutch packs were sticking and need additional friction modifer. Lesson learned, when I do this again I will put the friction modifier in first ( 3-4ozs), then the gear lube. Thanks!!

 

[hammong]

I was reading the procedure just yesterday before doing my rear differential change, and it clearly said to fill about 3/4" BELOW the fill hole, and to use 6% friction modifier. I didn't measure my gear lube going in (it was coming out of a 27 gallon drum) but I'd say it had to be at least 2 quarts. 6% of 2 quarts is just about 4 oz.



At 3/4" below the fill-hole, you had enough room to "add" more modifier if necessary. Over-filling the rear could cause your bearing seals on the end of the axles to leak.



Greg