Rear Axle Synthetic Lube Question

[FAllen]

Hi Group !



Need some advise regarding replacing the rear axle lube with a synthetic

type.



Does the old rear axle lube have to be flushed out ?



Also, the rear axle is the limited slip axle, do I need a specific synthetic

lube type for this type of rear axle ?



Truck is a 1999 2500 SWB with the Cummins 24V.



TIA



Best regards



Fred

 

[Alan Reagan]

I didn't flush mine. I drained it by (of course) removing the cover but then I jacked up each side (one at a time) so that the axle housings could drain toward the differential. I carefully wiped out the inside with lint free wipes. It's important to use lint free.



I used Valvoline Syntek 75W-90. I, too, have limited slip and did not need friction modifier with the synthetic. A search of the posts on TDR will indicate the same for Amsoil. Next go, I'll use the 75W-140 because of the towing. The LSD functions fine with just the synthetic. Don't add it unless you get chatter.



A note: I had to do this twice in a week because the initial black sealant recommended by NAPA here did not hold up to the synthetic. After three days I had lube streaming out of the rear. I ended up using the copper sealant in the copper colored tube. Can't remember the brand but you can get it in the blue, black, or copper. There were no leaks with the copper and it is a high temp application if you need it. It comes out red so be careful not to overdo it or you'll be wiping off excess like I had to do. It looks good though.

 

[OILBRNR]

Alan, how long did you let the sealent sit b4 filling it back up?



What's up with the lint free cloth issue?

 

[John Berger]

I changed out the lube in my transmission a few weeks ago. I have an Eaton-Fuller type filter and housing on the passenger side PTO and this required the use of the orange (copper?) colored RTV. I filled the transmission up after letting it set for about half an hour. I didn't run the truck until the next morning. As far as lint free cloth is concerned, it's just to ensure that no cloth is torn off in and around the gears. Alan may have a different take, but there is my reasoning. Hope it helps.

 

[Alan Reagan]

I believe the silicon I used was Permatex Copper Plus. I let it set for five minutes per the instructions. That allows time for it to skim over.



John is right on the lint free with a little addition. Supposedly, the lint can get into the bearings and cause problems. I know, don't ask me how lint can cause more problems than shavings from the LSD clutches. Anyway, the service manual says lint free. NAPA says "Don't forget to get some lint free wipes". A buddy of mine said use lint free, so I say, if you have the choice, use lint free. I will pass an observation. I did assist on a change where lint free wasn't used (not mine) and the paper towels used started dissolving and the shop towels left balls in the bottom that we carefully wiped out by hand. Not fun.



Edit: Also, steel wool works real good to get off the final factory sealant after scraping with the gasket/putty knife. The steel wool and some brake cleaner really clean things up. I also used the brake cleaner to clean the bottom out of the differential. Sorry to be so long. Just trying to tell what helps.

 

[OILBRNR]

Ok, next stupid question, where did you find lint free wipes? Also at NAPA?

 

[WadeMetzinger]

Not sure how well they would work, but coffee filters are lint free...

 

[Mundgyver]

I did mine about a month ago. Used Amsoil in the rear end. As far as gasket materil. Get a can or Gasket (The Right Stuff) from Napa. Looks like a black cheese whiz can. You will not have to wait for it to set. It will not leak at all. It is a OEM ButalRubber compound. If you have a compressor use that to blow out any lint or garbage you think might have gotten in there. That was my method.

 

[Alan Reagan]

Yeah, NAPA has the big bundles. They are white with a blue wrapper. They are great towels/wipes and are so absorbant that it only takes two or three. I hadn't thought of coffee filters but they are like a thick version of coffee filters. Very absorbant. Another thing is those guaze type wipe things they have at hospitals. They come about a hundred to a pack. They are great and they are lint free. They are about 4 inches square.