rear diff clunk cure for now

ctoliver · May 30, 2003

my truck had the rear diff clunk bad, so i decied to change the diff oil, drained it, no metal little fuzz on the magnet then refilled with amsoil 80-90w gear oil, wow i havent heard it clunk yet! i think the stuff really works! so if you have the clunk try some amsoil 80-90w!

2001 silverado 1500 ext cab

4.8L running amsoil still has csk

k&n drop in air filter

hypertech tuned

ct

bigtruck21 · May 30, 2003

why didn't you use the 75w90? Also did you use a gasket or rtv silicone sealant? How many qts?

ctoliver · May 30, 2003

thats all i could get, i know it calls for 75-90w but im in the south and we have mild winters here. i dont know what gm puts in but it looked like water it was so thin. you dont have to remove the diff cover on the bottom of the diff is a drain plug use a 3/8 extention to get it out and on the right side top of input shaft is a fill port use same extention to remove. on my truck it says on the axle at the fill port to service 40mm to 15mm below the hole i put 2 quarts in put it at 15mm below the hole. i took a piece of wire and bent it 90 degrees 40mm long to use as my service gage

ct

bigtruck21 · May 31, 2003

your saying the bottom of the rear diff has a drain plug!? I'll have to check, I've never looked. I've always wondered why they didn't have one in the first place. I noticed my tranny has a drain plug finally which is nice. I wonder if there is still a benefit to removing the cover to get all the shavings and sludge out, or is it a complete enough drain from the plug. Do you know what gm has for the factory seal to the cover...a gasket or rtv?

Frank S · May 31, 2003

Yeah it should have a drain plug like ct told you.I have the same basic differential in my ZR2 and I know it has one so I don't see why all the others wouldn't.

BTW,I'm also running 80w90 in mine and have been for about a year and a half with no problems.

Dihappy · May 31, 2003

Yes the NBS trucks have a drainplug and there is no gasket from the factory.

bigtruck21 · June 2, 2003

well, i looked and my truck does not have a rear diff drain plug. That sucks. It's got a solid square piece the sticks out on the bottom that looks like a drain plug should go there, but nothing. What year silverado's have the drain plug?

ctoliver · June 2, 2003

mine is a 2001 drain plug is not in the cover its in the housing, did you see the fill port?

ct

bigtruck21 · June 3, 2003

I looked all over the bottom of the housing at the lowest part facing the ground of the diff (not the cover). I see the fill port just fine.

Dihappy · June 4, 2003

Wow, thats strange. Wonder why they would change it for the new trucks??

So you did notice that the fill plug is a 1/8 drive thingy?

bigtruck21 · June 5, 2003

Somebody in another forum said "It all depends on what rear end you have. 8.6 " don't have one. 9.5", 10.5", 11.5" and 9.75" ones do have drain plugs. If you do have a rear end with a drain plug it is located on the front side below the pinon gear" I wasn't aware of this. It's still better to take the cover off to inspect though.