How to change differential fluid on this rear end

[Warrantw5]

Never been a Mopar guy.  Not sure if this is the original rear end, but I can only find one plug.  How do I drain and fill this thing?  Thanks guys.

[Burdar]

That's an 8-3/4 rear.  There is just (1) fill plug...no drain plug.  You can try sucking out the fluid through the fill hole, then replace.  If you want to completely drain the rear, you'll have to remove the driveshaft, wheels and drums.  There will be holes in the axle flange where you can insert a socket to removed the bearing flange nuts.  Once those are removed, the axles need to be slid out a few inches so the splines disengage the side gears.  Then the center section nuts can be removed and the center section can be pulled out.

If you are going to go that far, you might as well re-pack the wheel bearings.  The bearings do NOT get lubed by the gear oil.  They get packed just like the front bearings.

[Warrantw5]

Well, that explains it.  I thought there was some Mopar hidden plug.  I will pump it out. Thanks.

[jimynick]

One small addition if I may? If the car has a SureGrip (posi), don't forget to reload the SG additive when you refill the diff.  Mother Mopar sells it at the dealership or there's other places as well. Fill until it dribbles out the plug hole. 

[Warrantw5]

I bought Amsoil Severe Gear 75W-90.  I will check and see if it has the additives.  Thanks.

[Warrantw5]

My differential is an Auburn Pro Series.  I checked before replacing the oil with Amsoil.  Auburn absolutely says NO synthetic.  80w90 with the limited slip additive.  Someone on another thread mentioned synthetic could cause issues. 

[Chryco Psycho]

You can usually pick up a suction gun for under $20 & get most of it out that way .

[7212Mopar]

I have done it by gravity using a squeeze bottle with a 3/8 clear hose attached. Elevate the car on jack stands. Insert hose with the end at the bottom of the case and secure with some wires. Get suction started and drain by gravity. The oil is thick and won't loose vacuum easy. It gets slow near the end but it will remove most of the oil. Make sure you have at least 2 feet elevation difference cause the oil is heavy.

[anlauto]

Problem with the suction gun, is it just leaves enough of the old oil and all the crappy sediment at the bottom, to contaminate the new oil 

[Burdar]

Has anyone added a plug to the bottom of the housing?  I'm considering this.  You could use some type of shallow, shouldered allen head plug.

[Cudamike]

This was there when I bought the car.

[Brads70]

Has anyone added a plug to the bottom of the housing?  I'm considering this.  You could use some type of shallow, shouldered allen head plug.

I don't have a picture but on all the 9" rear ends I've built I always add a drain plug, also did it on my 8 3/4. Easy enough with access to a lathe, , use a 2 dia by 1/2" think and drill/tap it for a  1/2" pipe plug. Then weld it on. Also doubles as a jacking point where the jack won't slip off of also! 


Not a mod you would do on a "numbers type"  of car I guess?

[Scooter]

This was there when I bought the car.

Makes sense to me... like buying a replacement tranny pan with a drain plug. Could never figure out why one was not there to begin with.

[Chryco Psycho]

I believe the reason transmissions do not have a drain plug is to force you too pull the pan & change the filter but it is such a pain to drain a trans without a drain plug ! SO yes  I agree trans pans should have drain plugs 

[Ns1aar]

  loosen but do not remove the nut on lowest stud of axel housing. Run the nut up to the top of the stud. Lightly tap the assembly until the splines disengage with the housing the oil will flow out although not very fast. When the oil is out tighten the nut it will pull the stud through the housing and seal the hole. Only good a few time though