which oil in the diff?

[1930artdeco]

Need to drain and flush the diff out. What weight should I use for oil? Anything I can use to flush out any old oil/debris?

Thanks,

Mike

[glr7533]

I assume that you don't have a limited slip differential so I believe 80W90 gearlube should be fine. I have used diesel fuel in the past with good results to clean parts. If you are working on the rear brakes it might be a good idea to pull the axles and replace the bearings and seals. If the bearings have been sitting for a long time you don't know what shape they are in and the seals are probably hard and will start to leak. You can also pull the gears out at this time and take a look at them and you can also see what is in the housing for sludge. I changed the wheel bearings and seals in the axle when I did mine but was to lazy to change the pinion seal. It hadn't been leaking in the garage so I convinced myself it was good. After I got the car on the road within a few hundred miles it was leaking.

[mustang6984]

When I worked in the oil field we used to hear up diesel fuel (yes...you can do that it will not flame on unless you get it REALLY hot or use gasoline to ignite it) and then clean the rig legs with it. also used it to clean up before going home each night. Should be just fine for leaning your rear-end. Heat the can with a torch...we used a metal 5 gallon bucket...heated it with a propane torch. Don't try to heat the diesel directly...like I said...if you get it hot enough it will flame on.

[hiball3985]

80-90 is fine, just be sure it's a Hypoid type and not any of the newer GL5. GL5 is synthetic and doesn't play well with old style seals.

[rmk57]

  I'm trying out 75w-90 extreme pressure full synthetic. Seems fine so far, although I don't put on very many miles in the year. Also use it my lead screw, bed ways, external gears on

my South Bend lathe. It seems to really cling or stick, so I guess that's a good thing.

[1930artdeco]

Ok, question, how does one remove the axle? I think I remember them having to come out with a slide hammer as I have not seen it done in a VERY long time. The book just shows a picture of a tool on the threads of the flange and that is all.

Mike

[hiball3985]

Maybe I have just been lucky but I have never had to use a slide hammer to get the axle out of any 9" rear end. Just a good jerk by hand has always worked for me.

[rmk57]

If you don't have a slide hammer you can use the brake drum. Place the brake drum on backwards, thread the wheel nuts on part way and use it to pop the the axle out. I've had to use that

technique a couple times on really stuck axles and it does work.

[RICH MUISE]

When I had my rear end narrowed and redone w/ 31 spline axels and Yukon trac-loc, I made the mistake of using a synthetic oil. Noisy rear, especially when cornering. I did some checking and found Yukon says NOT to use synthetic. I did the change to conventional 90w and the noise went away.

[rmk57]

When I had my rear end narrowed and redone w/ 31 spline axels and Yukon trac-loc, I made the mistake of using a synthetic oil. Noisy rear, especially when cornering. I did some checking and found Yukon says NOT to use synthetic. I did the change to conventional 90w and the noise went away.

  May have something to do with the clutch pack inside your Trac-Loc. I run a Detroit Locker, so no clutch pack and it clicks a little when you turn corners anyways.

[mustang6984]

If you don't have a slide hammer you can use the brake drum. Place the brake drum on backwards, thread the wheel nuts on part way and use it to pop the the axle out. I've had to use that

technique a couple times on really stuck axles and it does work.

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Have done this before...and yes...it works great. And cheaper than buying a puller. Backyard mechanic innovations at their best! 

[Wirenut]

Rich, I have been experiencing some noise in my Yukon differential ever since I installed it. I installed synthetic oil too. I honestly thought it needed more break in time. When I turn it makes noise. I'm going to change the oil, this weekend. You may have solved my problem. Thanks for your input on the oil.