sludge in rear axle

[The_Handier_Man1]

From: jddrivfour  (Original Message)
Sent: 3/5/2005 9:33 PM

getting ready to put brake drum assy back on axle stub and I looked into the end of the tube with a flashlight ansd saw about 1/4 inch thick layer of sludge laying on the bottom of the rear axle tube. The inside of the tube has some rust on the top, Is this a big deal not to clean it all out? Not sure how I would flush from the center out. Does this sludge just collect on the bottom while the axle carries some gear oil outward to the bearings?
Spicer 70 HD rear.



From: denison
Sent: 3/6/2005 9:13 AM

That sludge and rost was there in my rear axle too - even some rust on the axle shaft. All the rear axles I have had apart had the same situation. It seems to be normal. You could scoop it out if you want, but the best thing to do is to replace the differential oil after you have gotten the drums and wheels back on. You would need to put in some replacement oil anyway, due to the amount that dribbled out.
In driving the axle gets warmed up; and when it cools down at night it pulls in outside air. The moisture in the outside air mixed in the oil is what causes the sludge on the bottom of the axle tube, and the rust on the top. If you always drove it hundreds of miles a day, and lived in a dry climate, the sludge would be minimal.
Normal driving brings oil from the differential out along the axle, and some spins off onto the axle tube walls, some wicks along to the end of the axle shaft, inside the hub. The amount that isnt needed to lube your wheel bearings eventually oozes back into the differential chamber. Now that you bring this up, I think I should drain and replace my differential oil. I use 80W90 hypoid oil. It has the -extra high pressure- lube additive. Probably zinc-something.
Clean the axle breather-tube too. On mine it is a hollow bolt that hold the brake fitting to the axle. 



From: jddrivfour
Sent: 3/6/2005 10:55 PM

I knew the sludge had metal shavings from the bearings. I sprayed PB rust penetrant- THE Best penetrant ever- and then connected a 3/8 thin wall copper tube to heater hose to shop vac. I squished the copper tube closed half way and bent it down about 45 deg angle. I used this as a scraper and vaccuumed out the sludge. I was suprised how well it took most of it out. The shop vac had about 6 OZ. when done I will probable drain and fill several times to try and get the metal shavings out.



From: denison
Sent: 3/7/2005 5:10 AM

The shop vac use is a great idea! I would like to find a differential drain plug with a maget in it - to capture any metal shavings that might be floating around in mine. 



From: ClydesdaleKevin
Sent: 5/6/2005 3:53 PM

I wonder if any aftermarket company sells a differential cover that HAS a magnetic drain plug for a Spicer 70HD?  I know from my days of off-roading in a Jeep MJ that just about every axle imaginable (this was about 10 years ago) had companies offering aftermarket covers.

Kev and Patti Smith



From: jddrivfour
Sent: 5/7/2005 2:14 AM

You can buy one with magnetic drain plug and has dipstick which I found is important to fill level initially higher so the low area in the brake hub gets some oil. In my opinion the bottom of the existing plug is too low. I forgot the name of the company but is easily found with a google search on spicer 70 covers

JD