Prepping diffs for install?

[Bfaulken]

Hey guys, I have new (to me) front and rear diffs from craigslist to put in. I have several questions before I go at it, because obviously this needs to be done correctly.

1. Should I clean the rear gears before I start? Since the rear 3rd is exposed, some amount dust has probably gotten into it i'm guessing, but it doesn't look like any big particles have gotten in. Recommendations on the best way to clean them, or If I even need to?

3. What about the front, what all should I do to prep it? Since the gears are pretty secure in the housing, they should be good, right?

4. A search came up the answer to use 75w90 oil, so am I ok to install the diffs, then fill em with oil? or do I need to do anything to the internals first since they've been off of a truck?

Any other things I haven't covered or any additional recommendations?

Thanks in advance!

 

[NachoPitt]

Hey guys, I have new (to me) front and rear diffs from craigslist to put in. I have several questions before I go at it, because obviously this needs to be done correctly.

1. Should I clean the rear gears before I start? Since the rear 3rd is exposed, some amount dust has probably gotten into it i'm guessing, but it doesn't look like any big particles have gotten in. Recommendations on the best way to clean them, or If I even need to?

3. What about the front, what all should I do to prep it? Since the gears are pretty secure in the housing, they should be good, right?

4. A search came up the answer to use 75w90 oil, so am I ok to install the diffs, then fill em with oil? or do I need to do anything to the internals first since they've been off of a truck?

Any other things I haven't covered or any additional recommendations?

Thanks in advance!

1. Brake Cleaner is a wonderful thing - My local napa has it for 1.74 a can. I would use a can for cleaning the third and another can for the housing. Mine was rebuilt and I still cleaned the hell out of it - it is the best time (and only) time that you can really clean them.

2. Front is the same as the rear in terms of prep.

3. You have to fill them after you install them - take a look at the FSM before you do it.

The hardest part will be wrestling them under the truck. I documented my rear diff install I did two weeks ago in my build thread.

Hope this helps.

 

[awpsome]

75w-90 is correct.
If anything since the front diff is already out, loosen the fill plug before install. Usually opening up that Allen key fill plug while mounted can be a pain sometimes.. So having it already loose will help.
You want to fill while installed cause it will help with proper fill amount. Also you have to anyway for the rear since is open without being mounted.
Other then that it's straight forward.

Having a second pair of hands help cause if you don't have it up on a lift getting those doffs in always gives that hard angle with the weight behind it makes it sometimes a pain. Iirc the rear diff is about 60 pounds or so.. Lifting that awkward angle while lining the bolt holes and all that combined makes it a pain.