Differential Fill -

My 51 3100 does not have a stock rear axel. The stock one was replaced before I bought it.

With the help of this group I determined it must be a 3.90 rear end, which is good.

I cleaned the differential cover and was about to install it when I realized I wasn't sure what the orientation of the plug was. Is it at the top or the bottom. Then of course I realized that was stupid question since to be filled, it must be the top. OK

In my searching I saw that the earlier style differentials didn't have drain/fill plugs. So question- how did they do it? How was the 90w gear oil put into these differentials?

Haasman

 

Rear diff fills are not part of the cover. Opposite the cover near the input shaft you will find a plug generally with a square drive or allen key plug in it. This plug hole is where you fill the diff after its installed on the truck and sitting at its normal stance. The fluid will start to pour out of the hole when its at the level it needs to be. To drain the diff you just crack the lower section of the cover by loosening bolts. If yours has a square drive for the plug a 1/2" ratchet extension works great.

 

Curious - what is the correct orientation for the differential cover?

Is this correct or should I reverse it?

 

See the bumps at the 11:30 and 6:30 position? I'm pretty sure these are to clear the ring gear which means it only fits one way.

 

So obvious, right. Just wanted to be sure so that I fill the diff enough with gear oil.

Thanks

 

oops i misunderstood your post. My bad.............

 

Haasman, are those copper washers I am seeing on the rear cover bolts?

 

They are copper. I had a box left over from some project years ago. Remarkably they fit like a glove.

When I took the cover nuts off to clean them I noticed what was on there was copper. I also thought they looked like they sealed since so soft.

Haasman

 

Neat! Should also help to protect that nice paint you have on the cover too.

 

As Always ,

The Devil is in the Details .

Nice work .

 

I notice on my cover there is not many washers on the bolts and leaks. So where could I find some washers for the diff coverr and a new gasket I am sure it needs?

 

I believe the copper washers came from Fastenal. I used a paper gasket and black form-a-gasket. I made sure, of course, all the previous years of gasket/sealer residue was removed.