Differential Repairs???

[bimini_blue]

I just purchased a 1978 280Z r200 differential from the local junkyard. I plan on putting it in my 72 240Z. When I got it home and cleaned it up, I noticed some repair of some kind had been made on the case. Looks like someone was welding on it? Since I am new at all this, I did not know if this is something that is normal, i.e. done at the factory?

Is this something I should be concerned about??

Thanks.

Photos are provided.

[dogma420]

That is not a factory weld; more than likely it is fine, as it isn't in a stress point (as far as I can tell)....you should probably do some detective work, and try to figure out what might've caused it, but would just go ahead and install it and 'test' it for a few thousand miles....if it passes, it's ok.

Just 2 cents

[panchovisa]

After spending many years in the patternmaking and foundry business I think I know what it is. I wish you had bigger picture from a couple of angles so I could be certain.

It looks like errosion of the mold. The sand mold (most likely "green sand") was formed by packing sand around a pattern. When the sand and flask was removed the foundryman would have used compressed air to blow out the mold. If he got the airhose too close to the sand he could have erroded the sand.

When the mold was assembled and filled with iron the erroded area would "look" like it had been repaired. Unless you see dis-similar metal (filler rod/braze) the defect in case is just normal casting defect and affects nothing except asthetics.

[bimini_blue]

The photo provided is one of three I found. Looking closer, it does look like it could be a casting defect/repair. I guess I'll put it in the car and see what happens. Can't see anything abnormal on the inside of the case?

Thanks.

Another angle of the one on the right side.

[bimini_blue]

Whoops, the last photo was the Left side of diff.

This one is of the right side.

[panchovisa]

Looks like it could also be a "chill" That would be a piece of cold cast iron which they would put into the mold to start the solidification of the molten cast iron.

In either case you can rest assured that there is nothing wrong with the cast case.

Now if the internals are good your in business.