[stucky2947]

How do I remove the differential plug to check the oil in a 1962 GP?

I read in the shop manual that you are supposed to thread a 1/2 bottoming tap into the plug and pull out as you turn. I guess that means that the plug is a press fit. After it is removed, can I re-use it or do I have to buy a new one? If I need a new one, where can I get one? Can I thread the hole after the plug is removed to add a threaded plug? Thanks for your help.

PS. What kind of gear oil do I use?

[Pontiac62]

The plug on my car is a pipe plug, with a 3/8" square recessed hole for a 3/8" square drive.


Good luck,
Les

[Stuart]

I think that plug you're looking at is a drain, there should be a fill plug like Les described on the back side of the rear end housing. Open that up and stick your finger in to see if you can feel the lube level.

[misterp266]

My '63 has the fill plug on the chuck. No plug on the housing.

[Stu Norman]

Yes, just fill the pumpkin up to the hole.

[65WJ]

90 weight iirc and if a posi you need the ? friction modifier ? something like that anyway.

patrick

[stucky2947]

Thanks ALL. I could not find that info in the shop manual, just the drain plug info. I feel real stupid after looking for it. If it were a snake, I would have been bitten MANY times. My entire rear axle is painted black, not nearly as awesome as misterp's. An automobile work of art.

I bought some Royal Purple diff lube, I would think that has the posi stuff in it, but I'll check.

THANKS again.

[misterp266]

I got all the rebuild parts and the posi additive from Brad @ Fabcraft. I went with Lucas 90W gear lube.

Rob...

[1963Steve]

I read this thread with interest because I had the exact same question, though my car is a 63 GP. By the end though, I wasn't quite clear where the drain and the fill plugs are located. I'm attaching the picture with my best guess. I'm a newbie to working on a differential so any help is appreciated. Is it a good idea to drain and refill the fluid? The shop manual only recommends it when repair work is being done. I have a feeling I have 50 year old fluid in there so it seems like a good idea to change it.

[jww]

My '62 has no drain plug on it anywhere. I simply backed off the nuts holding the diff to housing, pried the differential forward enough to let the old stuff run out.

However, if yours has not been apart in, say 50 years, you're most likely gonna tear the paper gasket which means pulling the axles out of the gearset, then pull the diff out and put a new gasket on there.

Not a big job, just a heavy one!!!

Hope this helps...............Jerry

[Alf ista]

With no drain plug, could you just suck the old oil out with a hand pump? Seems a lot easier than pulling it apart. Interested as I was under my car last night and was looking at my diff and considering checking the level.

[63gpman]

That is how I do most of my diffs. I use a suction/vac canister to get the lube out. Not the best way as there is always a little left in there and you don't get to inspect the gears for wear issues, but works for reg maintenance.

On that one, I would be tempted to take it apart, check things out and reseal and maybe new wheel bearings. Standard 80/90 with GM friction modifier is what I have been told for lube many times over for these old posi units.

[1963Steve]

Ok. So, is the "Fill?" label correct in the picture?

[Sirrotica]

Originally Posted by Pontiac62

The plug on my car is a pipe plug, with a 3/8" square recessed hole for a 3/8" square drive.


Good luck,
Les

X2 and it's on the punkin, not the housing.
Not sure what the service manual is talking about either.

[Engine-Ear]

Originally Posted by 1963Steve

Ok. So, is the "Fill?" label correct in the picture?

Yes. Stick your finger in the hole and see if it gets wet. If it does, you have enough lube for proper operation. If not, add until it runneth over.

Also, removing the fluid thru that hole is the least hassle (not the least messy, just the least HASSLE).

Good luck with it and welcome aboard!!

[1963Steve]

Thanks, I'll try that, and thanks for the welcome Engine-Ear. I've been poring through old threads to help answer questions and found this forum is a wealth of information. I've got a slew of issues to work out with my 63, so I'll be back with questions I'm sure.