Replacement fill plug for Ford 9"

[Cvcoda]

Does anyone know where to get a replacement fill plug for a 9" housing? I tried the one that JBG offers and it didn't fit. I also tried a Yukon replacement and it didn't work either - I could only get about two threads to screw in. I think I read that the threads on the stock plug are NPT (staggered?).

Anyone know where I can find one that fits???


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[NC-Fordguy]

If you're referring to the stock one which is on the drop-out try the self help section at O'reillys or Advance auto.

I got a replacement from one of those places once years ago, just don't recall which place.

 

[langester]

Do you have access to a wrecking yard? You might try a used plug. You might also try to chase the threads with a tap, maybe they are fouled up somehow.
If you cant find a used one, I think I have an extra housing laying in my shed I could get one from if you are interested.

Good luck!

 

[Broncobowsher]

Stock fill plug on the side of the diff just behind the yoke is ½" NPT. You can even get a brass one from Home Depot or your local Ace hardware store.

Are the threads clean?

Being a tapered fit (that "T" in NPT is for "taper") it does get tight as it goes in. Couple of threads, going in square, that is correct. Snug it down.

Sealer on the threads? This is just like doing any other NPT threads. Today that would mostly be natural gas line and shower heads. Sealer is good if you don't want leaks. Recommend paste over tape. The tape gets real stringy and nasty when you take it back out later.

 

[Cvcoda]

I think the threads are ok because the stock one still goes in without any trouble. The Yukon replacement, which I still have, does look to be tapered but I didn't think it would be that tight of a fit. How much force should I use to screw in? I don't want to ruin the threads on the housing.


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[grant_71]

I think the threads are ok because the stock one still goes in without any trouble. The Yukon replacement, which I still have, does look to be tapered but I didn't think it would be that tight of a fit. How much force should I use to screw in? I don't want to ruin the threads on the housing.


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Snug it up with a wrench. A strong one hand tightening will do the trick.

The stock one is probably a little worn, or undersized compared to the new one. If the Yukon goes in 2 threads and seals, that is fine too.

Because the threads are tapered it never "tightens" in theory, you would just keep tightening until the plug or housing deformed. The taper is what allows it to seal. IF you do chase the threads only do what you need, it is very easy to over tap taper threads and then the plug will never tighten.

 

[B RON CO]

Hi, X2 on what Grant said. Pipe threads, NPT, are wider at the top. Bolt thread are straight from top to bottom and can be chased and cut easily. Even if you have a NPT tap it is easy to over do it. If you don't like or trust the replacement plug I would try a different one before sticking a tap in there. Put the two plugs together thread to thread to see if they match perfectly. Maybe the Yukon is metric thread. Good luck

 

[Cvcoda]

Thanks guys, appreciate the advice. When I compared the two, both threads looked to be exactly the same.


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[Apogee]

There are two common variations of 1/2" NPT, with the Dryseal version having a 3/4" taper per foot and the Flush Seal having a 7/8" taper per foot. I don't know what is commonly used on the 9", but it's something to be aware of.