GT350/GT350R Rear Differential Drain Plug Size

[D.J. Todd]

Does anyone know what size the drain plug is on a GT350 rear diff? I managed to damage the first couple of threads in the diff housing by cross-threading the plug after draining. I need to buy a tap to clean them up, but I'm not sure what size I need.

 

[D.J. Todd]

3/4"-14 NPT?

 

[TMSBOSS]

Could be. Remove the fitting and take it with you when buying a tap. The clip, purple piece on the left side of the plug in your pic should come out releasing the fitting. Take it with and size it up with pipe fittings at hardware store and put the tap that matches. Put the fitting back together and replace the clip.

 

[JAJ]

Does anyone know what size the drain plug is on a GT350 rear diff? I managed to damage the first couple of threads in the diff housing by cross-threading the plug after draining. I need to buy a tap to clean them up, but I'm not sure what size I need.

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It's 1/2 NPT - I'm sure because I have one sitting on the desk beside me. But what on earth inspired you to take it out in the first place? Take the little purple clip off, slip the fitting out of the barrel and drain the oil. Put it back the same way when the oil is done draining.

 

[D.J. Todd]

@JAJ This was my first time draining the diff fluid in the GT350R, and the YouTube video I watched showed the diff fluid being drained by unscrewing the plug. I've never seen that type of clip before either. The plug is not difficult to unscrew, but the line connected to the plug makes it tricky to realign when you put it back in, hence the cross-threading.

 

[JAJ]

@JAJ This was my first time draining the diff fluid in the GT350R, and the YouTube video I watched showed the diff fluid being drained by unscrewing the plug. I've never seen that type of clip before either. The plug is not difficult to unscrew, but the line connected to the plug makes it tricky to realign when you put it back in, hence the cross-threading.

Ahhh... That's the problem with the internet - it's full of people making videos of how to do things the hard way. In your situation, you might just be able to disassemble the connector (pull the clip, pull the connector apart) and screw the fitting back in straight with a bit of thread sealer on it. The original threads are still there, just damaged, so if you can start with the good ones, you should be able to get the part back in straight and get going again.

UPDATE: My sympathy for the OP is increasing. I was reading a comment from someone on another forum about changing the diff fittings to AN, so I Googled a video on how to change the GT350 diff fluid so I could remind my self whether the hoses were flexible or not. First video I came to showed that the job had been done wrong the previous time, and then the guy making the video demonstrated how he'd done it wrong the last time by doing it wrong again. It's frightening what's out there.

 

[D.J. Todd]

Yes, I was able to clean it up fairly easily with a 1/2"-14 NPT tap. So for you future internet searchers out there, the rear diff drain (and fill) plug thread size is 1/2"-14 NPT.