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TR6 Replacing Trans Fill Plug with Hex Head - NPTF or BSPT threads

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PGSberg

PGSberg

Freshman Member
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'75 TR6 - Have a stubborn Trans Fill Plug. Ends are buggered a bit. Will file. Ordering a 7/16th 8point socket. My plan once I get the Transmission fill plug out is to replace it with a Hex Head. Which threading is correct for my application? Not wanting to assume. Teflon tape OK?
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NPTF (National Pipe Taper Fuel) and BSPT (British Standard Pipe Taper) threads differ in several ways, including:

Thread form - NPTF threads have a Unified thread form, while BSPT threads have a Whitworth thread form. Whitworth threads have rounded peaks and valleys, while NPTF threads have flat peaks and valleys.

Thread angle - NPTF threads have a 60° thread angle, while BSPT threads have a 55° thread angle.

Taper - Both NPTF and NPT threads have a taper of 3/4" per foot.

Sealant - NPTF threads provide a leakproof mechanical seal without the need for a sealant, while NPT threads require a sealant to ensure a leakproof seal.

Usage - NPTF threads are commonly used in plumbing applications, while BSPT threads are widely used in applications involving fluid and gas connections, such as plumbing, hydraulics, and pneumatic systems.

Region - NPT threads are common in the United States and a few other countries, while BSP threads are widely used in many other countries.
 
IIRC, NPT and BSPT have a different number of threads per inch - so you'll want to get the correct thread pitch for your application.
 
groupdeville said:
IIRC, NPT and BSPT have a different number of threads per inch - so you'll want to get the correct thread pitch for your application.
Click to expand...
That is what I was trying to get from this post. LOL. Hoping a expert would be able to tell be witch to buy, NPT or NSPT.
 
No expert here, but it is 3/8" NPT. I replaced the original square headed one with a brass plug that has a hex head. Also, I cut an access hole in the tunnel cover to be able to check the oil level without crawling under the car.
Berry
 
titanic said:
No expert here, but it is 3/8" NPT. I replaced the original square headed one with a brass plug that has a hex head. Also, I cut an access hole in the tunnel cover to be able to check the oil level without crawling under the car.
Berry
Click to expand...
Thanks for the reply. My research looks to be the same as your input, NPT. I ordered a 3" rubber hole plug. Luckily I have a 3" hole saw that should cut the hole in the tunnel.
 
I also made a flap in the carpet over the access hole and bound the edges. I guess I am paranoid about checking the trans. oil level as my OD insists on leaking.
Berry
 
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