Have a 1/2" hole, what pipe thread size

[asand1]

Helping a friend rebuild an NV3500 in his 5.2L Dakota. We want to replace the shift rail detent plug with a tapered pipe plug rather than the interference fit one. The bore is 1/2" and I would like to know what size pipe tap would work without any more drilling/reaming?

This is the second time the trans has been apart and we are worried about it popping out on the road or the difficulty of future removals.

 

[resist]

Originally Posted By: asand1
Helping a friend rebuild an NV3500 in his 5.2L Dakota. We want to replace the shift rail detent plug with a tapered pipe plug rather than the interference fit one. The bore is 1/2" and I would like to know what size pipe tap would work without any more drilling/reaming?

This is the second time the trans has been apart and we are worried about it popping out on the road or the difficulty of future removals.


Oh that is a great upgrade. Those darned things are always falling out or getting stuck.

 

[LEADED]

9/16 -12 standard thread , drill size .508 hole . If you need fine tread you can upgrade good luck

 

[Trav]

This will do the job, they sell it with the drill bit below. The hole needs to be opened up slightly to 37/64 so its not a large increase from 1/2". This will give you 3/8 tapered NPT threads for a 3/8 tapered pipe plug.
Not top shelf quality but for a couple of holes its good enough.


https://www.amazon.com/Hanson-1904-HANSON-Tap/dp/B000UE1VCM/ref=sr_1_3?ie=UTF8&qid=1513946764&sr=8-3&keywords=3%2F8+tap+npt

 

[Linctex]

Originally Posted By: Trav
The hole needs to be opened up slightly to 37/64 so its not a large increase from 1/2". This will give you 3/8 tapered NPT threads for a 3/8 tapered pipe plug.


Yes, exactly what is needed!