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71GMC_3/4T · 09-14-2002, 11:50 AM

Randy,
The Helicoil tap is special. The drill size is listed on the tap, usually. You should be able to pick up a helicoil set for 3/8-16 from a local hardware or autoparts store. Try to get 1 1/2 D helicoils. They length is sized by diameters, hence the D.
Make sure you run the tap in straight and don't wobble. I assume you're doing a tranny tailshaft? I found it easiest to use the electric drill to run the tap in and back out slowly. Use WD-40 for cutting fluid in the aluminum.
If you can't find a tap, let me know. I have one laying around somewhere in my toolbox, with helicoils I could loan you.

09-14-2002, 11:50 AM	#2
71GMC_3/4T Weapons Of Construction Join Date: Apr 2000 Location: Colorado, USA Posts: 1,095	Randy, The Helicoil tap is special. The drill size is listed on the tap, usually. You should be able to pick up a helicoil set for 3/8-16 from a local hardware or autoparts store. Try to get 1 1/2 D helicoils. They length is sized by diameters, hence the D. Make sure you run the tap in straight and don't wobble. I assume you're doing a tranny tailshaft? I found it easiest to use the electric drill to run the tap in and back out slowly. Use WD-40 for cutting fluid in the aluminum. If you can't find a tap, let me know. I have one laying around somewhere in my toolbox, with helicoils I could loan you. __________________ 1971 GMC 2500, 402/TH400 4.10 Daily Driver Lafayette, CO