Rear brake drum

[lrcormier]

Just dug out my rear brake stuff to see what will be needed to complete and install (again old project Ive had for 38 years). Although the rear drum is new it appears that it was manufactured by lefco and the lug holes are not threaded. Not sure if this was common practice with these aftermarket brake drums, the hole diameter is aprox 5/16, I do need to purchase new lugs, does this hole size sound right for standard size lugs and what thread tap would I need? Anyone else ever use one of these drums, not sure if lefco even still makes them?

[Rubone]

The factory lugs are a special thread, 3/8-20. Taps are available.

[lrcormier]

Rubone, I did find a thread on the PANHEAD AND FLATHEAD SITE where somebody stated that the correct thread is 3/8-20 BSF, can you or anyone verify?

[lrcormier]

Just re-read that thread and now I'm confused as to what tap I need, do I need 3/8-2- BSF or 3/8-20 NS?

[Rubone]

BSF is British Standard Fine. The Thread pitch angle is different than US threads 55 degree versus 60 degree. The NS is a National Special thread, same pitch angle as all other US threads Just a non-standard number of threads per inch. H-D used lots of special bolts, such as Flathead and Knucklehead head bolts (7/16-16), many screws and small bolts (1/4-24), etc. No BSF screws or bolts anywhere on an H-D.

[lrcormier]

Thanks Robbie, I'm on the hunt for a 3/8-20 NS TAP.

[ammorest]

I recommend McMaster Carr Industrial Supply. They have them in taper, plug, and bottoming. $30.00 each. Good products and good service. Their nearest facility to you is in LA. Check out their website.
Dave

[exeric]

I agree with Dave about McMaster Carr. I buy all my taps, and particularly odd-ball taps from them. You'll find their catalog is one of the most extensive you'll ever see.

[larry]

I recently installed a Lefco drum. I had to throw it away. I seldom throw anything away.

[lrcormier]

Larry, what was the issue you had with the LEFCO drum. Mine would of been purchased in 1982 and other then the lug holes not being tapped it appears to be a good hub.

[lrcormier]

I looked on MCMASTERS web for 3/8-20 NS and all i could find is 3/8"-20 1 1/4" 2 15/16" 8.2 mm 0.3228" 4 UNS H3 Square 2595A192 $30.00. Is a UNS Tap the same as a NS Tap?

[larry]

My drum was soft and the shoes stuck and chattered. Harley drums are tempered.