Installing a second zerk in steering knuckle.

[pszikszai]

I am in the process of rebuilding the front end of my current project.
I am going to add a second zerk in the steering knuckle at the bushing location.
The zerk will be the same size as the one already in the knuckle.
Does anyone know what size hole I need to drill and what size tap.
Usually charts give you the number sized drills, which mean nothing to me since I never worked in any kind of shop.Thanks
Paul

[Tom Bredehoft]

I have two grease zerks in hand. One is 10 - 24 diameter (.245 OD) Just under 1/4 inch. The tap drill for this is .150, very close to 5/32. The other is 1/4 - 27, tap drill is .339, just under 11/32. I would imagine a FLAPS would have both drills and taps. If you've not tapped before, use oil on the tap and turn it in 1/2 turn, back out 1/4, and repeat. This will break the chips and let them fall out of the way, rather than jamming in the flutes of the tap. Clean the finished hole as if your bushing depended on it.

When discussing taps with the salesman be sure you show him the zerk you want to screw into the hole. There are major differences in taps.

If Studebaker had thought the bushing needed a grease fitting, they would have put one there. But, its your car.

[img=left]http://www.alink.com/personal/tbredehoft/Avatar1.jpg[/img=left]
Tom Bredehoft
'53 Commander Coupe (since 1959)
'55 President (6H Y6) State Sedan
(Under Construction 540 hrs.)
'05 Legacy Ltd Wagon
All Indiana built cars

[Neal in NM]

The two most common (small) size zerk fittings are 1/4-28 and 1/8-27 pipe. The tap drill size for the 1/4 is #3, and the 1/8 pipe is a letter R. Most of the grease fittings I have run into on my Stude truck are 1/8 pipe. Neal

[JimmieD]

Another trick is to lube both the drill & tap with grease. Where you're going into a hole that you don't want to contaminate with chips the grease holds them to the flutes of drill or tap. You can drill down to close to end, drilling very slowly, remove drill & clean, new grease, finish hole. Same with tap, taking it down close to the depth and then backing out & cleaning tap & reapply fresh grease to finish.

BTW: zerk fittings are invariably near junk metal so a very minimum of torque should be used to tighten, just enough to prevent leakage. That's surprisingly light pressure and exceeding it can cause a bad day with a broken zerk that now needs to be extracted & replaced!