Drilling for wheel studs?| Grassroots Motorsports forum |

Saturnguy New Reader
10/21/19 2:19 p.m.

I'm working on a project to swap the wheels on my truck but I've ran into a bit of a problem. I'm drilling a new bolt pattern the wheel hub is hardened steel and the high speed bits just aren't holding up. I got 1 hole done and have 31 more to go. What bit would work best? It's an odd size 15.5mm and needs to last long enough to get the job done. Any ideas?

Jumper K Balls (Trent) PowerDork
10/21/19 2:27 p.m.

I have yet to run into a hub that is undrillable. They can be a really tough alloy though. To much hardening would make them too brittle for their purpose.

Anyway, worst case scenario use one of these but a regular HSS bit should do it at around 450rpm

79rex Reader
10/21/19 7:41 p.m.

how are you trying to drill them? best thing to do to make your drill last is to reduce cutting speed and feed.

KyAllroad (Jeremy) UltimaDork
10/21/19 8:28 p.m.

I'd take it to a machine shop. Let them fight with it and get the holes in the right circle.

newrider3 New Reader
10/21/19 8:53 p.m.

Hand drill or drill press? Correct drill speed is important, but adequate feed pressure is more important. It's a common misconception that you need to reduce your feed rate to be kind to your drill. Especially for a 15.5mm hole, you'll have a tough time getting adequate feed without a drill press or mill.

Some tips and tricks:

https://youtu.be/QhpOg186fks?t=284

Saturnguy New Reader
10/21/19 9:57 p.m.

Drilling by hand. I started by getting a set of wheel adapters then knocking out the studs, drilling all the way through them on a drill press then bolting them to the truck to use as a template/guid

Cooter UltraDork
10/22/19 6:06 a.m.

Drilling horizontally down around knee height by hand is going to make this task nearly impossible.

jimbbski SuperDork
10/22/19 3:02 p.m.

To make a large hole start with a small hole. I usually use a 1/8" drill bit to make the hole, then use the large drill bit to make the hole the correct size.

Also if the 1/8" bit dulls you can sharpen it or just buy a new one as their much cheaper then your large bit.

Saturnguy New Reader
10/22/19 7:29 p.m.

I was having good luck using a step bit till that got destroyed. I might have to wait till next year to continue the project with winter layoff coming up but when I get back to it I'll probably start with new 2wd hubs and get my lowering spindles installed while I'm at it. Hopefully this will finally get me over 25mpgs