drill size Q's

[383 240z]

I picked up some moroso studs at a swap meet lask week and the knurl size is .560 what size should I drill my hubs to? I figure .010 is a good interference fit but the closest fractional bit is 35/64" or 0.546 sounds good right? Well try and buy this bit every hardware store in the area tells me I'm on crack it does not exist and the can't order it if it did!! what am I to do?? Keith

[Mike C]

I had mine drilled out at a machine shop for $25. I used Moroso studs as well and I think it told you the interference on package? Maybe not, but a call to Summit should net that. From that you can deduce what size bit you need.

[Guest Anonymous]

If you find that drill bit , it may cost $25.00. I was looking for a 37/64ths and it was over $25.00. I recently paid almost $20.00 for a 9/16th Those studs will be super strong and will not be easy too force thru an undersize hole and not good to slop around in an oversize hole. Cheaper to get a machinist to do it with the exact right size

[BLKMGK]

McMaster Car (sp?) and other places like that sell bits liek this. I suggest you get the most expensive one in th ehardest alloy. Trust me on this - the rear flanges are a BITCH! My last set was also done at a machine shop - when I did it myself I was slightly off on one stud and pushing the disc over the studs was a bit of a PITA

[Modern Motorsports Ltd]

Keith, your drill bit will not create a hole precisely it's own diameter so you want to drill it below the intended interference ID. 10 thou doesn't seem that tight but I've left that work to my machinist now for some time as my experience was similar to BLKMGK's when I did it myself. It worked (and I'm still using those) but I will be replacing them with 'machined' ones this spring like the sets I just sent BLKMGK and a few others. As others mentioned, a truly tight interference fit isn't the easiest to pull thru properly and my machinist even made a fixture to help maintain the square alignment when they're pressed in. Only a slight taper over the 3" stud is quite noticeable in rotor/wheel install etc as BLKMGK and I found out.

 

For drill bits I got two standard higher strength jobber bit for $16 tops. One would have lasted easily IF I was using a drill press and appropriate lubricant....the right lube makes it like a hot knife thru butter along with correct drillspeed etc. Assuming you can locate them properly initially which I erred on when I did it myself.

[pparaska]

The other thing to consider, whether just putting in new studs in the OE 4 hole locations, or doing the 5 lug conversion is that the holes must form a near perfect square (4lug) or pentagonal (5 lug) pattern. And that pattern should be centered on the flange so it's concentric to the race parts of the stub axle. And as Ross mentions, the holes should be perpendicular to the flange.

 

Adding all this up, the price of drill bits, the need for a hole in the right place and at the right angle, and the need for a good press fit, I see no reason to not source this whole operation to a machinist.

 

And in light of the failures that can occur with the stub axles, as Eric's post recently points to, it'd be an EXCELLLENT idea to have the bearing removed, the axle magnfluxed, shotpeened, and the weld polished as (was that John Coffey on the 240Z-club list?) said to do. You might end up doing the weld polish yourself once it comes back.

 

Seriously, the price to have this done is small, considering the consequences of the stub breaking. And having the studs all in a nice even concentric pattern doesn't hurt for tire balance, runout, etc.

[383 240z]

Yea I figured I would give it a shot but I finally found a machine shop that would do the job in a timly manner and at a fair price!! thanks for the advice everybody. Keith