rear wheel studs and brake rotors

[neilkuy]

I have a donor IRS from a 2018 GT. I used the diff out of it and have bought new hubs. I pressed out the studs from the rear hubs as directed and replaced with the supplied 1/2 studs. These 1/2 studs have a smaller diameter than the original that were on the 2018 hubs. My concern is when I put the rotor on it has a fair bit of play - as would be expected with a smaller diameter stud. lots of people have noted that these studs are plenty strong for the forces they will see, however is there not a concern about oversized holes in the rotor allowing the rotor to rotationally slip during hard braking.
Note, as mentioned my setup is a donor IRS from a 2018 GT. The manual has me using the rotors and calipers from the donor - I was planning to buy fresh ones but I am uncertain what rotors I should be getting - 2018 (which fits the IRS setup but with oversized holes for the new wheel studs) or 2004 (which fits the lug size but may have issues elsewhere).

any help is appreciated.

Thanks
Neil

[Alphamacaroon]

My thought would be that it's unlikely that the rotors would slip— there is a huge amount of clamping force over a large surface area if the lug nuts are properly torqued. And even if they did slip, it'd be a one and done type of thing— unless you ride the brakes while accelerating, there would be no reason for them to reset back and forth.

That being said, I'd worry more about the rotor not being perfectly centered and potentially being unbalanced, or worse, coming in contact with the bridge of the caliper. If you're worried about it, in the scheme of things a new set of rotors isn't the worst-case scenario— I'd just buy a properly sized set.

[edwardb]

Don't know about your OE rotors. But Wilwoods I've used are hub-centric. So don't depend on the studs for centering. Maybe yours are the same? Plus as already mentioned, the clamping force of five lug nuts at 85+ foot pounds isn't going to allow the rotors to rotate.

[neilkuy]

Thanks for the response. What you say makes sense, what is the properly sized set?
I thought the ‘15 to ‘23 rear brakes are the ones intended.

[neilkuy]

Confirmed, they are hub centric. I am sure then these are fine.
Thanks for the input.

[Alphamacaroon]

Confirmed, they are hub centric. I am sure then these are fine.
Thanks for the input.

Agreed— you are good to go.