Hot Rods Redrilling Buick Drums for different bolt pattern

Good Morning Hamb'ers

I have a quick question and looking to learn from the experiences of others here:

For my upcoming project, i will have to redrill Buick Drums and Hubs from a 5x5 paatern down to a 5x4.5 pattern.

My question is are Buick Drum hub-centric, or lug-centric? I ask because i'd like to know if i should use the center hub opening as reference to redrill the holes, or can i use the lug as a reference?

If others want to shed light on how they redrilled to different bolt patterns, i'm all ears.

Adrian

 

When my friend and I clamped my Buick drums in his CNC mill to redrill the pattern we centered on the center hole. I can’t understand why Buick would make the center hole a different reference than the lug holes.

 

i guess that makes sense as when drums are cut on a brake lathe, they are centered on the center opening, not the lugs.