brake drum retaining screw threads

[hamo]

Hi everyone, I am in the process of rebuilding the brakes on my series 3 109 six cylinder. just wondering what thread the three small drum retaining countersunk screws use. Had to use the welder to get two of them out, and the threads cut into the hub now need cleaning up, but no idea what tap to buy.. (I already have replacement screws..

 

[Shippers]

was doing my hubs on 101 FC today there's only 2 screws the third hole is to help shift drum by using a screw to force against hub...have you run a screw through drum while it's off to clear threads?

 

[hamo]

thanks shippers, I think the forward control must be different, my 109 pickup has three screw holes in the drum and hub on each wheel, the screws go through the countersunk holes in the drum and into the threaded holes in the hub- to hold the drum to the hub. obviously the drum cant come off because it is clamped on by the wheel, but they must be there for a reason.. i will check they arent just gunged up, but im pretty sure the threads have been mangled by various bodge diy jobs, and they need to be re tapped, im guessing its a UNC thread or something...

 

[Edlandy]

Don't loose too much sleep over them, can be used without, drums not going anywhere with the wheel on