Here is what I did
I was trying to fix my SC nose seal on my XR7 and I put the pulley back on. When I tightened the nut down I used an impact tool. REAL DUMB!!! I forgot I had it set on high torque and twisted the threaded end right off. Aw, ****!!!!! So what to do now. I ground the end smooth where the threaded part twisted off. I then, very carefully, drilled a hole about 1.50 inches deep in the end of the shaft and tapped it for a 5/16-24 bolt. I then put the pulley back on, put a normal flat washer and a lock washer on the bolt and tightened the bolt. The bolt does not have to be real tight as you know since it only holds the pulley on the shaft. In other words there is no load on the bolt. I ran it like that for 30,000 miles with no problems until I replaced it with a 94 blower.
Hope this helps!
Ed Springer
90 Black XR7 5-speed: 70mm TB, Fresh Air Intake, '94 Supercharger, 5% SC Pulley, Raised SC Top, I/C Fan, UD Pulleys, 190 l/h Fuel Pump, 36# Injectors, Headers, Magnaflow Muffler (no cats) with stock resonators, 3:27 Gears, Ripper Shifter, 73mm CL MAF (Blue Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants and Rear Spring Air Bags.
94 Red SC Auto: 70mm TB, Fresh Air Intake, Stock 90 SC Pulley, Raised SC Top, I/C Fan, Under-drive Pulleys, 190 l/h Fuel Pump, 38# Injectors, Headers, Raven Muffler (no cats) with stock resonators, 3:73 Gears, 76mm CL MAF (Gold Tube), Magnacore Wires, NGK Iridium Plugs, Royal Purple Lubricants, TRANSGO Shift Kit, Pro-Torque 2500 Stall TC, Haydon Auxiliary Transmission Cooler, Tokico Struts & Shocks, American Racing 17” Sniper Wheels, Michelin Pilot Sport A/S Tires and 235 RWHP with 315 LB-FT Torque.