offduty

When switching from the 6.5 pads and going to the 4" pads on the Porter Cable do you need to change the counter weight. I tried a 4" backing plate with the orig weight and it hobbled all over. If so what weight do I use and where can you get one from. Thanks for any advise

Starting to show my age here. 1st car was a 1965 chevrolet Covair. Had to save up the $50 bucks to buy her but it did the job untill I bought my 1st Mustang. 1969 Mustang mach 1 428 cobra jet for $800. If I new then what I know now I would still have her and a asset of around $100,000.00