I was just going to replace the upper ball joints on a new chassis I'm building for a 1972 Buick GS and ran into a little minor issue that got me thinking. The original rivets that came out were 1/4" and the new ball joint bolts are 5/16" So I thought I would check some other 72 buicks and I have some with 1/4" bolts and 5/16" Bolts but don't ever remember drilling the larger? I was using AC delco ball joints part number 88911380 Anyone ran into this?
Should be 1/4 -28, I've never had any ball joints come with 5/16, can't even see that being possible the nut fits super close to the metal boot retainer as it is
Same thing being talked about in this Thread: http://www.v8buick.com/showthread.php?189626-Upper-Ball-Joint-bolts
I have had replacement ball joints that came with 5/16 bolts. When replacing a riveted joint with a threaded fastener, it's common to move to the next size up. However, it this case I think you'll be fine with 1/4-28.
