they cracked because they are cast aluminum and very brittle. if the hub face is even remotely imperfect , they will eventually crack. when i returned them , i was told that they get a lot of them back and they instantly gave me my money back. they were torqued to 80 lbs, exactly what was on the sheet. i went and bought some 1" thick ,billet adapters , 4" to 4 1/2 off ebay for 69.00 a pair shipped. i ran those for over 2 years on the front and back. i trust those with my life. the billet aluminum is much stronger and wont crack. im not trying to worry you, just sharing my adapter experience. ive ran a lot of these over the years, and the cast aluminums should be discontinued in my opinion
