Hello,
I am currently working on a 1976 Mercedes 240d. The other day while driving a horrific grinding noise developed in the passenger rear wheel, which I quickly identified as a compromised bearing. It was difficult to research, but I removed the half-shaft and acquired the tool designed to remove the grooved nut on the inside of the wheel on the hub assembly. However, no amount of force, no matter how insane, can seem to get this nut to budge. I spent $80 on the tool and it seemed robust, but after using a 48'' breaker bar I began to bend the prongs on the tool itself, and yet the grooved nut has not budged. I do not know the repair history on this vehicle, but after looking at the exploded view of the hub assembly I cannot see any locknuts or tabs that I should be addressing. Perhaps someone has done this procedure before and knows something that I do not. I am going to attempt the use of a high impact drill, and if that doesn't work I will have to find a new or used semi-trailing arm with a good hub assembly in it. Thank you in advance for any wisdom you may have in either endeavor.