Torque specs questioned for front suspension mount
 

I am replacing my front suspension guide rod mounts on my 300sdl. As I was torquing the rear bolt, # 134 in the picture attached, to the indicated 80 nm, I felt the torque suddely lighten up with this empty feeling in my stomach. As much as I hated to take it all apart again to see what was going on, I did and what happened is that the aluminum insert inside the large bushing cracked where the bolt goes through.

Did I miss identify the torque spec? 80 nm seemed quite high for this sized bolt but not that unusual. As a comment, it took probably over 120nm to loosen the bolt iinitially.

Ideas?

I haven't done much suspension work so I can't help you there, but this is exactly why I don't use a torque wrench. I'd rather use my feel and use torque values only as a guidance, or if none is given, I just use common sense.

Most likely it was the part Labeled 137 that failed they are not made very well 80NM is the correct torque

Part 137 in aftermarket are crap from my experience. Threads are off and weaker than OEM.