vee12

Just a cautionary note for those considering this upgrade. I "upgraded" my idler pulleys to Speedriven's billet set at 63K miles on my V12TT for no other reason than I thought they looked cool and the serpentine belt need to be replaced...while you're in there what the hell. The factory pulleys were still running fine. Yesterday at 82K miles the lower Speedriven pulley failed and locked up completely. Fortunately, I caught it before it sawed completely through the belt and left me stranded. Upon examination, the bearings in both billet pulleys were shot...one completely locked up, the other crunchy and stiff to turn. So, I got over 60K miles out of the factory pulleys (which were not bad at the time of replacement) and 19K miles out of the Speedriven part....and another $455.00 to preform the belt/pulley service back to Benz parts. Not trying to bash Speedriven here...just relaying my personal real world experience with these parts. Now I could have just replaced the bearings in the billet pulleys...but still...19K miles? No thanks.

NRL

Thanks for the heads up.

I put in OEM Mercedes pulleys a few months back at 89kmiles.. One of the pulleys was starting to go bad but not completely gone.
Definitely needed a new belt.