Broken Lower Rear Shock Bolt

[cannondale27]

These bolts break because they are over torqued and then the stress of shock shears off the stretched bolt.Slot isnt a perfect fit for shock so when you tighten it enough to keep slop out stresses old little bolt too much.Just use bigger bolt.

[Canniboomer]

Yep the larger bolt also has finer pitch threads, 12x1.25 instead of the coarse 10x1.5mm on the earlier bolt. I have the 4-pcs OEM update; a 12mm shockbolt, 2 larger ID Ohlins bushings, and the fine-pitch flangenut, for $20 if you need, very convenient and fast. You can use a 15/32" bit to ream out for the 12mm bolt in the swingarm flange (it's snug, but a great fit). If you want to try and also drill out your 10mm bushings, the bolt/nut combo is $7...but it's difficult to hold those bushings and get a smoothly reamed hole without some damage... it's really better to save the old ones for 10mm spares at the top or front, and just buy the pricey 12mm bushings.

The installations from the factory did not use washers under the 12mm bolthead or flangenut, but the 10mm bolts got 2 washers per the parts manual at least -- I could see where omitting a washer or 2 could cause that bottoming out that kdeal mentioned. A single washer could be added to the 12mm bolt also, at the nut, and might be a good idea.