Richard's ST2 pages - engine mounting bolts

Information on this page last updated 2/16/02.

I replaced my engine mounting bolts with a pair from Nichols Manufacturing. These bolts offer some key advantages over the stock bolts:

• The bolts, nuts, and washers/spacers are designed such that the threads are well outside of the area exposed to shear forces. The stock bolts place the threads (the weakest part of the bolts) right in the shear zone.
• The bolt diameter is ~10.3mm vs. ~9.9mm. This makes the difference between a slightly sloppy fit in the frame lugs and the cases vs. a nice snug fit that should help elimate movement between the engine and the frame.
• There is much more thread mating area between the nuts and bolts.

Their instructions talk about drilling to allow the bolts to fit but I believe this is only required on the SS and monster, not on the ST2/ST4. Mine went in nice and snug with no drilling at all.

But why spend a couple hundred bucks on a couple of fancy bolts? Take a look at the flattened threads and evidence of slippage on the stock bolt in the photo below:

This was at about 12000 miles when I did the swap. I had been religious about torquing the bolts ever few months or so. Still, the bolt shows signs of wear. More than one member of the ST2 owner's mailing list has suffered a failure on the left side of the rear engine mount where the bolt broke and the engine case cracked. I have received emails from others describing similar problems.

Many owners reported that their bolts were loose upon inspection. This leads me to believe that the stock setup is not sufficient to prevent movement in the joint and loosing of the bolt. Not sure which happens first but I would guess the movement is there even when the bolt is tight as mine showed signs of movement and I made sure it was kept at the recommended torque.

If you had a problem with this while the bike was under warranty then I'm sure Ducati would take care of it. But even so, would you want to be stranded somewhere with such a failure? Or without the bike for a potentially long period of time while a dealer orders a new engine case and installs it on you bike? This is not a small job and requires near complete diassembly of the engine and transmission.

If your bike were out of warranty, not sure if this would be covered as a "good will" item or not. I decided not to take that chance, and to spend some money to hopefully avoid the problem in the first place.

If you have already suffered a broken or cracked case and Ducati does not offer to replace it then you might consider consulting a professional welder who does a lot of work with aluminum. One of the mailing list members was able to get his cases repaired this way and I believe it was done without disassembling the engine. A good welder should know whether or not this is possible based on the extent of the break/crack and their ability to weld quick and/or do something to slow down heat transfer into the the rest of the engine.

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