Hello Currently rebuilding my 2006 999 engine due to a failed LHS main bearing. Ducati specify a bearing pre-load of 0.3mm. This preload figure of 0.3mm appears in a number of ducati workshop manuals across a range of different models. (An exception being the 999R manual which states 1.5mm) There is some discussion on the web which suggests this preload figure is too high and contributes to early main bearing failure. My question is…….. should i accept that Ducati know what they are doing and rebuild to the 0.3mm figure…….. or should i accept internet wisdom and reduce the preload to a lesser figure? i welcome your own experience/opinions regards chris
I use less when I do an engine. 0.15mm, too tight and the balls don't turn but skid on the race. Ducati did specify a figure for wobble on the crank end which shows the amount of preload applied which bends the crank
Thanks for that. Interesting regarding the skidding balls. Can you give me some idea of just how common is this type of bearing failure? Are there plenty of 999s out there with cranks loaded to .3mm that don’t experience these problems? The internet tends to highlight failures as opposed to those bikes that have a trouble free life. Regards. Chris
I would guess from new the engines were preloaded to the original spec, there is plenty of info around about preloading. I had two sets of mains go exactly as your picture with original preload, then nothing after I changed the loading. Bearings were correct angle thrusts from ducati.
Thanks for your reply. My calculations show that i need a 2.1mm & a 2.2mm crank shim to reduce the preload down to 0.15mm. Can you recommend the best place to get these or perhaps somebody on here may have these in their own spares stash? Regards Chris
