Originally Posted by
frewster
It's definitely possible for the collet to put too much preload on that inner race. I had it happen when I was replacing the front bearing on my B6. I thought it was fully seated, but when I tightened down the clutch but I could feel crunch in the bearings. Had to tear it down, heat up the area around the bearing, and tap it into place in order to be able to tighten the clutch nut without causing problems.
Originally Posted by
timjs
Gahh... dragging me back in.
That's only if the bearings are not fully seated into the crankcase. I would say your experience wasn't typical. The distance between bearing races has clearance designed into the dimensions of the crankcase. If you had to tap in the bearing further, it wasn't assembled correctly in the first place so I don't think you can use that as an example of a collet applying bearing preload!
Yes the clearance is designed in, on our engines it's 0.1mm like I mentioned. So assuming everything again is perfect, no problem. Have something out of whack though and you do, just like he mentioned in the example above. Use the method that I mentioned and it completely removes any chance of ever loading the bearings but most importantly ensures every single time that you assemble an engine/clutch that the crankshaft is all the way forward when it is locked into position by the users placement of the collet so that the crank pin is not dragging on the back plate. It's how I was taught to do it running 1/8th on-road back in the 90's and it's the same way that I've seen all of the Italian engine guys that I've worked with over the years put together their engines/clutches for drivers and/or testing. Do you have to do it this way, no. It's just an easy way of doing it but if you have a better system that works for you feel free to use it.