22-02-2019, 09:45 AM
Only an opinion Ruairidh but I think you are right, C3 are used where there is a risk that thermal expansion will close up the bearing clearance. I don't think this applies to A7's by any stretch of the imagination.
Possible arguments for using one?
Unusually tight fit on the shaft can close up bearing clearance slightly - but in that case you'd do better to rectify the shaft if needed (in the case of A7 rear main I believe a tight fit is a good thing).
Crankshaft whip - more slack in the bearing may accommodate a bit of deflection. But this is loading the rollers the wrong way and doesn't seem a good plan to me.
Or that you simply can't get anything else - in which case I'd use one!
Possible arguments for using one?
Unusually tight fit on the shaft can close up bearing clearance slightly - but in that case you'd do better to rectify the shaft if needed (in the case of A7 rear main I believe a tight fit is a good thing).
Crankshaft whip - more slack in the bearing may accommodate a bit of deflection. But this is loading the rollers the wrong way and doesn't seem a good plan to me.
Or that you simply can't get anything else - in which case I'd use one!