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Anders Nilsson
New User
Username: nilssan

Post Number: 8
Registered: 04-2013
Posted on Thursday, 23 December, 2021 - 21:25:   Edit PostDelete PostView Post/Check IP

I am in the process of restoring the engine of my 1981 Rolls-Royce Corniche (SCAYD42A0BCX03353). I have purchased a NOS crankshaft, and now comes the question from the machine shop about the process of balancing it.
Consulting the SZ Workshop manual TSD4400, section E5, it says “The crankcase has integral balance weights and is dynamically balanced before it is fitted to the engine. When the engine is partially built the crankshaft, connecting rods, and pistons are dynamically balanced in the crankcase.”. Is it then correctly understood that there is no need to balance the crankshaft itself before the assembly into the engine?
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Cliff Biggs
New User
Username: cliffy

Post Number: 17
Registered: 09-2021
Posted on Friday, 24 December, 2021 - 02:50:   Edit PostDelete PostView Post/Check IP

From previous engine experience I would think that if the rotating mass (crank, rods pistons etc) were balanced in complete assembly form (dynamic balance) in the crank case that changing any one of them would throw the rotating balance out from what it was. To just rebalance the crank would not account for the other pieces in the rotating mass that were balanced as an assembly originally.
A conundrum to what to do now.
One could balance the crank and then balance the pistons to the same mass and then do each end of each connecting rod and then assemble the engine

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