taken this from a garret agents site....
Turbo Balancing
We are frequently asked by customers who purchase our rebuild kits if the turbo will need to be rebalanced after they complete the rebuild. You will not need to have your turbo rebalanced if the following applies:
- Neither of the wheels (compressor and/or turbine) have touched or rubbed the housings
- There are no worn, chipped, or bent fins on either of the wheels
- You were careful to mark the position of the wheels in relationship to each other prior to disassembly and rebuilding, and then realigned these marks upon reassembly