Why a turbo must be balanced
The faster something spins, the greater the centrifugal force created by even a tiny imbalance. In a turbo that force grows with the square of the speed – so an inaccuracy you’d never feel on a road wheel leads to vibration, the typical “siren” whistle and rapid wear of the bearings and seals.
An unbalanced turbo may run for a while, but wear is accelerated, and in the worst case the wheels start rubbing against the housings.
How a turbo is balanced
Balancing is done in two stages. First the individual rotating parts are balanced – the shaft with the turbine wheel, and the compressor wheel. Then the cartridge (centre housing with shaft, bearings and wheels) is assembled and checked and corrected as a whole, because assembly tolerances also affect balance.
Correction is made by very precisely removing material from defined points on the wheels or the shaft nut, without touching the aerodynamic surfaces of the blades.
When balancing is needed
- On every turbo rebuild where bearings, shaft or a wheel are replaced
- When there is whistling, whining or vibration from the turbo area
- After replacing the compressor wheel
- Whenever a turbo has been dismantled, even if the parts look fine
Frequently asked questions
Can a turbo run without balancing?
It can, but not for long. Uneven loading wears the bearings many times faster and the turbo starts whistling and leaking oil.
Is a new cartridge balanced?
Quality new cartridges are balanced at the factory. With cartridges of unknown origin, a check before fitting is recommended.