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JFairman JFairman is offline
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Join Date: Jul 2006
Location: S. Florida
Posts: 7,289
The turbine wheel and shaft are one piece in a Borg Warner turbo and they probably are in a Garret too. The compressor wheel is held on the shaft with a nut and gets removed so you can take the rest of it apart.

The "nut" on the turbine wheel with the grinding marks is there for high speed balancing.
The"nut" is magnetized in a VSR turbo balancing machine and an electronic pickup is swung over and placed around it and the turbo is spun up to speeds between 100,000 ~ 200,000 rpms using air pressure.

Any imbalance of the turbo cartridge assembly will cause a high frequency vibration at those speeds that the pickup reads and sends to a computer. Then the turbo is stopped and the LCD monitor on the VSR balancing machine computer display will point to where the "nut" needs metal ground off to balance the cartridge assembly.

That process is repeated until the turbo is perfectly balanced so it can end up with a bunch of different grinding marks depending on the balancing machine used and operator skill.

According to Durabilt Turbo in Illinois there are only 3 VSR high speed turbo balancing machines in the USA and they have one of them. They are made in Europe, very expensive, and you can google it to learn more and watch you tube videos of one in use. or you can just assume everything and spend your money blindly on friendly hearsay like most people do.
Old 08-18-2011, 02:07 PM
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