How has the GT15-25 Thrust Bearing Design Evolved?
In the beginning, there were two main types of GT15-25 turbo, those with a sintered steel 270° thrust bearing and those with a 360° stamped brass alloy thrust bearing.
- Sintered Steel
- Copper impregnated
- Used mid 90’s-2003
- Stamped brass alloy
- Used until 2002-2006
- Small thrust pads
Melett’s replacement for both of these bearings is 1102-015-324
Original 6 pad design
Original 10 pad design
Newer large pad design more resistant wear and thrust force
- Garrett are unable to make any changes due to Homologation
- Melett only use the latest design in all CHRA
- Hot forged design – not sintered!
In 2003-2005 Garrett moved to using a hot forging process to improve accuracy in manufacture (Hot forging produces a more robust blank by re-forming the grain in the material into the finished shape and also allows the use of a high strength alloy). A harder material with silicon, which acted like a non-stick surface, was then used and they also altered the thrust pad designs for different run-up requirements.
Melett uses the 1102-015-324 thrust bearing in all GT15-25 core assemblies
There are several more features on the thrust bearing which are important to the operation and life of the turbo, these include: oil pockets, size and finish and even what appear to be scratches on the surface on the GT15-25. These are actually designed into the product to increase the surface retention of oil, which will hold the oil on the thrust bearing for longer. This helps reduce wear on cold start-ups.