Evo and Ralliart SST transmission wear and maintenance

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Whiteline have carried out some more laboratory analysis on the stock Diaqueen SST-F fluid today. The fluid sample was an interesting one because:

  • This sample is from a Ralliart Lancer
  • As a rule these cars load the transmission less hence wear should be lower
  • This car had been used on the track
  • Sample had completed around 50 laps
  • In total this sample had covered just on 6000km (not very far)

We test the fluid using a Filtegram procedure, which has a fluid sample put under a high powered microscope in controlled industry standard conditions, so that each and every contaminent in the fluid can be uniquely identified, and the source of the wear determined. The photograph that follows is directly from the microscope slide zoomed in at 500x magnification:

SST fluid sample - note the gold pieces

While this might not mean much to the casual observer, this sample follows the trends we are seeing in hard driven SST transmission vehicles - whether they be an Evo or a Ralliart. The points of concern as the gold pieces you see, as they are of considerable size (5 - 7 micron range) and are created by pure metal/metal contact in the transmission. We call them '3-body-fatigue wear particles' and they are created when the thin hydrodynamic film (oil film) between the gear faces breaks down with the resulting heat and friction tearing these fragments of metal away. The transmission filter did not catch these pieces.

Now, this wear isnt at a critical stage in the transmission at this point, however after the test distance of approx 6000km there needs to be a fluid change to avoid the metal thats already in the transmission transferring through the system and creating more.
 Our engineers live by the motto that one piece of metal in the transmission makes 10 makes 1000 makes a million. Once wear metal is present you must flush it out to avoid accelerated wear.

The testing method shows that SST transmission wear can be slowed down, by more frequent SST fluid oil changes (we would suggest approx 5000km - 8000km if using the factory fluid) or a higher grade lubricant with greater film strength (ie. WR35TMX). Regardless, the SST transmission isnt a 'set and forget' part free of service requirement, it needs to be considered as part of the overall vehicle maintenance plan.

If you own an Evolution X or Ralliart with SST transmission, make sure you change the transmission fluid regularly.