Project Logs

Collapse

• OEM fluid test

  Thomas • 09/20/2020 at 16:56 • 0 comments

  OEM european power steering fluid (15-851OEM)
  

  Appearance: green colored light liquid

  May be similar to CHF 11S. Reported here 11S should be compatible with HNBR/NBR:
  

  https://forums.mercedesclub.org.uk/index.php?threads/abc-valve-block-rebuild-pics-is-this-right.138407/page-2

  SRAM oring tested in fluid:

  • OD swell 20% after 24hrs (10->12mm)
  • Thickness seems unchanged
  • Caliper seal thickness did increase ~10%, enough to make it unusable

  SRAM oring should be EPDM. So maybe 851OEM oil has very similar compatibility to standard mineral oil?
  

  NBR oring:

  • No swell

  VQM (silicone):
  

  • No swell

  https://forums.mtbr.com/brake-time/o-ring-material-question-680609.html

• Synthetic hydraulic fluids

  Thomas • 09/20/2020 at 02:21 • 0 comments

  Various available fluids found online that may be appropriate for hydraulics:
   
  

  Pentosin CHF 11S:

  • Viscosity (40C): 18.7mm2/s
  • Viscosity index: 313
  • SDS indicates 68649-11-6 1-decene dimer hydrotreated (also used as a skin product, grinding oil, etc.)
  • Recommended on MTBR forums many times

  OEM power steering fluid (European):

  • Contains highly-refined mineral oils
  • Made by Recochem Inc code: 15-851OEM
  • SDS has no useful information, other than not hazardous. So maybe does not have major additives?

  OEM power steering fluid (Asian):
  

  • code: 15-891OEM, probably the same as above product

  Prestone European power steering fluid:

  • Stated as alternative to CHF 11s, or CHF202 (which is partial synthetic)
  • Contains "seal conditioners and anti-corrosion additives"
  • Ingredients: different base oil, and a few additives (zinc and anti-wear)

  FEBI hydraulic fluid M6162:

  • Viscosity (40C): 16mm2/s
  • Seems to be mineral based, not synthetic?

  Synthetic DOT3 (eg lucas oil synthetic):

  • Different base oil (9004-74-4), could be more hazardous

  Advantage of synthetic:
  

  • Wider temperature range
  • Maybe more compatible with materials? (seems to not be the case)

  Viscosity index: lower = change more with temperature, higher = change less.
  

  Viscosity: higher = thicker. 

  Kinematic viscosity: how fast fluid is moving when force applied.
  

  Links:

  https://www.pinkbike.com/forum/listcomments/?threadid=140344&pagenum=3
  

  https://forums.mtbr.com/brake-time/mystik-mineral-hydraulic-oil-brakes-1070783.html
  

  https://www.ncbi.nlm.nih.gov/books/NBK304428/ (mineral oils study)
  

• o-ring sizes

  Thomas • 09/17/2020 at 03:42 • 0 comments

  SRAM force 11sp brake caliper:
  

  • 2pc 22.4 x 18 x 2.2mm square cross section (piston seal)
  • 2pc 8mm x 1.2mm (inner seals)
  • 1pc 10mm x 1.0mm (hose arm seal)
  • 1pc 5 x 1mm? (bleed port seal)

  Brake lever:

  • ? piston o-ring seal bottom, top
  • ? cable entry seal bottom, top

  Piston: 17.85mm (aka 18mm)

  Piston seal sources:
  

  • Official seal/piston kit (sram # ..)
  • MYA-018 is close
  • Stack two 1mm or 1.2mm round (not thick enough)
  • Use single ~18 ID x 2.5mm dia round o-ring (not ideal)
  • Ebay: https://www.ebay.ca/ulk/usr/pavlina_kyrychova possibly

  Different size piston available here (26mm OD) labeled as PE: https://www.aliexpress.com/item/4000509364502.html

• o-ring compatibility

  Thomas • 09/17/2020 at 03:36 • 0 comments

  O-rings compatible with:

  Mineral oil:
  

  • NBR (nitrile/buna-n)
  • PTFE, AU, FKM (fluorine green color)
  • VQM silicone (maybe, 10-20% swell)
    

  DOT5.1 brake fluid (DOT3, DOT4):

  • EPDM
  • SBR
  • PTFE, FKM
    

  Synthetic based hydraulic oils:
  

  • EPDM
  • SBR
    

  Source:
  

  • https://www.marcorubber.com/o-ring-chemical-compatibility-chart.htm

  • https://www.parker.com/Literature/O-Ring%20Division%20Literature/ORD%205700.pdf

  Brakes that use:

  • Mineral oil: Shimano, Tektro (Giant),

  • DOT5.1: SRAM

View all 4 project logs